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Powerwall Compatible HVAC

miimura

Well-Known Member
Aug 21, 2013
6,106
5,708
Los Altos, CA
Any variable speed (inverter drive) compressor based HVAC system will probably be compatible with Powerwalls.

If you don't need the A/C to work when the grid is down, then this doesn't matter at all because the grid will provide the startup current.
 

Cstreet

Member
I am running Mits mini splits on my 3 PW's 3 compressors, 10 heads.
I'll second the Mitsubishi, we have the a 60k BTU heat pump the MXZ-8C60NA2 which works great with 3 Powerwalls. It heats and cools a 3000 sq foot house. I generally see 2500-4000 watts in the winter for heating and 3000-4500 watts in the summer when it's running. We are in California so a milder climate.
 
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zƬesla

Member
Apr 16, 2020
328
99
US-NH
+1 Mitsubishi. 2 outdoor compressors and 5 indoor heads (currently 2 Powerwalls). I did have a compressor go out just before the 5-year warranty expired, so only paid labor for replacement. Only other issue has been running dehumidify a couple of years ago which caused some mold on the inside of the units; since having them cleaned and only using heat or A/C it has not come back.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
7,810
8,638
Riverside Co. CA
My Tesla install, the guys actually installed a slow starter onto my AC without me doing anything. 2 PW installed Nov 2020.

Depending on the AC system size and number of powerwalls, and make / model / of the AC, that may or may not work. If having the AC on the powerwall side is a "must have" then one must do a lot of research to make sure it can happen, research if their particular AC unit is compatible with those "soft start" / "hard start" type devices, and buy the appropriate number of powerwalls for ones situation to ensure it can start.

if starting the AC while on backup is a "nice to have, but not necessary", then none of that research needs to be done and one can just let the installer figure out if it can be done or not, and what they want to install to try to make it work.
 

bayareaever

Member
Jun 17, 2013
314
158
East Bay Area
I'll second the Mitsubishi, we have the a 60k BTU heat pump the MXZ-8C60NA2 which works great with 3 Powerwalls. It heats and cools a 3000 sq foot house. I generally see 2500-4000 watts in the winter for heating and 3000-4500 watts in the summer when it's running. We are in California so a milder climate.
Are these compatible with ducted systems (Ie swap out existing NG furnace)? If not, do they make one that is?
 

h2ofun

Active Member
Aug 11, 2020
1,678
273
auburn, ca
Do you have solar panels and want to keep your natural gas furnace for when the power is out?
So so many detailed questions that need to be answered before anyone can say PV or PW's would "help" a person. In most cases, no decent ROI.

I was just reading yesterday the average life for a male is like 76 now. I am 64, So when folks say but wait, there is a 20 year ROI, well, from the tables,
I am dead.
 
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RKCRLR

Member
Apr 13, 2020
285
106
Garden Valley, CA
So so many detailed questions that need to be answered before anyone can say PV or PW's would "help" a person. In most cases, no decent ROI.

I was just reading yesterday the average life for a male is like 76 now. I am 64, So when folks say but wait, there is a 20 year ROI, well, from the tables,
I am dead.
Yes, but when you plan for retirement you don't plan for the average life expectancy. You plan for "worst case" of living well beyond the average life expectancy to make sure you are covered. I think the ROI needs to be planned similarly.
 

h2ofun

Active Member
Aug 11, 2020
1,678
273
auburn, ca
Yes, but when you plan for retirement you don't plan for the average life expectancy. You plan for "worst case" of living well beyond the average life expectancy to make sure you are covered. I think the ROI needs to be planned similarly.
Yea, and look at how many never get close to that "worst case" age! I still make my comment, who would ever invest in anything with a 20 year ROI? And having read some real estate comments that PV and ESS add zero to the value of a house at sale, ....
 

dareed1

Member
Jan 15, 2021
34
26
Belmont, CA
Are these compatible with ducted systems (Ie swap out existing NG furnace)? If not, do they make one that is?
[The question refers to Cstreet's 60k BTUh Mitsubishi heat pump system.] The MXZ outdoor unit has to be coupled with at least two indoor air handlers if it is to be used as a ducted system. We replaced a gas 100BTUh 2 stage 80% efficient gas furnace with a Mitsubishi SUZ/SVZ 30k BTUh unit. The "S" in SUZ means it is suitable for a single air handler. So this was a quite straightforward replacement with the SVZ air handler taking less space than the furnace did. Our house is 2100 sq ft, built in 1968. About half of the exterior walls are uninsulated, the ceiling is R30, double pane windows, no insulation in the floor. The hot air ducting runs in the crawl space with R6. I did a Manual J calculation with CoolCalc that suggests a heating load of 25k BTUh.

I choose the 30k BTUh system because it is spec'd to be about 25% more efficient than Mistusbishi's largest size (36k BTUh) in the SUZ/SVZ line. It is big enough to keep the house at 70F, but as expected there isn't much margin. So we don't program the temperature to a lower value at night because it takes quite a while to bring the temperature back up in the morning. Of course the previous gas furnace could go into second stage and deliver 80k BTUh, so it had a lot of margin.

We really like the quiet operation, both for interior and exterior noise. It looks like even if we didn't have solar, our total utility bills would be less with the heat pump system than with gas furnace. We have two PWs, but our heat pump power consumption can reach 35kWh if the outside temperature is in the 30s, so if we have a winter time power outage, we'll want to sharply reduce the interior temperature.
Mitsubishi documents
 
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h2ofun

Active Member
Aug 11, 2020
1,678
273
auburn, ca
[The question refers to Cstreet's 60k BTUh Mitsubishi heat pump system.] The MXZ outdoor unit has to be coupled with at least two indoor air handlers if it is to be used as a ducted system. We replaced a gas 100BTUh 2 stage 80% efficient gas furnace with a Mitsubishi SUZ/SVZ 30k BTUh unit. The "S" in SUZ means it is suitable for a single air handler. So this was a quite straightforward replacement with the SVZ air handler taking less space than the furnace did. Our house is 2100 sq ft, built in 1968. About half of the exterior walls are uninsulated, the ceiling is R30, double pane windows, no insulation in the floor. The hot air ducting runs in the crawl space with R6. I did a Manual J calculation with CoolCalc that suggests a heating load of 25k BTUh.

I choose the 30k BTUh system because it is spec'd to be about 25% more efficient than Mistusbishi's largest size (36k BTUh) in the SUZ/SVZ line. It is big enough to keep the house at 70F, but as expected there isn't much margin. So we don't program the temperature to a lower value at night because it takes quite a while to bring the temperature back up in the morning. Of course the previous gas furnace could go into second stage and deliver 80k BTUh, so it had a lot of margin.

We really like the quiet operation, both for interior and exterior noise. It looks like even if we didn't have solar, our total utility bills would be less with the heat pump system than with gas furnace. We have two PWs, but our heat pump power consumption can reach 35kWh if the outside temperature is in the 30s, so if we have a winter time power outage, we'll want to sharply reduce the interior temperature.
Mitsubishi documents
I just dealt with this winter. 64 degree settings on my mini splits and I was still using 20 to 50kwh per day. So, looking at getting more solar, so I can bank in the summer.
 

bayareaever

Member
Jun 17, 2013
314
158
East Bay Area
[The question refers to Cstreet's 60k BTUh Mitsubishi heat pump system.] The MXZ outdoor unit has to be coupled with at least two indoor air handlers if it is to be used as a ducted system. We replaced a gas 100BTUh 2 stage 80% efficient gas furnace with a Mitsubishi SUZ/SVZ 30k BTUh unit. The "S" in SUZ means it is suitable for a single air handler. So this was a quite straightforward replacement with the SVZ air handler taking less space than the furnace did. Our house is 2100 sq ft, built in 1968. About half of the exterior walls are uninsulated, the ceiling is R30, double pane windows, no insulation in the floor. The hot air ducting runs in the crawl space with R6. I did a Manual J calculation with CoolCalc that suggests a heating load of 25k BTUh.

I choose the 30k BTUh system because it is spec'd to be about 25% more efficient than Mistusbishi's largest size (36k BTUh) in the SUZ/SVZ line. It is big enough to keep the house at 70F, but as expected there isn't much margin. So we don't program the temperature to a lower value at night because it takes quite a while to bring the temperature back up in the morning. Of course the previous gas furnace could go into second stage and deliver 80k BTUh, so it had a lot of margin.

We really like the quiet operation, both for interior and exterior noise. It looks like even if we didn't have solar, our total utility bills would be less with the heat pump system than with gas furnace. We have two PWs, but our heat pump power consumption can reach 35kWh if the outside temperature is in the 30s, so if we have a winter time power outage, we'll want to sharply reduce the interior temperature.
Mitsubishi documents
Good to know, thanks. What was the total cost to swap out the furnace with the heat pump system?
 

dareed1

Member
Jan 15, 2021
34
26
Belmont, CA
Good to know, thanks. What was the total cost to swap out the furnace with the heat pump system?
In total, $29K. However, that included $10K to replace all of the ducting in the crawl space, and another $2K for other stuff, like a HERS test. Base proposal to replace the furnace with the heat pump was $17K. I believe that one can buy the hardware for this model for around $6K, and at one time in my life I would have installed it myself. I've gotten old and lazy!
 

Cstreet

Member
In total, $29K. However, that included $10K to replace all of the ducting in the crawl space, and another $2K for other stuff, like a HERS test. Base proposal to replace the furnace with the heat pump was $17K. I believe that one can buy the hardware for this model for around $6K, and at one time in my life I would have installed it myself. I've gotten old and lazy!
We paid about $31k for our swap which was the main air handler plus adding a second slim "pizza box" air handler and ducts in an addition, plus all the existing exposed ducts being replaced.
 

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