Solar (Heliocol) heater vs PV + Heat Pump Heater?

[Rootyb]

We're in Northern California and have an 18,000g in-ground that we're currently heating with a somewhat-undersized Heliocol setup on the roof.

Since it's undersized, we have to run our variable-speed pump on high for quite a bit of the day for heating (I think I currently run it for ... 7h/day?). Today, I noticed a leak at one of the pipe junctions, and am planning on repairing it, but since we've also considered installing PV panels (and the Heliocol panels are currently taking the best spot for PV solar panels), I started thinking about the possibility of installing PV solar and a heat pump for the pool.

It would theoretically cut back on the time I'm running the pump (and could run it at lower speeds), get a potential source of leaks/roof damage off my house, and allow for heating year-round if desired. And I could run the heat pump during off-peak hours, when energy is cheaper.

The main thing here is, I'm not sure how to figure out how much energy my pump uses to compare it to the amount a heat pump would use. I'm fairly certain the pump/solar heater uses significantly less energy than a heat pump would, but I'd like to try to quantify that somehow to make an educated decision.

Any advice?

 

[mas985]

What is the RPM used for solar and what is the filter pressure when solar is running?

 

[Rootyb]

RPM is 3450. Not positive of the pressure. My pressure gauge is pretty yellowed and hard to read. I pretty much just use it to see when it’s high and the filter needs to get cleaned.

 

[mas985]

My best guess would be around 1300 watts.

But you really shouldn't need to run at full speed. Have you tried lower speeds?

 

[PoolStored]

I was gonna say 1443W, according to your pump data (@mas985). 7 hours a day at high speed would be 307 kWh for the month.

Heat pump use 5 kWh per 100k BTU per hour. That would get you 61.4hours of run time using the same total kWh as the pump. Or 2 hours of heating per day.

With a 100K BTU heat pump, without jumping through hoops on efficiency, it would take about 1.5hours to raise your pool temp by 1 degree. Runtime will depend on demand.

Best calculator for you situation is below. Leave the gas cost blank and use your electrical rate.

Heat Pump Cost Estimator - AquaCal Website

www.aquacal.com

 

[mas985]

I was gonna say 1443W, according to your pump data (@mas985).

That is for Curve C. Solar tends to run closer to Curve A because of the higher head loss.

 

[Rootyb]

I haven’t, really. I’m not sure how to tell whether a speed is high enough, so I’ve been erring on the side of caution.

I was gonna say 1443W, according to your pump data (@mas985). 7 hours a day at high speed would be 307 kWh for the month.

Heat pump use 5 kWh per 100k BTU per hour. That would get you 61.4hours of run time using the same total kWh as the pump. Or 2 hours of heating per day.

With a 100K BTU heat pump, without jumping through hoops on efficiency, it would take about 1.5hours to raise your pool temp by 1 degree. Runtime will depend on demand.

Best calculator for you situation is below. Leave the gas cost blank and use your electrical rate.

Heat Pump Cost Estimator - AquaCal Website

www.aquacal.com

And I’d still have to run the pump for heating/filtration.

Thanks so much for the info and link!

 

[mas985]

I haven’t, really. I’m not sure how to tell whether a speed is high enough, so I’ve been erring on the side of caution.

Slowly lower RPM until you see air coming out of the returns, then bump it back up 10%.

Another way is to use filter pressure. If the panels are install 20' above the filter gauge, the filter pressure needs to be at least 10 PSI (Height (ft) / 2.31 * 1.2).

Both of these methods assume a VRV is installed near the top of the panels.

 

[Rootyb]

Slowly lower RPM until you see air coming out of the returns, then bump it back up 10%.

Another way is to use filter pressure. If the panels are install 20' above the filter gauge, the filter pressure needs to be at least 10 PSI (Height (ft) / 2.31 * 1.2).

Both of these methods assume a VRV is installed near the top of the panels.

Roger that, thanks! I do have a relief valve at the top.

 

[Rocket J Squirrel]

I run my solar at the lowest speed that fully closes my 2 VRVs. For me, that's 2500 rpm. Anything slower and the VRVs drip.