in floor heating?

[Deacon16]

I am in early planning stages of building my first shop.
Any one have experience with in floor radiant heat pros and cons
thanks for the advice in advance
Deacon16

 

[kd3pc]

a lot of information here....

pros - if done correctly it provides comfortable work space,

cons - pricey to install, and pricey to use. It will increase your bills.

 

[Randy in Maine]

For most of us it is a constant heat, in that I turn mine on at Thanksgiving and turn it off in April. My shop stays at 50º air temp all winter. Cozy.

I run mine off my house boiler so I didn't have to put a separate unit in the shop. More efficient to heat up a huge thermal mass (concrete floor) than a bunch of air. Mine was cheap to install and operate since it is really just 1000 feet of pex tubing and 2 manifolds. 2" of insulation under the floor pays off big time as does a well constructed building that is well insulated with little infiltration.

 

[jack stand]

I've heated 2 different shops of mine. Both have 16' ceilings. The shop with a hanging LP "Modine" type would really seem to "stratify" the air temps. Form very cold at the cold uninsulated slab, to hot up against the insulated ceiling. You could put your hand up and feel the heat up there, so I would turn on the ceiling fans. Yes they moved down the warmer air but it felt more like a cold draft and added little to the actual comfort. Another drawback is a Nascar pit crew couldn't open the door (12x12) and pull a vehicle out fast enough to not loose all the heat.
The radiant (like Randy) go's on around Thanksgiving and off some time in April. If you can work on cars, you can install the radiant. I did mine myself but hired out the design work. Now I heat with a wood (gasification) boiler with wood off the property, keep the shop (38x64) at 60* for the season. Door opening is a non issue as the slab & objects are heated, not the air. I insulated the **** out of the building and no matter what your heating system is, insulation is worth every penny you spend on it and it will return your costs in more than dollars. It's definitely hard to add "step's" and cost's early on in your build, especially if your building in the warm season, and the big step (and cost) of the slab can be hard to interrupt with foam insulation & tubing purchase & installation. Just do it. I really find it hard to believe that it's more expensive to operate (continuously) thru the season over cold/hot repeat cycle of more conventional systems.

 

[2012Eli3]

"and pricey to use. It will increase your bills."?

Not here. Natural gas fired boiler R48 ceiling R15 walls in a 32x56x14.5 been on since October set at 65* highest bills in $80's this winter. Quiet and comfortable. Cooler in summer too.

 

[theoldwizard1]

a lot of information here....

pros - if done correctly it provides comfortable work space,

cons - pricey to install, and pricey to use. It will increase your bills.

I don't buy that "cost of operation" statement ! Yes, it is expensive to install and does require under slab insulation and vapor barrier. Done correctly, it should not be more expensive.

Another downside is it is slow to recover. If you let the slab temp drop below 50F, it is going to take awhile for it to recover.

 

[finn]

I have it and concur that it is expensive to operate, as it is a 24/7 system not suitable for use with a setback thermostat or a shop not used every day /all day.

I keep the thermostat as low as I can and use a hanging propane heater to bring the temperature up to a comfortable working temperature.

Pros are that it's comfortable (although some people complain that the warm floors make their feet sweat) and the floor dries quickly in the winter.

I also have it in my house. It's a better fit for the house, but again, no setback at night as response is slow.

 

[extropic]

I have a 60x80x20 shop with hydronic heat. The fuel is used oil. I love the comfort of the system. It's why I bought this property.

For planning purposes, you need to (or have a professional) figure the BTUs required to maintain your desired temp in your cold months, considering the method of construction and insulation ratings. Then figure the costs of various available fuels to generate those BTUs.

If I were going to build another similar shop in the future, I would try to improve the thermal isolation of the slab (better than what I have). Following are some factors I would consider implementing.
1) Be certain that all ground water has easy exit from beneath your building. Whatever site prep/drainage system is needed for your location.
2) Concrete stem walls (12" high minimum) all around to keep the water further away from the construction materials. Conventional insulation on the interior of the stem walls.
3) The stem walls and structural piers (red iron frame) would be separate and poured first.
4) insulate the structural concrete from the slab pour. 2" rigid foam w/vapor barrier under slab. Minimum 1" foam between stem walls and slab (got to be better than edge of heated slab exposed to exterior weather).
5) Anticipate, as best you can, any areas that you will want to anchor something down to the concrete. Think about the best way to ensure that you don't drill into the PEX. At the very least, make an accurate drawing of the "as built" layout of the PEX including enough "monument pins" (accessible in the finished building) in the slab pour so you're confident where it's safe to drill for anchors.

 

[joes169]

One more actual owner with heated floors that found they're more expensive to run than hot air furnaces. As mentioned above, I think they're great in a house where you might walk around in stocking feet, but unless you spend most of your time bare foot in the shop in winter, laying directly on the floor, or you keep your shop heat at a steady 68* plus, hot air is far most cost effective IMO.

I haven't turned my in-floor on in years, I wish I had the money back that I invested in the system to pay for years (maybe a decade?) of propane to burn through the Modine.

 

[Voi]

I work occasionally in a shop with hydronic floor heat.

I love how quiet it is when the shop machines aren't running and it's comfortable without being warm (at least on a cold day, more on that later).

I do think it's ideal for shops with tall ceilings since the heat is concentrated near the floor. Climb the stairs or a ladder in this shop and it gets cooler as you go up.

Snow melt/evaporation and recovery times on a cold day are great, even if the overhead door is left open for a while for unloading something.

What I don't like about it has to do with our local climate. We get a lot of temperature fluctuations and warm days following cold nights.

These warm days are not comfortable when the slab is still cooling down. When I pull up on a somewhat warm day and see the overhead doors raised part way I know it's going to be uncomfortably warm in there.

I have read about ways to design for this but only for home applications. I don't recall much about it but I believe they could be applied to a shop situation.

For what it is worth, everyone local I know who has had in slab hydronic heat has not done it in their next home or shop. In one case it was due to initial costs but in other cases it had everything to do with the slabs holding too much heat on these swing days we have.

I would still want it in my dream shop but I would take care to make sure it was designed correctly.

 

[Shop Specialties]

In floor is not more expensive to operate unless it was designed/installed improperly OR you start cranking the thermostat up/down in large increments. You only need about 1/3 the BTU to heat the same space as compared to forced air.

 

[theoldwizard1]

I have it and concur that it is expensive to operate, as it is a 24/7 system not suitable for use with a setback thermostat or a shop not used every day /all day.

Okay, are you saying it is expensive compared to a system that you can TURN OFF for a large percentage of the heating days/hours during a heating season ? If that is your comparison, you are correct.

 

[James-W]

I have forced air (modine type heater) in my garage and I leave it turned down to 50 degrees when I am not out there working. When I am working in the garage I crank it up to 70 degrees and it only takes about 20 minutes to get up to that temperature. I am well satisfied with what I have, but I do think in-floor heat has its advantages.

My thinking, right or wrong, is that in-floor heating is wonderful if you leave it set at the same temperature all the time. If you turn it down, or worse, if you turn it off when not working in the garage, then I don't think it is such a good idea.

 

[finn]

In floor is not more expensive to operate unless it was designed/installed improperly OR you start cranking the thermostat up/down in large increments. You only need about 1/3 the BTU to heat the same space as compared to forced air.

I've seen those wild claims before, but can't come up with ant thermodynamically sound rational that support that cost savings.

You may be able to set the thermostat a few degrees lower because the heat is at floor level, but that's about it.

Any massive energy savings would be due to the design details like a well insulated slab, walls, and ceiling, which can be applied to any heat source.

I have a second, albeit smaller shop / garage that was designed and built to be floor heat ready, and has windows which maximize winter solar load, even with our short, overcast days.

I never installed a boiler, but the building is comfortable with only a wood stove, occasionally supplemented by a hanging heater, as long as I heat it often enough to keep the insulated slab reasonably warm.

 

[Shop Specialties]

I've seen those wild claims before, but can't come up with ant thermodynamically sound rational that support that cost savings.

You may be able to set the thermostat a few degrees lower because the heat is at floor level, but that's about it.

Any massive energy savings would be due to the design details like a well insulated slab, walls, and ceiling, which can be applied to any heat source.

I have a second, albeit smaller shop / garage that was designed and built to be floor heat ready, and has windows which maximize winter solar load, even with our short, overcast days.

I never installed a boiler, but the building is comfortable with only a wood stove, occasionally supplemented by a hanging heater, as long as I heat it often enough to keep the insulated slab reasonably warm.

And once again these are not wild claims but fact from 26 years in the heating business.

 

[Thumper68]

It all comes down to where you are and what your heating needs are.

Here in northern MN I love my in floor, the heat is on from mid Oct to May set at 55* which is perfect for me working in there.

Typically I use the shop 4 to 5 days a week and find that it is very much worth the effort and cost of installation.

If you are not going to use the shop a lot, have a lift (so you are not working on the floor), like working with cold equipment and tools then in floor might not be for you.

On the other hand if you use the shop a lot, work on the floor, like warm feet, enjoy warm tools and equipment and want ease of use then go for it.

Next winter I am going to add a wifi thermostat and do a bit different set up to take advantage on my cheap off peak electric, right now my boiler runs a few times during the day, the plan is to turn the heat up higher from 7pm to 7am say 70* then make sure that the boiler does not come on during the higher rate hours.

 

[slackdaddy1]

Had it in my last shop and my current.
I don't see the cost to install?
Some PEX loops in the slab, about $200.00 worth of fittings and pieces of copper sweat together, a pump, a $25 Tstat and relay and hot water source. Oil fired Bock WTR HTR in the 1st shop (800.00 at the time). I had like 1600.00 in that set up. That was in an uninsualted block walled garage (no ceiling insulation, no slab insulation).
I set the Tstat at 45 deg and left it. plenty comfy working in there.
New shop is insulated everything, I will be using a small elec boiler (800.00)
Once again, I will have 1600.00 in the install, The boiler is 100% efficiency, my heat will be down where I am working (Slab)
So I'll throw the BS card on install cost and operating cost

 

[yeldogt]

The saving in operation result because typically the BTU's needed for comfort is lower with floor radiant vs forced air. This will only come with a properly installed system -- and occur in larger open buildings vs a typical house.

Properly installed = Good insulation -- continuous circulation with outdoor resent. My radiant is never off -- unless the temps outside are high.

If you only want to heat on the weekends --or want to change the temps all day long .. best do something else.

I use my radiant to maintain a set temp in my studio and bump it up when I arrive for a few days.. a week or month. -- I also have a propane sealed combustion unit that helps when I arrive.

Working in a large open space with radiant is great -- ideally you want enough BTU's to heat the first 8'.

 

[bzinsky]

In floor is not more expensive to operate unless it was designed/installed improperly OR you start cranking the thermostat up/down in large increments. You only need about 1/3 the BTU to heat the same space as compared to forced air.

You need the same amount of output btu's to heat any space, the input btu's is what changes with in-floor radiant.

The efficiency advantage from in-floor comes solely from it's ability to use lower water temps.

While it is indeed efficient, 1/3rd is a ridiculous exaggeration when talking about just the source of heating.

Any massive changes in efficiency are without a doubt due to design of the system and the heated space itself and have little to do with type of heat.

 

[forAK]

I work occasionally in a shop with hydronic floor heat.

I love how quiet it is when the shop machines aren't running and it's comfortable without being warm (at least on a cold day, more on that later).

I do think it's ideal for shops with tall ceilings since the heat is concentrated near the floor. Climb the stairs or a ladder in this shop and it gets cooler as you go up.

Snow melt/evaporation and recovery times on a cold day are great, even if the overhead door is left open for a while for unloading something.

What I don't like about it has to do with our local climate. We get a lot of temperature fluctuations and warm days following cold nights.

These warm days are not comfortable when the slab is still cooling down. When I pull up on a somewhat warm day and see the overhead doors raised part way I know it's going to be uncomfortably warm in there.

I have read about ways to design for this but only for home applications. I don't recall much about it but I believe they could be applied to a shop situation.

For what it is worth, everyone local I know who has had in slab hydronic heat has not done it in their next home or shop. In one case it was due to initial costs but in other cases it had everything to do with the slabs holding too much heat on these swing days we have.

I would still want it in my dream shop but I would take care to make sure it was designed correctly.

Out of curiosity, is your boiler a newer mod/con boiler with outdoor reset? I haven't noticed temp swing days being an issue.

 

[Voi]

Out of curiosity, is your boiler a newer mod/con boiler with outdoor reset? I haven't noticed temp swing days being an issue.

Not my shop so not sure. I know they were considering a new boiler so it's likely the system was never designed well. As it is they're going to add a forced air heater and keep the floor heat lower.

However, other people with radiant floors in my area have mentioned the same thing but it's hard to gauge the degree without having been in these shops or homes myself. Actually I have been in one of them but he's the one guy who said he'd do it again if he could afford it.

I don't know what your swing days are like in Alaska but here they are significant and frequent.

 

[2012Eli3]

If your up on stairs or ladder in a radiant heated floor shop and its "cooler" there is probably no insulation or vapor barrier. Its just a drafty building with a heated floor. Probably same reason your swing days its uncomfortable because no insulation keeping heat out.

 

[Randy in Maine]

If your up on stairs or ladder in a radiant heated floor shop and its "cooler" there is probably no insulation or vapor barrier. Its just a drafty building with a heated floor. Probably same reason your swing days its uncomfortable because no insulation keeping heat out.

Not mine. R40 everywhere as I have SIPS. Cooler at the top of the 12 foot ceiling by about 5º. Radiant heat radiants. Hot air rises. That is all right as I want it warmer where my feet are.

 

[kabinenroller]

This subject always seems to create controversy. I will state my opinion and leave it at that, no more response from me either way.
My shop is 40x60 with a 9' ceiling, stick built with a full foundation. I designed the building and the infloor heating system. The building was built and designed to keep the heat in and the cold out.
I over insulated the foundation, the walls, and the ceiling. The doors and windows are energy efficient and everything is finished drywall.
I use a Wall mounted boiler and have 5 loops of pex.
The building Does not cost that much to keep warm. I have the thermostat set at 60 and never touch it. I do not shut the system down ever, in the summer I once and a while run the pump for a few minutes ( not the boiler) just to circulate the fluid.
Everything in the building is the same temperature + or - a degree or two when I use my infrared tool, no matter if it is a machine, the floor or the ceiling.
I would not even consider any other type of heat.

 

[Voi]

If your up on stairs or ladder in a radiant heated floor shop and its "cooler" there is probably no insulation or vapor barrier. Its just a drafty building with a heated floor. Probably same reason your swing days its uncomfortable because no insulation keeping heat out.

The excessive warmth in the shop happens even when it's cooler inside than outside. Like on cool rainy days we can have the overhead doors raised a few feet and it's still borderline uncomfortable in there. The building just doesn't cool off quick enough. If anything that suggests the slab and/or building are too well insulated but maybe it's the opposite and the system has to work extra hard on the nights before days like this and that's why the slab is warm.

I'm not sure where you're coming from with the cooler temps near the ceiling suggesting no insulation or vapor barrier. This effect is discussed frequently on this site and others. It is considered a good thing.

 

[mygarageone]

The excessive warmth in the shop happens even when it's cooler inside than outside. Like on cool rainy days we can have the overhead doors raised a few feet and it's still borderline uncomfortable in there. The building just doesn't cool off quick enough. If anything that suggests the slab and/or building are too well insulated but maybe it's the opposite and the system has to work extra hard on the nights before days like this and that's why the slab is warm.

I'm not sure where you're coming from with the cooler temps near the ceiling suggesting no insulation or vapor barrier. This effect is discussed frequently on this site and others. It is considered a good thing.

I have read what you have said about your heating system and how it gets to warm when it warm outside etc. I have never experienced that in my shop , never and I have not experienced this from any of the jobs I installed .

I can not figure out why you are experiencing this issue ? Has to be a design or install problem .

 

[yeldogt]

A properly insulated slab with enough loops is able to modulate better vs one that has fewer loops. Poor slab insulation results in greater water temps needed .. so hotter slab.

Radiant high mass floors do suffer from potentially overheating the space in the shoulder seasons -- it is best mitigated with proper outdoor reset and the use of a slab temp sensor.

I turn my on/ off temp to a higher setting at this time of year -- and use the slab sensor to limit the temps. You don't want the slab to continue to heat in the morning ...

In a home setting w/ ducted AC -- installing a heat pump is a great solution. In early spring I turn the radiant down and use the HP to bump up in the morning and evening -- when the system is off I have the heat pump to inject some heat on those odd colder days in the late spring and early fall.

 

[Voi]

I have read what you have said about your heating system and how it gets to warm when it warm outside etc. I have never experienced that in my shop , never and I have not experienced this from any of the jobs I installed .

I can not figure out why you are experiencing this issue ? Has to be a design or install problem .

I wouldn't be at all surprised if this system in particular wasn't designed well. But others in my area have noticed the same thing whether it be in a shop or a home. I find it hard to believe all of these systems were designed poorly.

I think anyone who has spent considerable time in a shop with floor heat has noticed how quickly the comfort level rebounds after a large overhead door is left open for a few to several minutes on a cold day. That's a good thing and one of the benefits of floor heat.

So it's not hard to imagine that the same effect could be a problem if there is a rapid and significant temperature shift from cold to warm.

OP didn't have his area listed so I thought I'd mention it. If he was in the great lakes area like you or like where I grew up I probably wouldn't have said anything.

 

[theoldwizard1]

Here in northern MN I love my in floor, the heat is on from mid Oct to May set at 55* which is perfect for me working in there.

Typically I use the shop 4 to 5 days a week and find that it is very much worth the effort and cost of installation.

If you are not going to use the shop a lot, have a lift (so you are not working on the floor), like working with cold equipment and tools then in floor might not be for you.

On the other hand if you use the shop a lot, work on the floor, like warm feet, enjoy warm tools and equipment and want ease of use then go for it.
ours.

And that is the REAL bottom line. COMFORT !

Comparing cost of operation is EXTREMELY DIFFICULT ! Way too many variables. I still believe that a properly designed, well insulated, building with in floor, radiant heat would not be "significantly" different cost of operation over a heating season, UNLESS the "other" system used a different fuel OR had a set back thermostat that lowered the ambient temp for 8-12 hours per day.

 

[forAK]

Not my shop so not sure. I know they were considering a new boiler so it's likely the system was never designed well. As it is they're going to add a forced air heater and keep the floor heat lower.

However, other people with radiant floors in my area have mentioned the same thing but it's hard to gauge the degree without having been in these shops or homes myself. Actually I have been in one of them but he's the one guy who said he'd do it again if he could afford it.

I don't know what your swing days are like in Alaska but here they are significant and frequent.

I can guarantee our swing days are no way near yours! LOL Maybe a 20 degree difference. Just seems to me that an outdoor reset and mod/con boiler would be able to keep the slab at a cooler temp as the temp swings outside.

I could see it being a problem as that slab is one solid huge rock with heat in it and it has to go somewhere.

 

[Radix2]

There are several ways to control a radiant floor system - slab temp,air temp or some kind of combo. As well as using outdoor reset to use the lowest water temps for max efficiency.

This can help give different comfort feel to the rooms. The biggest factor though is the building insulation level. The better Insulated, the less difference between slab and air temp that is required.

In my just finished building which has foam and dense pack cellulose insulation, I use slab temp for control. I see only a 3-4 degree difference from slab temp to air temp. So typically the air is at say 68, the slab is 71 and still feels "cool" to the touch.