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Author Topic: Plate heat exchanger questions  (Read 3728 times)

abarton

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Plate heat exchanger questions
« on: January 09, 2012, 04:18:24 PM »

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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muffin

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Re: Plate heat exchanger questions
« Reply #1 on: January 11, 2012, 09:28:01 AM »

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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abarton

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Re: Plate heat exchanger questions
« Reply #2 on: January 11, 2012, 05:30:25 PM »

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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muffin

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Re: Plate heat exchanger questions
« Reply #3 on: January 12, 2012, 08:42:12 AM »

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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abarton

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Re: Plate heat exchanger questions
« Reply #4 on: January 12, 2012, 10:26:35 PM »

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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RSI

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Re: Plate heat exchanger questions
« Reply #5 on: January 12, 2012, 11:32:28 PM »

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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abarton

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Re: Plate heat exchanger questions
« Reply #6 on: January 13, 2012, 04:04:36 PM »

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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bigbird1

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Re: Plate heat exchanger questions
« Reply #7 on: January 13, 2012, 07:01:10 PM »

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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Ridgekid

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Re: Plate heat exchanger questions
« Reply #8 on: January 13, 2012, 07:37:33 PM »

bigbird- I got a 20 plate and have it running the same way. Do you use your HWH as a storage tank?
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