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HVAC recommendation?
- Thread starter Carbonfiber
- Start date
spsheridan
Member
Not sure what you mean by "a system that will pair well with solar". HVAC systems don't pair with the Tesla mobile app. Maybe you're referring to how much power the HVAC system draws vs. how much power your solar panels can deliver. But that isn't a limitation since your grid power will take up the slack if your solar panels can't deliver enough power. I'm assuming you don't have a whole-home battery (like a Powerwall). If you do, take care in selecting the right HVAC system that can be powered by a battery in the event of a grid outage. Could you provide more info on your home's power setup?
Number one advice for HVAC is to find a good installer. Modern equipment has great efficiency and comfort. You want someone that will calculate the load and size accordingly. I'm assuming you want efficiency.
With regard to the equipment, heat pumps are great in my experience. I'm partial towards inverter-based systems. I had a Mitsubishi installed in California rental and Bosch system in an AZ rental this year. In both cases my installers had different options and manufacturers to chose from. I didn't get the usual brands common in the US. I believed those brands were a better value. I also have a Carrier Infinity system in my house, pretty happy with that. It's a zoned system originally installed 15 years ago, and it made sense to stick with Carrier when the compressor went out. I went from a two speed heat pump to a much higher efficiency inverter-based system. A good installer will be able to tell you why you might want to go with one manufacturer over another.
With regard to the equipment, heat pumps are great in my experience. I'm partial towards inverter-based systems. I had a Mitsubishi installed in California rental and Bosch system in an AZ rental this year. In both cases my installers had different options and manufacturers to chose from. I didn't get the usual brands common in the US. I believed those brands were a better value. I also have a Carrier Infinity system in my house, pretty happy with that. It's a zoned system originally installed 15 years ago, and it made sense to stick with Carrier when the compressor went out. I went from a two speed heat pump to a much higher efficiency inverter-based system. A good installer will be able to tell you why you might want to go with one manufacturer over another.
If you are willing to spend a few $ then I would go for an inverter based system like Bosch or Daikin. I have both and they run super quiet and very efficiently. My Bosch (3 ton) has a 20.5 SEER rating, runs at 56db and the compressor can run as low as 25% output- which means it starts up running on super low (and efficient) to see if it can get the job done, if it needs more power it then increases in 1% increments until it hits the right balance. We installed it and a hybrid water heater (which I hate) at my lake house and our bills are down 75% this year. To be fair a good chunk of that is the WH and we are only there 5-6 days a month but still super impressive (and they replaced 7 year old systems).
spsheridan
Member
Since we installed solar and our electrical power is cheap, we got rid of our old gas furnace and installed a Daikin heat pump which provides two-zone (upstairs/downstairs) heating and air conditioning. We had a narrow installation constraint for the exterior unit and Daikin offered a narrow verticle unit that is very quiet and efficient. Daikin's heat pump has a multi-stage compressor and the blower has a variable-speed fan. If you eventually install a battery and want the HVAC to work off the battery, the multi-stage compressor is important because it has a lower max current draw when the compressor kicks in. Batteries don't like compressors that go from 0 to 100 quickly because they can't support the resulting current spike. Heat pumps can have challenges heating in very cold weather but I see you're in Los Angeles so a heat pump should perform well. There are lots of choices out there so let us know if you have any questions.
Last edited:
RKCRLR
Active Member
Solar without storage doesn't really come into play regarding which HVAC unit to get. If you are planning on adding battery storage then you may want to consider inverter AC/heat pumps that have a low starting draw if you want it to run during a power outage.
Find a good installer in your area. Talk to your friends, neighbors, look at online ratings, etc. As mentioned, a good installer is more important than the brand of equipment and each house is different. Get multiple bids. Many HVAC representatives are as bad as used car salesmen so make sure you have a good feeling about them.
You don't state what your current HVAC system is but I see you are in LA. A heat pump is probably the best bet these days since there are a incentives to get away from natural gas. But you may want to consider a dual fuel system if you currently have a separate gas furnace and AC.
If you currently have a central system with ducting then you will probably be better off with a conventional split system high efficiency heat pump (assuming your duct design is good).
If you don't have central ducting then a mini-split heat pump system would be a good option.
Find a good installer in your area. Talk to your friends, neighbors, look at online ratings, etc. As mentioned, a good installer is more important than the brand of equipment and each house is different. Get multiple bids. Many HVAC representatives are as bad as used car salesmen so make sure you have a good feeling about them.
You don't state what your current HVAC system is but I see you are in LA. A heat pump is probably the best bet these days since there are a incentives to get away from natural gas. But you may want to consider a dual fuel system if you currently have a separate gas furnace and AC.
If you currently have a central system with ducting then you will probably be better off with a conventional split system high efficiency heat pump (assuming your duct design is good).
If you don't have central ducting then a mini-split heat pump system would be a good option.
CrazyRabbit
Active Member
I’m not a fan boy of inverter based system because they are so expensive to repair.
Just go with a high ear or seer unit single stage and no variable fans.
The new unit will have a lower LRA then your old unit.
Just go with a high ear or seer unit single stage and no variable fans.
The new unit will have a lower LRA then your old unit.
We replaced our 15-year-old system in July last year with a Bryant (Carrier) 5-ton 16 seer system that runs very good with our solar. On startup it draws 5Kw and settles back down to 3.5Kw. Our Powerwalls handle the startup spike easily.
We have a Mitsubishi multi-split system that we really like. Very efficient, and super quiet in operation. No issues with running in generator backup because like all scrolling inverter systems it starts slowly and doesn't need soft start capacitors etc... I think there are offers available now due to the recent infrastructure bill passage, and I don't know about others, but the Mitsubishi systems have an excellent track record for reliability.
The rest of the world has been using them for a long time and the bugs have really been worked out.
The rest of the world has been using them for a long time and the bugs have really been worked out.
I am also looking at Bosch BOVA60HDN1M20G 4-5 TON HEAT PUMP to replace an ancient two 5 ton ( oversized ) Carrier AC and Furnace system.
Did your Bosch replaced an existing AC/Furnace and if yes, did you reuse the existing line set ?
How much square feet your Bosch is heating/cooling ?
I am in Bay Area and have a 3375 sq ft two storied 1992 built home with good insulation. I am wondering if two 4-ton or two 3-ton Bosch system will be good - one for each zone ( floor ). I called HVAC contractors for estimating the project , but none are ready to do calculation following any process ( Manual J etc ). I am apprehensive of trusting their guesstimates.
I ran across this video recently and it has me really intrigued.
signaturesolar.com
I would want to get a setup that would utilize my existing ducting rather than wall mounted head units, but being able to install additional solar panels (say on a pergola) that are not part of my interconnected system would be so amazing.
In the summer I use a portable AC unit in my office; replacing that with the 12k BTU version and a couple solar panels would further reduce my net grid use.
EG4 Hybrid Solar Mini-Split Air Conditioner Heat Pump AC/DC| 24000 BTU | SEER2 21| Energy Star Certified | Plug-n-Cool Do-It-Yourself Installation
Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL
signaturesolar.com
I would want to get a setup that would utilize my existing ducting rather than wall mounted head units, but being able to install additional solar panels (say on a pergola) that are not part of my interconnected system would be so amazing.
In the summer I use a portable AC unit in my office; replacing that with the 12k BTU version and a couple solar panels would further reduce my net grid use.
Did you find some local Bay area authorized installers for the Bosch heat pump? When I looked up on the Bosch site, I could only find one of the few listed that actually did HVAC, and that one curtly told me the Bosch BOVA/BOVB were very backordered. This was back in the spring though, the supply chain and demand might be quite a bit different now.
I also couldn't easily get anyone to provide a ManualJ calculation, so I did it myself using the nearly free software from CoolCalc. IIRC, after carrying out the calculation, I paid $10 to allow the calculation to be transferred to a PDF file. When I did this a couple of years ago, the $10 allowed 5 or 10 different scenarios, which was useful because I was considering whether to add insulation. Actually using the software, as well as making the measurements of exterior wall sizes and window sizes, took about me about 5 hours. There is a learning curve for the software. I also spent perhaps 10 hours watching videos and reading up on the calculation before starting.
Even with guessing the U value of our windows, the calculation proved to be accurate within 10%, based on our usage of power to run the heat pump.
We are successfully using a smaller heat pump than the contractors recommended using their rules of thumb. For the Mitsubishi heat pumps, the smaller size provides a better COP, so I think the time I spent on the calculation was well worth it.
I know you were addressing @aks20000 but I'll share my experience.
In my memory serves me, Bosch is able to reuse the line set. I believe that's one of the reasons my AZ installer recommended it over the Mitsubishi. When I had a Mitsubishi unit installed in my California bay area rental they installed new line sets.
Bay area HVAC folks seem to be very reluctant to do a manual J calculation. I suspect a big part of the reason is historically customers would be unhappy with recommendation that manual J will spit out. The problem is our climate is historically so mild most people don't run their AC (if they had it) unless we are in a massive heat wave. This means the AC is turned on only when the thermal mass is way behind and you need an oversized system in order to catch up. My 2800 sq. ft. house two story house in Cupertino has a 3 ton unit. On the hottest day of the year it will start lagging a little bit at peak load but it is not an issue if the house was conditioned the entire time. 10-15 years ago we did exactly what I described above, run the AC only the hottest days and and experienced the issue with catching up. Once we figured it we would run the AC earlier on the days that we knew it would be hot. These days the HVAC is always on.
I ran across this video recently and it has me really intrigued.
EG4 Hybrid Solar Mini-Split Air Conditioner Heat Pump AC/DC| 24000 BTU | SEER2 21| Energy Star Certified | Plug-n-Cool Do-It-Yourself Installation
Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL
I would want to get a setup that would utilize my existing ducting rather than wall mounted head units, but being able to install additional solar panels (say on a pergola) that are not part of my interconnected system would be so amazing.
In the summer I use a portable AC unit in my office; replacing that with the 12k BTU version and a couple solar panels would further reduce my net grid use.
Oh wow that’s a very interesting product! Would be awesome for a large shed or ADU + non connected solar panels.
I recently installed a standard mini split and it’s already amazingly efficient.
I just ordered a Bosch Max Comfort 2.25 ton 3 headed minisplit for 3800 + tax. It's rated for 27k, and came with 25-foot lines, and (2) 12k and (1) 9k indoor units.
I had originally chosen a cheaper DIY model made by MRCool, that was about $700 less but then I realized that the MRCool outdoor unit was going to be 64 dba!!
Where I live, we hear no cars and only sounds of nature typically. I couldn't shatter that silence with a loud appliance. The 2 different bosch units I was looking at were either 34 dba for the normal Climate 5000 energy star, and I selected the slightly more expensive Climate 5000 Max Performance at 20 dba! That is like a whisper 5 feet away.
I will not hear the compressor unless I am standing right next to my Powerwalls.
This higher-quality unit will require commissioning, but when doing my research that's not a huge deal. I could buy the supplies and tools for $300 ish but I will probably pay a friendly tech to commission it for me.
Looking at the Solar direct unit above, I like it! I do not like that the outdoor unit might be 57 dba though. Maybe when my bosch unit dies, this technology will have matured and include multi headed mini split versions with direct solar inputs that are exceptionally quiet.
I had originally chosen a cheaper DIY model made by MRCool, that was about $700 less but then I realized that the MRCool outdoor unit was going to be 64 dba!!
Where I live, we hear no cars and only sounds of nature typically. I couldn't shatter that silence with a loud appliance. The 2 different bosch units I was looking at were either 34 dba for the normal Climate 5000 energy star, and I selected the slightly more expensive Climate 5000 Max Performance at 20 dba! That is like a whisper 5 feet away.
I will not hear the compressor unless I am standing right next to my Powerwalls.
This higher-quality unit will require commissioning, but when doing my research that's not a huge deal. I could buy the supplies and tools for $300 ish but I will probably pay a friendly tech to commission it for me.
Looking at the Solar direct unit above, I like it! I do not like that the outdoor unit might be 57 dba though. Maybe when my bosch unit dies, this technology will have matured and include multi headed mini split versions with direct solar inputs that are exceptionally quiet.
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