HVAC / mini split experts: Energy consumption, what am I seeing?

[rbstern]

In search of saving some propane, I installed a 9000 BTU (SEER2 23 rating) mini split in our master bedroom. 2200 sq ft ranch, with a partially finished basement. 2nd furnace in the basement is kept at a low settings and rarely runs, but the house has high ceilings on the main floor, and we burn about 700 gallons of propane each year, which includes heat, hot water, range, fireplace starter. Most of that propane is going to the furnace. The strategy is turn the furnace down low at night, yet remain warm via the mini split when we are asleep. So far we're enjoying the setup, and it's nice not hearing the big furnace run.

I know these mini splits are efficient, but I wanted to get a sense of how much electricity is being used, so I can calculate total cost vs. propane (won't know the propane savings for a while, but I can tell the propane tank is emptying slower than normal).

The outside unit (230v) of the mini split is rated at 6.1A for the compressor, and 0.6A for the fan. I put a clamp meter on the mini split's power line. With outside temps in the low 40s, I watched the clamp meter for about fifteen minutes at a few different settings. Got 0.7A with the mini split set at 70 degrees. 1.6A set at 78 degrees. The unit is blowing hot air inside during the entire time, providing a lot of warmth (we've typically been setting it at 70 or 72 degrees overnight).

Are these power use numbers realistic? Seems ridiculously low.

Any input appreciated.

Clamp meter shown with the unit blowing hot air at 78 degrees.

 

[DanKATL]

If installed correctly, as in good placement of both the outside and all inside units those little heat pumps are very efficient as long as the outside temps are in the magical temperature range for them. Too cold an outside temp to suck the heat from and you're usually better off switching to the central unit.

 

[rtross]

This is what I understand:
Once upon a time, those units (and most heat pumps) worked well down to mid 30s. But when it got colder than that, they became quite inefficient.
But in the last year or two, heat pump technology has astronomically improved.

Subscribed for education

 

[DanKATL]

With outside temps in the low 40s

If installed correctly, as in good placement of both the outside and all inside units those little heat pumps are very efficient as long as the outside temps are in the magical temperature range for them. Too cold an outside temp to suck the heat from and you're usually better off switching to the central unit.

"With outside temps in the low 40s"

40s are in the magic range even for the oldest/cheapest ones. It's when you get below 30 that some of them start to fall apart.

 

[rbstern]

I only have a little bit of data so far, but as best I can tell, our weekly propane use has dropped somewhere between 50 and 60%.

Don't yet have a handle on added electrical cost. Not expecting it to be a lot. So far, this setup looks like a winner for winter temps.

Will post more precise numbers as I accumulate usage data.

 

[THREEJAYS]

In

 

[CIAO BELLA!]

In. I have been looking at mini-splits for the garage and addition.


What brand?

 

[cskiles]

What is the manufacturer and model number of the unit that you installed?

 

[fslc94]

Ole heat pumps have been struggling these really cold mornings until it gets up closer to 40 for sure!

 

[Granite3]

Last house with heat pumps, (have furnace now) we added those little oil radiators to the bedrooms, they worked great at keeping the cold at bay and significantly dropped the power bill from running the heat pump all the time.