13 years & 7 months later. Reduce Sanyo power use?
 

13 years, 7 months (approx) after installing this Sanyo mini-split, I've decided the Crankcase heater is wasting too much power on cool spring days & mild summer nights.
Not sure when it comes on, but it might be around 50F.
It's 86F now, and in the morning it will drop to 44F.

Now that power cost is 30 cents per KWh, I'm noticing all the power being used this spring when no heat or cooling was needed. The heater connection could be unplugged during mild weather. (upper left of diagram) Or, I could add on a toggle switch to made it easier to switch on or off as needed.
Anyone have any pros or cons?

http://i46.photobucket.com/albums/f1...CL/outdoor.jpg

Instead of completely disconnecting, could you add an additional thermostat in series, so it still turns on, but at a lower temp.
Or instead of a manual 2-postion switch, use a 3-position switch for ON(stock t-stat)-OFF-ON(additional, lower t-stat).

a firmware thing?
 

There's a Compressor thermistor and an Outdoor thermistor connecting at lower left on the board diagram.
My guess is the firmware looks at both the compressor (crankcase) and the outdoor (air) temperatures and decides when to turn on heating coil.

That's how I would do it, if I were the firmware coder.

It seems like the easy way would be to cut the AC to the heater.
I can't remember how much power the heater uses.
IIRC it's about 40 watts. Maybe that's not enough to worry about.
I have a spare heater on the spare parts unit. Maybe I could install it on the compressor, and wire it in series to get 20 watts of heating.
It's not like we're in Minnesota or Norway. ;)

Is it possible the manufacturer has updated or different firmware for milder climate areas?
Or a hidden method to change that setting? Maybe they could help us (you) understand why its set where it is? Likely a compromise for all areas its sold.

The firmware is in a ROM, so I'm stuck with the shipped version.
This unit is very old and out-off date.
I checked the docs and it says the heater use is 30 watts.
So, that 30w+ the parasitic 10w waste of the system is 40w.
I think that might be much less than I'm using on smart-home devices that are always on.

There is no information about configuring the heater for use in a warmer climate.
So, I'll take a look at the guts of this old Sanyo when I do the Spring cleaning. Maybe install a switch..

Even if you do nothing, you are ahead I think.

I should have learned by now,
if it ain't broke, don't fix it.. :cool: