Heater recommendations, South Florida

[PoolBrews]

It is about how fast, not efficiency.

A larger HP will use more Kw for a shorter period of time then a smaller HP running longer at lower Kw. Their electrical use per BTU will be about the same.

You pay once for the larger BTU HP and then have the flexibility to heat in colder conditions. Efficiency during operation is about the same.

If you look at the efficiency rating, you will see that the larger heaters have a much better rating than the smaller heaters - i.e. they cost less to run. It's not just about fast. If you get the larger heater, you get fast and efficient. I would always go with the largest heat pump available. I have a 7K pool with a 144K Hayward heater and I keep my pool at 89 all winter with no issues in central Florida. If you go too small, it's a very costly mistake. For only a couple hundred more you can install the largest available. In addition, the larger heater will run less which should translate to greater longevity.

 

[wireform]

If you look at the efficiency rating, you will see that the larger heaters have a much better rating than the smaller heaters - i.e. they cost less to run. It's not just about fast. If you get the larger heater, you get fast and efficient. I would always go with the largest heat pump available. I have a 7K pool with a 144K Hayward heater and I keep my pool at 89 all winter with no issues in central Florida. If you go too small, it's a very costly mistake. For only a couple hundred more you can install the largest available. In addition, the larger heater will run less which should translate to greater longevity.

My decision would be made right there.

 

[dcaton]

Over design to get it right. It only costs you once

I do understand that, and did exactly that when I replaced the filter recently. It's fairly easy to calculate the filter size based on the number of gallons in the pool, and I doubled that. But we're not talking a lot of money there. My SWG is also 2x oversized.

Heaters are a different ball game. The difference between a 60K and a 140K heater is over $2000. How can I over-design if I don't know what the baseline even is?

 

[ajw22]

How can I over-design if I don't know what the baseline even is?

You seem to be an engineer.

All the specs for different size HPs are published.

BTU calculations are straightforward.

You can do your own modeling of expected water and air temperatures to determine what heating performance you want to buy. Folks have pointed you to some of those models.

There is no right or wrong when it comes to climate forecasting.

 

[dcaton]

I have a 7K pool with a 144K Hayward heater and I keep my pool at 89 all winter with no issues in central Florida

Ok, now we're getting somewhere. You're in a similar climate, I'm just south of Vero Beach.

You keep your pool at 89 all winter, even in Dec and Jan?

 

[dcaton]

You seem to be an engineer.

Programmer. But I do tend to overthink or over analyze things sometimes. I guess this is going to cost me a bit more than I thought, but that's nothing new...

 

[JamesW]

The UltraTemp 110 has the highest COP at 6.1.

There are many different calculators available, but none are going to be able to give you an exact number.

You have too many variables like weather, pool set temperature, covered or uncovered etc.

You can get the smallest one available and hope for the best and maybe it will be satisfactory and if not, you just live with the times when it does not meet your needs.

Or, you can get a bigger unit to ensure that it will probably meet your needs all the time.

With a heat pump, when the heat loss is the highest, the production is lowest.

Contact the manufacturers to see what they say.

There are several manufacturers in Florida that should be able to give you a better idea what size you need.

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[ajw22]

Better Than the Competition – Built Right Pool Heaters

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Phone: 941-505-1600
28110 Challenger Blvd, Punta Gorda, FL 33982
Open Mon – Fri: 7:30am – 5:00pm

 

[ajw22]

Note that as temperatures drop all the HP's have the same efficiency COP at 50F...

 

[wireform]

I guess this is going to cost me a bit more than I thought,

But that's money well spent !

 

[Katodude]

Buy once, cry once.

There are a lot of factors involved in how much you will need to use the heater. Get the biggest you can and in a year you will have forgotten how much you spent, but you will enjoy your pool more.

 

[PoolBrews]

Ok, now we're getting somewhere. You're in a similar climate, I'm just south of Vero Beach.

You keep your pool at 89 all winter, even in Dec and Jan?

Yes, I do. During December, January, and February I use a solar cover as well. It prevents the heat from dropping too much overnight. I have the heater set to kick on at 11am. The pool is usually 82-85 in the morning, and my heater runs anywhere from 1 hour to 2 1/2 hours to bring the heat back up to 89. If I don't use a solar cover, the pool drops to 76-81 overnight, and heating times are doubled. I've been doing this for 3 years now. My electric bill is generally $30-$50 more per month during these months.

I am an electrical engineer and I did a LOT of research and calculations for every aspect of my pool prior to installation. If my PB hadn't been locked into Hayward, I would have went with the AquaCal SQ225. It's 10dB quieter than anything else out there, and has the highest CoP of any heat pump. That will be my next heat pump when this one eventually goes (unless someone builds something better)

 

[dcaton]

AquaCal SQ225

Yikes, now we're over $6k. I was just telling my wife this morning that we'd probably be around $5k. I do like the 7 year warranty on the AquaCals though.

My electric bill is generally $30-$50 more per month during these months.

I assume that's using the pool cover. I was expecting a much higher cost/month.

Thanks very much for the detailed info, this is exactly what I was looking for.

Edit... The Aqua Cal SQ145 actually has the highest COP of 7.1 (vs 6.5 for the SQ225). It's only 121K BTU but it's $800 cheaper. I wonder if the higher COP would at least partially offset the lower BTU.

 

[PoolBrews]

Yikes, now we're over $6k. I was just telling my wife this morning that we'd probably be around $5k. I do like the 7 year warranty on the AquaCals though.

I assume that's using the pool cover. I was expecting a much higher cost/month.

Thanks very much for the detailed info, this is exactly what I was looking for.

Edit... The Aqua Cal SQ145 actually has the highest COP of 7.1 (vs 6.5 for the SQ225). It's only 121K BTU but it's $800 cheaper. I wonder if the higher COP would at least partially offset the lower BTU.

I wouldn't give up 22K BTU for the increased CoP - just my opinion. The CoP can't make up for less BTU. The unit is more efficient at heating, but still only delivers 121K BTU. If you find you need that little extra, there's no way to add it without another heater. Your pool is half again the size of mine, so heating time will be longer than mine, and you may really need that extra heating capacity come January.

 

[dcaton]

The CoP can't make up for less BTU

The difference between a 143K and 121K unit is about 16%, so all else being equal, I'd have to run a 121K unit 16% longer than a 143K unit to achieve more or less the same results. If that's correct, it doesn't seem too bad.

But a 7.1 CoP vs a 6.5 CoP is 8.5% more efficient, which should offset the longer run time somewhat.

A 121K (@5.1 kW) uses roughly 20% less energy than a143K (@6.4 kW), so the longer run time should not translate into additional cost.

Your setup takes about 60-150 minutes to get to 89. My pool, roughly 50% larger would probably take about 90-180 minutes with a 143K unit or 104-208 minutes with a 121K.

This is based on static data from the manufacturer; no doubt the real-world calculations are far more complex. And the difference in CoP between the two becomes less significant the lower the ambient temp gets. But it seems to me that the tradeoff here is that it will take a bit longer to achieve the same results from a 121K unit and there would still be sufficient headroom.

My thinking could very well be faulty though, and my quest to save $800 a fool's errand.

 

[dcaton]

For anyone who's following this, the mental anguish is over . A got an early black Friday deal on the AquaCal SQ225 143K BTU, $500 off. That plus free shipping and no sales tax made it hard to turn down, even though it's a bit more than I wanted to spend. I might be able to heat my neighbor's pool as well, but I don't think this will have any problem heating mine.