Natural Gas vs Heat pumps for heating

[EL0NTRK]

This is an interesting thread as I'm in the process of building my retirement home in Houston area where houses tend to be bigger than most.
As we build a high performance home, we have the luxury of considering several quality of life items on our list.

• House will have solar panels and 4 PWs to feed up to 3 EVs in the long term.
• Heat pump AC system: considering Lennox XP25 heat pump for our central air system with zoning. probably will use 3 as we have 2 stories and a conditioned attic.
• Water heater: we want to use tankless water heaters but it seems the gas version is the most cost effective and efficient. I have looked into electric tankless but I don't think they compare to the gas version. Am I correct?
• I want to put a ductless mini split in the theater and the garage, maybe Mitshubishi ones. Definitely the garage but not sure it's better to have the theater using the central air and have it on a separate zoning.

 

[charlesj]

This is an interesting thread as I'm in the process of building my retirement home in Houston area where houses tend to be bigger than most.
As we build a high performance home, we have the luxury of considering several quality of life items on our list.

• House will have solar panels and 4 PWs to feed up to 3 EVs in the long term.
• Heat pump AC system: considering Lennox XP25 heat pump for our central air system with zoning. probably will use 3 as we have 2 stories and a conditioned attic.
• Water heater: we want to use tankless water heaters but it seems the gas version is the most cost effective and efficient. I have looked into electric tankless but I don't think they compare to the gas version. Am I correct?
• I want to put a ductless mini split in the theater and the garage, maybe Mitshubishi ones. Definitely the garage but not sure it's better to have the theater using the central air and have it on a separate zoning.

If you have a separate zone for the theater and is on while watching you may be able to hear it. If it on with the other zone, you could shut the opening so you would not hear it.
Consider a hot water recirculating pump and well insulated hot water pipes. With that tankless, it would run when water is not running to have hot water at faucets.

A high performance home should have staggered stud exterior walls for added insulation and less outside noise entering.
Of course double pane windows. Check out air tight drywall approach/method.
High R value in ceiling and under floor if not on a slab on grade. And, even on slab, consider foam insulation under the slab, again a good R value.

Theater: make sure you have ethernet to equipment cabinet; HDMI run to projector if one is used. Don't use ceiling speakers for your 3 front speakers and surrounds, only for Atmos setup; Two locations for possible subwoofers with power and RCA cable.; 12/14ga speaker wire, not expensive audiophile cables .
If a projector is a possibility, a way to darken the room totally.
Vent equipment space to cool amps.
Don't have seating against back wall.

Ethernet cable in other areas besides a study. Sure wi-fi is good but ....

 

[holeydonut]

This is an interesting thread as I'm in the process of building my retirement home in Houston area where houses tend to be bigger than most.
As we build a high performance home, we have the luxury of considering several quality of life items on our list.

• House will have solar panels and 4 PWs to feed up to 3 EVs in the long term.
• Heat pump AC system: considering Lennox XP25 heat pump for our central air system with zoning. probably will use 3 as we have 2 stories and a conditioned attic.
• Water heater: we want to use tankless water heaters but it seems the gas version is the most cost effective and efficient. I have looked into electric tankless but I don't think they compare to the gas version. Am I correct?
• I want to put a ductless mini split in the theater and the garage, maybe Mitshubishi ones. Definitely the garage but not sure it's better to have the theater using the central air and have it on a separate zoning.

IMO, I had such a terrible experience dealing with a Lennox dealer, any time someone says they want Lennox I just tell them to look elsewhere. I know Lennox is based out of Richardson and people in Texas like Lennox... but I sure as heck don't hah.

Some things I dislike about Lennox are:

1) I guess you may not have to worry about this issue with your heat pump and probably since your house is a custom build through a high-end contractor, but Lennox simply won't stand behind their systems. I bought two complete Lennox systems (2x condensers, evaporators, furnace+air handler). I thought complete Lennox meant good gear throughout. But instead they subbed in a tiny-azzz evaporator coil made by Lennox's lower-brand ADP that had lower SEER. I actually contacted Lennox HQ about this and they said that Lennox as a brand was just that... no more or less premium than other less popular brands. Basically implied when you get a Lennox you're overpaying for premium that isn't any different from a Bryant or American Standard. Nice.

2) Zoned systems with Lennox to my knowledge rely on a combination of the iComfort S30 communicating thermostat and a somewhat poorly thought out zoning hardware/system. One thing that seemed to be a big miss is that the remote temperature sensors for the zoning aren't very useful. For example, I have an upstairs where the thermostat sits directly under a skylight. So what happens is the thermostat detects a lot of heat, while the rooms with registers controlled by this thermostat are more normal with sun exposure. You would naturally want remote temperature sensors so the S30 could treat the remote parts of the house instead of relying on the spot temperature where the thermostat is mounted. Nope. Not with Lennox. Fail.

3) Lennox is also kind of funky in terms of their outdoor hardware just being kind of cheap. Yes, the XP25 is a "big azzz" unit and seems fairly well built. But the outside case RATTLES LIKE CRAZZZYYYY. Like holy smokes I have two XC21's sitting outside of a downstairs bedroom. THEY BUZZZZZZZZZZZZZZZZ because they rattle like hell. If I put my hand against the exterior panels of the condensers, the vibration sound goes away. So I took an impact gun and tightened the living hell out of all the tapping metal screws. I also put some thin rubber seals on between a ton of the panels and nothing works. I had a authorized Lennox contractor out here and he's like "too bad man happens all the time" and left.

Being said, a variable speed heat pump sounds like a win. So the design you're shooting for seems good.

If I had a blank slate empty house to build to perfection, I'd also get radiant flooring in the rooms with high traffic/occupancy. The radiant flooring is clutch and helps especially if that room has vaulted ceilings. I think the hybrid water heaters still let you get a lot of bang for your electric bucks and would be a good compromise vs a all-gas-tank-heater.

 

[slcasner]

As to installing it in parallel with an existing gas furnace, it should be possible, although it's not something I have any experience designing. [Although if the heat pump is adequate for the design load, you could just remove the gas furnace and resell it.] I can certainly imagine a parallel installation where the compact air handler and a gas furnace share the same return and supply plenums, with a couple motorized dampers to avoid air flow short-circuiting backwards through the non-operating unit. Or you might be able to put them in series and disconnect one of the two blowers, wiring the other blower to come on when either unit runs.

How about installing in series rather than parallel? I have a gas furnace and A/C sharing the air handler -- the furnace is mounted on top of the box for the indoor coil. So with a normal ducted heat pump, couldn't that same physical arrangement be used?

 

[EL0NTRK]

If you have a separate zone for the theater and is on while watching you may be able to hear it. If it on with the other zone, you could shut the opening so you would not hear it.

This is one of the things that I even consider mini split for the HT. Many people recommend it on the AVSforum if you want to insulate noise. The downside is that it's more messy since you have to clean the head out often. I have to think about how much noise I can tolerate if going with the central air and use some specialized return/supply vent.

Consider a hot water recirculating pump and well insulated hot water pipes. With that tankless, it would run when water is not running to have hot water at faucets.

Yes, the house will have 2 tankless gas heater with a recirculate loop (with a pump) that will provide hot water instantly.

A high performance home should have staggered stud exterior walls for added insulation and less outside noise entering.
Of course double pane windows. Check out air tight drywall approach/method.
High R value in ceiling and under floor if not on a slab on grade. And, even on slab, consider foam insulation under the slab, again a good R value.

I will have a post tension foundation, open cell foam insulation on all exterior wall and attic roof as well as 2x6 construction. Attic will be conditioned with its own 2 ton AC.
I will go the extra step to have a separate dehumidifier and a air filtration system so I may not have to oversize my AC system.

Theater: make sure you have ethernet to equipment cabinet; HDMI run to projector if one is used. Don't use ceiling speakers for your 3 front speakers and surrounds, only for Atmos setup; Two locations for possible subwoofers with power and RCA cable.; 12/14ga speaker wire, not expensive audiophile cables .
If a projector is a possibility, a way to darken the room totally.
Vent equipment space to cool amps.
Don't have seating against back wall.

Ethernet cable in other areas besides a study. Sure wi-fi is good but ....

All good points and taken into account.
HT will have double wall, floor with green glue. Floor will be glue and screw to avoid noise.
It will be atmos ready with a projector. HT is fully light control since it has no window. Entry will be double door and lead to back row instead of front of screen.

Every room will have cat 6a run into them and conduits everywhere for future upgrade. I will have cat 6a drop to every access point, camera, etc.

 

[EL0NTRK]

IMO, I had such a terrible experience dealing with a Lennox dealer, any time someone says they want Lennox I just tell them to look elsewhere. I know Lennox is based out of Richardson and people in Texas like Lennox... but I sure as heck don't hah.

Some things I dislike about Lennox are:

1) I guess you may not have to worry about this issue with your heat pump and probably since your house is a custom build through a high-end contractor, but Lennox simply won't stand behind their systems. I bought two complete Lennox systems (2x condensers, evaporators, furnace+air handler). I thought complete Lennox meant good gear throughout. But instead they subbed in a tiny-azzz evaporator coil made by Lennox's lower-brand ADP that had lower SEER. I actually contacted Lennox HQ about this and they said that Lennox as a brand was just that... no more or less premium than other less popular brands. Basically implied when you get a Lennox you're overpaying for premium that isn't any different from a Bryant or American Standard. Nice.

2) Zoned systems with Lennox to my knowledge rely on a combination of the iComfort S30 communicating thermostat and a somewhat poorly thought out zoning hardware/system. One thing that seemed to be a big miss is that the remote temperature sensors for the zoning aren't very useful. For example, I have an upstairs where the thermostat sits directly under a skylight. So what happens is the thermostat detects a lot of heat, while the rooms with registers controlled by this thermostat are more normal with sun exposure. You would naturally want remote temperature sensors so the S30 could treat the remote parts of the house instead of relying on the spot temperature where the thermostat is mounted. Nope. Not with Lennox. Fail.

3) Lennox is also kind of funky in terms of their outdoor hardware just being kind of cheap. Yes, the XP25 is a "big azzz" unit and seems fairly well built. But the outside case RATTLES LIKE CRAZZZYYYY. Like holy smokes I have two XC21's sitting outside of a downstairs bedroom. THEY BUZZZZZZZZZZZZZZZZ because they rattle like hell. If I put my hand against the exterior panels of the condensers, the vibration sound goes away. So I took an impact gun and tightened the living hell out of all the tapping metal screws. I also put some thin rubber seals on between a ton of the panels and nothing works. I had a authorized Lennox contractor out here and he's like "too bad man happens all the time" and left.

Being said, a variable speed heat pump sounds like a win. So the design you're shooting for seems good.

If I had a blank slate empty house to build to perfection, I'd also get radiant flooring in the rooms with high traffic/occupancy. The radiant flooring is clutch and helps especially if that room has vaulted ceilings. I think the hybrid water heaters still let you get a lot of bang for your electric bucks and would be a good compromise vs a all-gas-tank-heater.

Nice post.
I'm brand agnostic and I believe the quality of installation and system design are very important. The company the builder work with has their own engineering team who will take the blueprint and build something that most efficient to your needs.
The builder is practically my neighbor and has build dozen of high end custom houses in the neighborhood for the past decade or so. I think he won't cut corner since he will have to deal with his customers on a daily basis.

 

[nwdiver]

• Water heater: we want to use tankless water heaters but it seems the gas version is the most cost effective and efficient. I have looked into electric tankless but I don't think they compare to the gas version. Am I correct?

You really can't beat a heat pump water heater for efficiency. The new Rheem ProTerra provide up to 4 units of heat for every unit of electricity. They're available at home depot for ~$1500 depending on size.

 

[CrazyRabbit]

i recently got hit by lightning. strike came in thru electrical system, whole house Ethernet, cable and aerial antenna. I've changed my stance on having everything wired as possible, make everything wireless as possible...

i also added Ethernet and RJ6 surge protectors... now no surge protector will protect you against a direct lightning strike!!!

House has/had surge devices in each loads panel, that didn't appear to help or perhaps did since some stuff survived. ~20 APC UPS's, 8 of which failed. still 40K in damages.

do a hybrid hot water system with a recirculation system... No gas on demand. also do induction cook top.... also build the house to minimize heat loss (wall area vs interior volume) and heat gain (exposure)...

 

[nwdiver]

i recently got hit by lightning. strike came in thru electrical system, whole house Ethernet, cable and aerial antenna. I've changed my stance on having everything wired as possible, make everything wireless as possible...
i'm also adding eithernet surge protectors... now no surge protector will work with a direct lightning strike!!!

From my experience proper grounding is more important than surge protection. It's somewhat anecdotal but we installed a ~22kW ground mount ~2 years ago and sank ~8 ground rods spaced ~20' apart. That customer has had zero issues with lighting while his brother that lives ~1000' away has been hit twice since then destroying a lot of random stuff. The 1 or 2 ground rods that normally ground a house are usually no where near sufficient to dissipate the energy from a lighting strike.

 

[dhrivnak]

This is an interesting thread as I'm in the process of building my retirement home in Houston area where houses tend to be bigger than most.
As we build a high performance home, we have the luxury of considering several quality of life items on our list.

• House will have solar panels and 4 PWs to feed up to 3 EVs in the long term.
• Heat pump
• Water heater: we want to use tankless water heaters but it seems the gas version is the most cost effective and efficient. I have looked into electric tankless but I don't think they compare to the gas version. Am I correct

I have been VERY impressed with our Rheem heat pump water heater. Very efficient and much better than the tankless ones I have looked at. We have an Amana full inverter heat pump that even when 11F resistance heat never comes on. For a lot more ideas you may like this book. Driving to Net 0: Stories of Hope for a Carbon Free Future: Hrivnak, David J: 9780692143834: Amazon.com: Books

 

[sorka]

Lets see, I have 10 heads, 4 compressors, about 10 tons, and yea about 40K. You are not counting if you started from scratch, the cost of putting in all the ducting would make your "normal" HVAC way way more expensive. We LOVE our mini splits. 100% zoned. NO loses from duct work, and wasted space taken in our house. But it is tough to justify if you are only replacing the multipack, and not all the ducting.

Is your system ductless or slim ducts?

 

[sorka]

I have been VERY impressed with our Rheem heat pump water heater. Very efficient and much better than the tankless ones I have looked at. We have an Amana full inverter heat pump that even when 11F resistance heat never comes on. For a lot more ideas you may like this book. Driving to Net 0: Stories of Hope for a Carbon Free Future: Hrivnak, David J: 9780692143834: Amazon.com: Books

Do you have a gen 4 or gen 5 Rheem?

 

[sorka]

So my stupid builder put in a recirculating system and the majority of it is in the slab with little to no insulation

and it’s setup as a long loop, so the farthest fixtures become practically useless if the system isn’t on.

That's the way mine was built. No insulation on the hot water piping or return line at all. I do use the recirc line but the pump runs just long enough to get it to whatever room I need it in based on pressing a button in that room. Takes about 10 seconds to get it to the closest bathroom and about a minute to get it to the kitchen sync 89 feet away. Fortunately we have a 9600 watt POS tankless heater under the sink that heats the water very quickly until the hot water from the tank gets there and then it tapers off as it doesn't have to heat as much and eventually at all.

 

[sorka]

Theater: make sure you have ethernet to equipment cabinet; HDMI run to projector if one is used. Don't use ceiling speakers for your 3 front speakers and surrounds, only for Atmos setup; Two locations for possible subwoofers with power and RCA cable.; 12/14ga speaker wire, not expensive audiophile cables .
If a projector is a possibility, a way to darken the room totally.
Vent equipment space to cool amps.
Don't have seating against back wall.

Ethernet cable in other areas besides a study. Sure wi-fi is good but ....

And make sure you use all 4 ceiling atmos speakers and non of this firing up and bouncing off the ceiling crap. That's just for posers

 

[sorka]

You really can't beat a heat pump water heater for efficiency. The new Rheem ProTerra provide up to 4 units of heat for every unit of electricity. They're available at home depot for ~$1500 depending on size.

This is the one I was going to buy until I discovered that the gen 5's they started making last year are 65 to 70 db instead of the 49db they are speced for:

https://www.reddit.com/r/Plumbing/comments/m0qmym

They are aware of the issue and there are now two posts that claim their recent replacements are back down to 49 db. But it seems Rheem has shut down the line for now. 3 different distributors in the last two weeks have told me that Rheem has discontinued the product line. What I'm hoping really happened is that they jus shut down for a while to fit the line with the new quieter compressor, but it could also be they are just running into supplier issues.

 

[h2ofun]

Is your system ductless or slim ducts?

Not sure what slim ducts mean, but I have no ducts anymore. Were all removed. We just LOVE the minisplits. I love not having the holes in my floors for registers, and love having the return air ducts gone. When so many say they want to be green, but still have gas heating, well, .....

 

[aesculus]

Not sure what slim ducts mean, but I have no ducts anymore. Were all removed. We just LOVE the minisplits. I love not having the holes in my floors for registers, and love having the return air ducts gone. When so many say they want to be green, but still have gas heating, well, .....

And how do you filter your whole house air, especially wood smoke?

 

[iPlug]

And how do you filter your whole house air, especially wood smoke?

Sounds like in theory it could be done, but not sure how this works for mini-splits and availability/costs for different quality air filters.

For out central ducted heat pump, we use washable (low filtration) filters in the return air registers for most of the year when PM 2.5/10 is low. During the smoke season we replace these with MERV 12+/FPR 10+ filters.

 

[sorka]

Not sure what slim ducts mean, but I have no ducts anymore. Were all removed. We just LOVE the minisplits. I love not having the holes in my floors for registers, and love having the return air ducts gone. When so many say they want to be green, but still have gas heating, well, .....

The slim ducts are just the heads mounted in the attic(or outside if there there's no crawlspace or attic) with an in and out duct into the room going back to the head in the attic. It hides the head and tends to be even quieter.

 

[sorka]

And how do you filter your whole house air, especially wood smoke?

Although I have HVAC central ducting, I stopped using the fan only for filtering years ago. I have a positive pressure system that brings in air from outside going through a 3 stage hepa filter. I got it because when I got a CO2 monitor, I watched it build up 800+ PPM with just 3 people in a 4000 sf house by the end of a weekend if we all stayed home. The positive pressure system filters air from outside and brings it in. This also prevents dust and other air from coming in from any imperfect sealing in the house. Smoke gets in easily through microscopic cracks and holes. The positive pressure prevents that and also drastically reduces stuff coming in from outside when we open doors to go in and out.

My air quality stays at a level that is equivalent to 0 on Purple Air.