Costs of using radiant floor heat in the shop?


My shop is under construction this week and next, a 30'x26'x12' pole building. The floor is my responsibility, and my thought was to install 2" foam insulation on the gravel then pour my concrete on top of that with the pex tubes in the concrete.
My area is a Zone 5 usda, meaning we have signicant below 32 days, and some days below 0 every year.
Is there a fellow wrecker that uses radiant floor heat that could comment on their fuel source and their cost of operation on a month to month basis?
Thanks Alan
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arw01 wrote:

I used to work in this shop and it had radiant heating. http://tinyurl.com/q8pzu The comfort level is unbelievable even with several doors roughly 60'x200' and below zero temps. I wouldn't worry about a few pennies a month, even if it does cost a little more radiant is the way to go.
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One thing I'd comment on is that I BELIEVE (note emphasis) that the under-floor radiant heat systems are slow to warm up, and slow to cool down. In other words, you're not just going to crank up the heat when you walk in the shop each morning (or on Saturday morning, if you're a weekend type dude/tte), and enjoy toasty-warm temps right away. You'll waste a lot of energy (i.e. $$$) with fluctuating temps.
My kids cranked up the basement underfloor heat in a rental property we were in, and it took days for it to cool off to liveable temps again.
Clint

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I would like to second the remarks by Clint. We have radiant and love it.....but, since the bathroom is on the same zone as the bedroom, we always have a cold bathroom. Warmup time is lots of hours; shop is not a good application for radiant. I use a through the wall indirect hot air heater in my shop.
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Dave W wrote:

What is an indirect hot air heater?
My shop/garage is unheated and I can't tie into the house because it is forced air. My propane torpedo heater warms it up quick but man does it stink.
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wrote:

I have radiant heat in my house and it is superb. We use a Buderus (sp?) G215 oil fired boiler. It takes about 48 hours for the house to reach temp. After that the boiler fires about 30% less as per my estimates. Thus, not only is the *feel* of the heat superior, the system saves about 500 gallons a year. I live in coastal NH.
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arw01 wrote:

Two things come to mind: you don't need to insulate from the ground under the building, unless that ground gets cold somehow. With a heated building atop it, it doesn't get cold. So, what use is that insulation? Unheated buildings aren't kind to tools (you get condensing moisture and all the chisel edges rust), so that isn't a pleasant branch to consider.
And, concrete is less comfortable than other floors (end-grain wood makes a very nice looking industrial floor, and it's easier on the ligaments). And even if concrete IS OK with you, it does some shrinking/cracking during curing, and might damage the tubes. Settling during the next three years can open new cracks, too.
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You need to insulate either the perimeter or under the slab, or both! We do a bunch of in floor heat where I work and just about always insulate under the slab. The floor will respond faster without the heat sink of the ground below it. Myself I would not hesitate to put floor heat in a shop, even one that gets random usage. I would control the floor temp with a slab sensor, and put in a small heater like a Hot Dawg to boost the temps when needed. If the floor is warm, your feet will be warm and you will more comfortable at a lower air temp. Greg
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On Thu, 31 Aug 2006 15:58:04 -0500, "Greg O"

Correct, you will need to insulate. If not you'll have major heat loss. There are various types of insulation for slabs. I'd do some research and talk to some contractors. In my house -3 floors- it was all wood framing. In this case foil face is required.
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I can't give you numbers on operating costs, but I expect it is fairly inexpensive to operate. My shop is about 20'x28', set in the back corner of our attached garage (3 bays wide, 2 deep). Twelve foot ceilings, 6" exterior walls, 4" interior walls, all insulated. There is 2" foam under the slab and two feet deep around the perimeter. The PEX tubing runs to an ordinary propane fired hot water heater in the basement with a circulator pump, expansion tank, air bleeder, etc. The heater is set to about 90 degrees ("vacation" setting).
Here in central Ohio, I generally keep the shop thermostat at about 50-55 degrees. This keeps the tools rust-free and is comfortable for shop work on weekday evenings with a long sleeve shirt. If I can expect a full day in the shop, I'll turn up the heat before I go to bed the night before and it will be up to 65 by 7AM. I've tried higher settings, but I feel silly wearing shorts in January. I think I fire up the system around Thanksgiving, and shut it down about the end of April. Our propane tank is shared with the kitchen stove, clothes dryer and barbecue grill, so I can't separate the shop usage, but altogether we use less than 100 gallons a year. I would guess that maybe a third of that could be for shop heat.
I think the most important factor affecting your operating costs will be how well you insulate your building. The more you insulate, the better the shop will retain heat, and the less you will spend to replace the lost heat. The car parking portion of my garage has no heating, but is well insulated. Even on zero degree days, it has never dropped below forty degrees inside. I've seen the air temperature go up eight degrees just from engine heat when my wife parks her Camry.
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i have floor heat in my shop, it's great. i put the pex in the sand about 2-3" below the concrete and insulated around the slab, creates a heat storage sink. i sell outdoor wood furnaces www.centralboiler.com needless to say i heat with wood here in minnesota. burn about 12 cords a winter to heat my shop, house, dry kiln and i get my domestic hot water heated through a water to water heat exchanger. my shop is warm all winter. ross www.highislandexport.com
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arw01 wrote:

I don't have radiant heat in a shop, but I have installed systems and lived with them. Radiant would be a wonderful way to heat a shop. The heat source is where you are, not up at the ceiling or the perimeter of the space as with most alternative heating systems. Infrared would work, but I wouldn't want the exposed infrared elements in a woodshop. Your feet and legs are always the first things to get cold when standing on concrete. I notice it particularly at the end of the day when my legs are tired. Due to the efficient heating nature of the radiant heat, you'll be comfortable at a lower temperature than you would be with other systems. Most of the better radiant controls have smart thermostats - they learn how long it takes to heat up to the desired temperature and will turn themselves on at the appropriate time so that your set temperature is correct at the right time.
How much it would cost to operate is dependent on many factors such as energy costs in your area, amount of insulation, air infiltration, etc.
R
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