HVAC questions

[Fallon]

I've been reading about how heat pumps work for a long time.

I know they harvest the heat from the outside air, even when it "cold" outside but..........

Seems to me most the heat is generated when the gas is compressed?

Heat isn't created (other than small friction byproducts). Heat is moved. If you go stand near the outside of an AC unit you'll feel it blowing warm or hot air. That's just the heat being moved from inside.

A hear pump usually has a greater than 100% efficiency. Seems like it violates laws of thermodynamics or what not, but true. Ots merely moving heat around not creating it like burning fuel or resistive electrical heating.

More expensive initially, but often good in the longterm. Using less fuel or electricity is good for the environment too.

 

[RustyA]

18 seer heat pump here with two stage propane furnace. Heat pump will work to zero degrees but takes a lot more electric to extract the heat as outside temp drops. Ours is programmed to stop heat pump below 30 degrees and on off peak rate of $.06 per kWh that is equivalent to $1.00 propane cost. If propane rises dramatically we can adjust that cutoff downward. AC in summer is also more efficient due to 18 seer pump and off peak/dual fuel rate.

 

[MasseyFerg231]

As someone said earlier, it’s very specific to your region , resources, usage, and lifestyle.

heat pumps have come along way.

Rinnai now makes a heat exchanger/furnace that is heated by a hot water loop on a tankless which is interested.

you can buy mini splits direct now that are precharged wit quick connect lines.

check utility company rebates as well.

 

[npalen]

I think that at least some of the mini split systems use an inverter powered compressor which runs at a slower speed when demand is less to minimize short cycling.

 

[Smokeydog]

11 year old Mitsubishi is dc inverter, variable speed compressor. 23 SEER. Best return of investment.

Ran 1” lines to spring for a ground source heat pump. New mini splits are so efficient that pumping the water for ground source costs more for our application. Do have wood heat back up for a old log farm house.

Electric to heat 300-400% more efficient than resistance heat. Heat pump doesn’t make heat energy only moves it. Never blows cool air in heat mode. Air conditioning dehumidification one of the best. Wife and I installed. Drilled through 8” oak log for line set and 20” stone foundation for power to the outside unit. Had HVAC guy use vacuum pump on lines and indoor coil before opening precharged outdoor unit. $120 service call. Be great ever since. Only negative is that it has taken me years to perfect the yearly cleaning technique of the indoor unit. Saves money and we are more comfortable.

 

[RalphVa]

Geothermal would be most efficient followed by ductless then regular HVAC, all WAY more efficient than straight electric, like about 25 to 33% of the energy.

We've ductless for here in the basement. Work great. Main thing is they have no noise. Ours are Fujitsu.

 

[m1garand762]

Just put in a wood burner or a pellet stove

 

[robstaples]

I have 4 Fujitsu mini splits in south east Michigan. The 2 newer ones are 9k and 12k , SEER 33 heat pumps. Rated to -20f. I measured the coils with a IR gun when it was -10f and they were about 78 degrees. But that doesn’t translate to btus as I don’t know the air volume. My reaction is the house temp will drop when it’s -20f. Higher losses and less supply. But that temp is only every few years. We like them and use nat gas for supplemental heat. I’ll get some current readings tomorrow.
My suggestion is careful planning for placement of outside unit so it doesn’t get rain on it. Today, we had rain at near freezing 32-35 degrees and the fans suck in the water / water vapour and it freezes and then triggers a defrost cycle. Rain helps the efficiency in the summer but makes it worst in the winter.

 

[geteh]

I need to install HVAC in a 2 story building. At this time the walls and floors are pretty much open. My only real options are propane or electric for the most part.
Have read some about the mini splits and comb heat pumps. Some of the combo heat pumps say they are quite efficient, SEER values from 16 to 27. They advertise the heat pumps now work to -20F. They advertise they would save heating/cooling costs of about 25 % over other systems in smaller units and no need necessarily for ductwork. I know one can promise anything. Just hoping some have had real world experiences with the newer high efficiency units.
My daughter has an older mini split system and does not like it for an add on room. My neighbor has a somewhat newer unit and likes it. Thoughts?
However, it's essential to consider real-world experiences, as satisfaction with these systems can vary. While your daughter may not prefer her older mini-split system, your neighbor's positive experience with a newer unit suggests that advancements in technology may have improved performance Maxim Air AC Company.

Given your situation, high-efficiency combo heat pumps could be a viable option for your two-story building. They offer the advantage of providing both heating and cooling efficiently, with SEER values ranging from 16 to 27. These units can operate effectively even in colder temperatures and may save on heating and cooling costs compared to other systems.

However, it's essential to consider real-world experiences, as satisfaction with these systems can vary. While your daughter may not prefer her older mini-split system, your neighbor's positive experience with a newer unit suggests that advancements in technology may have improved performance.

Before making a decision, evaluate factors such as energy costs, climate conditions, installation requirements, and user feedback to determine the best option for your needs and budget. Consulting with HVAC professionals can also provide valuable insights tailored to your specific situation.