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[blakeusa]

I have a Central Boiler classic and a 30K inground gunite pool.   Have been using my ventral boiler to heat the spa and the pool for the second year now... but can't seem to get it really working.

Central Boiler has really not been any help as their diagram and brochures do-NOT match up to reality. 

My problem is that within 30-40 min my boiler goes from 190 to 140 and I have tried all kinds of pump and flow combinations.  Not running any domestic heat-- just the pool.

Using 1 1/4" pex to Flatplate MP38 plate heat exchanger- about 50' run.  Using TACO 007 circulator.  Have tried 009.  Water going in at 160% coming out at 95%- I have to really turn down the flow on the pool side- it is already mixed to get it working- this gets me 110+ water going out.   Have a variable speed pool pump and a couple of flow valves.

AND I can go through a cord of wood in a week no problem.

Have gone from 48% to 71 and now trying to heat from 71 to 80+

Just cant keep the heat up in the boiler.  Have a fan, tried the door open and an extra fan-have good hard wood.

THe only solution I can find it to run the pool heat for 30-40 min then let the boiler recover for 60 min or so then go again.

I have yet to find anyone heating a large inground pool...  any help or ideas would be appreciated. 

 

[yoderheating]

 Pools just take a lot of heat and 30,000 gal is a big pool. You can't have huge heat draws without burning a lot of wood. If your heat exchanger is pulling down the furnace to fast you could try and install a bypass around the heat exchangers with a valves where you can send some pool water through the heat exchanger and some through the bypass.

[RSI]

Pools just take a lot of heat and 30,000 gal is a big pool. You can't have huge heat draws without burning a lot of wood. If your heat exchanger is pulling down the furnace to fast you could try and install a bypass around the heat exchangers with a valves where you can send some pool water through the heat exchanger and some through the bypass.

I would do that on the boiler water instead. Just adjust the valves till the temperature can be maintained. You need to send less boiler water through the heat exchanger.
You need about 250,000 BTU for each degree you raise the water temperature in the pool and that isn't figuring in what is going into the air and ground.

The only way to heat the pool faster is to get a bigger boiler.

[willieG]

i am no expert at this stuff but would make a suggestion to slow the pool water down until your temp drop from boiler is 20 degrees (boiler water in at 160 and out at 140) your furnace should be able to recover as long as you have wood in it. this will take longer to heat the pool but as long as the heat loss from the pool is not greater than what the boiler is heating, it will heat the pool but take longer. Really, your boiler is no match for the amount of water in your pool but i would give it a shot. As long as you are not in a big hurry i think it can do it (you must like to swim an awfull lot to cut that much wood )

[muffin]

Is this an enclosed pool?  The amount of heat to heat pool water is huge as I am findoing out right now.  I just installed a 25K gal pool, but it is enclosed.  I heat the room to 85ish which helps a ton.  Still, the ground is 55F and it has a lot more surface area with the pool.  I estimate the heat loss to the ground on the order of 500K BTUs per day.  I am in the market for one of these furnaces to take over for my propane heater which is costing me a fortune.

[willieG]

if you are allready heating your pool with propane, you should be able to figure out how many BTU you are using and convert that to the BTU's you can get out of a pound of wood (or a cord or what ever you need to do) then you can actually see how much wood you will require. you should be able to do this with out the knowledge of your current propane use but it may be more convienent for you to figure.

we all know the  formula of 1 BTU to raise 1 pound of water 1 degree F so calculate your pool water into wieght (somewhere close to 9.6 pounds per imperial gallon) then you will know how many btu are required to raise that amount of water 1 degree..then multiply by how many degrees you want to raise the water temp. the tricky part will be calculating heat loss. that is why if you are currently heating with propane you can convert your propane use to btu's per day or week or month and then figure out your wood usage that way. I do remember when my uncle was heating his pool in the spring with gas he said it cost more for a month than to heat his home in the dead of winter for a month, and he had a cover to put over top when not in use to help against heat loss to the air. i would think that heat loss to the ground would be tremendous!

[willieG]

here is a link i pulled off the net. It may help your calculations if you are buying yoru gas in therms too


http://www.swimmingpool.info/pool-heater.html

just a quick look at this chart and if you live in the "wrong" place it could cost you a winters wood to heat your pool for a few months!!

and look at the savings for a pool cover (if this chart can be believed?)

[Coach]

I've heated our 16 x 32 in ground pool for 2 years.  It really knocks the boiler temperature water down
for the first couple of days but once the water in the pool is warmed (85 - 90 degrees) I can maintain the pool temperature by running the pool pump only 12 ours a day.  The kids say we have the biggest hot tub in town......but my wife really likes it.   

[Russ Brumit]

Second year for heating the pool. 15x30 above ground.  Works good . Takes a solid day to raise temp 12* or so.  I use a cheap pool solar cover when its still cool at nights. Without it you lose lots of heat. Once water is up to 85* plus its easy to keep it there. Haven't got around to hooking it up in auto mode.I just flip a switch at the furnace for the pump and make sure the filter is running. Nothing like having a warm pool.