Wood boiler piping

Robert O'Connor_3

A friend of mine has a Hardy H-4 wood boiler that he wants to install. He just put up an implement shop and had a contractor install oxygen barrier pex in the slab for heat. For whatever reason he did not use the contractor to hook up the wood boiler to the system. The only thing he got from the contractor regarding heat load was 77000 btuh. He put in 3/4" pex on 16" centers with 6 circuits.
He also wants to tie the boiler into his house boiler for supplemental heat.
I have a couple of questions:
1. He wants a simple control design for the shop. I'm looking at putting in a valve to mix down to 120-130 degrees for the floor and running the pump off of a t-87 stat. Any thoughts?
2. I looked at the wood boiler and noticed that it runs at 0 pressure. Meaning, you can look right in the top of the water jacket at the water circulating. I'm assuming that the circulator pumps actually work as pumps and create lift to the system unlike a normal house circulator. So... how do you tie it in with the house pressurized system. I thought about using a nurse tank or a heat exchanger in the house to keep the 2 systems seperate. Am I off the wall or on track? Thanks for any responses. Matt

Arthur

Wood boiler

Provided the boiler is ABOVE the radiant pipe in the floor (well actually the higher the better) there is no reason why it shouldn't work oK, How do you intend to mantain the water level in the boiler, You would probably need a feed tank mounted at the same hieght as the boiler. hope the boiler is covered in as otherwise you could get a lot of evapouration from the water if its exposed to the atmosphere. Pump from the top of the boiler to the radiant and bring the return back in at the bottom. Is the Boiler steel or what as with a open boiler to the atmosphere there is likely to be a lot of air (oxygen) infiltation to cause corrosion if it's steel.

Robert O'Connor_3

Astually there is a cover that you can pop off to look in at the water.

kevin coppinger_4

wood boilers can be ...

such a headache...is there a dump tank of say 1000gals. You will definately have to go with at least 1 heat x-chger. Did the contractor give him the lenghts of each loop/circut? Most wood set up from what i have seen require a lot of piping AND controling...more than most wood boiler people types are willing to spend.get with the Mfg. and see what they reccommend...HR has done many of these and knows a lot more than me...kpc

Steve Ebels

Hardy wood boilers

Have a float and solenoid system to maintain the water level in the boiler. This is why they require a third line to feed fresh water to fill the boiler. They are stainless steel inside and out. Yes, use a mix valve to get the water temp down to the floor. Yes, you have to use a heat exchanger to isolate the house side of the system. Getting rid of air in a 0 psi system is nigh to impossible and the O2 will eat whatever ferrous components are in the system. Use bronze or stainless pumps on the open side of the boiler and piping. Wood boilers work well but they do have a lot of "issues" you have to deal with.

If you install them using iron pumps, polyethylene tube, unrated heat exchangers like the local hack does, then all this stuff must not make a difference to you.