Heat Pump One Week Analysis

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J

Jd5996

0
Jun 19, 2017
27
Clearwater, Fl
Hi everyone!

So I thought I would post my first week of heat pump analysis to maybe provide some real world info that sometimes seems hard to come by. I will try and be as specific as possible.

Heat Pump: Rheem 5350ti-e 95k BTU
POOL:11800 gal chlorine TFP maintained solar covered(8mil) 20+ hrs/day
Start Date: 11/1/17 @ 11am
End Date: 11/8/17 @ 11am
Start Temp: 67.6*on Rheem, 63*in pool
End Temp: 89.9*on Rheem, 85* in pool
Avg Air Temp: 85* daytime, 70* overnight
Starting Kwh: 47489
End Kwh: 48384
Total 1 wk Kwh used:895, approx 123kwh daily
Kwh Cost: $.053
Total 1wk Cost: $47.44
Total Temp Increase: 22.3*= approx 3.17* daily
Extrapolated Monthly Cost (running 24/7): $189.76 (avg monthly elec was $150 before turning on the heat pump)

Again plz keep in mind this is running the pool pump and heat pump 24/7 for the entire week.

Also, kwh use includes usage for the entire house as I have no way of separating kwh for just the pool equipment.

Hope someone finds this info useful!

Thanks,

JD
 
In my experience running a heat pump I've found its most efficient to run them only when the sun is up and air temps at their warmest for the day. Typically for me that means the heat pump is on at around 10am and I have it shut off around 630pm. That schedule keeps the heater in its higher efficiency range and limits the overnight convective loses from running the pool pump at night. Running your pool pump at night is a good way to cool down your pool. If you are trying to keep the heat in only run the pump during daytime.

On average when my heat pump is running every day like in may, june, and september it adds about 100-130 to my electric bill. I'm paying about $.18 per kW.
 
No cooling here Chuck, not yet anyway lol.

With an avg overnight temp of 70 degrees my overnight water temp increase has been .4 degrees all nights except one which was .5. Not much I know, but when you are trying to bring the water temp up from 63 degrees every bit helps.

Plus, if you factor in an avg of 2-3 degree overnight temp loss that would normally occur with 70 degree ambient air temp then I am in the net gain column to the extent of 2.4-3.4 degrees. Roughly lol. That is not including daytime use/gains!

Of course once overnight temps fall below 65 then I too will begin to run my Rheem from about 9am-6pm to make up for any overnight temp loss, but for now I have found that my overnight water temps do continue to increase albeit only slightly.

Overall though I have been pretty pleased with a 20+ degree increase in a weeks time... even if only a minimal amount of that occured during the overnight hours.
 
Target temp is 88 therefore I have the heat pump set at 92 as there seems to be about a 4 degree difference between the water passing through the heat pump and the pool itself.

Yes, we plan on keeping it there all winter long and I will be sure to update this post with as much info as I can.
 
I'd bet you will around be around 100-150 a month to maintain temp. Granted that's weather and use dependent and if you stay on top of keeping the solar cover on. Without the solar cover your heating cost will roughly double.
 
Joshii said:
Wow do you really only pay 5c per kwh? We pay about 10c per kwh, but we also have a 10c per kwh transmission cost. So our total cost is 20c per kwh! 4x yours!!
Click to expand...

Yes sir, we are fortunate to be with a CO-OP electric company. Our daytime rate is .053, and our nightime rate is .051. My trusty calculator tells me that averages out to .052 :)

Like you we have a transmission cost but ours is a fixed rate of $30. When I factor that $1 per day into the equation I come back out to .053.

I thought it was a mistake when I first read my account so I called the company and they verified lol. It has to be one of the lowest rates in the nation!

Also, at the end of every year we get a few hundred dollar refund or credit as part of our share in the company.

When the wife and I put all this together we decided there was no way we were NOT going to heat the pool all
winter long lol.
 
We have had some very unseasonably warm winters the last three or more years. When/If we get back the usual 60's, it will be harder to heat. Just keep a solar blanket on the pool when not in use.
 

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ccasanova said:
Watching closely as we’re considering heating through most of “winter” here in Louisiana if we ever finish installing the pool.

Our co-op rate is $0.05194
Click to expand...

Congratulations ccasanova...I think we both have some of the lowest electricity costs in the nation!!!

I will post a more detailed report on Wednesday of this week as that will be the 2 week point in my little experiment. We have decided though to continue to run the heat pump 24/7, except one night where the air temp dropped to 63 degrees and we turned it off around 8pm. We lost 2 degrees that night so the next evening we decided to run it through the 62 degree overnight temperature and that night we only lost .5 degrees!!!

Since then we have returned to 24/7 and will do so until the end of the month so that we can understand the monthly "worst case" scenario of running 24/7. Now we are back up to 92 degrees...just got out of the pool for a nice evening swim and it felt awesome!!! Ambient air temp is about 65*.
 
TWO WEEK UPDATE 11/16/17

Ok so exactly two weeks after turning on my heat pump 24/7 (minus one overnight as explained in previous post) I have a pretty good idea of what to expect.

Total 2 Week Kwh consumption = 1753Kwh, factor in about 8hrs where I turned both pumps off for about 8hrs(approx 41Kwh) and its feasible to round off to 1800Kwh...24/7

Approx 128Kwh per day or 42Kwh per 8hrs or approx 5.3kwh per hour.

So about 3600Kwh/month...again this is running 24/7 and includes the entire house.

Average use prior to this is about 1500Kwh so I expect my November electric bill to be a bit more than double its average of about $150...probably about $325.

Again, we have decided to run the pump 24/7 for the entire month of November in order to know for certain what our worst case scenario would be...beginning Dec 1 we will start to maintain temp and run just during the daytime, cutting back Kwh usage by approx 2/3.

For us $300-$350/mo "worst case scenario" is very acceptable to be able to swim through the winter months...wife and I took a morning swim today for about an hour and it was incredibly refreshing and as I said earlier we usually swim every night after work. So well worth the extra $$$ for us.

Some things I have noted so far...

...from 64/65* to about 70* overnight temp and the unit will actually pick up .3* -.5* during the overnight hrs.

...from about 60* - 63*-ish it will hold its temp overnight without gain nor loss

...and from 56* - 60* it has lost about 1*

...last night which hit about 51*, we lost 2 whole degrees.

Daytime gains have replaced any/all overnight losses so far, as our daytime temps have been about 80* this past week. Today will be the first day we don't hit 80 (high will be 78*) but should be close enough to makeup any overnight losses.

Evaporation loss is nonexistant and chlorine levels remain incredibly stable at about 5ppm. I'm adding about 16oz of 10% chlorine every three days or so when it falls to about 4ppm.

In order to keep more heat in the pool we have begun to unroll only about a 6 foot section of the pool which will allow us to do "laps" after a hard days work lol. Not certain that it helps to keep the pool from losing more heat but it seems to work. On weekends we uncover the pool in its entirety for a few hrs and let it get some fresh air...then the cover goes right back on.
 
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