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-   -   Wood Stove, and Furnace hot water system (http://www.diychatroom.com/f17/wood-stove-furnace-hot-water-system-83052/)

shendog 10-04-2010 05:14 PM

Wood Stove, and Furnace hot water system
 
I have a hot water heating system question I hope someone here can help with. I recently purchased a home. The primary heat is oil hot water, but there is also a wood stove connected in to the hot water system. The system does work, and either the furnace or the stove can be used to heat the house.

The problem is this: When the valves are open connecting the wood stove to the system; the 2nd floor heat registers barely get warm. I tried bleeding the 2nd floor registers, but there was no improvement.

I examined the pumping between the furnace, and wood stove and I believe I know why this is happening. It seems to me that the plumping is not routed correctly, and the wood stove is basically in parallel with house heat registers. This is greatly reducing the pressure, and very little water is making it up to the 2nd floor.

I uploaded a basic drawling of the heating system (I can't really call it a diagram lol). Is system like this typically routed in this way? Why wouldn't the wood stove be connected in series? (furnace >> hot water system >> wood stove) I would greatly appreciate any help you can offer.

Shen

http://shenssite.nmax.net/images/heatdiagram-small.JPG

beenthere 10-04-2010 05:42 PM

If it was piped in series. then when the wood fire went out, and the oil boiler took over. You would be paying to heat the wood stove.

What pressure does your pressure gauge say the boiler is at?

shendog 10-04-2010 07:32 PM

Hey Beenthere, thanks for the reply! If the valves are open to the wood stove, and the oil furnace is running; its heating the stove anyway. If I rerouted the plumbing, with the stove in series I could add a bypass across the inlet and outlet.

I just started up the stove for the night, its already down to 49f here. I'll check the pressure guages when the circulator pump kick on.

beenthere 10-04-2010 07:36 PM

You should check it without the circ running. The circ running will make the reading useless.

AllanJ 10-04-2010 07:59 PM

You have neither a series nor parallel system as it stands.

To convert to a parallel system you need to:
1. Add a down flowing circulator at the extreme lower right or move the existing circulator higher up so it serves both the pipe to the oil furnace and the pipe to the wood stove.
2. Reverse the direction of flow to and from the wood stove (arrows at top left and bottom left). (Happens automatically when you add the circulator).
3. Use the valve at top center and the valve at top left as well as switching circulators (if you added the second) on and off to manually select wood stove or oil furnace. The other valves can be left open unless you are doing maintenance.

If you do nothing and open the valves, the bulk of the water goes back and forth between the stove and the furnace as your arrows show, and very little goes up into the house.

beenthere 10-04-2010 08:05 PM

He has series parallel piping.

shendog 10-04-2010 08:30 PM

The pressure guage on the wood stove slowly creeps up to almost 30psi as the water temp rises When the temp reach 185f the circulator pump turns on, pressure drops to about 20psi. The pressure guage on the furnace seems to read about 20psi regardless.

Hey Allenj, this is basically what a friend at work suggested. I see a couple of problems with this scenario. First the pump is bolted to a flange pile on the furnace, and would be difficult to move. The other is that very little, or none of the water flowing through the stove would travel through the furnace. As the residential hot water (Faucets, washing machine) is heated by the furnace, the wood stove could no longer be used for this purpose.

beenthere 10-04-2010 10:30 PM

See what the water pressure is when the boilers are cold.


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