Adding heat pump away from the pool pad?

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R

rynoshark

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Mar 8, 2018
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Seattle, WA
I'm about to replumb my pool house (next to the pool) and was planning on adding an AquaCal SQ150 heat pump behind the pool house, but as I thought about it, it seemed to be quite loud where I'm trying to relax ;) My second thought is to move just the heat pump behind the garage. Besides not ever hearing the heat pump, the other benefit is that I actually have sufficient 150A panel in the garage to be able to power the heat pump, and don't need to run a new electrical conduit with expensive 8 AWG wires from behind the house to the pool. Instead, only a short run is necessary from the panel in the garage to the heat pump.

However, there is a downside. The added distance AND the fact it will have about a 6' elevation off the pool where it enters the heat pump. The existing sand filter/heater piping is about 3' off the ground already (so really just adding 3' more elevation). I am switching to an IntelliFlo variable pump.

Now, I'm concerned about the distance. From the pool skimmer to the existing pool pad is 14 feet of 1.5" Schedule 40, and slightly smaller back to the return. From the existing pool pad the water would travel down Schedule 40 (buried underground, which should help with heat loss) from the pool pad about 48' to garage corner, than another 18' to the rear of the garage. So a total of approximately 80' overall distance (not including added distance within the pipes inside pool house) from the skimmer to the heat pump...and back.

Is this a bad idea? See attached photo for my plans. The red line is the full Schedule 40 pipe run to the red heat pump behind the garage.

Pool Heat Pump Location.jpg

Alternatively, if I install the heat pump right next to the pool house, I would need to excavate out about 3 feet behind it, for the platform for the heat pump and clearance, plus running about 80 feet of new 6AWG wiring from the electrical panel to the pool house to upgrade the wiring to handle 60+ amps. Plus possibly new underground conduit for a 20-foot section of that.

Thank you so much for any insights. Without TFP, I'd be lost with my pool.
 
I believe this would put a lot of strain on the pump and slow down movement, but maybe someone else will chime in as well. Nothing a small CD radio/Bluetooth could not handle to drown out some of the noise. Personally, I have my heat pump, 2 AC units next to each other, a little bit away (and I am so used to the noise), that I do not even hear anything. Actually, quite relaxing.
 
As long as the pipe is big enough, the extra resistance on the pump is minimal.

The heat pump could be a mile away and it wouldn't make any difference as long as the pipe was big enough.

The elevation change doesn't matter as far as flow rate.

What flow rate will be used?
 
Are you able to locate the heat pump in an area that would receive full sun all day? My heat pump is in full sun. I operate it all day to raise the temperature and then I turn it off and turn on outdoor speakers when we get in.
 
Fantastic points!!

Regarding sun exposure, the location I am considering is right around the corner of the garage (so the sun would heat the ground about 3 feet away, generating heat). I don't have a good location that receives sun all day where it the heat pump would not be sitting in the middle of everything viewable to all.

If the pipe was 2" piping, would that be ok? What about the short runs of 1.5" piping from pool pad to the pool, would that cause problems for the whole system even though the rest was 2"? I'm wondering if I should have a bypass for the heat pump leg, just to be able to shut that off when not used (which would skip that long run out to the heat pump). My controller still has an open wiring spot for controlling a 3-way.

Regarding pump strain, before adding this long heat pump leg, I was planning on running my VS pump at a pretty low rpm, so I could always bump it up a bit.
 
At 62 gpm, 160 feet of 2" pvc would add about 11.4 feet of head loss (5 psi pressure increase). Water velocity would be about 6 feet per second.

160 feet of 2.5" PVC would add about 4.8 feet of head loss (2.1 psi pressure increase). Water velocity would be about 4.24 feet per second.

At 62 gpm, I would suggest 2.5" PVC.

However, the flow probably can be much lower. Check the heat pump installation manual for the flow requirements.

You probably won't need to exceed 30 gpm for good system performance.

Most likely, 2" PVC will be plenty.

2" pvc at 40 gpm is 3.9 ft/sec. At 160 feet of pipe, you add about 5 feet of head loss (2.2 psi pressure increase).
 
James, fantastic calculations. The biggest takeaway: my idea of locating the heat pump so far away from the pool house/pump is not crazy. I'll add a valve so water can be bypassed from the long run and just stay within the pool house.

AquaCal SQ150's recommended flow rate is 30-70 gpm. Further they suggest:

"Design the plumbing system to maintain at least 50-GPM flow through the heater under worst case conditions (i.e.: filter fouled to 10 psi rise); the heat pump will not operate correctly, nor reliably, with less than 50-GPM of water flow supplied."

Should I just use 2.5" PVC for the long run (even though at the end it would go down to 2" PVC within the heat pump and would be 1.5"/2" in the pool house itself)? I'm wondering the downside of doing that...well, there is the cost downside, which is about $1 more per foot to go 2.5" over 2" with Schedule 40 PVC pressure rated pipes. That is another $160 in materials along for the pipe.

https://www.homedepot.com/p/2-in-x-10-ft-280-PSI-Schedule-40-PVC-DWV-Plain-End-Pipe-531137/100161954
 
I guess one other issue is how to hook up the remote heat pump to the automation controller to set in spa or pool mode. I guess a long run of wiring from the control center will work. Eventually I'd like to get something like the Pentair IntelliCenter setup, but for now I use a basic Intermatic setup.
 
In my opinion, 40 gpm is better than 50 gpm.

Even at 50 gpm, 2" PVC should be ok. It's 4.88 ft/sec. It adds 7.67 feet of head (3.32 psi pressure increase).

Note that the heat pump uses a pressure switch instead of a flow switch to detect flow. It assumes that if there's pressure, there must be flow.

But, with a bypass, you can trap pressure in the heater with no actual flow.

This can make the heat pump operate without flow.

So, be careful with the design so that the heat pump can't run without actual flow.

Maybe put a flow switch in the plumbing and put it in series with the pressure switch.

Also, since the heat pump will be higher than the pool, the pressure switch might not operate properly. A flow switch would be a better choice. Just disconnect the pressure switch and use the flow switch.

Just get the 2"pvc T and flow switch that turns on at about 30 gpm and connect it to the terminals where the pressure switch connects to. Leave the pressure switch disconnected.

Flow Switch Pool, Spas, Salt Chlorinators Model Q-12 Harwil
 

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Great suggestion regarding the flow sensor vs pressure sensor. I'll have to read the schematics of the heat pump and make sure this will all work.

Perhaps I should skip the complexity and just always run all water through the remote heat pump.
 
What you're proposing is not uncommon in solar heating systems, so the plumbing and equipment should be able to handle it. I'd be more concerned about the heat loss from the underground pipes (mother earth is a great heat sink). Temperature differentials with heat pumps are quite small as it is and you may be running it longer because of this heat loss (translation, costing more).
 
Another way is to put a larger 6 inch sewer type pipe that your two 2 inch pipes would travel inside. That would give air apace around your heat pump pipes.. I did this in a darkroom. The hot wash water ended up warming the rinse water before it went to the heater.

Just a thought
 
The whole pool and existing plumbing is in the ground losing heat to the ground.

So, I don't think that it's going to increase heat loss that much.

Maybe a foam type snap on pipe insulation would be worthwhile.
 
While insulating and containing the heat in the ground is a great idea, the more important aspect is containing the heat in the pool. If your pool is like your drawing, a solar cover is a worthwhile investment. Get the smallest mil cover and cut down the middle, but overlap by about 2' at least on one of them. Next time, I will overlap the covers. Also, I use 1" PVC to roll the cover up and store.

My heat pump will gain 1 degree per hour with the cover on, even when temperatures are in the upper 70's and 80's. I have not tested anything lower because once we reach this time, the pool is almost closed.
 
I do have a solar cover but it is a real pain to put on/off. I've been thinking of some sort of rolling system, like Catanzaro suggested.

I will investigate some insulation of the pipes, since it doesn't cost much more to do when putting it in the ground.

Thanks everyone!
 
I do have a solar cover but it is a real pain to put on/off.
Click to expand...

If you can cut the solar cover 12' by 16 feet, then you can install in 3 sections. Each section will overlap the other section of a little more than 1'. If you can do a little more than 12', like 13' or 14', that would be better. Then take 1" PVC (10') and glue some round end caps to each one. Use these to help you roll the cover and put away somewhere. The edges will hang a little bit, but nothing major so easily manageable. Your cover would have to be at least 16'*36' to accomplish this. Next time, I will do this. Made a mistake by doing a perfect cut. You want to do this so the cover stays and does not move. Also, you can take the 10' PVC and drop on top of the cover the long way to help support the cover as well. Even with strong winds this does not move. I actually will take some pictures and link up.
 

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