Hayward hp50ha questions

[Dmartin411]

I just fired up a hayward hp50ha I have a 7000 gal. Gunite pool. When I first turned it on it said the water input temp was 73 and output 77. Now after running for awhile it says water input 76 and output 77. Why is the output temp not rising? Also I have a vsp and am running it at 3200 rpms. Is that a good speed or should I lower to try and change the flow to have a more rise in temp?
I know it's a small heater but figured it would be perfect for my pools size I just imagined it would heat the water more.

 

[pooldv]

It should be fine for heating your pool. I installed the same heat pump last fall and it worked well heating my 20k pool along with solar. 3200 is probably plenty depending on what hp pump you have. You can probably lower it. You can add your pool info to your sig as shown here, Pool School - Read This BEFORE You Post. I have a 3hp VS pump and I run it at 2000rpm when running the heater. The real way to measure pool heating effectiveness is what is the water temp now and what is it an hour later, 2 hours later, 6 hours later, etc. You are looking for an over all water temp increase over a period of time. The input/output temps at a moment in time aren't all that meaningful, the compressor may have cycled off or who knows what.

 

[Dmartin411]

Thanks I added it to my sig. I don't know I figured with the calculations on my size pool it would roughly increase temp 1 degree an hour. 7 hours 3 degrees. I just left for 2 hrs and went up 1 degree

 

[pooldv]

Here is the formula to calculate pool heating times. 1 btu will heat 1 lb of water 1 degree in 1 hour not counting heat loss and heater efficiency.

Here is the easy math formula
7,000x8.3 = 58,100 lbs
58,100÷45,000btu = 1.29 hours per degree

Then you lose some for heat loss, especially if there is no solar cover (depending on air temp and wind) and you lose some for heater efficiency. So, about 0.6 degrees per hour is a pretty good estimate.

You might try lowering pump rpm a bit to get to 2-3 degree F temp differential to see if that improves efficiency a bit. But, more flow through a heater tends to be better as far as picking up the most heat.

 

[Dmartin411]

Thanks guess I didn't take that all into consideration, wind ect. Seems that 2600 rpm is the sweet spot for a 3 degree difference. Not really a big deal except it is gong to be running more than I expected, just see how much it costs. Is it better to keep it at temp that I like or better to keep it lower and just raise it a while before I use it. I am using a liquid cover. I know they are not as good but I have 2 large dogs and one is a little nuts. He has fallen in the pool 4 times since we got it don't last month. So a little nervous about using a cover that he can get stuck in

 

[pooldv]

I understand about the dog. LOL I've got one of those too but he only fell in twice before it seems like he has learned his lesson. Our boss dog barks at him a lot when he falls in like she is telling him to stop it! Very amusing. I would definitely be leery of the dog getting trapped in the cover. If they are in overnight though the cover would help a lot. If not, then my theoretical calculation is that it costs at most $0.27 per hour to run the heat pump at 10.25c/kWh. I haven't verified actual amperage draw to confirm, it could be less. Should be less really.

Keep it warm vs warm to swim depends on how you use the pool.
If you only swim on the weekends I would be tempted to let it drop. Calculate the approximate time to bring back to temp and turn it on Wednesday or Thursday for the weekend. If you swim a couple of days during the week too then it is better to keep it heated. One thing I learned recently is to shut off the pump on colder or windier nights. Water moving through the plumbing and circulating in the pool cools more than still water does. So, if you decide to keep it heated and there is a cold night on a Monday or Tuesday or Wednesday then shutting off the pump will save some electricity and help to conserve heat.

You might also consider a solar cover and this DIY reel, DIY Solar Cover Roller. Then you could put the cover on and off fairly easily for cold days/nights when you are around to keep an eyeball on the dog.

There is some discussion on heating my pool in my pool thread linked in my signature that might be helpful.