Manual J load done — trying to determine kWh for ductless heat pump

Richard_ | Posted in Energy Efficiency and Durability on July 20, 2017 06:37am

Here are my numbers for 700 square foot guest home, zone 4b
Heat Load 9,725 btus/hour
Cooling Load 7,503 btus/hour

I know there are several variables but the unit I am looking at is a Ceiling cassette rated at 20.2 seer 12k btu unit

My question is there anything that has been published that could give me a good estimate of what my kWh could be.

Or some numbers at different temperature conditions

Thanks
Richard

Answer

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Martin Holladay | Jul 21, 2017 05:57am | #1
Richard,
Q. "Is there anything that has been published that could give me a good estimate of what my kWh could be"?

A. It sounds like you want to know your annual heating energy bill and your annual cooling energy bill. To determine those numbers, you need to use an energy modeling program like REM/Rate. (Lots of variables enter into these calculations.)

If you want to know the power draw of the equipment, here's a back-of-the-envelope calculation:

If your design heating load on the coldest day of the year is 9,725 BTU/h, that is equivalent to 2.85 kW of heat.

To provide 2.85 kW of heat at a COP of 2.0 (a typical COP on a cold day) would require 1.4 kWh of electricity for every hour that you operate the equipment. (In other words, the equipment would draw 1,425 watts.)
Richard_ | Jul 21, 2017 07:59am | #2
Thanks Martin
That helps
I did find one source by energy star that could help as a guideline also
https://www.energystar.gov/index.cfm?c=most_efficient.me_cac_ashp