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06-10-2020, 11:14 AM
(This post was last modified: 06-10-2020, 11:33 AM by Tapper.)
I am planning to construct a building on my property; will be a separate three car garage with the center section for a sizable RV. Although I've built many buildings in the past I've never used in floor (concrete) radiant heat. Did some research but just getting started. I can power the boiler either with propane or electricity. Would like to hear from others who have done this in the past, pros and cons.
Another obvious option is to just install a heater hung from the ceiling to blow in warm air. Less efficient I'm guessing but also less expensive.
Thanks,
Doug
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If you compare the cost per MBTU between electric and LP, I think you'll find that LP is a lot cheaper. I have no idea about the ceiling hung efficiency (compared to radiant) but it's what I had in my last shop as well as the current one. there are disadvantages to forced air heat to be sure, but the cheaper installation was what made it my choice (current shop, which I had built). My last shop was an existing building so the in floor wasn't an option.
I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.
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Doug,
I think the primary question is really radiant floor heat versus forced air. Then fuel source after that.
Like Fred, my shop is heated with a hanging furnace. It's powered by propane. My unit is 80% efficient, even with a sealed combustion chamber and outside source of combustion air. I don't think you'll find a hanging unit much higher than 80%, at least according to the HVAC guy when I installed this one six years ago.
My dream heating solution would be a geothermal radiant floor solution for the woodshop. If I'm gonna dream, might as well dream BIG.
What activities are you going to undertake in this new building? If it's just storage of vehicles, I might wonder why one would go to the expense of radiant floor heat. If you're going to spend a lot of time out there, and you want the temp to remain fairly constant, that might change the equation in favor of radiant floors.
If I understand correctly, radiant floors are great solutions when one wants a constant temperature. Forced air is likely better if one wants to warm a space quickly, but then let it cool during periods of non-use.
Just some thoughts...
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Are you planning to have a workshop in that building, or some other need to have a heated floor? Radiant floor heat doesn't make a lot of sense to me if the building is only for storage of vehicles. You have to run radiant floor heat constantly to keep it from freezing, or run glycol solution but that lowers the heat transfer efficiency when it is running. Seems like an expensive solution to provide heat unless you have reasons other than just keeping your vehicles happy. If you don't then an indirect fired propane heater would be a good option with lower operating cost than electricity in most places.
John
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Thanks to all thus far - great responses - just the reason I've posted here.
I live in Montana (as John knows) and it can get pretty chilly out here in the winter. I was thinking that radiant heat might be the most efficient, i.e. the entire floor would be a gigantic heat sink. Once you get it heated (at least in theory) it doesn't take excessive energy to keep it warm. I do not plan to have a shop in this building. I already have a shop in part of the walk-out basement of my home; was part of a home addition/remodel project several years ago. I may do large projects in it during the summer months when the weather is milder (should the need arise), but do not plan to move my shop out there.
At least right now, this space would be used for vehicle storage only. Although I've wanted to do this for several years now, the driving force is the motorhome. Don't want it to be left out in the weather during the winter months. I've located a nice spot that is convenient and kind of isolated, so I'm ready to move forward. Maybe propane forced air heat is a better solution. I'll have to do some sort of "energy consumption" calculation to dial it in I suppose. Maybe something for the architect to look at.
Doug
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Doug, a BTU is a BTU. Putting it into a slab of concrete is no more efficient than putting it into the air. The benefit of radiant heat is that it's fairly constant (which is not a good thing if you want to change the setpoint), down at your feet, and doesn't require blowing hot air around. Those are all good things for a house with people inside, but your vehicles don't need warm feet and could care less where the heat is coming from. And only the engines and batteries care about any heat at all. You could keep the building just above freezing so the snow melts off your cars in the Winter and more pleasant to get into when you need to head out. I assume you are planning for floor drains through the slab, too, to get rid of the melt water. If you plan to heat this building putting in a really good insulation package will go a long way to keep the heating costs low regardless of how you heat it.
When the world returns to semi normal I'd sure love to take a road trip out your way.
John
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Doug,
I was a plant manager for a few years for a radiant heating manufacturer (radiant tube heaters). If you have high ceilings they might be something to consider. Pricing isn't too bad and they would do a much better job heating up your vehicles than in floor radiant or forced air heating.
Lonnie
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Radiant floors are good if you plan to keep it at a consistent temp. They are horrible for infrequently used buildings since they can take days to warm up from dead cold. Also if it's a poorly insulated building the floor temp will have to be high to add enough heat and working on a hot floor is uncomfortable on the feet. It has been done in hangars and it sucks as a heating source since your feet get hot.
Forced air is better for quick climate control but you need large units to get it to temp quickly so those manual J calcs won't help other than to tell you that you need way larger than what it suggests.
The most important part is to insulate the building well including under the slab before you pour it. I'm not sure what type of building construction you are planning but... If you are planning a conventional metal building butilt with welded 2x2 square tube make sure you use sheet foam insulation attached to the outside of the frame then attach the steel. If you do the typical metal building fiberglass you will be sorely disappointed as all that framing will radiate heat in and out to the skin since there is no insulation between it and the skin. Spray foam is slightly better and Ok for a garage since you don't need to attach anything to the walls.
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(06-10-2020, 02:38 PM)jteneyck Wrote: Doug, a BTU is a BTU. Putting it into a slab of concrete is no more efficient than putting it into the air. The benefit of radiant heat is that it's fairly constant (which is not a good thing if you want to change the setpoint), down at your feet, and doesn't require blowing hot air around. Those are all good things for a house with people inside, but your vehicles don't need warm feet and could care less where the heat is coming from. And only the engines and batteries care about any heat at all. You could keep the building just above freezing so the snow melts off your cars in the Winter and more pleasant to get into when you need to head out. I assume you are planning for floor drains through the slab, too, to get rid of the melt water. If you plan to heat this building putting in a really good insulation package will go a long way to keep the heating costs low regardless of how you heat it.
When the world returns to semi normal I'd sure love to take a road trip out your way.
John
John, I'm beginning to think a regular ceiling mounted propane heater might be the way to go. My thinking is to keep the building at a constant 55 to 60 degrees F. during the winter. I think that would do the job. I do plan to insulate it well. We use a lot of spray insulation out here; I used it extensively when I renovated and added on to our home. I have a Rinnai propane wall mounted heater in my shop and keep it at a constant 60 degrees, which is comfortable all winter.
As for the drains, I've discussed it with a couple of folks and there are pros and cons. Pros are obvious if the vehicles move in and out of the garage frequently during the snow season. Cons are that it is more work and it is necessary to slope the slabs in all three bays to the drains. The vehicles in this garage will not be our daily drivers so will not be used a whole lot in the winter. Since the humidity out this way is so low most of the time, not sure it's necessary. I'll give it more thought.
As for the trip out here, you're welcome any time!
Doug
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06-10-2020, 11:27 PM
(This post was last modified: 06-10-2020, 11:37 PM by Tapper.)
(06-10-2020, 03:06 PM)Mr Eddie Wrote: Doug,
I was a plant manager for a few years for a radiant heating manufacturer (radiant tube heaters). If you have high ceilings they might be something to consider. Pricing isn't too bad and they would do a much better job heating up your vehicles than in floor radiant or forced air heating.
Lonnie
Lonnie,
I'll need to take a look radiant tube heaters and do some research. The ceilings in my plan will finish out at 14'.
Doug
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