Heat Pump before or after Solar?

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G

gr8t8

0
Sep 26, 2017
9
Beachside, Central Florida
I'm adding a 50000BTU heat pump to my system which already has solar. Live in Fl so pool is pretty warm already so the HP will be used to keep/maintain a good temp for year round swimming.
My question is whether to plumb the HP before (which I think is correct) or after the Solar. Anyone have actual experience or direct knowledge of this?
If I plumb it after I will have to play with temp sensor in the HP as it will be getting hot water directly from the solar panels and not from the pool thus causing it to shut down as it will 'think' pool water temp is higher than it actually is.
 
gr,

I think the basic concept is to get the free stuff first then you only have to add a little more heat with the heater.

I looked at my automation system manual and it has several plumbing designs.. They all show, Filter, then Solar, then Heater, then the salt cell..

It seems to me that if the water coming out of the solar system is hotter than you want your pool, then you would not want the heater on to begin with... :confused:

But, I don't have a heater or solar, so just going by what I have seen..

Thanks for posting,

Jim R.
 
Jim, thanks for the reply. I have seen those plumbing diagrams but they relate to LP, NG or Electric Heaters and not specifically to Heat Pumps. As you know HPs are a special case and work in a very different way to the former three mentioned.

I talked to the guys at Raypak and they said for an HP and Solar, before or after is fine, either will work because I probably won't ever run both HP and Solar at the same time.

They do think before might be better because of the temp sensor in the HP.
If the HP was after the solar and the Solar was on, the temp sensor would be reading Solar heated water not pool temp water so on a cloudy day the HP would continually cycle on and off as the Solar came on when the sun appeared - as opposed to staying on and maintaining the set water temp... these cloudy conditions we get in Dec, Jan and Feb when I would need the HP. All other months the HP is going to be off and I will only need Solar...

I don't know, it's still a bit of a mystery.
I need input from someone in a similar climate who has both Solar and a HP and has experienced this setup...
 
gr,

If you don't plan to run them at the same time, why not plumb them in parallel with a valve that allows you to select one or the other???

Not that it matters much, but I don't understand your worry about solar water entering the heat pump.. unless you are concerned that the heat pump will try to "cool" the water???

I am not sure heat pumps will automatically switch back and forth the between heat mode and cool mode like that. But... at this point I'm sure you probably know more about pool heat pumps than I do. :D

I too hope that we can get one of our Heat Pump experts to chime in on this one..

Thanks again,

Jim R.
 
gr8t8 said:
Hi Brent, I looked at your install and setup and see your HP is after the Solar however I have so questions... Do you ever run Solar and Heat Pump at the same time? How do you determine when each one runs?
Thanks.
Click to expand...

Hi, so because of the size of the pool we get about 2 degrees in rise per hr running solar on a hot day. Add the heat pump and we get about 4 degrees in rise per hr. We use the solar as the main source during the summer. We swim a lot at night so in the cooler months we use the heat pump in the evening after the sundown to maintain temp of the pool. We like out pool at 88-91 degrees.
 
There are plenty of times where I use both solar and heat pump at the same time. Actually most days the heat pump runs for at least an hour or two before the temp coming out of the solar panels is warm enough to turn off the heat pump.
 

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gr8t8 said:
Solar would be off and water would not be going to the panels when there is no sun. The solar controller has to sense at least a 4 degree difference between the temp at the panels and the pool water...
Click to expand...

I suppose you could do that.
 
The only time it really matters is when both solar and the heat pump are working together (e.g. quicker heating). Then, you should have solar first to reduce the heat loss and improve efficiency. Higher water temps will lose heat faster in solar panels (with or without sun) so it is less efficient to send heated water from the HP to the panels first.

Also, if you put the HP first, it has significant head loss and will lower the pressure at the solar VRV and in some cases, it may not stay closed. This is especially a problem with VS pumps as you will need to run at a higher RPM to keep the VRV closed.
 
mas985 said:
The only time it really matters is when both solar and the heat pump are working together (e.g. quicker heating). Then, you should have solar first to reduce the heat loss and improve efficiency. Higher water temps will lose heat faster in solar panels (with or without sun) so it is less efficient to send heated water from the HP to the panels first.

Also, if you put the HP first, it has significant head loss and will lower the pressure at the solar VRV and in some cases, it may not stay closed. This is especially a problem with VS pumps as you will need to run at a higher RPM to keep the VRV closed.
Click to expand...

Makes sense. I will install the HP after the solar because there are times they will run together.

Thanks!
 
mas985 said:
The only time it really matters is when both solar and the heat pump are working together (e.g. quicker heating). Then, you should have solar first to reduce the heat loss and improve efficiency. Higher water temps will lose heat faster in solar panels (with or without sun) so it is less efficient to send heated water from the HP to the panels first.

Also, if you put the HP first, it has significant head loss and will lower the pressure at the solar VRV and in some cases, it may not stay closed. This is especially a problem with VS pumps as you will need to run at a higher RPM to keep the VRV closed.
Click to expand...

Thanks mas985 for that explanation I knew there was a reason but I could not remember :cheers:
 
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