Hayward Setup for Gas Heater + Heat Pump

[C365]

Hello everyone,
I've got a 400k btu heater installed in line (before) a 140k btu heat pump. Right now the configuration has priority to the heater, so the heat pump is never used.

How do I make use of the heat pump? Seems like it would be good to run the heat pump at the same time to boost the temperature since the pump is already going.

Or it seems like I should program a schedule to run the gas for 2 hours and the heat pump for 4 hours or something like that. But I can't specify which to program in the hayward app.

Any guidance on how to program this?

 

[ajw22]

What model Hayward HP do you have? The square one or the round one?

I suggest you call Hayward and discuss your setup with them. It does not sound like it conforms to their installation instructions.

Page 10 in https://www.hayward-pool.com/assets/documents/pools/pdf/manuals/Heat-Pump-Owners-Manual.pdf says...

Installation in Combination with Solar or Gas Heaters
If you are installing a heat pump in combination with any other type of heating device, please call the Hayward Service Department at (908) 355-7995. We will advise you of installation practices that will help keep your warranty valid. Other pool heaters, such as gas-fired or solar-powered devices must be installed in a parallel circuit and operated independently (only one at a time) for your warranty to stay valid.

NOTICE - Because of the intense heat that can be generated by gas ansolar units, isolating it with a shut-off valve and a check valve when gas or solar heater is in operation protects the heat pump. Failure to follow the instructions
may result in property damage.

Notes:
1. Isolate the heat pump from hot water flow of heating devices such as gas or solar heater.
2. Install bypass loop for heat pump unit.

The Hayward recommendations is different then Pentair who recoomends the HP be inline and before the gas heater. And you run the HP first and if the HP cannot get the water to desired temperature then it uses the gas heater for supplementary heat. The Pentair automation controls the two heaters.

 

[JamesW]

The heat pump should be before the gas heater.

The minimum flow should be 10 gpm per 100,000 btu/hr.

For example, the minimum flow for a 400,000 btu/hr heater is 40 gpm.

At 10 gpm per 100,000 btu/hr (84% efficiency), the temperature rise from input to output is 16.8 degrees Fahrenheit.

If both heaters are controlled by the automation, you set the heater thermostats to maximum (104 degrees).

For example, if the water going into a 140,000 btu/hr heat pump is 86 degrees (40 gpm), the water exiting will be 7 degrees hotter (86 + 7 = 93).

The water entering the gas heater will be 93 degrees and the exit temperature will be 109.8 (93 + 16.8).

 

[JamesW]

https://www.hayward-pool.com/assets/documents/pools/pdf/manuals/HeatPro-Installation-HP2xxxxT-HP2xxxxBT.pdf

 

[C365]

Thanks for the key replies. I'll see about getting things moved around asap. Just had it installed by the pool builder yesterday... go figure. But I've got the gas turned off and bypassed now. I'm assuming this requirement is because the water gets so hot out of the gas that you risk feeding too high heat to the heat pump? Fortunately, the water going into the gas heater was 65-70 from the pool, so it's not sending water that's too hot to the heat pump. If the gas bumps the output temperature up to 15-20 degrees.

Incidentally, before reading this, I did notice the hayward config settings in omnilogic, I could turn "run for" to 0 in the heater bypass section and both units would run at the same time.

The notes from the manual about operating one at a time seems odd in this light because their programming seems to support both running at the same time.