Outdoor Wood Furnace Info
All-Purpose OWF Discussions => Plumbing => Topic started by: abarton on January 09, 2012, 04:18:24 PM
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I have a twenty year old Taylor wood boiler that i have been rebuilding. It came with a factory installed domestic coil and not knowing the condition of it, I opted to remove it in favor of the plate type heat exchanger. My question is do plate heat exchangers supply a continuous supply of hot water for domestic use and what is the average temperature of the water. Also what gpm pump are ya'll using that seems to work best.
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I have a 20 plate exchanger for my hot water. They do supply endless water as it is made on demand. I would say my water is very close to the boiler temp. I have a mixing valve to cool it off. I initially had a small taco 09 pump and it did fine. I think that is around 8 GPM. I upgraded to a 30-40 GPM pump for my pool exchanger. Still works great. I even have a bypass on it so only part of the flow goes through it.
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Thanks for the info. I guess I'll be fine with the thirty plate then. I too have a pool and toyed with the idea of later on heating it. What kind of discharge temps do you get above water temp (delta-t) and how many gallons is your pool and what size hx are you using for that? Hope thats not too many questions. Thanks Andrew
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No problem. My pool is indoors and is 25K gallons. I will caution it is a big load on the furnace, but by far the cheapest heating option except solar which I use in the summer. My system is a salt water version so I had to go with the more expensive titanium tube in shell type. I got a 155K BTU exchanger. I do not seems to be getting that out of it though, but I put it at the end of my line so it gets the leftover heat when nothing else needs it. I get about a 20* boiler temp drop across it and the pool water increases about 5-10 degrees at ~60 GPM. So it runs for 4-5 hrs per 1-1.5 degrees increase. I got a really nice thermostate for it that has a 0.3*C differential. I loose about 1-2 degrees a day into the earth :(. My water table is very high and despite all my efforts I still get water behind the liner which really draws the heat out.
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Thats pretty good for 60 gpm. Thats almost 500 pounds of water per minute!! Thats about 500k btu but I did'nt figure the degrees C. but thats still pretty close. What size heater do you have?
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Thats pretty good for 60 gpm. Thats almost 500 pounds of water per minute!! Thats about 500k btu but I did'nt figure the degrees C. but thats still pretty close. What size heater do you have?
My calculations don't match yours. I get about 30,000 pounds of water per hour at 60gpm. That comes out to 150K btu at 5 degree rise or 300K for 10 degree rise.
If the boiler water temperature is dropping 20 degrees and the pool water is rising 5 degrees then assuming the 60gpm is correct then the boiler water is going 15gpm.
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Sorry your correct RSI! It was late and I was just guessing at it. I did not know if the formula would work with centigrade measurements or not. Since you pointed it out I grabbed a calculator and came up with the same thing GPM=.002xBtu/deltaT
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I went with the 30 plate, we can take two showers and run the washer, but I was always one for over doing things, it puts out close to what you have the boiler temp set to , so if you have kids put a mixer in line. My wife likes it hotter for dishes and cloths so I didn't put the mixing valve in yet.
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bigbird- I got a 20 plate and have it running the same way. Do you use your HWH as a storage tank?