# Heating and Cooling with water



## kendall j (Mar 30, 2007)

I was talking with a farmer who was setting up a wood boiler to heat his home. His plan was to run it through a radiator which he would build a box for and using a blower heat the air forced through his existing ductwork.

That sounded like a good idea. He also was thinking of cooling the water by pumping it through a loop in his pond in the summer. I had thought of a similar idea using a radiant flooring model but decided against it due to condensation issues that would likely arise in this climate (eastern NC) such as mold growth in the crawlspace, etc. Would using it in this radiator/forced air set up be viable, or would the same issues arise? If so, are there work arounds in his set up that might allow it to work where it likely wouldn't with a radiant floor type set up.


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## Ross (May 9, 2002)

He needs to remember to put a condensate pan and drain under his rad to collect condensing water from the air hitting the cold coils. It won't be AC cold but it should take off some temp and humidity. I can't see it working on infloor coils without depositing water where you don't want it.


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## Fat Charlie (Sep 9, 2010)

I don't think piping the hot water direct from the boiler to the radiator is a good idea. Working up a heat storage tank with a heat exchanger along the lines of Gary's solar water heater would be better. That way your guy can get more useful heat out of the boiler and run the fire when he wants to instead of every time he wants heat.


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## Ross (May 9, 2002)

If the boiler is like ours it has a storage tank built in for a steady supply of heated water. but the fire really has to stay going at some level all the time in the cold. Essentially the 200 gal resevoir has three circ pumps pulling 4gm off to whatever heat exchanger is used with a delta T of 20 degrees. So if the water starts at 180 its 160 on the return. Unless there's a fire there the stored water temp is going to fall pretty quick at 12gpm total draw losing 20 degrees each pass through the exchangers. I'm not sure if adding another storage tank to boost the capacity of the system is helpful or not, a person could add a float system to maintain water levels at the same time in that tank. 

Garys system seems to be for DHW not space heating and yeah it looks like a reasonable way to pass generated heat (all types) into domestic hot water use. I use a side arm exchanger which has a pretty slow recovery rate but works well. (I really need to store 100 gallons of hot water for a family of 7!) There are other better exchangers like a plate exchanger and I could add a second side arm heater. I could mess with the valves and raise my delta T (which on the side arm water heater varies alot as the temp rises in the potable water side) but I'm in kind of in a happy place with it as is. There are storage tanks commercially made that pass boiler water through coils to heat domestic water too, they might have an edge over anything I'm using or homemade but they are pricey too!


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## Ross (May 9, 2002)

Kendall tell your neighbor he wants to look for a water furnace, a fan coil unit or an air handler (all the same thing). They're commercially made units to do what he is thinking of building, they take boiler water (or water heater water) and put the heat into the air. Just easier to use something premade than building something. Done it both ways Lennox makes a popular water furnace but there are many others.


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## Fat Charlie (Sep 9, 2010)

I wouldn't want to store my hot water outside. 

The plumbing details inside Gary's box don't really matter- what matters here is that he built a heat storage tank inside the insulated house. The way you harvest the heat is up to you, but if you store the heat inside then any leaked heat still benefits you, which you can't say for heat leaking from your outdoor storage tank. The only reason to have outdoor heat storage is so the outdoor boiler manufacturer can sell you a package that doesn't also require a large footprint inside the house.


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## Ross (May 9, 2002)

The fire outside is part of the point of course. I can tell you we can have a foot of snow on top of the storage tank, there isn't much heat loss!


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## kendall j (Mar 30, 2007)

Thanks for the advice everyone. I will pass it along to him when I see him next.


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## Windy in Kansas (Jun 16, 2002)

How far away is the pond and what will it cost him to pump water for cooling?

I wonder if it wouldn't be cheaper to just power an AC?


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## solidwoods (Dec 23, 2005)

Furnace plenum hotwater heat exchangers are available off the shelf. By the biggest one you can afford, that lets you run the water at a cooler temp.

For AC. He won't get a cold enough water temp to cool the house unless he uses a whole bunch of evaparator coil,, I mean a whole bunch. If he runs it through the boiler the water could pick up heat from the ambient air temp. 
I'd look at pumping pond water up to cool an ac units condenser coil. One may be able to use a much smaller hp ac unit if the condenser were cooled with 50deg water. Also add in elec/maintenance of pumping water. And the freakishness of the concept may make it hard to get a pro to put it together.
jim 
Not a fan of creating then storeing then using hot water. I create it use it repeat.


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## artificer (Feb 26, 2007)

solidwoods said:


> For AC. He won't get a cold enough water temp to cool the house unless he uses a whole bunch of evaparator coil,, I mean a whole bunch.


I agree, to a point. Chilled water cooling coils are typically 2-12 row units. Its simple math to size one, and they are also available off the shelf.

Using pond water itself would cause problems if you didn't filter/treat the water, but an in-pond heat exchanger might work. The cooling coil will have to have a condensate collection pan, and a way to drain the water to a safe place, just like a normal AC coil in the duct work. Not sure what you mean by "radiant floor model." If you mean coils in the floor, then no, it will not work. You'll have all the condensate sitting there. If you meant the coils on the wall, near the floor... thats still not a good option, since they do not provide much surface area. A box with 2-6 stacked radiators with a blower would be a good start if he can't afford one of the commercial fan coil units.

My uncle built a new house in an old corn field. He wanted a wind break, and needed some irrigation for the trees. (pines) He installed a big truck radiator in the furnace duct work, and ran the irrigation water through the radiator. For a well insulated 1990's home, it was enough cooling except on very hot days in Wisconsin. One thing it did was to dehumidify the air, even if the air wasn't as cold as you normally see with a regular AC unit. A commercial chilled water coil would do a better job.

Michael


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