Roof top A/C and heat pump
Planning on replacing my 15,000 BTU A/C, came across a Dometic unit with a "heat pump". How does this technology work, are they as efficient as the forced air propane heaters ? How much amps do they...
Forum Discussion
I use my Coleman Mach 15,000 BTU/hr heat pump for most of my heating needs March and April, September through November outings in this part of the country.
It puts out air about 20F warmer than it takes in, so if thermostat is set for maintaining house temperature about 70F, you heat with a larger volume of warm (about 90F) air from above, rather than a smaller volume of hot (120-150F) air delivered at floor level.
The noise is no greater heating than cooling, and in my bedroom with ducted air, I find the furnace and heat pump equally annoying, either will wake me when cycling on.
Efficiency? Measuring BTUs in fuel burned, a RV propane furnace delivers 70-80% of the heat to the interior of the RV (used to be as low as 60% in older furnaces).
Electric resistance heat is 100% efficient if you measure KWH you buy to BTU delivered to interior. A heat pump is usually 200% to 300% efficient, by that measure, thus it can deliver at least twice as much heat from the same power, compared to a resistance heater.
How that measures against propane, BTUs for fuel burned, depends on efficiency at the electric power plant and transmission losses bringing the power to you. Your fuel burning power source may be less than 70% efficient (especially your RV generator at about 20-25%) or it may burn no fuel at all if wind power or hydro. Figuring out fuel efficiency of an electrical device is pointless if you have no control over how the power is generated and how far it is transmitted.
It puts out air about 20F warmer than it takes in, so if thermostat is set for maintaining house temperature about 70F, you heat with a larger volume of warm (about 90F) air from above, rather than a smaller volume of hot (120-150F) air delivered at floor level.
The noise is no greater heating than cooling, and in my bedroom with ducted air, I find the furnace and heat pump equally annoying, either will wake me when cycling on.
Efficiency? Measuring BTUs in fuel burned, a RV propane furnace delivers 70-80% of the heat to the interior of the RV (used to be as low as 60% in older furnaces).
Electric resistance heat is 100% efficient if you measure KWH you buy to BTU delivered to interior. A heat pump is usually 200% to 300% efficient, by that measure, thus it can deliver at least twice as much heat from the same power, compared to a resistance heater.
How that measures against propane, BTUs for fuel burned, depends on efficiency at the electric power plant and transmission losses bringing the power to you. Your fuel burning power source may be less than 70% efficient (especially your RV generator at about 20-25%) or it may burn no fuel at all if wind power or hydro. Figuring out fuel efficiency of an electrical device is pointless if you have no control over how the power is generated and how far it is transmitted.
