When to run Heat Pump

dwnsth

LifeTime Supporter
Aug 14, 2007
16
0
SE Louisiana
#1
I'm a very new pool owner and we had a heap pump installed with our pool. Since we live in S.E. Louisiana I haven't had much chance to run this yet other than heating the spa a night (very quickly I might add). Are there any suggestions for how often and when the H.P. should be run. I'd like to keep a suitable temp for swimming as long as possible. Our nighttime temps will only occassionally get into the 30's in late December and January. In the winter I would still like to continue using the spa. Since this is an integrated system, should I try to keep the entire pool temp up in order to heat the spa quickly when needed?

Thanks for any guidance.
 

JasonLion

LifeTime Supporter
Platinum Supporter
TFP Expert
May 7, 2007
37,879
5
Silver Spring, MD
#2
You will get the most efficiency by running the heat pump during the day. Heat pumps are more effcient when the outside temperature is higher and most don't work at all when the air temperature is down around freezing.

Heating the entire pool through the winter will tend to be enormously expensive.
 

dwnsth

LifeTime Supporter
Aug 14, 2007
16
0
SE Louisiana
#3
Thanks,

Being from south Louisiana, we don't get much of a winter so I'm hoping to keep pool at good temperature through November and start heating things up again in March but still use the spa all winter if possible. Anyone from this part of the country with good or bad experiences using heat pumps? What about the spa, can the HP bring temp up in spa with temps in the 40's. This is about the biggest non-commercial HP you can get so I'm hoping it handles things well.
 
#5
I'm Guessing on these volumes : Pool 22 x42 = approx 31,000 gallons Spa 7' round = 600 gallons

you can calculate the approximate amount of time it will take to heat the spa alone by the following:

Gallons of water x 8.3 (lbs/gallon) = X lbs. of water
X lbs of water x your temperature increase = Y BTUs required
Y BTUs required / BTU output of your heater = Z Run Time in hrs.

Example:
600 gallon spa x 8.33 = 4998 lbs of water
4998 x 50 (50F to 100F = 50 degrees in increase) = 249,900 BTUs required
249900 / 158000 BTUs = 2.5 hrs to get it up to your desired temp.

I used 50 F to 100F because although you mentioned 40 degrees, the ambient air temps do not always equate to the water temperature, and I used 100F because most people will get in when it's actually around 95 or warmer. I used 158,000 BTUs as I was not able to find a Rheem model 8000 and the largest I was able to referece was an model 160 (158,000 BTUs). You can play with the numbers BUT - use your actual numbers in the equation.

NOTE:
These are "ideal" calculations and does not factor in the decreased BTU output of the heat pump during cooler air temps, heat loss from the spa shell to ground, or the dissapation of heat of an air blower or the aeration of therapy jets.

In SOME cases, you're better off keeping the pool heated, so that when you need to use the spa, there's a much shorter period for the spa water to reach your desired temperature. What is very important is that you use a solar blanket to help retain the heat you've added during the day.

Compare this to maintaining your pool at temperature (again, with a solar blanket):
Your heat pump would run about 10 hrs/day during the coolest winter months to maintain 83 degrees, but the heat up time to use your spa would be much shorter.

If you're not planning on using your pool during the winter, it doesn't make sense (in this case) to keep it heated, for the sake of the spa. Just plan on turning your system on at least 2- 3 hrs before you plan on using it.

Hope this helps,
 

dwnsth

LifeTime Supporter
Aug 14, 2007
16
0
SE Louisiana
#6
Thanks for the great info. The heater is a RayPak (rheem) 8300ti, 137000 BTU. I'll probably do some evaluation over the comming months and see how electric bill is affected along with how the heating goes. Will try to track things so I can post something meaningfull for others next spring.