Heat pump / natural gas hybrid questions

[Max W]

My daughter needs to replace her natural gas hot air furnace and is looking at a hybrid heatpump / natural gas combination. It looks like a good choice with rebates and other incentives. Her condo in northern Massachusetts, close to NH, was built in the ‘80s with the building practices of that time. It seems from what I read these systems the heat pumps are generally designed to switch over in the 30’s. Why is this when todays heat pumps are being designed to heat efficiently to lower temps? Has this just got to do when the cost of heating with the heat pump becomes greater than that of gas? I 10 years of satisfaction with our mini split but just starting to learn about these hybrids.

Are there common pitfalls to be avoided when purchasing one of these hybrid units and getting it installed?

 

[begreen]

The switchover temperature should be configurable. Depending on the system configuration this could be at 10 or 15 degrees if the heat pump is very efficient and sized correctly.

 

[ABMax24]

Could be due to energy costs too. At 30f it could be that natural gas is just cheaper to heat with than the electric heat pump.

 

[bogieb]

Got curious so did a quick Google and found this

 

[Eman85]

We had a Comfortmaker package unit installed a couple of years ago. Switchover from heat pump to gas furnace is programmable, thermostat has an outdoor remote for temp/humidity info. Works great for us compared to the split system we had before with gas furnace and outside compressor unit.

 

[Whitenuckler]

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I watched this last night - Good info on keeping the COP high even in cold weather

 

[stoveliker]

I had a hybrid nat gas furnace/heat pump back in TN.
The heat pumps they install there are poor in the sense that they conk out at 40 F. They would go to "emergency heat", i.e. resistive heat coils in the air handler. Rather expensive to run even with the kWh prices there.
Moreover, and this is where the combo units shine, a heat pump will take quite some time to heat up a room/home when it's colder out (hence the advice to maintain temps rather than have them drop down during e.g. the night). Yet the gas furnace was fantastic, as it could heat our home by 10 F in 10 minutes when it was 20 F outside. (As compared to the emergency coils running for 2 hours.)

The air temp coming out of the registers was so much warmer - it was really nice waking up in a cold room, having the gas heat come on and feel that warm air (in the bathroom) and have breakfast in a normally warm room.

I loved the natgas/heatpump combo unit.

 

[begreen]

Our previous 2006 AmStd 2 stage HP would switch over at 25º to resistance heaters (no nat gas here). The replacement is good to -5º with a COP of 2.1 at that temp. With 15º being about the coldest we will see, I don't expect to need resistance heaters anymore.

Could be due to energy costs too. At 30f it could be that natural gas is just cheaper to heat with than the electric heat pump.

That is a good scenario to keep track of. Unfortunately, I expect nat gas prices to be on the rise in the future, so keep track of this if so.

 

[EbS-P]

Our previous 2006 AmStd 2 stage HP would switch over at 25º to resistance heaters (no nat gas here). The replacement is good to -5º with a COP of 2.1 at that temp. With 15º being about the coldest we will see, I don't expect to need resistance heaters anymore.

That is a good scenario to keep track of. Unfortunately, I expect nat gas prices to be on the rise in the future, so keep track of thi

I think we will keep installing resistive strips in the south for quite some time. For the simple reason that the heating needs are larger than cooling but they tend to size a system for cooling. Adding the resistive heat always them a cheap way to get that low end. There are a lot package units down here and there are not that many (or any ) inverter package units with variable output.

 

[Max W]

She went with a Bosch system. When I last talked with her about this the furnace was up and running and the heat pump was going in. She thought the heat was great. She lives out of state limiting how involved l can get. I would have liked to talk to the contractor to learn more but I guess it comes down to trusting my kid to make good decisions on things like this as she does on other things. I have two home owning daughters in different states. There have been times when I packed my tools and headed out for a big project or repair but mostly its just wishing we were closer when something comes up.

 

[ABMax24]

That is a good scenario to keep track of. Unfortunately, I expect nat gas prices to be on the rise in the future, so keep track of this if so.

I think there's some merit to that, there's also some evidence pointing to a global surplus of LNG coming in the future, which could start to reduce exports and moderate gas prices.

Also, pending the region, electricity prices follow natural gas prices, so this change-over temperature may not change all that much. As it's likely electricity prices will increase accordingly.

 

[begreen]

I read recently that the competition for NG is getting fierce. The gluttonous power appetite of new AI data centers is competing with the rising LNG market. This is while NG wells' outputs are in steady decline. They don't self replenish, so output in 5 yrs is likely to be lower. The best drilling sites are mostly tapped; out. Future growth will depend on exploiting more challenging reservoirs with advanced technologies. At some point capacity seems likely to plateau.

 

[EbS-P]

The best drilling sites are mostly tapped; out. Future growth will depend on exploiting more challenging reservoirs with advanced technologies.

The cheap gas has been tapped. US policy is to increase exports. Many renewable energy generation projects are paused indefinitely. AI is on pace to increase electricity demand on a timescale faster than new generation projects.

NG prices will be going up. So will electric rates. I’m getting a feeling that there is a building AI bubble. what happens to energy prices if it pops? I doubt much. Most proposed new gratin projects will be nearing completion and will still need to be paid for.

 

[ABMax24]

I read recently that the competition for NG is getting fierce. The gluttonous power appetite of new AI data centers is competing with the rising LNG market. This is while NG wells' outputs are in steady decline. They don't self replenish, so output in 5 yrs is likely to be lower. The best drilling sites are mostly tapped; out. Future growth will depend on exploiting more challenging reservoirs with advanced technologies. At some point capacity seems likely to plateau.

I wish we had the problem in my region, we still have a glut of gas, prices went negative this summer again, and producers have began flaring it during those times.

Natural gas prices are very regionalized, restricted mostly by access to export capacity in pipelines.

 

[ABMax24]

The cheap gas has been tapped. US policy is to increase exports. Many renewable energy generation projects are paused indefinitely. AI is on pace to increase electricity demand on a timescale faster than new generation projects.

NG prices will be going up. So will electric rates. I’m getting a feeling that there is a building AI bubble. what happens to energy prices if it pops? I doubt much. Most proposed new gratin projects will be nearing completion and will still need to be paid for.

I think the AI bubble, and AI energy demand are differing topics. I don't see there being a sudden drop in AI energy demand (short of a technological disruption that makes AI significantly more energy efficient) that causes a drop in energy demand. It think the data centers that are built will continue to run and consume electricity.

I do believe that AI company valuations are a bubble, and it's projected growth is over estimated. Unfortunately this bubble is costing consumers in many fronts, electricity prices are one. Now the rapid price spikes in DRAM and NAND driven by competition for AI components are causing issues with PC prices, and will likely move shortly to items like tablets and cell phones driving their prices up as well.

 

[Eman85]

Seeing how they converted many of our electric plants from coal to NG I'd say it's an even bet if you want to stay warm.
I'm pleased for now with the whole unit being outside of the home. It's quieter than having the unit in the house like I did before and I gained a closet.

 

[begreen]

I'm also really pleased with the low noise of the new heat pump. Most of the time I don't know it's running.

 

[stoveliker]

Lol, same here. When my minisplit was installed, 6 ft from a bay window, one of the side windows of which opened towards the heat pump, and they said "it's running", I opened the window and told them they were wrong - no sound whatsoever.
They were right.
It was running with no sound whatsoever...
I have to get within two feet, my ears at the height of the unit, to hear it.
Yet I can hear the big unit (like I had in TN) of my neighbors from 50 ft away if I walk to the edge of my property...