Variable speed HVAC units?

[Valveman]

I have a perfectly good and working heat pump system that I gave $5K for about 20 years ago. I serviced it, cleaned the fins and coils this morning. It still looks like new and has a simple compressor, coil, fan, and control board. Because of MY age, I was looking to replace it. The new one is now $15K and has a variable speed compressor, fan, and pump, along with an inverter and two way complicated thermostat. Several of my friends and neighbors have complained about the high cost, short life, multiple problems, and lack of qualified or willing service technicians to keep these systems working. I just want a simple long lasting system like the one I have now and those don't seem to even be available anymore. Has anyone else had one of these systems for 10 years or more and been happy with it, or unhappy?

 

[breplum]

I empathize. Having had both plumbing and heating licenses, seeing what's new and the prices are sobering.
I put in my Trane equipment 28 years ago and should do a swap out, maybe here in Calif, before we can't buy gas/hybrid heat pump systems before the Feds ban all gas equipment. Ugh.
I was a Bryant dealer and mostly was very pleased with the equipment more than Trane which I had started with earlier on. I should do full heat pump bc I have PV array, but it wasn't sized for full heat pump, just gas heat with AC.
I will say that my neighbor's modulating Carrier outdoor unit is sooo quiet you wouldn't believe it...but I am no longer an expert since pre-covid with I stopped doing HVAC and aren't even a dealer any longer.
I have been very unimpressed with the high end Trane fully modulating 90+ gas heating equipment from earlier generations.

 

[psomerville]

I have replaced 8 HVAC systems in the last 10+ years. The most recent was a couple of months ago. You are right about pricing. There has been significant inflation since Covid. I understand that they are coming out with a new refrigerant in the next couple of years, so if your equipment is working, you may want to hold off replacing the system until the new refrigerant comes out, as they may stop making R-410, and it will end up as expensive as R-22.

I also suggest going to a mid level system. You usually get a variable speed fan and compressor. The system will be quieter both inside and outside. I've purchased York, Rheem, Bryant, Trane an Lennox equipment - both heat pumps and AC/gas heat systems. They are all major brands and come with 10 year parts warranties. A lot of folks like Carrier/Bryant. Trane is another popular brand. I currently have Lennox equipment installed in my newer home. It is builder grade and not as quiet as the mid level Trane equipment I had with the variable speed fan that I installed in my previous house.

 

[JEG in Raleigh]

I have a perfectly good and working heat pump system that I gave $5K for about 20 years ago. I serviced it, cleaned the fins and coils this morning. It still looks like new and has a simple compressor, coil, fan, and control board. Because of MY age, I was looking to replace it. The new one is now $15K and has a variable speed compressor, fan, and pump, along with an inverter and two way complicated thermostat. Several of my friends and neighbors have complained about the high cost, short life, multiple problems, and lack of qualified or willing service technicians to keep these systems working. I just want a simple long lasting system like the one I have now and those don't seem to even be available anymore. Has anyone else had one of these systems for 10 years or more and been happy with it, or unhappy?

Here's my take on it: I have a very energy efficient house. It was designed and built to Passivhaus standards.....a very rigorous certification, way beyond Energy Star. The building envelope is extremely well insulated and air-sealed.....R-50 walls, R-75 ceilings. Then I had a Rheem heat pump system installed, much as you described.....multi-stage, variable speed blower, communicating thermostat. WITHOUT FAIL, that damn system broke down every summer to the tune of $1500, minimum......every summer since it was put into service in 2016. Plus, the coil failed 4 years ago and the variable speed blower motor failed 2 years ago, plus the ERV failed this year. I had an entire new Trane system SEER 17, and new ERV installed this year at a cost of $17,000. It should be more reliable than what I had, but still has a level of complexity that makes me nervous. COMPLEXITY = GREATER POTENTIAL PROBLEMS. Same goes for heat pump water heaters and tankless water heaters. Try to have as energy efficient an envelope as you can and then lean towards simpler rather than complex mechanical systems, despite the loss in energy efficiency, unless you have surplus funds and patience. Go with a basic, single speed Trane heat pump.

I have a perfectly good and working heat pump system that I gave $5K for about 20 years ago. I serviced it, cleaned the fins and coils this morning. It still looks like new and has a simple compressor, coil, fan, and control board. Because of MY age, I was looking to replace it. The new one is now $15K and has a variable speed compressor, fan, and pump, along with an inverter and two way complicated thermostat. Several of my friends and neighbors have complained about the high cost, short life, multiple problems, and lack of qualified or willing service technicians to keep these systems working. I just want a simple long lasting system like the one I have now and those don't seem to even be available anymore. Has anyone else had one of these systems for 10 years or more and been happy with it, or unhappy?

 

[Mitchell-DIY-Guy]

At my primary home in Michigan, rather conventional two story built in 1992, we changed out the original 92+ efficient unit in 2009. Unit was zoned, with 5 ton AC and 125,000 BTU gas furnace. Home was about 3100 square feet; any larger they would have put in two systems instead.

We changed out to a York dual fuel heat pump. Gas furnace operated from low up to about 37 degrees F; that was the crossover point. At 37 or above the heat pump was used to make heat. Below that it was the gas furnace.

The zone control was totally separate from the HVAC setup; it was basically an interface between the stats and the unit. Mine was made by Jackson Systems. The two zone dampers lasted 2-3 years each before either a spring or motor went; so I used to keep a spare around so I could simply swap in place and fix it at my leisure.

I have not heard of variable speed compressors, but we did have a two stage compressor, which operated basically on a standard and high mode. No VFD involved. It had to be a very difficult cooling cycle in order for the 2nd stage to kick on.

The air handler/blower "claimed" variable speed, but it actually operated at only five speeds. Lowest on speed was 10%, (40-60-80) highest 100%. During heating most of the time it never went past 60%. I don't know if there was a VFD involved in the or not but it operated for 10 years for me without issue. It may have been a DC motor instead. I should point out that the first blower in the first system, a conventional ac blower unit what was only on or off, failed within the first year.

The gas burner was modulating. Not 100% variable as they may lead you to believe, but it was stepped like the air handler. Most of the time when heating (10 degrees-37 degrees) it never went above 60% and often lower. It went on high when we had those 15 below zero nights.

We set this up to leave the air handler/fan on at 10% silent velocity all the time. This prevented "heat or cool stratification" and our temperatures in the home were more uniform. As the equipment was located in the basement below the family room, this modulating setup was a welcome change as it was quiet only expect in extreme heat and cold when it had to "throw all it has" at the problem. We further improved the air flow in the home by putting a large return in the finished area of the basement which sucked air from the upstairs. In the winter this kept the basement warmer than normal and in the summer the naturally cool air was used to help cool the home.

Due to a rate plan in place at the time we had a separate meter for the a/c compressor. We paid $0.10 kw/hr from May 1-Oct 1, the cooling season, and a flat $0/08 the rest of the year which made heat pump heat pretty cheap. During those summer months they could turn off the compressor for up to 20 minutes per hour, no more than 4x per day, only between 9-5.

I used conventional Honeywell thermostats, with setback capability.

Aside from some initial setup issues, the whole system was very reliable. Setup was because their techs didn't know the equipment well. Once sorted it was trouble-free. I'd do the same kind of thing here in a heartbeat. A heat pump is just an a/c unit operating in two directions. I cannot tell you why my blowers and compressors didn't fail on my York, but they worked well. I bought the unit on a special when they priced a heat pump the same as their a/c unit.

Passivhaus and EnergyStar are great, but they are only for the exceedingly costly custom homes, for the 1%. I cannot retrofit such things to an existing home, and the search for a qualified builder do something truly custom would be maddening. Builders don't like any changes to process or materials. I've seen multi-million dollar homes built on the lake here and Lennar starter homes in Charlotte; basically the same subcontractors building everything.

 

[RickFlorida]

I live in Florida so HVAC is important. I did a lot of research when I bought my last system and I even had to get new ductwork done as well. I also have lots of life experience with AC systems here. In short, the variable speed new systems are great in terms of efficiency but they DEFINITELY don't last as long as single speed blower motors in the air handlers. Just ask if the warranty covers blower fan motor because they fail a lot more often than the older single speed blower fan motors. That is the biggest weakness of the new systems I believe.

 

[Mitchell-DIY-Guy]

By the way, I did check on the specs of my older York equipment, in the house I sold back in 2019 when I left Michigan.

The blower motor for the air handler that was an ECM motor, which is a brushless DC motor. No brushes to wear out… This is quite a bit different than an AC motor with a VFD drive.

I know some of you have a bias against VFD drives and that’s OK. The next HVAC system I buy, I will probably be searching for an ECM DC blower.

When I owned the car wash years ago, my main touchless system had a 25 hp 3-phase motor with a carryon suitcase size Fujitsu VFD drive. it was rocksolid reliable (never a hiccup despite constant use) but then again it was a very highly engineered product, not mass produced like HVAC systems for homes.