Heat pumps vs Aqua Hot

[96 Wideglide]

Wondering when people who have these two systems, run, one or two of the heat pumps. I'm plugged in to 30A at home, and it seems I'm using about the same amps, running one of the 15,000btu heat pumps, or running the Aqua hot on AC. Your generally going to need hot water anyways, meaning running the AH, so, when do you use the heat pumps?

[pasdad1]

I might imagine that the heat pumps could be considered "backup heat" in case aquahot failed for some reason.

[96 Wideglide]

Yeah, I suppose. As long as it's not too cold for the heat pumps to operate.

[Mike Canter]

You are correct in that if you are using the electric element in the Aqua Hot it is using about the same power as one heat pump. The problem is that the heat pumps are not efficient down below about 38-40 degrees and just will not put out heat and will run the compressor all the time. And the single electric heating element will not give you much in the way of baseboard heat below 45*. It was really on designed to heat your hot water unless you are lucky enough to have a dual electric element Aqua Hot.

[BCooke]

The warmer it is outside the more heat you will get from the heat pump.
The Aqua hot will always give you the same btu output.

[EZDZIT]

And with a properly designed system, the evenly distributed Aqua Hot heat is wonderful!

[Dr4Film]

I have only used the heat pumps once in 10 years. My Aqua-Hot had been removed and I was waiting for a rebuilt unit to be installed.

I prefer the baseboard heat of the Aqua-Hot over listening to the heat-pumps overhead.

I would run two ceramic heaters before using those heat-pumps.

Dr4Film ----- Richard

[Coma]

Originally Posted by Dr4Film

I have only used the heat pumps once in 10 years. My Aqua-Hot had been removed and I was waiting for a rebuilt unit to be installed.

I prefer the baseboard heat of the Aqua-Hot over listening to the heat-pumps overhead.

I would run two ceramic heaters before using those heat-pumps.

Dr4Film ----- Richard

To add to this, the Thermostats will go to Aqua-Hot (Aux) if Heat Pump is selected and they don't put out enough heat. That said, I use them if electricity is free and I'm not there to hear them.

[Dr4Film]

Originally Posted by Coma

To add to this, the Thermostats will go to Aqua-Hot (Aux) if Heat Pump is selected and they don't put out enough heat. That said, I use them if electricity is free and I'm not there to hear them.

Not one size fits all.

I have separate thermostats for each of the three Aqua-Hot zones. My rooftop A/C's and heat-pumps are controlled by the 5 Button CCC unit on the bedroom wall.

So I could have the heat-pumps running and the Aqua-Hot too, not that I would BUT I could.

Dr4Film ----- Richard

[Coma]

Originally Posted by Dr4Film

I have separate thermostats for each of the three Aqua-Hot zones.
Dr4Film ----- Richard

Nice, I don't think I like the 4 button model.

[K7JV]

The choices are practically endless. In our '06 Dynasty, with three zones, and when heat is required, we pretty much do the following:

Front zone (Living room)
Cool outside - Use just the front heat pump
Somewhat cold outside - Use the heat pump with a 750 watt space heater on steady
Quite cold outside - Heat pump with the space heater steady on 1500 W.
Very cold outside - Aqua hot, with the diesel burner enabled AND the 110V element

Middle zone (bathroom)
Most all heating regimens - Aqua hot, with 110V only, unless other zones need diesel

Rear zone (bedroom)
Cool outside - no heat
Somewhat cold outside - Probably still no heat
Quite cold outside (above 35) - Aqua hot
Very cold outside - Aqua hot

With the Aquahot, on electric power only, think of it as a 1400 watt electric heater that has to heat your domestic water as well as any space heating load you want to put on it. It can handle the bathroom and the domestic hot water, generally with no problem. But any more space heating than that, and it is quickly overwhelmed.

With the Aquahot on diesel, or diesel and electric, you likely won't be able to run it out of hot water or space heating capability. The diesel source turns it into a really highly capable and powerful heating unit.

One think you might consider is that there will be times when you don't want heating or cooing air from the heat pumps and/or the Aquahot in other parts of the coach, and you will have to open and/or close ceiling vents to keep the appropriate air going where you want it.

As an FYI, I did some experiments and some calculations and I believe that the cost of heating with diesel, with the Aquahot is roughly commensurate with heating with the heat pumps when the overnight temperatures are cool to chilly, and with diesel prices in the $3.00 per gallon range, and electrical energy in the $0.14 per kWhr range. That's a pretty general statement, but several required assumptions were needed that preclude an accurate and exact comparison.

Lots of flexibility! But it's nice to have multiple choices. Use the Aquahot for the bigger, harder jobs, and the heat pumps for the smaller, easier jobs.

[96 Wideglide]

Great answer K7JB
Do you have a regular hot water tank, as well as the Aqua Hot ?

[RVNeophytes2]

Originally Posted by EZDZIT

And with a properly designed system, the evenly distributed Aqua Hot heat is wonderful!

I've used both, and consider AquaHot an immense improvement. I've kept the coach warm on engine block heat via AquaHot, down to 9 degress F.

[K7JV]

No, the AquaHot does the space heating and domestic water heating job. For domestic water, it brings cold water in, on demand, and runs it through a fairly long coil in the AquaHot tank. It "comes out the other end" hot, pretty much regardless of the flow rate demanded of it. So it really is an awesome source of continuous (on diesel) hot water, on demand and no other water heater is required.

Remember, though, with only the 110V heat source enabled, it becomes just a 1400 watt water heater. The AquaHot reservoir has sufficient fluid it it to provide quite a bit of hot water and/or space heating from its stored heat, but the speed of recovery will depend on whether the diesel or electric or both are used.