how much 3/4"copper tube do i need to put into a 800 gallon tank to get a reasonal tempature gain from a 700 000 btu boiler would like to heat it 50 degrees an hour thank for your input.
heat tranfer info
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PassionForFire&Water
Minister of Fire
I gathered some more info elsewhere: how many feet of copper tube 3/4†do i need to put in a 800 gallon tank to heat it to 180 in 4 hours with a boiler that puts out 700000 btus
So, it looks like you want to heat 800 gallons from 130F to 180F (delta T = 50F) in 4 hours
How many BTU's you need?
> 800 gallons x 8.35Lbs/gallon = 6680 Lbs of water x DElta T of 50 = 334,000 BTU overall
Or 334,000 BTU / 4 hours is 83,500 BTU/hour.
This is not a big number, so instead of using copper I would suggest to use a water/water flat plate heat exchanger that can handle this load of 83,500 BTU/hour,
You just need 1 additional pump/circulator and control.
To design it for a copper coil you need more info: tank dimensions, insulation value for tank, Temp of area where tank is located, ...
An "educated guess" would be 3 to 4 pancake coils 100' long (OD 5/8") connected in parallel and a balanced flow path.
These 4 coils would run you already $300 to $400.
The capacity of the tank seems a little bit undersized for the boiler, or vice versa.
Curious what others have to say.
So, it looks like you want to heat 800 gallons from 130F to 180F (delta T = 50F) in 4 hours
How many BTU's you need?
> 800 gallons x 8.35Lbs/gallon = 6680 Lbs of water x DElta T of 50 = 334,000 BTU overallOr 334,000 BTU / 4 hours is 83,500 BTU/hour.
This is not a big number, so instead of using copper I would suggest to use a water/water flat plate heat exchanger that can handle this load of 83,500 BTU/hour,
You just need 1 additional pump/circulator and control.
To design it for a copper coil you need more info: tank dimensions, insulation value for tank, Temp of area where tank is located, ...
An "educated guess" would be 3 to 4 pancake coils 100' long (OD 5/8") connected in parallel and a balanced flow path.
These 4 coils would run you already $300 to $400.
The capacity of the tank seems a little bit undersized for the boiler, or vice versa.
Curious what others have to say.
PassionForFire&Water; said:I gathered some more info elsewhere: how many feet of copper tube 3/4†do i need to put in a 800 gallon tank to heat it to 180 in 4 hours with a boiler that puts out 700000 btus
So, it looks like you want to heat 800 gallons from 130F to 180F (delta T = 50F) in 4 hours
How many BTU's you need?
Or 334,000 BTU / 4 hours is 83,500 BTU/hour.
This is not a big number, so instead of using copper I would suggest to use a water/water flat plate heat exchanger that can handle this load of 83,500 BTU/hour,
You just need 1 additional pump/circulator and control.
To design it for a copper coil you need more info: tank dimensions, insulation value for tank, Temp of area where tank is located, ...
An "educated guess" would be 3 to 4 pancake coils 100' long (OD 5/8") connected in parallel and a balanced flow path.
These 4 coils would run you already $300 to $400.
The capacity of the tank seems a little bit undersized for the boiler, or vice versa.
Curious what others have to say.
I'm planning on connecting the boiler to my salt water pool this season, and I ran the formula you gave and came out with the following.
11,500 gallon pool
60 KW boiler (204,728 BTU's per hour)
10 degree gain on average needed
11,500x8.35= 96,025 lbs. of water
96,025x10= 960,250 BTU's needed overall
960,250 / 204,728 (boiler output/hr.) = 4.69 hrs. to raise the pool temperature 10 degrees.
If I use a 240,000 BTU Cupro Nickel Salt Water Pool Heat Exchanger it looks like it will raise the pool 10 degrees in under 5 hours.
Did I calculate this correctly?
Any evaporation or sensible heat loss from the pool?
I might give the heat exchanger vendor the boiler data and flow and the pool temperature and flow to see what they say.
I might give the heat exchanger vendor the boiler data and flow and the pool temperature and flow to see what they say.
Definitely will run the numbers with the distributor first.
Out Door Furnace Supply (advertises on this site) has a specification sheet for the heat exchangers.
The 70KW model (240,000 Kbtu/hr) is suited for a pool in size up to 26,000 gallons and will produce a 1 degree rise for that size pool.
So for a pool with 11,500 gallons it should produce a 2.26 degree rise per hour?
Just running numbers for now, but it seems that the temperature rise will be pretty fast. That makes me happy.
Out Door Furnace Supply (advertises on this site) has a specification sheet for the heat exchangers.
The 70KW model (240,000 Kbtu/hr) is suited for a pool in size up to 26,000 gallons and will produce a 1 degree rise for that size pool.
So for a pool with 11,500 gallons it should produce a 2.26 degree rise per hour?
Just running numbers for now, but it seems that the temperature rise will be pretty fast. That makes me happy.
I have one of those that ODFS sells 135k model and that thing works great. The big Delta T between boiler water and pool water plus big flow on pool side, best thing I got in the whole system.
For reference I used my oil boiler set for 175000 btu output to heat my 26500g pool. It seemed close to 11-12 hours for a 10 degree rise.
So based on the experience of "Bigburner" and "Steam man", the numbers seem to be correct.
Since I have salt water in the pool, a cupro-nickel heat exchanger is necessary. They start at 240,000 btu's, so that what I plan on getting.
Can't wait to have a warm pool and a relatively fast warm-up rate.
Since I have salt water in the pool, a cupro-nickel heat exchanger is necessary. They start at 240,000 btu's, so that what I plan on getting.
Can't wait to have a warm pool and a relatively fast warm-up rate.
Ya my 100K NG heater will do about a degree an hour 12,000 gal pool, would boiler is about the same with 140 degree boiler water +/-
PassionForFire&Water
Minister of Fire
JimboM said:
Numbers are OK, but you need to factor in also the heat loss of the pool, especially in winter and the shoulder seasons.
Depends where the pool is located, inside or outside.
If it is inside I would derate the numbers in function of the delta T between pool water and pool house for that matter.
Also, run the numbers again, to see how long it take to heat up the pool at a much lower starting condition, say 35F or so pool water temperature.
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