Replacement for aging Mastertemp?

[eameres]

I have a Mastertemp 250 that's getting towards 10 years old which has fought more than a few battles with mice and the elements and is getting more and more cranky about kicking on. I've supplemented that with DIY solar coils which have actually done a pretty good job. The mastertemp uses propane (again, usually just our spa). Since our initial install, we have added a photovoltaic solar system to the property and have an excess of electricity produced. I'm seriously thinking about a heat pump, but I'm concerned with how quickly it would heat up a spa. We're located in the Northeast (upstate NY) and typically use our spa well into October. We heat our house with a hybrid propane/heatpump.

Is a heat pump a realistic option for our use? Anyone have any experiences they want to share? Looking for recommendations.

(ps, I am watching that other thread that's contemplating a gas+HP solution, but I don't know if I want to double the cost... plus propane is $$$)

 

[ajw22]

Maximum HP BTUs is 120K-140K and the BTU output declines as the air temperature deceases. So figure that it will take your spa 2X - 3X as long to heat as your 250K propane heater. Also HPs shutdown when air temperature approaches 50F.

 

[eameres]

I was just reading up about the Pentair hybrid HP/Propane. It's pricey, but it would pretty much be a drop-in replacement, right? 220KBTU vs 250KBTU, but I think it has an efficiency bump due to the titanium heat exchanger.

I see where some people recommend going with separate units rather than the hybrid, but would that complicate the Easytouch setup and rule out my DIY solar being controlled?

 

[ajw22]

The ET supports dual heaters. The MasterTemp gas heater connects to J19 and the UltraTemp HP connects to the RS-485 J20 Com Port. The UltraTemp ETI Hybrid heater uses the same connections. I don't think there is a difference in the way the ET controls two heaters or one hybrid heater.

 

[eameres]

Follow-up question... What would be the equivalent of that 220K hybrid? a 140K UltraTemp HP + MasterTemp 175K or 200K ? Seems like the combo would kick the hybrids Rear in terms of output capacity. My pool is 25K gal with a typical 500g spillover spa.

 

[ajw22]

If you have a spa I would get a 400K heater. The difference in cost is small and you get quicker heating. Your propane usage would be the same if you have a 400K, 250K or 220K heater. You would use the same amount of gas in a shorter time to heat to s specified temperature.

Then supplement with a 140K HP if you want.