Hot Water Heat

[Av8r3400]

... cause I can't spell hydraunic, that's why.

I'm building a house this spring and I am considering using a hot water heating system.

Specifically:

• In floor in the basement and garage concrete
• heat exchanger type water heater
• air-handler/heat exchanger with ac for ventalation in the rest of the house.

I have envisioned eventually adding (in the future)

• more under floor heat in some other areas of the house (under tile)
• possibly (if someone markets a decent one at a reasonable price) an outdoor wood boiler.

I know there are some hvac folks here, what can you tell me about this type of system other than it is $10k more than a regular forced air system. Links to good information?

I need some of the collective FF wisdom, please.

 

[bczoom]

I'm far from being a HVAC guy but have heard a lot of good things about the newer outdoor wood burners. Thinking of getting one myself.

 

[dzalphakilo]

www.radiantec.com

Never worked with, or used this company, but looks to be useful to the homeowner.

 

[Raspy]

There is no better heat than in-slab radiant.

There is also a lot of hype and overcharging for stuff.

Some basics are these:
Use 1/2 inch PEX oxygen barrier tubing.
Space the tubing at 12 inches by tying it to rebar at the same spacing.
Tubing in structural slab is best, topping slab OK.
A topping slab upstairs over subfloor is best, in joist bay OK but hard.
If installed in joist bay under floor, do not use fins on tube.
A loop should go to the perimeter and then back and forth to center.
Keep each loop at a max length of 300 linear feet.
Try to make the loops about the same length, more loops is better.
Install in all areas of the room to be heated.
Hold it back from the perimeter about 1 foot or so.
In bathrooms run the tubing closer, maybe 9 inches.
Don't kink the tube!
Make separate rooms separate loops so you can balance the heat.
Use a good quality manifold like Zurn for easy zoning and good conections
A thermostat will control a group of loops.
Make separate rooms and separate levels on separate thermostats.
Use programmable thermostats to adjust heat level at different times.
Adjust your supply water to about 120 degrees max.
Keep the heating system as a closed loop with about 12 to 15 PSI cold.
Expect an average floor temp of about 80 to 85 degrees for comfort.

This is just about the distribution side. I can suggest on the supply side if you wish. Have fun!

 

[dkmclean]

If your going to heat a concrete slab be sure to use 1'' to 2'' of good styrofoam under the slab and along footings.
Also, be prepared to burn 8 to12 cords of fire wood per season.
A good chain saw is a must.
I heat a 32'x32' garage and the house with this system and burn around 12 cords.

 

[bczoom]

I heat a 32'x32' garage and the house with this system and burn around 12 cords.

Damn, that's a lot of wood. A cord being 4x4x8.

You didn't say where you're from but getting/prepping that amount of wood makes me wonder if it's cheaper to just turn on an electric, air-blown heat.

 

[Av8r3400]

Must be running an outdoor wood-waster.

 

[bczoom]

Must be running an outdoor wood-waster.

Please elaborate (including starting a new thread) if you would.

Are the outdoor wood burners that inefficient where they flat-out waste a large degree of wood? I was thinking of getting one.

 

[nixon]

Please elaborate (including starting a new thread) if you would.

Are the outdoor wood burners that inefficient where they flat-out waste a large degree of wood? I was thinking of getting one.

I don't have one , but it seems that You either swear by them ,or at them .
You can find posts about them at these two sources ,to name but two.
http://www.hearth.com/econtent/index.php/forums/
http://www.woodheat.org/

 

[Raspy]

It's hard to accurately generalize about how much wood you will need. And whether you deliver the heat to the slab or to the air you will still be faced with the same overall losses from the building.

Radiant can be the most effecient delivery system because it does not pump air around and against the cold windows, it runs at a cooler setting, you only heat the areas you are using and it can be tied easily into solar. If you go with gas you can get boilers that run at 95% efficiency and will heat your domestic hot water too.

Out west I design for a 7 BTU/sq ft loss and a delivery of about 25 BTU/sq ft or more.

Even if the cost to operate was the same as forced air, or even if it was higher, there is nothing like having a warm floor in places like the baths, the shop and the basement, or even for snow melt.

Slab insulation becomes more important around the perimeter if you don't hold the tubing back from the edge. But underneath, as long as the ground is dry, it's not that important. It makes for a slightly quicker response but not much extra heat loss. Again, depending on the layout.

It's not accurate to generalize that radiant will cost $10,000. more than air. It may be more but the big extra cost is the slab and you may be able to avoid that. I find a lot of people want to do some of the work themselves and that saves a lot. The tubing installation can easily be done by a homeowner or builder, then the boiler can be set and fired up by a qualified installer. I do this all the time.