When should I have the heat pump on?

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cnr1089

cnr1089

0
Aug 29, 2010
33
Southern NH
So, first year with my pool. Have had the pool open for a little over a month and the weather has been really erratic. I am trying to figure out exactly when it makes sense to use the heat-pump for heat vs. propane heater.

Everyone says, that if you want heat quick, use the propane heater (I get about 1 degree/hour with the propane heater). But we also have a heat pump, and with propane at around $3/gallon, I want to use the heat pump when it makes the most sense.

Clearly, if I am just looking to maintain my heat (lets say 84) during the warm summer months, the heat pump is the way to go. But how about when the temperature varies between 58-72 on a daily basis (with a few days hitting 80 at the peak). Is it a waste to use the heat pump? I tried running it for several hours (5) with 0 heat gain when it was 76 in the pool and about 74 outside.

Does the heat pump do ANYTHING if the pool temp is higher then the air temp?
 
You already answered your question. When you want to maintain heat the HP is the way to go.

The heat pump will generate heat when the water temp is higher than the air temp. You don't say what size the HP is, and that might be your problem with building heat.
 
Ah, a heat pump in New England!

At 74 degrees, it should heat it up a little. I put 5 degrees in my pool with mine a few days ago when the high got to 65, but it took nearly 12 hours to do it. But, then again, mine is 120,000 BTU on a 14,000 gallon pool. Not sure what size yours is though. I'm in central mass, so i feel the pain too. The problem is that the air temps just aren't that warm right now. Even at 70 degrees, it just doesnt stay warm enough, long enough to do much good. By the time it hits 70-74, its 2 pm. Then, it cools to 50 again right after dark. There's just not enough heat to do much good right now. Plus all the rain we've had, it just saps the heat out. I've said it before, and i'll say it again. A heat pump in New England is not much more than a hunk of metal until we get a consistent high in the 70's and the low at night doesnt go below 62 or so. A heat pump will struggle at best and at worst just spin the electric meter on either end of the swim season. I have propane as well. Thats why i spent the money to install the heater, install tanks, and buy propane. I got tired of not being able to heat the pool in May, September and early October.
 
I installed 2 Aquacal SQ175 heat pumps on a 20'X60' X3.5'X10' Commercial pool Saturday afternoon. The daytime high hasn't broken 60 degrees, but yet the pool is at 72 degrees after 2 days of heating. Within 3 days it should be heated to 80ish, and maintain just fine.

I have a similar installation that started heating last Tuesday, and they were Swimming on Saturday morning.


This time of year the weather in Seattle is Identical to NH weather. 60 was today's high and it was 45 last night. We have only seen one 70+ degree day. It should be 84 there Tuesday so you will be able to gain some ground then.


1. Are you covering your pool? This is very critical.
2. How long do you have you pump set to run?
3. How large is the heat pump?
 
racket said:
. It should be 84 there Tuesday so you will be able to gain some ground then.
Click to expand...
I wish, but not likely.
Was 55 and rain here today. I ran mine 12 hours, with a cover, and got 4 lousy degrees. I put in what i lost last night, but nothing more.
We'll have to agree to disagree about the efficacy of heat pumps in New England.
 
I wonder if its that aquacomfort heat pump lack the efficiency of others. There may.be a reason that they are not listed with AHRI.

I have many pentair , and aquacal units in coastal areas much colder than both of our.climates that perform very well.
 
I dunno. It's the same basic unit as a Rome/Solarium I believe.
I dont know what the deal is. I know several people with different brands (i.e. Jandy, Heat Siphon, and one guy with an Auqacal) and none perform well this time of year in this type of cool, wet weather. I think a lot of it has to do with how long it stays warm during the day. Even if it does get to 62-65, it takes nearly all day to hit the high and then quickly drops back down.
I know you say the weather's the same, but it's really not. I've been to Seattle quite a few times in the spring and believe me, it's not the same as worcester mass :mrgreen:
 
From what I can tell, the unit outputs 137k BTU (from what I can tell, that is at 80F).

I am using a solar cover, but I can't wait to stop (it is a PITA, and gets very dirty).

My pump runs for 3 hours on full speed and another 8 on low speed. I can adjust this of course, and when the heaters are on, it runs at full speed.

Today it is going to be low 80s, although rainy this afternoon. The pool is at 72, I am going to use propane to get it to 76, then use the heat pump to keep things there for the rest of the week (the high all week is now all above 72). I am ok with the concept of the heat pump only being useful when it is warm out, I am just trying to understand when it is best to use it.
 

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So, today I had the heat pump on from 10am till 5pm. It raises the pool temp from 72 to 80. The outside temp was between 75 and 82 during that time. Note, however, the temp probably would have gotten to at least 76 on it's own, based on how much sun exposure we get.

Chris
 
cnr1089 said:
So, today I had the heat pump on from 10am till 5pm. It raises the pool temp from 72 to 80. The outside temp was between 75 and 82 during that time. Note, however, the temp probably would have gotten to at least 76 on it's own, based on how much sun exposure we get.

Chris
Click to expand...

Bout the same here. I'd throw mine on the scrap heap if I had natural gas. The 4 grand I paid for it would have bought a lot of propane.
The plus is now with the weather getting better, it should maintain temp now without a lot of trouble. I'll use the pool this weekend im sure, so I'l use the gas to bump it up to 85 or so. The heat pump should keep it around 80 with about 4 hours run time as long as the night time temps dont go below 55-56 and you use a solar cover. But like you said, in full sun, you will get a couple degress on it's own.
I've been VERY disappointed in the performance of the thing.
 
It costs about $2.20/hour to run my pump and heat pump (according to an energy meter I have and the .15/kwh for my electricity). It costs about $3/gallon of propane, and I suspect I use about 5 gallons/hr (I have no idea on this one, but if I have a 400k BTU heater, and propane provides something like 89k 100% efficient, then that is just a guess), so $15/hr for propane. The propane heater can get me 1F/hr (it should be more, and it really depends on the temperature outside, I guess).

BTW, while the heat pump is on, I can feel the heat pumping into the pool (about 2 degrees warmer then the rest of the water). The propane heats the water about 8 degrees warmer then the water going in.
 
I have a 400k too and nearest I can tell it burns a touch over 4 per hour. I get about 3 degrees an hour but my pool's smaller.
I get about 1.5 degrees warmer water out than in and with gas about a 10-12 degree difference. Same electric and gas rate as you. Like I said before, I like it ok to maintain temp from memorial to labor day. But on each end of the season, its a hunk of metal. Given the .15 cent electric rate and 1.20 a therm NG rate, I'd have gone that route. But the builder of my division went the oil route for heat and stuck us with LP for anything else. Sad thing is NStar has gas up on the main road. The builder got cheap and didn't have it run up here.
 
Ok, some more info...

This morning, I turned the pool on and it was about 73 degrees (it lost close to 7 degrees last night, with the solar cover on). It was probably a low of 55 last night.

Turned the heat pump on (the temperature outside quickly rose from 64 to 75, then eventually 80 in the afternoon). The pool got up to 78 in about two hours (again, combination sun and heat pump), then got to 82 over the next few hours. The heat pump then came on every time the sun went behind a cloud (I suspect that the temperature gauge is affected by direct sunlight), but more like 10 minutes once an hour. So, not too bad.
 
cnr1089 said:
Ok, some more info...
This morning, I turned the pool on and it was about 73 degrees (it lost close to 7 degrees last night, with the solar cover on). It was probably a low of 55 last night.
.
Click to expand...

Wow that seems like a LOT of heat loss with a solar cover on. My experience is with solar panel heat - this week in Northern CA we get highs in the 60s and lows in 40s - the pool is getting to ~78 and falling back to 73 - but with no solar cover on.

When I have used a solar cover the overnight heat loss was much less. One thing I noticed with a solar cover is that pool temp is layered (warmer at the top) if little circulation.
 
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