Garage Build Thread

[RaYzerman]

Gas fired infrared heat (tube heater) is the way to go in a shop if open concept. Cheap to operate, floor is never cold, no open flame to ignite any solvent, gasoline fumes or dust. Love mine. I have a 24 x 40 with 10' high ceilings, walls are R23, ceiling R50, several windows, slab on grade. The heater is a 20' tube, 40,000 BTU and doesn't need to be any more if insulated well. An experienced heating contractor said it's better they aren't too big and have more run time, thus more even heat.

 

[Upt' North]

I built a "workshop" last year. It have been planned for a long long time but I did not have the time to make it work. It uses something called socket systems which is no longer in business. The size is 45' x 24'. What I like about it most is the interior height is about 14' which means I can lift a 4 x 8 sheet of plywood or whatever and not worry about hitting the ceiling. The support members (6x6 ports) are assembled on the ground and then lifted in place in a "socket"

I have a "garage" the same size up near the house. This building is located about 100 yards from the house and house my MF 1250 tractor and various woodworking and welding equipment and some lumber storage to allow treated wood to dry out before use.

Nice job sir. I need to move house!
Upt'North.

 

[sennister]

Gas fired infrared heat (tube heater) is the way to go in a shop if open concept. Cheap to operate, floor is never cold, no open flame to ignite any solvent, gasoline fumes or dust. Love mine. I have a 24 x 40 with 10' high ceilings, walls are R23, ceiling R50, several windows, slab on grade. The heater is a 20' tube, 40,000 BTU and doesn't need to be any more if insulated well. An experienced heating contractor said it's better they aren't too big and have more run time, thus more even heat.

They do work well. The only experience I have with them is as I mentioned in the Army but I have no idea what they cost to run. In that case where they heat the hangers 24x7, big open space like you mentioned and retrofit of an in-floor system isn't practical it is an easy decision. If new construction or if the slab is coming up I don't know which way is a better solution.

I have a buddy that had the IR system in his shop but took it out. He was selling it so I could have gotten it pretty cheap for the pole barn but I didn't. My pole barn has 12' ceilings and I have NG to fire it. However like I said I am not out there all the time. I think like with in floor it takes time to warm things though I guess if it is running it would warm you. Though you wouldn't feel it if you were in a cold shop and crawled under a vehicle.

The only reason he took it out is that he has quite a bit of land. They split some of the property so his son built a new house next to his parents. They then built another pole barn and put up one of those outdoor wood boilers which heat all 4 buildings. Between the two of them there is pretty much always someone home to keep the fire going so that was cheaper than any NG solution. They also had a wood source.

I think the one concern I would have is if you have any issues if you add a car hoist. It isn't like the hoist is going to move around and you could probably position the IR heat tubes to have enough separation. I would hate to bake the paint but maybe they don't have that issue. I didn't look into it enough as I passed on the deal. I did think about it and there were times I wish I did it.

That is a good point about sizing a system. I didn't size the boiler for the new garage. Best to leave that to the pros. There are lots of calculations that they have to do based on room size, ceiling height, insulation values and such to determine the proper size boiler or IR heat pipe. Bigger isn't always better.

 

[Andrew Shadow]

Dave:

Thanks for all of the information- I do appreciate the time it took you to write it out. It sounds like you have done a bunch of research.

In my case there is no car parked in there so no large frozen mass coming in to cool the garage off. I use the garage primarily for my motorcycle and as a workshop for things that are to messy or smelly to work on in my basement workshop. It is also a small area- 12' X 21'. I want to heat it so I can work on the bike and whatever else in the winter. Our winters are way to cold to work in an unheated garage so I get stuck doing my bike maintenance during riding season which I am not happy about at all. For the most part in the winter the garage door gets opened to get the snowblower in and out.

The ground under the concrete floor has sunken and the concrete is beginning to break everywhere. I will be ripping it up, laying down insulation and pouring a new concrete floor.
I don't have natural gas on my street, I don't want a big propane tank hanging around, I don't already have hot water heat that I could pipe out there, I don't have room to install a forced air furnace in there and a city ban against wood burning appliances took effect last fall due to smog. That leaves me with electricity. I imagine that I would keep the garage heated at a low level and only bump it up when I plan to be in there working. For that reason, and because I want the air conditioning in our hot humid summers, I already know that my main source of heat will be a heat pump installed in there. My neighbor is an air conditioning contractor and he is going to take care of the heat pump for me at hopefully a neighbour's discount price. My only thought was whether or not I should add in-floor heat at the same time becaue I keep hearing about how wonderful it is when you in there working. I haven't looked in to it enough to know whether or not it is worth it in my case.

I also need to figure out if I will need some other source of heat to supplement the heat pump when it is minus 25 outside because I don't know how cold it can get before a modern heat pump can no longer extract enough heat out of the air to heat the building. My neighbour told me that there are heat pumps on the market now that are rated to minus 30 so maybe I don't need a secondary heat source at all.

I also gave some thought to those companies that pump foam under a sunken concrete slab to raise it back up. You then just float a new surface over the existing concrete to smooth it out. That option is definitely a lot less work but I don't know how much insulation value it would provide. It also would not allow me to insulate the side wall like I could when the floor is torn up.

Thank you for that link- I will going there to do some research.

Andrew

 

[SMSW]

I also need to figure out if I will need some other source of heat to supplement the heat pump when it is minus 25 outside because I don't know how cold it can get before a modern heat pump can no longer extract enough heat out of the air to heat the building. My neighbour told me that there are heat pumps on the market now that are rated to minus 30 so maybe I don't need a secondary heat source at all.

Andrew, I've installed electric floor heat in a number of bathrooms in the tile floor. These systems are not meant for environmental heat, but only to warm a floor because they typically do not have a heavy plastic insulation and are fairly light gauge wire (heat output is relatively low). Raychem (Tycho Thermal once upon a time, now Pentair) makes the cables used to melt ice in outdoor settings and for floor heat. The cables are beefy and interesting to work with (read they are a pita to work with). If you want to talk to me, let me know and maybe we can set up a time to talk over the phone.

A great person to talk to would be Kim Erwin, she was a national project manager for their ice melting roof cables and has worked for Raychem for something like 30 years. She was wonderful to work with whenever I had a question. I'd call her cold and ask who to talk to about their products for slab floor heating. She is difficult to reach but very responsive. Alternatively, call Raychem's tech support line and ask them for a link to their website describing products that would be applicable to your project. An old phone number that I have for their tech support would be 800 542-8936 (it might have changed). If you want to talk further, email me.
Peter

 

[RaYzerman]

My tube heater runs on propane, yes I have a big tank out there but don't notice it any more... wish I had NG here, but.... put up a screen, plant some shrubs... I keep the temp at 10C (50F) and bump it up to 15C (60F) when I go out there. It doesn't take long to warm things up at all. Not sure if you can relate because I don't know what you pay for propane, but if I spend C$500 for a season, it means I was out there a lot. BTW, the infared 40k BTU unit was C$1000, paid C$300 or so for gas line install and leak test and B-vent ducting. Has to be done by licenced gas fitter otherwise your gas guy won't hook up. Heater itself is way easy to install yourself. If you need tips, just ask.
As far as insulating a slab, certainly insulate the perimeter, with rigid foam R20 down at least 2 feet. Your choice on the interior... if using hot water or electric I'd insulate it as well. Build your slab on crushed stone and put a vapour barrier on top of that before your pour.
As for heat pumps, not an expert but a little experience... air to air are good to about freezing, then they are basically an electric heater. For ones that go -30, they would have to be geothermal, involving a circulating loop in the ground or wells. Long payback.
If you want to know what any heat system is going to cost you, do a heat loss calculation (there are calculators out there), factor in the cost of fuel and weather parameters in your area, and compare heating systems, cost of the equipment, etc.. That will widen your eyes and point you to the right choice.

 

[SMSW]

Heat pumps are basically reversible air conditioners - they pump heat from one location to another. They all obey the laws of thermodynamics and their efficiency drops (for heating your house) as the outside temperature gets lower and lower. There is a break even point somewhere around 30 deg F - at this temp you put in one unit of energy in order to get one unit of energy out - or you expend 1 btu to move 1 btu into the house. For this reason, all heat pumps have supplemental electric heating coils in the plenum and as the outside temp drops, the cost to heat your house goes up (efficiency goes out the window) until the electric coils kick in. At this temp, you are paying for electric heat. Geothermal simply uses a different reservoir from which to extract the heat that is blown into your house. The installer can drill wells and drop a loop of plastic pipe into the hole and back fill with a special sand and bentonite clay mixture, or dig a trench below the frost line and drop the loop in the trench. Another option is to drop the loop in a lake. Geothermal does not change much in efficiency since it is not likely that you will deplete the ground of btu's, assuming the system is properly designed. However, each well or loop is rated at the number of btu's that can be extracted (I was told by an installer his were around 1 ton) and if your house needs more tons (btu's) because of heat loss at very low temperatures, then you need more wells (or loops).

As with all other trades, not all geothermal installers are created equal. I talked to one guy who told me he used barbed fittings and permanent clamps in the loops that went into his bore holes (well), another said anything less than a permanently welded loop was folly, you do not want a break in the loop in the middle of winter.

 

[Andrew Shadow]

These systems are not meant for environmental heat, but only to warm a floor

That is what I have read and also what many contractors have told me. I have relatives who have heated concrete floors in their garages but the heat source is hot water. Electric doesn't sound like it is anywhere near as good.

If you want to talk to me, let me know and maybe we can set up a time to talk over the phone.

Thanks for the offer. Right now I would just be wasting your time. I have to do some research so I know more about what I am talking about first. I'll keep your offer in mind though.

I have a big tank out there but don't notice it any more...

I agree but a tank isn't in the cards. If we had NG I like the idea of that heater. Had them in several places I have worked and they do well.

As for heat pumps, not an expert but a little experience... air to air are good to about freezing, then they are basically an electric heater. For ones that go -30, they would have to be geothermal, involving a circulating loop in the ground or wells. Long payback.

I have a heat pump for heating my house. At the freezing point it pumps out heat like crazy. It provides the main source of heat for the whole house down to -12 deg. C. The -30 ones are indeed air-to-air units. My neighbour has installed a few for some of my other neighbours and they seem happy with them.

There is a break even point somewhere around 30 deg F - at this temp you put in one unit of energy in order to get one unit of energy out - or you expend 1 btu to move 1 btu into the house. For this reason, all heat pumps have supplemental electric heating coils in the plenum and as the outside temp drops, the cost to heat your house goes up (efficiency goes out the window) until the electric coils kick in. At this temp, you are paying for electric heat.

As written above 30 Deg. F is no problem for my heat pump. It pumps lots of heat at that temperature and well below that. At 30 Deg. F I am easily getting well over 100 Deg. F coming out of the plenum and my heat pump is over 10 years old now. Our electricity provider, Hydro-Quebec, considers them efficient to at least -12 Deg. C (10 Deg. F). based on a very old program based on the old heat pump technology like mine. The newer ones are much more efficient.

There are no supplemental electric heating coils in my plenum. Heat pumps are very common up here. Everyone I know has one and none of them have an electric coil added to the plenum. If the heat pump needs some assistance my oil furnace will kick in to help it out but that happens rarely and usually under extreme conditions.

 

[SMSW]

As written above 30 Deg. F is no problem for my heat pump. It pumps lots of heat at that temperature and well below that. At 30 Deg. F I am easily getting well over 100 Deg. F coming out of the plenum and my heat pump is over 10 years old now. Our electricity provider, Hydro-Quebec, considers them efficient to at least -12 Deg. C (10 Deg. F). based on a very old program based on the old heat pump technology like mine. The newer ones are much more efficient.

There are no supplemental electric heating coils in my plenum. Heat pumps are very common up here. Everyone I know has one and none of them have an electric coil added to the plenum. If the heat pump needs some assistance my oil furnace will kick in to help it out but that happens rarely and usually under extreme conditions.

I quote from Wikipedia: (read this article: https://en.wikipedia.org/wiki/Heat_pump )
"When there is a high temperature differential (e.g., when an air-source heat pump is used to heat a house with an outside temperature of, say, 0 °C (32 °F)), it takes more work to move the same amount of heat to indoors than on a milder day. Ultimately, due to Carnot efficiency limits, the heat pump's performance will decrease as the outdoor-to-indoor temperature difference increases (outside temperature gets colder), reaching a theoretical limit of 1.0 at −273 °C. In practice, a COP of 1.0 will typically be reached at an outdoor temperature around −18 °C (0 °F) for air source heat pumps.

Also, as the heat pump takes heat out of the air, some moisture in the outdoor air may condense and possibly freeze on the outdoor heat exchanger. The system must periodically melt this ice; this defrosting translates into an additional energy (electricity) expenditure. When it is extremely cold outside, it is simpler to heat using an alternative heat source (such as an electric resistance heater, oil furnace, or gas furnace) rather than to run an air-source heat pump. Also, avoiding the use of the heat pump during extremely cold weather translates into less wear on the machine's compressor."

My boldface. I was wrong about the limit of 30 deg F, evidently newer units reach that 1 to 1 ratio (COP of 1) at 0 deg F.

We are talking about two different products when it comes to heating w/ electric heat in floors. Warm floor products found in bathrooms and kitchens are relatively low power, low wattage density per sq ft and serve only to take the chill off the floor. Sure they contribute some environmental heat, but not enough to heat the room without another heat source. Call the folks at Raychem and ask about their other products. I recently threw out a lot of literature regarding electric floor heating. Not Warming. Heating. This product does exist, however, it is on par with all other electric resistance heat - as the wiki article says elsewhere, resistance heating uses high high grade energy for heat with a Coefficient of Performance of 1. This does not compare well with other heating systems. From what I read in the Wiki article, the most efficient system for you might be a heat pump that heats water/anti freeze and a circulating pump to push it through tubes embedded in your floor (hydronic heating), with an oil fired furnace backup.

From what I have heard from a friend who lives in Montreal, you guys get temps around -40 in the winter. Your heat pump using air for the heat source is trying to sqeeze blood out of rocks at that temp. That's when your oil fired furnace kicks in. (Well, long before it gets that cold.)

Maybe you and sennister need to buy some of those hot ST's, suck the excess heat out of the bikes (for use heating your shops/garages), and then sell the cool bikes having solved the problem.

 

[Andrew Shadow]

My boldface. I was wrong about the limit of 30 deg F, evidently newer units reach that 1 to 1 ratio (COP of 1) at 0 deg F.

That is what I wrote above. The heat pump heats the house just fine all the way to -12 Deg. C (10 Deg. F and mine is old tech R-22 Freon. My air conditioning contractor neighbour is installing units rated to -30 Deg. C (-22 Deg. F). I haven't looked in to it but that is what he told me.

From what I have heard from a friend who lives in Montreal, you guys get temps around -40 in the winter.

We definitely get brutally cold weather no doubt. When I installed my heat pump in 2008 Montreal averaged 12 days a year with temperatures below -12 Deg. C. The reality is the average temperature is closer to the freezing point a lot of the time which is what makes heat pumps a viable option here. If my neighbour is not full of it and they can provide heat down to -30 Deg. C that would be good enough for me. Even if -30 is "optomistic" on the days it is really cold to the point where the heat pump can't keep the chill off or it is to inefficient I'll stay out of the garage fore those few days and keep the heat low.

As I said, I know there will be a heat pump in there. I need to do some research to see if just a heat pump is a smart choice. I kind of think that no matter what there will be some kind of electric heater in there as an additional heat source if for no other reason then peace of mind. Having said that I am basing that feeling on my knowledge and experience with old and out dated heat pump technology.

Thanks to all who answered my questions and for the education.
I don't feel comfortable continuing this discussion about my project here as we have already high jacked Dave's thread to much.
Lets leave it here. When I need more education from you guys I should probably start a separate thread.

Sorry Dave.

 

[sennister]

No worries about the hijack.

As I mentioned the heat pump discussion is good information. More so because it is from people with similar weather conditions to what we face here in Minnesota. We can get -30f days but it is rare. We will normally have a few days in the -20f but ultimately temps in the single digits below and above 0 are most common in the middle of winter for us. However as I mentioned if I add a heat pump, it will be to augment the in floor system should I opt to maintain a lower constant temp and just want to bump the heat to work out there for a few hours. I never really looked at the lowest temps where they are effective. I am aware of geothermal systems and agree that they won't have the limitations but I don't plan on going that route at this point. Here is a silly question. At least with the Mitsubishi units there is the wall mount component or one in the ceiling. Then there is the condenser and such that is outside. What would happen if you were to put that in the attic of the building? Maybe it wouldn't be as efficient for AC use but it would be a little warmer up there from heat loss and might be more efficient for heating. Just a thought. Again not my primary heat source and I could easily say hey, it is -30f outside and I really don't need to work on this project on days that cold because of costs to bump the heat. The fact remains that these really cold days only normally last for a couple days here and here it isn't like it is the entire month.

Andrew, since you have a neighbor in the field he should be able to help you with some of the calculations and understanding what options might be best. Does he maybe know how viable an electric boiler would be with in floor heat? I see what you are saying about the garage space and some limitations. One thing you mentioned was jacking up the existing slab that has settled and pour a new top layer. Depending on how broken up things are that may or may not be a good idea. I would also factor in how much longer you plan on staying there. If this is your forever home, you may want to rip the slab up to make sure the base is solid and you can insulate and install a VB under the slab as well as add rebar. If it is badly broken up they may not be able to jack up much anyhow. Also I doubt that the mud they typically use provides any insulation value. If you went this route, you may find the new slab will just crack again in a few years if the base further settles. It would be less money though and might be an option if you are only planning on being there for 5 years. If this is your forever home, I would lean toward ripping up the slab and doing it right. Another thought is if you rip up the slab and insulate things, throw PEX in the slab even if your best option today ends up being a heat pump. PEX is pretty cheap and you don't have a crystal ball so something may change. I don't know where you live or how remote you are but it would suck if a couple years go by and all of a sudden NG is installed near your house. Or something else changes like electric prices go through the roof and you opt for that LP tank to heat your home. Now adding a gas fired boiler would be an option. You seem to think that electric is your best option, which it may be, I guess the next question though is how much power do you have available in the space? Are you going to have to upgrade power?

When we switched to a tankless water heater for the house we were sizing a system and I was initially leaning toward an electric unit because it would allow me to install it anywhere in the house which would mean it could be closer to the point of use and not have to worry about venting. Once I sized a unit I realized it would need 3 x 60A. Granted it wouldn't always pull full power but we only have 150A service to the house and it would take nearly all the power if it ramped up to full power. One of the problems with our property that I am tackling with this project is upgrading the power coming onsite from that 150A service to 400A service. 200A will go to the new garage and that will in turn feed the pole barn which only has 60A now. While 60A is fine for the shop, when my In-laws are in town with their 5th wheel, they need 50A service to run all the AC units and stuff in the camper. Even if not using all that, it is common I might be down to 20A available out there when I need to weld something. So the pole barn will get bumped to 100A as long as we are at this project. I upgraded the panel a couple years back to 100A so I just need to replace the wires which will happen anyhow as the feed wire is going to get hit when we dig the footings. While 200A is a lot in a garage space that will mainly be used for parking, it also prepares me for charge points for electric vehicles.

We just got several inches of snow and I will need to run out and clear the construction site before it switches to rain and everything melts. That is the only work happening over the next few days.

Here is a still from the security camera I installed the other day. The wall with the sliding glass door is the that will shift about 9' closer to the camera so that the porch width will match the 29' depth of the garage. Initially we were thinking of hand framing an extension to the trusses of the porch but then we would need to add a beam where the existing that wall is now to support the old trusses. Since we have to order trusses anyhow it is a wash in terms of cost to just order a few extra trusses for the porch vs paying for labor and materials to add the beam and hand frame. The new garage will extend out 40' from the existing porch toward the pole barn which is the building on the right. This will leave us about 15' of separation between the pole barn and new garage which is enough to get a well truck in. You can see our well poking up out of the snow right by the ":" in the timestamp.

 

[OhioDeere]

Garage 101.. BUILD THE LARGEST STRUCTURE YOU CAN ABSOLUTELY AFFFORD! I've built several. still wish i had bigger.. I've got a 60 x 80, a 36 x 42', a 28 x 30'. I still have trouble parking my daily driver somewhere in them. Never have enough room for everything.

 

[SMSW]

If this is your forever home, you may want to rip the slab up to make sure the base is solid and you can insulate and install a VB under the slab as well as add rebar.

One of the problems with our property that I am tackling with this project is upgrading the power coming onsite from that 150A service to 400A service. 200A will go to the new garage and that will in turn feed the pole barn which only has 60A now. While 60A is fine for the shop, when my In-laws are in town with their 5th wheel, they need 50A service to run all the AC units and stuff in the camper. Even if not using all that, it is common I might be down to 20A available out there when I need to weld something. So the pole barn will get bumped to 100A as long as we are at this project. I upgraded the panel a couple years back to 100A so I just need to replace the wires which will happen anyhow as the feed wire is going to get hit when we dig the footings. While 200A is a lot in a garage space that will mainly be used for parking, it also prepares me for charge points for electric vehicles.

There are formulas which tell you the max size rebar that can be put in any slab. Most standard garage floors are 3 1/2" which is not thick enough for even 1/2" rebar. And most residential cement contractors put cheap mesh on the crushed gravel and pour on top of it. It does nobody any good down there, because the mesh or rebar must be in the middle of the slab. When we poured our driveway (6 to 8" thick) and our garage (6"), I used 6 x 6 x 8 mesh - that's a 6" sq grid made of 8 ga wire. Rebar starts to add significant costs to a driveway or garage and must be placed on chairs to position it correctly.

The utilities here will not give a homeowner an upgrade in service unless he demonstrates a need for it. Lacking that, I can install a 200 amp mast, meter, and panel and they will still connect the same old 100 amp service drop to the new wires. Four hundred amp service here requires the utility to run calculations to see if this demand can utilize existing transformers or if you need your own t-former. You might end up paying for the wire and installation and they will not give you more juice until your bills and the meter show the need for it. Just because you have a 50 amp electric range, a 30 amp electric dryer, and a 50 amp hot tub does not mean you need 200 amp service. The NEC uses demand factors for calculating service loads and the utilities have their own methods of running the numbers. Consult a good electrician in your area for more inform

 

[Andrew Shadow]

What would happen if you were to put that in the attic of the building? Maybe it wouldn't be as efficient for AC use but it would be a little warmer up there from heat loss and might be more efficient for heating.

Around here as a general principle anything in the attic is considered a bad idea. With a properly insulated, sealed and ventilated roof system the difference between the attic and the outside air temperature is so inconsequential that it will not provide any advantage to the heat pump while operating in heating mode. In the summer the attic can be be hotter than the outside air which only stresses the heat pump even more as it tries to provide air conditioning. Any maintenance required to the heat pump becomes a nightmare because of where it is located. I have heard stories of some contractors who are not even interested in servicing a unit that is in the attic. They just won't take the job. I don't see any benefit to placing it in the attic.

Andrew, since you have a neighbor in the field he should be able to help you with some of the calculations and understanding what options might be best. Does he maybe know how viable an electric boiler would be with in floor heat?

He only does air conditioning and heat pumps. He doesn't do any other kind of heating system so I wouldn't call him a heating contractor. I will be talking to him about it however. Because he is in the business he should know people who can give me opinions on other options.

Also I doubt that the mud they typically use provides any insulation value.

The TV commercial I have seen they say that it is a foam that they inject. I just assumed that if it is a foam it would also provide insulation. I doubt that I will be going that route anyway as I want to add a drain so I will need to dig things up.

You seem to think that electric is your best option, which it may be, I guess the next question though is how much power do you have available in the space? Are you going to have to upgrade power?

I have a 200 amp. entrance to the house and I will installing a 100 amp sub-panel in the garage. I am not concerned about available power.

The main reason why I think that electricity is my best option is because we have really cheap electricity rates here that make it good choice financially. It might not be however. I'll explain why I think it is and maybe you will see it differently in a way that I had not considered.

Montreal is low in the St. Lawrence valley and because of that most of the smog days in Montreal are actually in the winter not the summer. The cold air acts like a roof and holds the smog in. Because of this wood burning appliances have been banned. There is talk now of banning oil burning appliances for the same reason and I can see that happening some time in the future. NG is all around me but for some reason it is not on my street. I suspect the next time the road is re-done it might be added so putting the heating pipes in the concrete is probably a good idea no matter what. Because of the proximity to the neighbour's property I don't have room to put a propane tank on the same side as the garage and the Mrs. doesn't want to know anything about a a "big ugly tank" stuck in her gardens on the other side. That leaves me with electricity no matter what the type of heat is at least until I have NG available.

Without doing tons of calculation electricity also has to be my cheapest option. Quebec has the cheapest electricity rates in North America. To give you an idea you are probably paying somewhere around 11 or 12 cents USD per KWH. The rate here for a residential customer is 5.9 cents CAD per KWH. But it gets better. Hydro-Quebec has a plan where if you have a dual energy heating system (electric and anything else not electric) you qualify for a special rate. This means that all of the electricity that I consume in the entire house 12 months of the year, not just the electricity used for heating, I am only paying 4.4 cents CAD per KWH as long as the temperature is above -13 Deg. C (8.6 Deg. F). When it is colder than that I pay 25.6 cents CAD per KWH. But the number of days where it is colder than that are not that numerous through the winter and it is generally during the night-time hours not the entire 24 hour period. The portion of my consumption that is billed at this higher rate is really inconsequential as a result.

I am assuming that heating using electricity must be my cheapest option. Before the heat pump all of my heat was provided by an oil fired hot air furnace. Installing a heat pump in the house dropped my heating bills by two thirds because of this dual energy program so the reason I am looking at a heat pump in the garage is because it uses electricity. Since it is also capable of providing me with both the heat and air conditioning that is another bonus. Despite being in a winter climate Montreal gets pretty hot in the summer. Because we are an island surrounded by water and low in the St. Lawrence valley it also gets very humid in the summer.

The only issue that I don't know about is whether or not a heated floor will make a difference as far as being being warm and cosy in the garage as opposed to just not being cold. That is what I don't know.

Garage 101.. BUILD THE LARGEST STRUCTURE YOU CAN ABSOLUTELY AFFFORD! I've built several. still wish i had bigger.. I've got a 60 x 80, a 36 x 42', a 28 x 30'. I still have trouble parking my daily driver somewhere in them. Never have enough room for everything.

Truer words were never spoken. In another life I had a 100' X 60' machine shed, another 60' X 40' storage shed and a 40' X 40' workshop. All of them had high enough ceilings and doors that you could bring in any size piece of equipment. That was heaven.

Dave;
I think that you wrote in an earlier post that you were going to have a large concrete pad extending out from the shop in to your yard. If this is going to be a continuation from the concrete floor from the shop make sure that a really good thermal break is installed between the two. If this is one continuous piece of concrete with no thermal break you will have a hard time keeping the floor in the shop from being cold all the time.

 

[sennister]

Garage 101.. BUILD THE LARGEST STRUCTURE YOU CAN ABSOLUTELY AFFFORD! I've built several. still wish i had bigger.. I've got a 60 x 80, a 36 x 42', a 28 x 30'. I still have trouble parking my daily driver somewhere in them. Never have enough room for everything.

I do agree. That said. At the end of this project I will have garage parking for 12 cars. We own 2. However in the winter we store my father's two Corvettes and my Father In Law's 1 ton truck. Then there are the motorcycles. I have my tractor and zero turn which take quite a bit of space. Oh then there is the golf cart. We really can't go any bigger because of needing to maintain separation not only to get a well truck back to service our well but per city ordinance. I am fine with that.

Cost wise. Yeah we are hitting that $$ limit. All said and done entire project is right at about $150-160K.

 

[sennister]

There are formulas which tell you the max size rebar that can be put in any slab. Most standard garage floors are 3 1/2" which is not thick enough for even 1/2" rebar. And most residential cement contractors put cheap mesh on the crushed gravel and pour on top of it. It does nobody any good down there, because the mesh or rebar must be in the middle of the slab. When we poured our driveway (6 to 8" thick) and our garage (6"), I used 6 x 6 x 8 mesh - that's a 6" sq grid made of 8 ga wire. Rebar starts to add significant costs to a driveway or garage and must be placed on chairs to position it correctly.

The utilities here will not give a homeowner an upgrade in service unless he demonstrates a need for it. Lacking that, I can install a 200 amp mast, meter, and panel and they will still connect the same old 100 amp service drop to the new wires. Four hundred amp service here requires the utility to run calculations to see if this demand can utilize existing transformers or if you need your own t-former. You might end up paying for the wire and installation and they will not give you more juice until your bills and the meter show the need for it. Just because you have a 50 amp electric range, a 30 amp electric dryer, and a 50 amp hot tub does not mean you need 200 amp service. The NEC uses demand factors for calculating service loads and the utilities have their own methods of running the numbers. Consult a good electrician in your area for more inform

Electric company was contacted last fall about this project and why I want the additional service. I explained the electric cars and described our property. They ran a report of our transformer and gave us the green light. Some of it depends on where you live. We are more of a rural area and not in town. We have above ground power here and there is only our house and one neighbor on our transformer. He already has 400A service. Well 200A in his house and a separate meter on his pole barn with 200A service. Our transformer is capable of providing the power based on the report that they ran for me and the overhead lines to the house are easy to upgrade. It is about a 40' run at most. They will likely need to be upgraded not only because of the load increase but they are the 3 separate wires where now they twist the three wires together into a bundle. We are sending 400A to the meter by replacing the meter box with a Meter Center. This will put the meter and two 200A breakers in the same panel. They seal the meter side and I have access to the breaker side. One breaker will feed the house and the other run to the new garage. This maintains code by having a breaker within __ feet (6' or is it 10') of the meter. It will be about 6". It also saves me the service fee of paying for another meter on property like my neighbor has. Well technically they said it won't be 400A but I can have two, 200A breakers. I think they said something like 320A or 360A. Something like that. Already been talking with the electricians on the plan and have a green light from everyone.

 

[sennister]

Dave;
I think that you wrote in an earlier post that you were going to have a large concrete pad extending out from the shop in to your yard. If this is going to be a continuation from the concrete floor from the shop make sure that a really good thermal break is installed between the two. If this is one continuous piece of concrete with no thermal break you will have a hard time keeping the floor in the shop from being cold all the time.

I was curious so I looked up the rates. Looks like $0.10815/ kWh June-Sept and $0.09241/kWh Oct-May. If I have electric heat it says $0.06287 from Oct-May. Not sure how they know how much was for heat of if I have electric heat then it is that for everything.

If I were you and you are ripping up the slab where it could be insulated I would look into using an electric water heater for infloor heat. Maybe your neighbor would know someone you could talk to about it. It is possible. With your cheap rates it might be effective. You would need to talk to someone about it though to determine sizing though as 100A service out there may not leave much available power. If properly sized, you can keep it warm and cozy if you can afford the electricity. Since NG is all around you it is even more of a reason to put the PEX in there just in case. I don't know what your neighborhood is like. For all I knew you were in a rural area 40 miles from the nearest NG customer. It is common around here for more rural homes that LP is the only option unless they have fuel oil, electric or wood.

https://www.eccotemp.com/blog/did-you-know-electric-tankless-water-heaters-are-great-for-radiantfloor-heating-/

The pad that is out behind the slab is separate. From the footings up is block. The block will be about 2 courses above ground so there will be a block separation as well as a thermal break. There are no access doors from the garage to the slab. From the mud room where the patio door is today will be the exit to the patio. Well that wall is shifting to the west a bit but the new wall will have a patio door and a small deck where you then make a 90 degree turn and go down 4 or so steps to the patio. Or walk around the garage.

 

[SMSW]

Electric company was contacted last fall about this project and why I want the additional service.

You have already gone through the process and received the green light. More than a few electricians here never notify the utility and simply install a larger meter center and panel and THEN call the utility for an upgrade. The result is no change in the delivered service to the house - and there is often non need for it. What is needed is a larger panel (more circuits) and since you cannot splice the service conductors (legally) and the old ones are often too short, it is frequently easier to just upgrade the mast, meter, and panel in one swell foop.

You are right about the service size*. They are giving you new service entrance equipment with those two 200amp breakers. And I would be very curious about the size of the overhead conductors that the utility runs to feed your mast (pipe coming out of the top of the meter box). The utilities use their own engineering data to size conductors; they are not bound by the NEC. I suspect that utilities also skirt the edge of what is actually needed compared to what they can get away with. A dirty little secret of the industry is that we do not have the infrastructure to charge everyone's electric car, and it will take a huge investment to upgrade the grid to get there. I suspect that they will give you what they think you need now (size of service drop) and install larger conductors when you demonstrate a need for it. In the end it really depends on the utility's work load and friendliness of the guy overseeing your project. Don't ask for a service upgrade immediately after a major storm when their work crews are overloaded.

One last point. The NEC says nothing about the distance between the overcurrent protection and the meter. This is convention - an amorphous distance enforced by each utility's inspector and this varys with the utility. In the Cleveland area they go with 10'. Service conductors are essentially unfused, not all secondaries leaving the transformer have a fuse, and many residential t-formers simply have a fused primary side. My guess is this is a holdover from years ago that never got updated.

*Circuit breakers will only pass a continuous load of 80% of their rating before tripping. Thus a 200 amp breaker will only give you 160 amps for 3 hours or more.

 

[sennister]

You have already gone through the process and received the green light. More than a few electricians here never notify the utility and simply install a larger meter center and panel and THEN call the utility for an upgrade. The result is no change in the delivered service to the house - and there is often non need for it. What is needed is a larger panel (more circuits) and since you cannot splice the service conductors (legally) and the old ones are often too short, it is frequently easier to just upgrade the mast, meter, and panel in one swell foop.

That is pretty much what we are doing. From talking with the electricians, the power company comes out, cuts power, they then rewire the mast, meter and panel (meter center) at once. They will leave a few feet of wire hanging out of the mast and the power company comes back out and does the final hookup.

You are right about the service size*. They are giving you new service entrance equipment with those two 200amp breakers. And I would be very curious about the size of the overhead conductors that the utility runs to feed your mast (pipe coming out of the top of the meter box). The utilities use their own engineering data to size conductors; they are not bound by the NEC.
I suspect that utilities also skirt the edge of what is actually needed compared to what they can get away with. A dirty little secret of the industry is that we do not have the infrastructure to charge everyone's electric car, and it will take a huge investment to upgrade the grid to get there. I suspect that they will give you what they think you need now (size of service drop) and install larger conductors when you demonstrate a need for it. In the end it really depends on the utility's work load and friendliness of the guy overseeing your project. Don't ask for a service upgrade immediately after a major storm when their work crews are overloaded.

From discussions with the electrician on site, they pointed out that our older overhead conductors which is the three wires each with a foot separation is the old way of doing it. Since the overhead lines need to be dropped to rewire the mast, they said they will most likely upgrade the overhead conductors. I am also going to take advantage of this window to cut down two pine trees that are really close to the overhead lines. One of which is dead. I can't easily drop them the other direction because of the fence on the property line. As you mentioned they are not bound by NEC and the electrician did mention that because the power lines are overhead and not buried, they can "get away with" a bit more load on them than what would normally be allowed on that gauge conductor. The open air cools them better compared to buried wire.

There was another thread here talking about future fuels for cars and such. I had mentioned the issue you also mention. Many of the housing developments where there are underground utilities will have an issue if everyone decided to trade in their gas powered cars for electric. The infrastructure can't handle everyone having 400A service. If it is a new development going in today they might be planning for this but this wasn't on anyone's radar for those developments build in the 70-90s. While people complain about the look of overhead utilities, the benefit is it can take a bit more load because it is air cooled and it is a lot easier (less expensive) to upgrade if needed compared to digging up everything.

One last point. The NEC says nothing about the distance between the overcurrent protection and the meter. This is convention - an amorphous distance enforced by each utility's inspector and this varys with the utility. In the Cleveland area they go with 10'. Service conductors are essentially unfused, not all secondaries leaving the transformer have a fuse, and many residential t-formers simply have a fused primary side. My guess is this is a holdover from years ago that never got updated.

*Circuit breakers will only pass a continuous load of 80% of their rating before tripping. Thus a 200 amp breaker will only give you 160 amps for 3 hours or more.

Yeah, there is a code here in MN on the distance from meter to breaker. I know it differs and that makes it harder to look up. I have seen 6' and I have seen 10'. I would say today ours is 6' or so and I think that is what the code is. It doesn't matter as much because with the meter center it will be less than a foot. One thing I was considering was rather than go with a meter center was to upgrade the meter and meter box then run from there to a automatic transfer switch. Even if there is no standby generator in place now, I could still prep for it now as we are considering it. The problem is that it was going to be pretty expensive because I would need a transfer switch sized to the 400A and I wouldn't really ever need a generator that big. I can see adding a standby generator at some point for the 200A feeding the house but I don't need to power the garage and such. The power does go out a couple times a year but I think we are going to hold off on that. I was going to add about $3K to install the transfer switch. Granted we are still spending part of that on the meter center anyhow but I want to say the meter center (box cost not installation) is around $600 vs $1500 for the transfer switch. It is hard to say what the meter change will cost as much of that is rolled into the overall project.

While I am not an electrician, I took a lot of electrical courses many years ago in college and still work around it from time to time in my job in the IT field. I have been involved in a lot of Data Center upgrades and new construction. That 80% is why I think the power company said we would have 360A or whatever it is. They are talking sustained. That 80% figure is what I have in the back of my mind when I am describing what I have for power today, mostly in regard to the pole barn situation and my In-laws 5th wheel hookup. I have 60A out there today which is 48A sustained, their camper hook up is a 50A plug but even with everything running it isn't 50A. However 40A which is 80% isn't out of the question, 35A for sure. Then if I am welding that is on a 30A plug so up to around 24A. We run into that 80% rule at lot in Data Centers as it is a sustained load that we deal with. Welding is just one use. I also have designed and built an electric brewing system for beer. That uses 50A 240V to power two 5500w electric water heater elements. Using my buddy Ohm's law that means they are pulling about 22A each plus circulation pumps and you are looking at close to 50A there but not sustained. That is run in the pole barn when the In-laws are not trying to run their camper. While an electric car can be charged on 110v, you can't to pre heat or cooling. I want to say that is normally on 30A chargers. Not saying we are pulling the trigger on two electric cars anytime soon. We can't pull our camper with one. I could see one of them in the next couple years. It will be interesting to see what our loads will be but I am tired of not being able to use things when I want. As it is, I can't brew or weld if they are around or I am running back to the house to reset the breaker. The more you trip a breaker, the easier it trips in the future.

One other thing we looked at was off peak power. We spoke the the power company about if we need a separate breaker for car charging or something like that to take advantage of off peak power programs. They said we don't need it. They have a smart meter they would install if we wanted to sign up for that program. I am not doing that now. Not until we get an electric car or something that would make sense. I just wanted to know if I should prep for a separate panel that is dedicated for off peak power or something. Some places require separate meters for this option. I just know that if some of these come up a couple years down the road it would be a lot more expensive and difficult to address compared to adding a second conduit into a hole that is already dug now.

 

[SMSW]

That is pretty much what we are doing.

You can install a transfer switch downstream of either 200 amp breaker and ahead of the panel it feeds. You could then use a generator to power loads from that panel (either house or garage). You can even get manual t-fr switches that look like a mini breaker panel and have a wiring harness and double throw single (and double) pole switches. Flip each circuit to generator power and it completely disconnects the wiring from the utility's feed. Google Reliance transfer switches, or Gentran. These will typically cost two or three hundred bux and can feed sumps, refrigeration, heat, and a couple of lighting/cooking circuits.

I've not seen 400 amp triplex in an overhead service drop. You are talking way north of 3/0 copper (200 amp rated) and this stuff gets very heavy and unwieldy. Even aluminum is going to be larger than 500 mcm. Every service of this size that I have installed has received significantly smaller than a 400 amp drop by the utility. When you start talking real 400 amp service for a commercial establishment, then they get serious and will often put a pole immediately adjacent to the building and mount a separate transformer on the pole. Individual secondaries drop down to the mast. Different utilities have different policies.

Regarding future upgrades, developments can plan for that by installing additional empty pvc conduit underground and whatever is needed can be installed in the pipe later. Many places have banks of underground conduits, only a few of which are used at the time of installation.

Regardless of what your loads are, if you were to read the NEC's chapter on calculating service size, you would be amazed at the derating factors that get used to size the feeders.