Home AC/Furnace Replacement

I am looking to replace my existing 12 SEER AC and Forced Air Propane 80% Furnace.

What I am thinking is a minimum 16 SEER 2 stage AC. Dual fuel Electric/Propane, 2 stage, 2 pipe 90%. The electric portion is basically a heat pump, with propane kicking in at 35 degrees. The 2 pipe uses one to provide fresh air for combustion and the other for exhaust.

The variable speed systems are considerably more expensive, but are more efficient and comfortable at low and high temp extremes.

Any experiences/ suggestions/advise is welcome.

Can't help you with that, but I can recommend shopping here. I saved 25% compared to buying local.

https://hvacdirect.com/

Where do you live?

Seer ratings are taken at 90-degrees F. If you regularly see summers exceeding this temperature then 20-seer is the maximum that you want to run.

A dual stage heat pump works well in climates where annual winter temperatures aren't often below 30-degrees. The advantage of electric heat is in efficiency, 1KW of electricity makes 1KW of heat, the disadvantage is that electricity usually costs more than gas.

Are you looking for lower electric bills, energy efficiency (they aren't the same thing), or better temperature control?

My family has been in contracting for 59-years this year, 40+ of that doing HVAC work of various types.

I'd guess your 12 SEER unit came with the house? It's not up to code for new installs here, and there would be rebates to replace it.

What climate zone are you in? Sealed combustion is definitely the way to go for anybkind of combustion appliance these days, but ductless heat pumps are making huge inroads into the heating and cooling market. Most modern stuff will laugh at temps down to -10F or so as long as you don't try to turn it off and then restart it. Do you have a lot of square footage with existing ductwork?

Central VA and That's the heat and AC when I built the house in 92. Propane was dirt cheap compared to electric and heat pumps sucked Ass. Seems like most in the area say the newer dual fuel systems work well but that is what they said about heat pumps back then based on the average temps. The problem was when temps dipped below 30 for a week you lost everything you gained. Glad I went with all propane back then but times technology and energy prices have changed and I am out of the loop.

In theory the 2 stage or variable stage sound like they would provide a cost savings and more consistent temps but I am not sure if they will really work as advertised

Depending on your budget, your yard size, and how long you plan on living in your current home, you may want to consider a closed loop geothermal heat pump system... Ground temp is a steady 60F year 'round below the frost line, and the system doesn't burn any fuel for heat- just the power to run the system; they are very inexpensive to run, but can cost up to forty percent more to install, with the average ROI running anywhere from 4-15 years.

You may already know this, but as the efficiency of systems increases- so does the amount of space they require for installation, because they're physically larger.

Other things to consider are: having both supply and return ducts installed in every room, all new insulated ductwork, a central dehumidifier, and UV lighting (kills some microbes) on the supply air side- because the new ductwork and UV light can really help with indoor air quality, and the central dehumidifier can reduce your energy consumption by reducing A/C usage, while allowing you to fine tune the "feel" of your house (Central AC does SOME dehumidifying, but not effectively) . Having both supply and return vents in every room also allows for better efficiency and comfort.

Trane and American Standard remain the most reliable brands in HVAC, but you pay a premium, just like we do for higher efficiency systems.

I'm not connected to the HVAC industry in any way, but was an HVAC student 20 years ago, and the subject still interests me.

Good luck with your HVAC project!

ETA: links to some general geothermal HVAC info- https://www.familyhandyman.com/heati...pump/view-all/
https://energy.gov/eere/articles/5-t...mal-heat-pumps

How old is your home? Is the ductwork well sealed and insulated? Connecting a 90%+ furnace to leaky ductwork yields only very sight reductions in energy use.

You have to look at the entire system, not just the heating/cooling source.

I looked at geothermal when I built the house. Adding insulation and sealing the ducts are on the list. The local electric coop did an energy audit several years ago. Their only recommendation was to upgrade to higher efficiency units.

We now use propane and wood stove heat. The reason I didn't do a heat pump when I built was the electric vs propane cost and also the fact that heat pumps do not put out air as warm as gas/oil. Even though the temp of the house is the same it just doesn't feel as warm because we felt the cooler air when heating. Air below body temp will always feel cooler than air above it, 90 vs 130 degree air output. There is a cost for that though.

I am sure there have been improvements in heat pumps over the last 25 years, but I believe the heated air temp is still considerably cooler than oil/gas. I am interested if the 2 stage and possibly variable speed blower would help with that. Even now in extreme high or low temps there is a blast of hot or cold air when the system kicks on. In theory the more constant flow should help keep the air at a more consistent temp. I am just not sure if it will still feel cooler because of the lower output temps.

There is no doubt that a newer system will be more energy/cost efficient, I am not sure if will actually feel cooler/warmer than my current system.

I guess there is no perfect system and the quest continues.