I've gambled on a Aquastrong 120v Pool Heater for a 4500gal AGP. Thoughts?

[DigitalGuru]

I searched the forum here for thoughts on a 110/120v heat pump and didn't find much in terms of actual usage / review, so I've gambled and bought this 35K BTU one from Amazon for $1,360 that should be here today. This is our 2nd year with our 9x18 Intex XTR and what my wife and I found last year was were just a few degrees cold from using our pool for much of the season. Our pool gets shaded around 5:30pm, so whenever we were getting home from work around this time any breeze made my wife too cold to want to stay in (she likes it near 90). Since our intention wasn't to extend our season, but to make our season less susceptible to the daily heat fluctuations, I hope that this 35k BTU heater can keep our pool temps to the upper 80s more of the time. I'm still considering adding the Asurion 3 or 4 year ($130 / $170) protection plans to the order (I have 30 days to buy), since this might be a risky purchase. Thoughts or suggestions on my gamble? Anyone own an Aquastrong products?

 

[ajw22]

Do you cover the pool to maintain the heat you will have paid for?

Your 35K HP will heat your 4500 gallon pool about 1 degree an hour.

 

[DigitalGuru]

Yes, we do have a solar cover. We were surprisingly good at covering it nightly last year, and now that we are paying to heat it, I plan on staying up on that.

Glad to hear that we'd get a degree an hour! That's better than I expected. It'll be interesting to see the electric bill difference this year with the heater and running the pump 24/7.

 

[SJPoe]

A solar cover will make a huge difference in retaining the heat - my own personal experience is that it is in the realm of 50% or more.

9 x 18 @ 5btu/sqft/hour/degree of difference = 810 BTU/hour/degree - so with 35000 btu, you should be able to offset about 40-43F of difference to ambient (assuming no wind, perfect efficiency etc).

Anything 'above' that amount adds to the heat in the pool... So an example :

Pool is 80F, Air temp is 60F. Thats a 20F difference. 20 x 810 = 16200BTU/hour - your heater can provide 35000. So 18800 BTU is left over and can heat the pool. Water needs 8.3 BTU/gallon to raise the temp one degree - you'd have 4545 gallons, so you'd need 36360 BTU to raise it one degree...you have 18800 'spare', so it'll take about 2 hours to raise it one degree.

As most of your heat loss is via evaporation, adding a cover reduces that loss significantly. A solar cover doesn't really 'focus the suns rays to heat the pool', really all it does is reduce the amount of heat lost so the temperature gain from that sun beating on it 'adds up'. If you reduced your loss by 50%, you now have 27k BTU, which means a degree every 40 minutes or so....

Of course, every degree you heat the pool is a degree more loss per hour

 

[DigitalGuru]

Great write up, thank you. That's a lot of math I had no clue about and easy to understand. Regarding the solar cover, I was only using it overnight (11pm - 8am) on the suggestion of Swimming Pool Steve from YT. Now I'm thinking of putting it on earlier to cut down on the late evening heat loss. Since I'm heating it this year, should I leave it on except when using it?

 

[ajw22]

Since I'm heating it this year, should I leave it on except when using it?

Yes

 

[InyoRich]

Evaporation is your enemy when you heat a pool, so leave the solar cover on the pool all of the time when you are actively heating the pool and not physically in it. You would be surprised at how much a gentle breeze will cool it off when it is uncovered.

 

[JamesW]

Assuming a 35,000 btu/hr input, your heating rate will start at about 0.92 degrees per hour, but the rate will decrease as the water temperature increases due to heat loss.

9 x 18 = 162 sqft of pool surface area.

If we use 87 btu/hr per sq ft for the loss rate, that is 14,094 btu/hr of loss.

35,000 - 14,094 = 20,906 btu/hr net gain.

That's 0.55 degrees per hour gain.

So, the heating rate goes from about 0.92 degrees per hour to 0.55 degrees per hour.

14/35 = 40% runtime to maintain the temperature.

 

[DigitalGuru]

Good to know, thanks. Given the solar cover will be on more this year, should I do a wall skimmer upgrade instead of our current floating skimmer? It seemed to work okay last year but everyone raves about wall skimmers.

 

[JamesW]

Heat Pump Basics - Further Reading

www.troublefreepool.com

 

[SJPoe]

Since I'm heating it this year, should I leave it on except when using it?

Our cover is on the pool any time it's not actively in use. There is certainly a 'hassle factor' that comes into play - I don't bother recovering in August if the grandkids come out of the pool for lunch...but if the pool isn't going to be used for a while, then yes, it only takes a couple minutes.

Given the solar cover will be on more this year, should I do a wall skimmer upgrade instead of our current floating skimmer? It seemed to work okay last year but everyone raves about wall skimmers.

I don't know how well the skimmer works with the cover on - I've never really noticed. I would think any surface debris is going to be somewhat 'stuck' by the cover.
As long as the floating skimmer doesn't 'eat' the cover, it probably wouldn't make a huge difference either way - but I'll let others chime in on that as I have no real experience beyond my wall skimmer

 

[DigitalGuru]

Thanks for input. Since I wasn't heating last year, I turned off my pump and used the solar cover overnight, so the floating skimmer wasn't "fighting" the cover most of the time. I know it won't pull surface debris with the cover on, but I was concerned that the floating skimmer and solar cover might create some additional resistance for the pump that a wall skimmer might avoid as it would still have unobstructed flow. I am leaning towards the wall skimmer, but don't want to lose the water depth. I was contemplating positioning it high enough that the screws go through the bonded area, possibly using a hot nail to melt the intial poke through, but not actually cutting the bonded area at all. Am I crazy to mess with the bonded area? It would only be 3 holes if I use this skimmer.

 

[JamesW]

TFP is a registered 501(c)3 non-profit that is maintained by user donations.

The people who answer questions are volunteers.

If you find the site to be a good resource, please consider making a donation to help support the site.

Thanks.

Become a TFP Supporter

Help Support TFP Trouble Free Pool is run by a dedicated group of volunteers that … Read more…

www.troublefreepool.com

 

[JamesW]

Y = 122.2623 - 52.2623e^(-0.017095X).

Y = Water Temperature.

X = Time in hours.

To go from 70 to 90 degrees will take about 28.2174, which is 1.41 hours per degree.

Y = 122.2623 - 52.2623e^(-0.017095X), y from 70 to 90 - Wolfram|Alpha

Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.

www.wolframalpha.com

___________________________________________________________________________________
Y = Heat loss in btu/hr.

X = Water Temperature.

Y=648X−44226, y from 0 to 35000 - Wolfram|Alpha

Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.

www.wolframalpha.com

 

[JamesW]

Water Temp (°F)	Time (hrs)
70	0.00
71	1.13
72	2.28
73	3.46
74	4.66
75	5.88
76	7.13
77	8.41
78	9.72
79	11.06
80	12.42
81	13.82
82	15.26
83	16.73
84	18.24
85	19.79
86	21.38
87	23.02
88	24.70
89	26.43
90	28.22

 

[VinnyinNJ]

Something that wasn't said is that if the pool is in the sun and has a solar cover on, the cover itself helps with heating the pool. We keep our pool covered with a solar cover and our pool can hit 90 degrees when it's been sunny for a few days. I get about 4 degrees a day rise when it's sunny. I would say technically it's not heating the pool but if the sun is shining the pool gets very warm so you can add solar heating to the heater so it probably would work better.

 

[DigitalGuru]

I've heard both, Swimming Pool Steve from YT, has a video that advocates to take it off during the day so light penetrates the entire water column, thereby heating and disinfecting more thoroughly. But I wonder if the loss by evaporation might counterbalance this effect.

 

[DigitalGuru]

I received our heater yesterday. The delivery was a freight shipment from Amazon so I had to be here to sign for it. It arrived in pretty good condition. There was a 2-in circular hole through the top of the box that went all the way to the unit itself but no damage. The base that it was screwed to had wood feet that were bolted to a wood platform that broke. So obviously the unit had gotten jarred at some point. Fingers crossed no internal damage. It did not come with a power cord but the manual makes it sound like there should be a a cord included. I sent support an email along with asking the question on Amazon and surprisingly I've already heard back from Aquastrong on both. They stated that while the unit currently doesn't come with a cord they will be supplying one for free and shipping it to me after it gets and Amazon's warehouses on the 10th. Which is about the time I would be setting up the pool so timing should work well.

 

[Newdude]

I would say technically it's not heating the pool but if the sun is shining the pool gets very warm

Its a matter perspective. Considerably less loss is percieved as a gain.

But I wonder if the loss by evaporation might counterbalance this effect.

Or the wind. (Day or night) Even a slight breeze ripples the pool turning --------- surface area into much more with ^^^^^^^, increasing the loss.

 

[VinnyinNJ]

I've heard both, Swimming Pool Steve from YT, has a video that advocates to take it off during the day so light penetrates the entire water column, thereby heating and disinfecting more thoroughly. But I wonder if the loss by evaporation might counterbalance this effect.

The truth is some people may be able to take the time to take the cover off in the AM and put the cover back on in the PM but not everybody wants to make that a habit, I can say we don't.

We don't take the cover off the pool usually even when we're in it. Sitting on floats and drinking a beverage we just push the cover back. IF there's really going to be use of the pool the cover comes off. I have taken the cover off to get more sunshine in the pool but I haven't done it enough to say it does or doesn't work for us. I can say on days the sun is shining the water will go up in temp and doesn't drop too much in temp at night. We like warm water and the cover is enough for us most of the time; we will use the pool less when the water is a bit cooler. We have actually had the water a bit too warm and it was not refreshing to be in it. Water going up 4 degrees a day is a big jump after 3 or 4 days of sunshine. A heater would be a nice addition for those days that the sun is not enough or it hasn't shined in a few days and/or it rained and dropped the water temp drastically.