Wood furnace with domestic hot water - how to hook up the hot water?

CowboyAndy

Hi everyone, I need some help. I'm not very gifted in the plumbing department.

Wait, that doesn't sound right.

Anyways, here's what I need help with. We just bought a forced air add on wood furnace that is going to be installed next week. It has domestic hot water built in to it. All there is on the frint of the furnace are 2 fittings for water pipes. I am a little unsure how to hook it up.

First of all, this will only be used in the winter, so the rest of the year our hot water comes via an electric water heater.

Can I hook it up to store hot water that has been heated by the furnace in the existing water tank?

If so, what lines will get hooked up where?

I really appriciate any and all help to get this beast installed...

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NateHanson

The simplest way to hook it up would probably be to plumb your cold water feed into one end, and plumb the other end of the wood furnace DHW coil to feed your electric heater. That way if the furnace is hot, the water will be pre-heated when it goes into the electric, and less energy or no energy will be used to heat that water. If the furnace is off the electric water heater will work just as it does now, getting it's cold supply through the wood furnace.

There are probably fancier ways to do it with circulator pumps and thermostats, etc, but I'll leave that mumbo jumbo to the plumbers.

CowboyAndy

So, what I should do is run a line from where the cold enters the tank to the furnace? (FWIW, I dont think there is any certain direction or anything on the furnace, just 2 inlet/outlets that are attached to a water jacket surrounding the firebox. I have looked, and neither seem to be directional.

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CowboyAndy

So I was thinking about it last night. Am I going to need to find a way to STOP the COLD water from entering the hot water tank?

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47_47

Nate has a great idea. Disconnect your existing cold water feed at the tee to the electric heater and use wood heater DHW coil output for your new feed. Put in a shut off valve to the cold input side of your stove DHW coil.

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What we've got here is... failure to communicate. Some men you just can't reach. So you get what we had here last week, which is the way he wants it... well, he gets it.

NateHanson

What would the shut off valve before the furnace coil do? Would you just put that there for maintenance?

I meant to have the cold water supply for the electric water heater always passing through the furnace coil first. When the furnace is hot, it'll assist the water heater. When the furnace is cold it won't make any difference that the water going into the electric heater has first passed through the furnace coil.

47_47

It would be for maintence/ service. Though not necessary for this hot water loop, I find it good practice that there be a shut off valve before every device.

__________________
What we've got here is... failure to communicate. Some men you just can't reach. So you get what we had here last week, which is the way he wants it... well, he gets it.