minisplit heat pump

solarfortheouachitassolarfortheouachitas Registered Users Posts: 3
Looking for some information and help, please. 

I'm a little unclear about how much wattage a minisplit heat pump uses when the compressor is in heating or cooling mode.

I realize that it depends on the model - but do they use 400 - 500 watts, more or less when the compressor is running?  

Also, if it has an inverter, does that mean that the DC fan can run at a slow or variable speed on the indoor unit, even when the compressor is not running? If so, what is the purpose of running a fan if the compressor is not on?

We've had a heat pump water heater in our off-grid cabin for a few years and it works fine.  

We are now considering adding a 1 ton minisplit heat pump/ac unit. We have a 3,725 watt array, with 10kwh AGM battery bank (usable capacity at 50%) and a Trace SW4024 inverter with a 220 volt transformer and are located in the Ouachita Mountains of western Arkansas.

Any help out there? 


Comments

  • PhotowhitPhotowhit Solar Expert Posts: 5,014 ✭✭✭✭

    Wattage at minimum draw will vary with the unit. I think the lowest I've read is around 330 watts. I live a bit north of you, in central Missouri, and our heat comes with sun. I can just set me window air to come on around 2 and the system will be in float so I won't draw down the system at all, once cooled off, even with my poorly insulated Tin can, the duty cycle is rarely above 50% even on the warmest nights, I just have it set to turn off around 2 am and I'm fine until morning. a similar cycling should work for you, cooling down at high and turning it to lower settings when the sun sets.

    Starting multiple threads just make things ugly, hard to follow. I think the Mini split threads are in the Energy Use so I replied here. I would suggest removing the other threads.

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • BB.BB. Super Moderators, Administrators Posts: 29,644 admin
    Can you measure your load with a Kill-a-Watt or similar meter?

    The inverter based mini-split heat pumps are usually pretty off grid system friendly.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • solarfortheouachitassolarfortheouachitas Registered Users Posts: 3
    Thank you.  

    I'm new to this and didn't intentionally create additional threads, so if there is an administrator who wants to remove a thread or two, that's fine with me.  Sorry.

    I do have a Kill-a-Watt meter, but it is a 120 volt model and built to plug in to a receptacle, so it may be hard to measure the 220 voltage voltage load. 

    What I'm still a little unclear of is: In general, how many watts does a 220 volt, 1 ton minisplit draw in the A/C mode when both the outside and inside units are running at max load? And, how many watts does the same minisplit draw when the just variable speed inverter is running the fan?  Also, what good is the heat pump when only the fan is running?

    As you can tell, I'm still struggling with the basics regarding a minisplit heat pump. 

    We are currently using a 120 volt 5000 btu GE brand window A/C unit in the summer and have it on a 15 amp plug-in timer.  

    Overall, it works pretty well but I'd like to study the specs to see if a minisplit in heat pump would cut my propane use during the heating season.  We recently increased the battery bank and array size and are hoping that the excess capacity will help run a minisplit in the winter.

     





  • LucManLucMan Solar Expert Posts: 223 ✭✭✭
    The FLA rating in the specs for the heat pump you are considering will tell you max amp draw for that system.
  • BB.BB. Super Moderators, Administrators Posts: 29,644 admin
    I have already deleted the duplicate threads (not a problem).

    As for measuring larger loads, you can get whole house meters (and some have multiple branch circuit taps) for reasonable amounts of money:

    http://theenergydetective.com/

    Or you can get clamp current meters--Which help, but do have their own limitations (you cannot measure total energy use, "surge hold" meters are more expensive, etc.).

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Raj174Raj174 Solar Expert Posts: 704 ✭✭✭✭
    Checkout this website for examples of various SEER and size models with the specs you're looking for.

    http://www.thermospace.com/ductless_split/mini_ductless_split.php

    They have 120v and 240v models. All the specs are given for any model selected. These include watts, amps, at high, medium and low speeds. It may be possible that since the 5000 BTU window shaker has been cooling well you might want to consider a 9000 BTU unit. 
    Most of the units have 3 fan speeds. My opinion is, running the fan without cooling or heating would just be for air circulation.

    Rick
    3600W PV, MNE175DR-TR epanel modified, MN Classic 150, Outback Radian GS4048A, Mate3, 54.4V 195AH LiFePO4 no BMS, 4500W genset.
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Raj174 said:
    Checkout this website for examples of various SEER and size models with the specs you're looking for.
    Thanks for the link.  I am looking at their 22 seer, 9000 btu unit which operates on 115 volts AC.  It has inverter technology with a DC compressor and draws a maximum of 13.5 amps AC while in operation. 

    However the specs also indicate that it has a LRA (locked rotor amps) of 33 amps and a "compressor RLA" of 4.59 amps.

    I don't know what "RLA" is... maybe a typo?  Also, I'm not sure from the specs whether that 33 amps is the startup surge that would be seen by your AC source.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • Raj174Raj174 Solar Expert Posts: 704 ✭✭✭✭
    RLA is run load amps. Might ask them about the LRA spec. The site has a chat tab. Maybe the inverter absorbs the surge as it ramps up rpm on the compressor. 

    Rick
    3600W PV, MNE175DR-TR epanel modified, MN Classic 150, Outback Radian GS4048A, Mate3, 54.4V 195AH LiFePO4 no BMS, 4500W genset.
  • solarfortheouachitassolarfortheouachitas Registered Users Posts: 3
    Thanks for the information.  Is my understanding of this correct: The variable speed compressor on the outdoor unit can run at different speeds eliminating frequent startup surges and as a result, consumes less power overall?
  • Belmont SolarBelmont Solar Registered Users Posts: 26 ✭✭
    LRA means "Locked Rotor Amps". (Pretty much the highest possible amperage draw ever)
  • LucManLucMan Solar Expert Posts: 223 ✭✭✭
    Do yourself a favor and only purchase major manufacturer mini splits. Mitsubishi, Fujitsu,Panasonic, Daikin, Carrier etc.. Parts will be available if you ever need them. Even they discontinue parts after 10-15 yrs.
    The off the wall brands not so, they have a poor parts network if any at all. 

    LRA is locked rotor amps that you will only ever see if the compressor rotor seizes and can no longer spin. This would require a replacement compressor.
  • vincevince Registered Users Posts: 79 ✭✭
    I have just installed and finally operating the fujitsu 9rls3, with an SEER rating of 33. The air conditioning unit runs between 300-500 W but the heat pump can surge to almost 2000W under special demand conditions, although nominally, it also uses about.600 W. With some planning and keeping it in setting for power saving, the use stays below a 1000w on automatic mode.
    Sunpower 3 x 435 watt panels, 48 v 215 AH battery bank (Sam's club), Midnite Kid and WBjr, Fujitsu 9RLS3 split duct AC, Outback FX 3048T + transformer 2000W 120/220V, GrapeSolar Fridge.
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