Heat Pump VS Solar Heating

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grey1988

grey1988

Well-known member
Nov 14, 2017
55
Las Vegas/NV
HI, I have a company coming out Friday for a quote on solar heating. I started doing some research on Heat Pumps and I am now considering that instead. My main concern is that I will not get enough heat from it. I am considering the Raypak 8450 Heat Pump which is 140k btu. I also have a natural gas heater as backup. My goal is to get 15 to 20 degrees from this unit. My pool is 22k gallons in Las Vegas, NV. IS there anyone with a similar pool size with a similar climate that can tell me their experience? I don't want to use a pool cover because it deters my family from using the pool when I am not around. Please help. I don't want to end up getting the heat pump and it can't do what I need. We want use the pool around 89 degrees when we are swimming.

Thanks in advance.
 
If I was you, I would install solar as primary and gas as back up. The reasoning is on cloudy cooler days the solar won’t get up to temp. A properly size solar system can easily fetch the temps you want, provided enough panels are used and facing south at about 18 degree tilt.
 
Pool_Medic said:
If I was you, I would install solar as primary and gas as back up. The reasoning is on cloudy cooler days the solar won’t get up to temp. A properly size solar system can easily fetch the temps you want, provided enough panels are used and facing south at about 18 degree tilt.
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Thanks for the reply, I am more interested if the Heat Pump would work as well. I prefer to save my roof for PV solar instead of pool solar.
 
Because of our very dry climate, and significant drop in over night temperature during spring and fall, when heating the pool water is needed, you will struggle to keep the pool warm with out covering it.
Heat pumps are designed to operate at peak efficiency at ambient temperatures of 80F and 80% humidity. We never have those conditions.
Without a cover, recovering your heat each day with a heat pump may be difficult.
Check out Pentair UltraTemp Heat Pump - Further Reading. Use the Heat Pump Calculator linked in the article.
 
mknauss said:
Because of our very dry climate, and significant drop in over night temperature during spring and fall, when heating the pool water is needed, you will struggle to keep the pool warm with out covering it.
Heat pumps are designed to operate at peak efficiency at ambient temperatures of 80F and 80% humidity. We never have those conditions.
Without a cover, recovering your heat each day with a heat pump may be difficult.
Check out Pentair UltraTemp Heat Pump - Further Reading. Use the Heat Pump Calculator linked in the article.
Click to expand...
How do you think it would so in the summer months?
 
Do you need to heat your pool in the summer? We surely do not. It rarely gets below 88F or so.
Pool water temperature, without a cover overnight, tracks the low ambient air temperature, more or less, in our dry climate.
If you feel you need to heat your pool in the summer, I am sure a heat pump will add heat to the water. Again, not very efficiently as they are not designed to work in our climate. Your gas heater will heat it easily. For not much cost.
 
For what it's worth, I live in Indiana so climate is a little different, however I'll just add this here. We just opened over the weekend. Pool temp was 52 when I turned the pump and heater on. It was upper 60's during the day and dropped to around mid 50's sunday night. The past 2 days our temps have been in the mid/upper 70's and today mid 80's. I've had the heater on 24/7 since sunday afternoon and current temp on the pool is 70. I'm not sure you could get that much increase on just a solar cover in 2 1/2 days.

Get the heat pump imo
 
I'm in Central Valley, CA - we are removing our Solar Thermal to put on Solar PV and I am replacing the heat with a Raypak 8450 that should be here any day now. The Solar Thermal works great, no cover needed although temps recently haven't allowed the water to get over 77F. If I had a cover we'd be at mid 80s by now. No cover needed during the summer and last summer had to frequently bypass the roof because the water was too warm. If I calculated correctly, we are getting approx 50k BTU/hour heating from the panels so a 140k BTU heat pump should be more than adequate replacement.
 

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I am still on the fence regarding heat pump or Solar. I am still waiting for feedback from someone in a similar client as Las Vegas to see how it works for them. It seems like Solar Heat is a pain when it comes to leaks and taking part of the roof away for PV solar in the future. I really prefer to go the heat pump route but would really be disappointed if it could not reach the numbers I am looking for. Jacob have you installed the heat pump? What do you think so far? Thanks in advance.

Greg
 
The plumbers are here right now installing the Raypak 8450. I have to have the electrician come back to wire the heat pump to the plug they provided and then I'll be able to turn it on.
 
One other aspect of solar that may influence your decision. I live in the high desert, so we are a bit colder than you. I have solar heat with propane backup - which I only use on the spa. The solar does a good job of heating all summer, but it takes much of the day to do it. Morning to evening the pool has a 5-7 degree swing in temperature. So if you want a hot pool in the morning, solar is not going to get it for you.
 
This was my experience with solar thermal as well with no cover. 384 sq ft of FAFCO panels (8 x 12x4s) comes out to something like 40-50kBTU/hour. It's not a lot. Hoping the 140k heat pump, even at extremely low humidity, will be able to at least provide 2x the solar heating, and probably more than that. BTU assumptions are 35-40k BTU per DAY per panel. I run pump approx 8 hours a day and have 8 panels. I'll save 8kWh/day running the pump at lower speeds since I no longer have to pump water to the roof, which is approx 1-2 hours of heat pump runtime.
 
@grey1988 the heat pump is now up and running. At 11am with ambient temps right now at 72F @26% humidity. I’m getting what I think are 14F delta air temp difference between intake and outtake and this is translating to 5-6F water temp rise with infrared thermometer on the pvc connections. The water feels warmer coming out the end, it’s similar to how the solar delta felt, but not warmer. We’ll see how it performs today as temps get up to 90.
 
Here are the last three days according to Screenconnect. The air temp sensor is in direct sunlight I believe - ambient air temp peaked at 88F the first day and is supposed to be 90F today. I have no cover and get quite a bit of heat loss at night, clearly.

First day no heat pump, no solar, no cover.
Second day, heat pump ran from 10am-6pm.
Third day is right now.

Without a cover this is going to be expensive. I haven’t measured running amps from the 8450 but I figure it’s in the 30A range. My electricity averages $0.31/kWh due to high usage and so this thing will cost me $2.10/hour to run - $17/day. Once I get the Solar PV installed and get a cover this will all make more sense. It was nice getting warmer water at dusk last night - solar thermal could not provide that. It’s still cheaper than gas if you consider here gas is $2/therm and 400k btu heater is 4 therms/hour. That’s two hours of gas heat (650k btu in pool) compared to 8 hours heat pump (800k btu in pool). And that’s assuming my 140k btu heat pump is deregulated down to 100k due to low humidity which I think is WAY conservative and probably wrong. And once the PV goes up I can dump excess generation into the pool instead of being reimbursed the absurd generation credit of $.05/kWh.
 

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Thank you for the update Jacob I can definitely see it is working. So if these solar panels are 1000 BTU per foot and you have 384 feet, wouldn't that give me more heat during the daylight than the max 140 btu of a Heat Pump? Am I doing the numbers right? I can see you are decent heat but did your thermal solar panels do better? If so why the change?

Thanks
 

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