Choosing a Heat Pump

Stoopalini

Gold Supporter
Jun 8, 2020
465
Central Texas
Pool Size
14060
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
We are considering adding a heat pump to our pool (no spa, just a pool) and could use some input on deciding which model to go with. I am thinking a unit which can do both heating and cooling would be good, since we are in central Texas, and the water will reach into the mid 90's during the summer. So I figured if I'm installing a new heat pump, why not have the option to cool the water as well?

I'm going with a heat pump because we don't have natural gas where I live, and I don't want to install a propane tank on the property.

I initially thought the Pentair UltraTemp 140k Heat and Cool unit (460958) would be a good choice; especially since I have all Pentair equipment, and it can connect to the EasyTouch's communicating terminals. As the name implies, it's output is 140k BTUs for heat, and 71k BTU in cooling mode. It uses a scroll compressor, so while not variable speed inverter driven, should be pretty efficient and fairly quiet.

Then I came across the AquaCal SQ150VS unit, which uses a variable speed compressor (inverter drive maybe?), and from my HVAC knowledge, I know this can be a ot more efficient, run quieter, and save quite a bit of operating cost. Although this one seems to only output 115k BTU at max speed. I can't seem to find the cooling BTUs anywhere in their literature though.

When comparing 140k to 115k BTUs, using this calculator, there seems to be about a 2 hour difference heating the pool 10*F; when plugging 70*F to 80*F into the calculator for 14k gallons. It'll take roughly 8 hours at 140k and take 10 hours at 115k ... So maybe this isn't such a big deal.

I'm not quite sure what features I should be looking for when doing my research. Here are some things I'm thinking about, but could use some input. Heatpumps are not new for me, but applying them to a pool is.

  • Should I be looking for one with a titanium heat exchanger, due to my pool being saltwater?
  • Does ScreenLogic have the ability to control both heating and cooling if I go with Pentair; or is there no mechanism to set a cooling temperature within the EasyTouch system, and it'll only control heat? If so, this means I would use the heat pump's set points, and therefore there's no benefit to going with Pentair over another brand.
  • Do I need to consider the minimum flow required to operate the heat pump? I run my pump 24x7 at 1200 RPM, which is enough to activate the IC40. Then I kick it up to 2500RPM 2x/day for one hour each time (for improved skimming). 1200 RPM pushes about 24 GPM. The Pentair unit seems to switch on at 1.5 PSI, but is adjustable. The AquaCal unit seems to kick on at 30 GPM. Based on those numbers, it seems the Pentair unit would engage at my 1200 RPM speed, but the AquaCal wouldn't.
  • Since this is a new install, I can plumb it whatever way is best. Should I put a bypass in, where the water is not passing through the exchanger when the heater is not running, or is it best to have some flow through it even when not heating or cooling? I have extra valve actuators for the EasyTouch system, so it shouldn't be a problem to automate the bypass.
Thanks for any input, it's greatly appreciated!

Oh, and maybe having a heater during this freak winter storm week we just had, would have alleviated a lot of stress on keeping the water moving and not-frozen?

1614090338263.png
 

cowboycasey

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Jul 3, 2013
4,761
Fletcher, OK
1. A heat pump would not have helped, they stop working below 45 degrees (not enough warm air to pull out).. And with no/intermittent electricity in Texas it would not have helped anyway...
2. Pentair is good and several people here like there heat pumps but I believe the Aquacal is a better heat pump.. I have never seen anyone asking how to fix one on here...
 

Stoopalini

Gold Supporter
Jun 8, 2020
465
Central Texas
Pool Size
14060
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
1. A heat pump would not have helped, they stop working below 45 degrees (not enough warm air to pull out).. And with no/intermittent electricity in Texas it would not have helped anyway...
Hmm, are you saying that heat pumps desegned for pools stop functioning below 45*F, or just calling out that heat pumps in general, don't function below 45*F?

My home's heat pump was cranking away, all the way down into the teens, and still producing a 20* ΔT. I did switch over to emergency heat mode (ie: electric heat strips) when we got into the single digits. But even then, I was still getting a 10 - 12 degree split.

2. Pentair is good and several people here like there heat pumps but I believe the Aquacal is a better heat pump.. I have never seen anyone asking how to fix one on here...
Ya, that's what I seem to be finding for the general consensus. I like that the Pentair will integrate with the comm ports on the EasyTouch, allowing me to set heat and cool targets in Screen Logic. I know the AquaCal can be swithed on/off by EasyTouch, but I don't think the integration is the same where I can set a cooling target in Screen Logic, and then the ET could enable the heating or cooling mode of the AquaCal ... I could be wrong though, still can't find any info on this.
 

cowboycasey

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Jul 3, 2013
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Fletcher, OK
They continue to function below 40/45 but they struggle to get the heat out of the air...(way less efficient) At What Temperature Is A Heat Pump Not Effective/Quit Working | Moncrief Heating & Air Conditioning.

I was told by my AC friend that they will run themselves to death below 40/45 degrees and it is better to run the heat sticks.. that is one of the reasons the power took a major hit because of all those heat sticks... I had 50KW of heat sticks in my house before I changed to gas, the first Jan it cost me 500 dollars to heat my house for the month... Never again, I was toasty warm with my gas furnace and it cost 36 dollars for the month :)
 

Stoopalini

Gold Supporter
Jun 8, 2020
465
Central Texas
Pool Size
14060
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
They continue to function below 40/45 but they struggle to get the heat out of the air...(way less efficient) At What Temperature Is A Heat Pump Not Effective/Quit Working | Moncrief Heating & Air Conditioning.

I was told by my AC friend that they will run themselves to death below 40/45 degrees and it is better to run the heat sticks.. that is one of the reasons the power took a major hit because of all those heat sticks... I had 50KW of heat sticks in my house before I changed to gas, the first Jan it cost me 500 dollars to heat my house for the month... Never again, I was toasty warm with my gas furnace and it cost 36 dollars for the month :)
Ya, that has historically been the case for many years. But modern heat pumps don't have the same limitations, especially the variable speed inverter driven models. They can operate down to below zero F actually.

Here's an example of one in action.

I think it's taking the pool industry a while to catch up though, and start putting this technology in the pool heat pums. It's one reason I want to go with the AquaCal SQ150VS model. Since it uses a variable speed inverter.
 

cowboycasey

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Jul 3, 2013
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Fletcher, OK
Wow, 10.8 amps for the whole house with heat pump running is amazing... The heat pump I had was from 2006 so it really sucked but even the one in this video is only keeping the inside temp at 59, I am not sure about you but I like 72 degrees heat inside my house (it was keeping the attic at 86 degrees so it would be nice and hot up there) :)
 

Stoopalini

Gold Supporter
Jun 8, 2020
465
Central Texas
Pool Size
14060
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
LOL .. the one in the video was just installed and switched on. It hadn't been running long enough to heat the house yet. The house was 58, and the air coming out of the air handler was 86. That thermometer in the attic was inserted into an air duct, not reading attic temp. So that was a 28 degree split with 32 degree outdoor ambient air temp.

I had a new heat pump installed in my house Dec 2019, and it's a 5 speed inverter driven model. It's very effective, even during the past week. The modern units are quite impressive.

In terms of the pool, I ended up finding a great price on the AquaCal SQ150VS model, and am going with that one. It should be very efficient with the variable speed compressor, especially combined with my variable speed Pentair circulation pump. It also appears the SQ150 can interface with the EasyTouch communications port, so I can still use ScreenLogic to set both heat and cool set points.
 
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cowboycasey

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I also had a 5 speed inverter 19 SEER installed but not a heat pump, just straight AC and furnace by Carrier and really love it, spends 80% of the time on speed 1 :) Congrats on the Aquacal, I think it will be great...

LOL on the temp, rewatched the video and saw he mentioned just starting it up...
 

Stoopalini

Gold Supporter
Jun 8, 2020
465
Central Texas
Pool Size
14060
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Here's some interesting info on AquaCal's website ...


AquaCal said:
Heat Pumps
A “heat-only” swimming pool heat pumpdesigned to only heat the water and not cool itcan work effectively down to the mid to lower 40s. However, the ambient temperature greatly affects the ability of air-source heat pumps to produce heat. The colder the air, the less heat your heat pump will be able to produce. You can extend the lower temperature limit for your heat-only swimming pool heat pump by winterizing it when the temperatures drop.

Reversible Units
Some units, like the AquaCal ICEBREAKER, are “reversible” and provide heating or cooling. Reversible units can also operate when the outside temperature is down to the mid to lower 20s, although that does not necessary mean it can heat the pool to 80° on a 20° day. As a rule of thumb, the highest water temperature rise you can get from an air-source heat pump under ideal conditions is 30°. For example, if the outside temperature is in the 40s, you can expect the pool to warm up only to the 70s.
I'll bet this is due to the Icebreaker models (like the SQ150VS) are using modern tech inside.

I emailed AquaCal and asked about the SQ150VS. My question was:
  • I am considering this heat pump for my pool, and see it is marketed as "Variable Speed"; but the literature only shows specs for 6000 RPM and 3500 RPM using a scroll compressor. The documentation doesn't say anything about an inverter drive, or any other RPMs beside those two. So is this truly a variable speed compressor, or is it a two speed only?

And their answer was:
  • The SQ150 is a true variable speed heat pump and uses an inverter.
    The VS 150 will operate with a COP somewhere between 5- 10.5 and higher. The COP will vary based on environmental conditions and load.
    Please let me know if you have any other questions.
 
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nobueno

Silver Supporter
Sep 25, 2019
82
Erie, CO
I went with the RayPak 8450ti-E-HC. 140k btu, scroll compressor, very quite, titanium heat exchanger and it was only $2800. Pretty happy with it so far.

Keep in mind the Aquacal's COP would only be that high with very high humidity, air and water temps and when it's putting out less BTUS because of the variable speed. Also if I'm not mistaken, it's cost is almost twice as much.
 
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Stoopalini

Gold Supporter
Jun 8, 2020
465
Central Texas
Pool Size
14060
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
It's that variable speed which drew me to the AquaCal. Once the water is at temp, it'll be able to maintain it with very little energy. And it'll be very quiet at those lower speeds too.

The COP looks pretty good. And the EER rating for cool mode is not bad either.

This is the chart showing the specs at half speed (3500 RPM):

1614289034356.png

1614289063607.png

The SQ150VS is also a scroll compressor, but is inverter driven for the variable speed capability. It has a titanium heat exchanger as well. But you are right, it's quite a bit more than the RayPak.