US Stove 1600 - Hot Water Coil

[08brute]

I need your opinions.

Here is my setup: US Stove Clayton 1600m Wood Furnace in the attached garage, ducted into the house and tied into the original duct work, 3200 sq ft home (New construction), cold air return from the house also ducted to the furnace, heats the house very well (propane backup)

Here is my goal: The stove is in my oversized 3 car garage (960 sq ft) and i am looking to heat the garage with my Clayton as well as the house. The garage has 6" walls and is insulated. Just the radiant heat from the wood furnace keeps the garage temp about 20* above the outside temp.

Here is my question: If i install the US Stove DHW coil ($199) and a pump, controller, and water storage and pump the water through an A coil sitting on a seperate furnace fan would it put off much heat to heat my garage? Would i be better off putting a T in my duct work and sacrifice some house heat for the garage? For some reason I feel like i am wasting some heat by not utilizing the DHW option.

What do you folks think? I already have an A coil, furnace fan and water storage (old propane tank).

On a side note - Could i rig up my own DHW coil instead of dropping $199 on US Stoves version? What about using a U shaped steel or copper pipe?

Thanks in advance for the input.

 

[smokinj]

I have about the same set up as you and I went with the tempering tank method no pump is need and it will even help with warming the water in the summer months. you just need a non working hot water tank with in 10 feet of your furnace.

(broken link removed to http://www.hilkoil.com/domesticcoil-install.pdf)

 

[laynes69]

Your better off running a duct or a register off the main trunk for the garage. I don't think you will get enough heat from the hot water to heat the garage. Those loops are for heated water for showers and such. If you don't have a problem heating the house with the woodfurnace, then i'd run a duct for the garage. Place a damper in the line so when you need it you could open or close it.

 

[smokinj]

Your better off running a duct or a register off the main trunk for the garage. I don't think you will get enough heat from the hot water to heat the garage. Those loops are for heated water for showers and such. If you don't have a problem heating the house with the woodfurnace, then i'd run a duct for the garage. Place a damper in the line so when you need it you could open or close it.

lane I was going to do just that heat a couple back bedrooms that way and I have all the parts and pex ran.It will take 2 of those coils to pull it off. So for now I am selling the parts and going to keep it simple. It can be done but I have 1000.00 in just heating the dhw.

 

[lexybird]

why take forced air and convert the btus over to water then only to go back to forced air ..seems counterproductive and inefficient

 

[smokinj]

why take forced air and convert the btus over to water then only to go back to forced air ..seems counterproductive and inefficient

the way iam running mine there is no more room for ducks the pex is much smaller and I am already heating my hot water that way.

 

[Gooserider]

As a basic principle - the annoying laws of physics dictate that heat exchangers will ALWAYS hurt efficiency, so you will lose something every time you go through one... If you have a water HX loop in your fire box, you will either lose combustion efficiency because of the cooler firebox, or you will get that much less heat at the air HX. If you have the HX loop on the air side, it will take heat away from the ducts without doing anything to the burning properties (the firebox has no way to know what it's heating)

In general theory, you are best off making heat in the form that you will be using it, so transferring the heat to air would be more efficient than heating water and then using the water to heat air; but the fact that water is so much easier to move around, and it's greater efficiency as a transfer medium make it better in actual performance...

That said, if you have constraints that keep you from using the ducts to move heated air, the proposed heating water and going through some variant of a Modine style coil & fan heater will work, but you will lose efficiency - this might or might not be a big issue depending on how you do things. I would NOT use the same loop for both heating and DHW, as that might result in drastic DHW temp drops when the heater turns on. Also I would suggest that even though it's a less effective heat transfer medium, you should make the garage loop a glycol loop in order to avoid risks of freezing it.

Gooserider

 

[smokinj]

As a basic principle - the annoying laws of physics dictate that heat exchangers will ALWAYS hurt efficiency, so you will lose something every time you go through one... If you have a water HX loop in your fire box, you will either lose combustion efficiency because of the cooler firebox, or you will get that much less heat at the air HX. If you have the HX loop on the air side, it will take heat away from the ducts without doing anything to the burning properties (the firebox has no way to know what it's heating)

In general theory, you are best off making heat in the form that you will be using it, so transferring the heat to air would be more efficient than heating water and then using the water to heat air; but the fact that water is so much easier to move around, and it's greater efficiency as a transfer medium make it better in actual performance...

That said, if you have constraints that keep you from using the ducts to move heated air, the proposed heating water and going through some variant of a Modine style coil & fan heater will work, but you will lose efficiency - this might or might not be a big issue depending on how you do things. I would NOT use the same loop for both heating and DHW, as that might result in drastic DHW temp drops when the heater turns on. Also I would suggest that even though it's a less effective heat transfer medium, you should make the garage loop a glycol loop in order to avoid risks of freezing it.

Gooserider

yep thats where I am at two loops is just a little to much for my system. Still think it can be none with good seasoned hard wood but for sure maxing it out all the time not for me...trying to use less wood.