# Thread: heating, degrees per hour

1. ## heating, degrees per hour

So heated her up today, to 86. Turns out water temp rose from 72 to 86 at about 1 degree every two hours. Ambient temp here on Whidbey today in the 70s and sunny. Is 1degree/2hours fine, medium, poor?

2. ## Re: heating, degrees per hour

Originally Posted by engrav
So heated her up today, to 86. Turns out water temp rose from 72 to 86 at about 1 degree every two hours. Ambient temp here on Whidbey today in the 70s and sunny. Is 1degree/2hours fine, medium, poor?
still is the rate fine, medium, poor?

3. ## Re: heating, degrees per hour

I will assume that Maxi-flo is a 260,000 BTU heater based on the model number. With the weight of water at 8.34 Lbs/gal and a 30,000 gal pool there is roughly 250,000 lbs of water to heat. Under ideal conditions you could see up to a 1 deg/hr rise. However, the 260,000 BTU is the input rating and most older heaters run around 70%-80% efficiency so that put the output just under 210,000BTU. Still not bad but now puts the temp rise at .83 deg/hr. Without a cover to help with heat loss I can see how you will be around 1 deg/2 hr. Something to keep in mind here. If you had, say, a 520,000 BTU heater and conditions the same, the pool would have heated to the same temp in half the time but, with the same fuel usage. Again, this is not taking into consideration all the extra factors such as wind, humidity, ambient air temp etc. which all affect the ability for a heater to heat and a pool to retain heat

4. ## Re: heating, degrees per hour

engrav:

Here's a heating spreadsheet you might want to play around with: Natural Gas Heating Time & Cost Calculator Spreadsheet.

As danpik stated, the actual net output of a gas heater is the actual BTU's that go towards heating the pool. The net BTU output is less than the labeled (gross) BTU. It will always take a certain amount of BTU's to heat water to a given temperature, given the ambient conditions. A larger heater will simply do the job faster.

5. ## Re: heating, degrees per hour

thank you both/all
so 1degree/2hrs is say "par"
turns out I burned 1.5" of oil yesterday which is about 12 gallons or about \$20 but
4 hrs of that was heating up and all of that included domestic hot water so this is not the bill for simply maintaining pool temp at 86; today is on maintenance at 86 and domestic hot water, should be less than \$20, will measure again tomorrow
but say the cost of maintenance and hot water is \$20 and I put on a solar cover at night
and say it is about 60 degrees at night and 75 daytime, no wind etc
how much can I expect the maintenance heating bill to decrease? 10% 25% 50%
with such estimate could estimate how long it would take to recover the cost of the solar cover
energy.gov says savings of 50-70% are possible, true?

6. ## Re: heating, degrees per hour

Solar covers will save you a dramatic amount of your heating bill, and will pay for themselves every couple of weeks. Of course they are something of a project to put on and take off.

The rate of heat loss, and thus the cost to maintain temperature depends on several things: how many degrees above the normal temperature you maintain the pool, how long the cover is on (if any), and how much wind you have, etc, so is difficult to predict.

7. ## Re: heating, degrees per hour

From my personal experience, I'll estimate my cover prevents at least 1/2 of the overnight loss.

8. ## Re: heating, degrees per hour

Originally Posted by Speedo
From my personal experience, I'll estimate my cover prevents at least 1/2 of the overnight loss.
ok
yesterday set to 85 degrees ran pump heater 24/7, was cloudy no wind
burned 6 gal oil @ \$3.71 per, so \$22; say 3/4 of it was pool, 1/4 domestic hot water
then consumed \$17 heating pool
say cover would reduce by 1/2, then would save \$8.50 / day.
say cover is \$200 dollars, then would recover cost in 24 heated days
say covers wear out in 3 years, would need 8 heated days per year
might be Ok investment save for pain of on/off

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