Radiant floor heat..how economical ?

[DaveL.]

I see many of you guys use radiant floor heat. I was curious how cost effective is it to operate? I know there are different factors to consider,(size of shop,climate,etc)but once you have the slab up to temp are your fuel bills expensive? Just wondering....

Thanks..Dave

[MyMopar]

I am now just doing a radiant system in my house. It is a retro fit so it will be a "staple up" installation between the floor joists. My house has 4 zone heat and 1 of the 4 zones I never use (I have a wood pellet stove in that area). Anyway, radiant heat is not that difficult as long as you understand the principals and theroies behind it.

As far as your question, it is very economical. In a garage, you could use a electric hot water heater, a gas hot water heater or a small tagi heater. You could go as simple or complex as you want. Some things to consider:

1. Very important that all circuits are the same length of tubing. Don't run tubing more than 300' per run.
2. Balance the system for the supply and return. Very important if you want even heat.
3. Get the correct size pump, one that will flow the water fast but no too fast (think radiator with no thermostat)
4. If pouring a slab, secure the tubing with zip ties. Always draw out a plan and make sure the runs are less than 15' difference in length. My uncle did a sunroom with a hot tub in it. When done, all 6 "circuits" were within 1 FOOT of each other in length, now that is planning.

Any other questions, just post up. The basic idea for tubing is to run 8" on center. I believe you can take the square feet, divide that by .75 and you will get a rough idea of how much tubing you need. The tubing isn't that expensive.

Also, if doing a slab install, when pouring the slab, have the tubing pressurized, that way if something happens, you know now and not after the floor has been cured.

Other things to consider, concrete takes time to heat and cool off. While it is just a garage and you might be able to deal wit hthe swings, if you really plan on spending time out there or have a high value car/tools, it would be wise to invest in a computerized controller. These controller aren't cheap, could actually cost moer than anything else you buy for the job. But they are worth every penny. What happens is the controller knows time of day, senses sunrise and sunsets, reads outdoor temp and indoor temp and factors all this into the controll of the floor. The main key is that if the sun is rising and it was 45* yesterday, it will know the precise time to kick on to keep a constant temp. Also as the sun sets, it knows it must kick on earlier because the radiant heat from the sun is gone. I think you can get the picture.

[bmwpower]

1. Very important that all circuits are the same length of tubing. Don't run tubing more than 300' per run.

Should you also consider location? If you have one circuit running along the wall (which will lose more heat in winter) and one running in the middle of the room, does the system somehow compensate?

[cork]

How do i selelct a water heater ? I have a 32x42 detached with 12' ceilings. Ceiling will be insulated R30. Walls are block and uninsulated. I think i want to use an LP fired water heater.

[86turbodsl]

I have radiant heat in my shop. It can be very economical to run, but you really need to be insulated well. It should be installed by a pro unless you are skilled enough to do a heat loss analysis. Nobody can tell you how big a water heater to get without you getting a manual-j analysis.

[ultgar]

There are some pretty good rebates from utility companies these days for high efficiency boilers. Water heaters, while cheap, are not that efficient. In NJ, after a $750 rebate, there are some pretty good boilers that can be had below $1500 net.

I'm currently redoing the heat in my garage and home office with a pair of 92% efficient Munchkin units. Working with the local rep yesterday, we managed to get a fair amount installed and hope to start running Pex after another few days.

http://www.ultimategarage.com/munchkin-20406-1.jpg

http://www.ultimategarage.com/munchkin-21706c.jpg

[z28toz06]

Check this web site out http||www.radiantec.com You can learn a lot there.

TEK MAR makes a controller for the heat system that will compensate for outside ambient temperature swings. So if its 0 out it will heat the water to 140 degrees. if its 40 out it will heat the water to 110.

Also if you will have flammables in there get a heater or boiler with a sealed combustion unit.

Get a hold of zo6vetteman, he has taught me a lot and knows his stuff.

[dlynch]

Beautiful installation! Workof art.

Dave

[Cheapstreet duster]

very neat and great info..
i have a little story to tell..
my grandfather had a custom house build on a lake (centenial in NJ)
they used Radiant floor heat in it.
because the mechanic shop used it and my grandfather liked the idea
well they installed a system in the driveway and walk ways outside the home
to prevent the snow from collecting and he wouldnt have to shovel the snow or ice off..
they only used it when the weather was needed
the system worked flawlessly and the snow never developed on the driveways
but at night the stray dogs and cats would congregate on the area to
stay warm and they would fight and cause a general ruckus...all night to the
point that my grandmother stop using it..
funny how things go...
JF