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Natural Gas vs Heat pumps for heating

dareed1

Member
Jan 15, 2021
113
103
Belmont, CA
No-one's mentioned a hidden cost of installing a high SEER heat pump.
By necessity they are either multistage or infinite variable.
Both of those require more wires between the air handler and the thermostat.

Any house over 25 years old is likely to be stuck with 4 wire thermostat wiring in the walls.
All the 13 SEER units are going to be single stage, and work fine on 4 wires.
There's tricks that can be done to expand this to devices that need 5 wires, but you need more than that for a high efficiency heat pump.

Ripping up walls and ceilings, and/or stapling a wire around half the outside of the house is an extra cost.
Our Mitsubishi heat pump uses RF communication between the thermostat and the air handler. No wires needed at all.
 

RKCRLR

Member
Apr 13, 2020
514
214
Garden Valley, CA
No-one's mentioned a hidden cost of installing a high SEER heat pump.
By necessity they are either multistage or infinite variable.
Both of those require more wires between the air handler and the thermostat.

Any house over 25 years old is likely to be stuck with 4 wire thermostat wiring in the walls.
All the 13 SEER units are going to be single stage, and work fine on 4 wires.
There's tricks that can be done to expand this to devices that need 5 wires, but you need more than that for a high efficiency heat pump.

Ripping up walls and ceilings, and/or stapling a wire around half the outside of the house is an extra cost.
My Carrier Infinity multistage hybrid heat pump/propane system only needs 4 wires. It is a communicating system and uses standard thermostat wire for Data A, Data B, Power (24v), and Common.
 

roblab

Active Member
Jul 15, 2008
3,819
3,300
Angwin (Napa Valley) CA
right at this moment, 29% of PG&E Supply is NG. At night, even more so. What do you think the winter would be if everyone heats by electric?
Well, if they'd buy solar and some battery backup, and use mini splits for zone heating, winter wouldn't be too bad. Problem is, everyone thinks it's too expensive. My wife and I now spend nearly all our time in one part of the house, which is the part we condition. 400 sq ft is big enough for all we do, and though we have 2000 sq ft more, we hardly ever go over there. PG&E pays us each month for power we sell to them, rather than us paying them $300/ mo.

It seems to me that the "American Dream" is to own a 4000 sq ft house and then rattle around in it feeling they've arrived. Usually the kids have married and moved away, and they really don't need more that about 500 sq ft. "Need" is something inside people's heads. My wife likes having all that room next door "in case the kids come to visit" but that happens only about twice a year. Most of the kids are too busy to come by, now living in other states, and even the close ones tell us they're too busy, and can't we just come over there. Our closest daughter lives 40 miles away and brings the family by about once a year to collect Christmas presents. We visit them several times a month.
 
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holeydonut

Active Member
Supporting Member
Jun 27, 2020
2,364
1,707
East Bay NorCal
My Carrier Infinity multistage hybrid heat pump/propane system only needs 4 wires. It is a communicating system and uses standard thermostat wire for Data A, Data B, Power (24v), and Common.

Yeah almost all the communicating systems are 4 wire setups. This isn’t really that big of a deal even if you do need a replacement. My issue was leading the pressure line going to the evaporator also needed to be replaced if I went with a heat pump and that is odd/expensive.
 

EL0NTRK

Member
Oct 16, 2016
297
521
Houston
Have anyone used a mix of central air/zoning and mini split effectively?
So, if we use minispilt for a whole house which has 6 bedrooms, the outdoor will look like a showroom. Maybe I'm not familiar with this but I wonder how you can heat/AC the bedroom and bathroom with one head/cassette?

Still trying to wrap myself around design a more efficient HVAC system that takes advantage of the latest tech without sacrificing discomfort.
 

tomuo

Member
Mar 15, 2021
49
17
Los Angeles, CA
Have anyone used a mix of central air/zoning and mini split effectively?
So, if we use minispilt for a whole house which has 6 bedrooms, the outdoor will look like a showroom. Maybe I'm not familiar with this but I wonder how you can heat/AC the bedroom and bathroom with one head/cassette?

Still trying to wrap myself around design a more efficient HVAC system that takes advantage of the latest tech without sacrificing discomfort.
Anecdotal : My neighbor's house has a large south facing family room, so they added a single mini split for that room to augment the central.
Another acquaintance with a house in Apple Valley, CA (gets very got) installed 3 individual minisplits when their central failed, and is very happy with the consumption.
Trane has multihead / multizone units that only need one outdoor unit. I think this style is common in Asia and Australia.

Four-ton and five-ton outdoor unit can support up to eight indoor units using branch boxes
seems to be just a small matter of plumbing?
 

zƬesla

Member
Apr 16, 2020
430
166
US-NH
For what it's worth, I have 5 indoor mini-split heads with two outside units (3 heads on one and 2 on the other). These are Mitsubishi Mr. Slims. Outside runs are along walls painted to match the house color so not too noticeable. Using them for both A/C and heat in northern climate.
 
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jboy210

Well-Known Member
Supporting Member
Dec 2, 2016
5,700
3,695
Northern California
Well, if they'd buy solar and some battery backup, and use mini splits for zone heating, winter wouldn't be too bad. Problem is, everyone thinks it's too expensive. My wife and I now spend nearly all our time in one part of the house, which is the part we condition. 400 sq ft is big enough for all we do, and though we have 2000 sq ft more, we hardly ever go over there. PG&E pays us each month for power we sell to them, rather than us paying them $300/ mo.

It seems to me that the "American Dream" is to own a 4000 sq ft house and then rattle around in it feeling they've arrived. Usually the kids have married and moved away, and they really don't need more that about 500 sq ft. "Need" is something inside people's heads. My wife likes having all that room next door "in case the kids come to visit" but that happens only about twice a year. Most of the kids are too busy to come by, now living in other states, and even the close ones tell us they're too busy, and can't we just come over there. Our closest daughter lives 40 miles away and brings the family by about once a year to collect Christmas presents. We visit them several times a month.
A good cautionary tale about house size as you get older. We have several rooms we never go in and a backyard that only the landscape guys enter.

Back on the subject, I would consider adding a mini-split system for the rooms we do use but they are on different floors and opposite ends of the house. I assume that would require multiple outside units or a lot of plumbing running through or around the house. Is that correct?
 

zƬesla

Member
Apr 16, 2020
430
166
US-NH
Back on the subject, I would consider adding a mini-split system for the rooms we do use but they are on different floors and opposite ends of the house. I assume that would require multiple outside units or a lot of plumbing running through or around the house. Is that correct?
We ended up this way simply because of having one side of the house done first, as it had no a/c, whereas the other had in-wall (window-like) A/C units. Later, we got rid of the two in-wall units and replaced them with mini-splits. Depending on how many heads you need, total BTUs, and location for outside unit, you may be able to get away with a single outdoor unit or multiple units at the same location.

Location can be important (e.g., if you don't want it visible from the road) as is proper installation. Indoor units are pretty quiet, as are outside units, however outside unit can cause vibration and if not properly bracketed, you can hear it in the house.

Something else to check on are any openings in the outside unit that critters can get into. The insulation inside makes for a cozy nesting place. Also, any runs outside the house should be well sealed.
 

Big Earl

bnkwupt
Supporting Member
Jul 12, 2017
6,122
11,721
Springfield, VA
A good cautionary tale about house size as you get older. We have several rooms we never go in and a backyard that only the landscape guys enter.

Back on the subject, I would consider adding a mini-split system for the rooms we do use but they are on different floors and opposite ends of the house. I assume that would require multiple outside units or a lot of plumbing running through or around the house. Is that correct?

Yeah, you'd want separate outdoor units for that.
 

ThomasD

Active Member
Nov 22, 2019
1,284
636
Breckenridge Co Ky
I'm looking at heating my 24x40 detached garage at my new place. Should I just go with a propane tank and heat or some sort of a mini split?
 

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jboy210

Well-Known Member
Supporting Member
Dec 2, 2016
5,700
3,695
Northern California
I'm looking at heating my 24x40 detached garage at my new place. Should I just go with a propane tank and heat or some sort of a mini split?
Ask your neighbors what they are doing. Unless the climate has really changed since the 80s in Breckenridge you do get a lot of snow and below zero temps on occasion.
 

Big Earl

bnkwupt
Supporting Member
Jul 12, 2017
6,122
11,721
Springfield, VA
you can have lots of heads on one outdoor compressor. I cut all my walls to run the mini split lines so nothing showing outside or inside

Of course, but different floors and opposite sides of the house seems like a better candidate for two outdoor units. Just my opinion given the limited info we have.
 
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holeydonut

Active Member
Supporting Member
Jun 27, 2020
2,364
1,707
East Bay NorCal
Further reinforces the insanity of not installing the correct equipment to begin with. Why are SEER 13s that aren't heat pumps still going into new builds? It's usually ~$500 more for a SEER 18 Heat pump and the labor is the same.

You also don't need an attic or HVAC knowledge to install a mini-split. Just a wall. Most houses I've seen have walls :)



BTW, to make you feel a little better about new construction... there is a federal requirement for all AC's sold starting 2023 to be at least 14 SEER (oooo much better than 13 heh). And up to 15 SEER in the really hot climates.


But realistically, this won't matter too much (edit: for California). Progress is super slow as it pertains to new construction / new housing-starts in California since most counties aren't even allowing for new single family or multi family zoning. It seems every county is NIMBY to new starts due to how it would hurt home prices, decrease beauty, and increase traffic. Lames.

I think making a dent in overall HVAC systems deployed across California will require making low-SEER illegal for replacement units... and basically throwing money at people to incentivize more efficient tech like mini-splits and heat pumps. Unfortunately AFAIK there are zero house representatives looking into such programs to deploy at a large scale (edit: for California).
 
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EL0NTRK

Member
Oct 16, 2016
297
521
Houston
So if I'm going to construct a new house today (2 story, 6 bed) which would be better: ducted heat pump HVAC system or ductless mini split for each room?
I think the ducted system will allow me to tie up into a separate dehumidifier, ERV, air filtration and allow for normal looking air supply. The downside is that there will be loss in efficiency with the ducting. Thinking Mitsubishi VRF system.

The fall back is to use the traditional central air HVAC with ducting and zoning via damper. Then use a heat pump like Lennox XP25. This is less efficient and the zoning is less than ideal.

Any pointer?
 

BGbreeder

Member
Jun 19, 2020
497
300
Bay Area
I would choose ducted for air quality. Hands down. If you are worried about efficiency, oversize the ducts, don't use flexible ducts, and insulate, insulate, insulate! (i.e. design the house so your ducts are in a conditioned space.)

All the best,

BG
 
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EL0NTRK

Member
Oct 16, 2016
297
521
Houston
I would choose ducted for air quality. Hands down. If you are worried about efficiency, oversize the ducts, don't use flexible ducts, and insulate, insulate, insulate! (i.e. design the house so your ducts are in a conditioned space.)

All the best,

BG
Thank you. I think mini split is great. Ducting allows me to connect to dehumidifiers and allow some other options as well.
What do you mean not using flexible duct? What is the other option?
 

Big Earl

bnkwupt
Supporting Member
Jul 12, 2017
6,122
11,721
Springfield, VA
I would choose ducted for air quality. Hands down. If you are worried about efficiency, oversize the ducts, don't use flexible ducts, and insulate, insulate, insulate! (i.e. design the house so your ducts are in a conditioned space.)

All the best,

BG

this ^^

Combine these tips with the Mitsubishi VRF system or some other internet-drive system and you should be very happy.
 
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