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nwngunner 01-25-2014 03:49 PM

Massive DIY undertaking
I am currently working on my house. The project consists of a full gut to the studs, rewire, new pluming “water and gas” windows doors roof everything.
Give some info about the house, the house is about 1500sq feet upstairs. There is a 24x24 section of the house that is on a slab that will not have forced hvac. The remainder of the house about 1000sq will be over a finished basement with a walk out door on the north end.

Currently there is only one main duct in the house and is going to be torn out. I am in the country and have a free standing wood furnace in the house, along with a new direct vent “condensing “gas furnace. The current lay out of the house, I want to do four zones. First will be the kitchen and eating area of the house. Second will be bedroom #1 and laundry area. Third will be the master bedroom and bathroom. The finished basement will be the fourth and final zone. The basement is going to be our primary living space, however we do have a working wood burning fireplace.
I am planning on putting both the wood and gas furnaces in to a single plenum, using a four zone controller with spring close power open dampeners. I am still working on my load calcs for each of the living spaces, for the cfms required for each.
What I want to do is the following. In the winter use the wood furnace as the primary source of heat in the house. However I want the gas to be a backup in case we are gone and the wood burns out. Now is there a four zone controller that will accept two thermostat outputs, one for each furnace. Otherwise how will that work? I know I am going to need a thermostat that has four probes for the different sections of the house.
Also there is a 2.5 ton Lennox central air unit, that goes with the gas furnace.
The other size of the house, approx. 570 sq feet will have a split wall mounted ac/heat pump installed. With the rooms being on a solid slab I don’t have any options.
The basement will have an r20 thermal break on steel studs with fiberglass drywall to prevent any mold or mildew issues if we ever have any water issues. The rest of the house is going to be r13 in the walls, with spray foam of 6 inches in the ceilings. The sad part is the ceilings are so low in the house I have to leave them vaulted and spray right to the sheeting. Doesn’t leave me much room for insulation but not much I can do. Anything will be better than the nonexistent insulation that was in the house before.
I know most of you are going to tell me to get a contractor to do the job. I am in no position to be able to afford to pay someone to come in and do the job that I can do. The last job my folks had done was imo substandard and out of the world expensive.

Thank you for any and all input you can provide.

beenthere 01-26-2014 04:49 PM

You'll need to add a relay that the zone panel controls to be ale to control both the wood stove and gas furnace.

You'll probably end up with 4 thermostats, and a 2 stage zone panel.

nwngunner 01-30-2014 04:20 PM

To make my life a little bit easier in the long run. I am not going to use forced hot air off of the wood furnace. After some looking, my wood furnace is provisioned for hot water. So what i am thinking is when i build my new plenum is to add another heat exchanger. Go from the wood furnace with a pump to the gas furnace plenum. How ever, what i am confused about, is what do i put in for filling the system. Do i need to build a spot to fill the system? Also can i run the boiler with good pex line or do i need to hard line it. Along with, is an expansion tank needed. I know a pressure release valve is needed, along with a drain port.

beenthere 01-30-2014 06:13 PM

Expansion tank needed and required. pipe a water feed line to it from your cold water line. Pex will be ok, if sized right. And you will need a drain port on the boiler. plus one for purging the system when you fill it.

nwngunner 01-30-2014 07:02 PM

I went and looked at my buddies out side wood burner. He has a pressure releife valve and that is all. He has a fill valve on the wood burner where he uses a hose then mixes in the correct amount of rv antifreeze.

I am going to be doing the same thing. How ever do i need to let the pump run constantly to keep moving the water so its always hot, or put it on a relay so that it only runs the pump when the furnace blower runs.

My wood furnace is a natural draft and has a powered damper on the front. I am thinking, i might take put a small blower fan on it, and have it run when the house calls for heat. Your thoughts?

nwngunner 01-31-2014 03:39 PM

So after doing some more digging, i found what i was wanting to do is impossible. Thanks to the limitations of the wood furnace. How ever i did discover that my grand parents, when they had the new gas furnace installed set it up as an addon to the wood furance. So that just made my life alot more simple.

Was thinking about placing a 5th thermostat with a remote probe in the plenum comming off of the wood furance. Then take the thermostat and tie it in to the lp furnace and set it to say 50. That way if the wood ever goes out when i am gone it will kick in and the zone controler will never know the difference.

That is unless if the two stage controler i got will do that for me?

beenthere 01-31-2014 06:43 PM

Not sure that panel will do what you want to do.

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