9 ms·

We moved to heat-pump a few years ago and disconnected from gas. It's been working great. Our biggest expense was insulating our house. It is an old house and t

We moved to heat-pump a few years ago and disconnected from gas. It's been working great. Our biggest expense was insulating our house. It is an old house and the 2nd floor was very drafty. You could feel a breeze coming through cracks in the wall. When we opened the wall there were just a few newspapers in there and no insulation. We had the 2nd floor siding removed, an extra layer of insulated wall added to the outside and then cladded with siding. It was like putting a big insulated hat on our house. Now the temperature is very consistent and absolute no drafts. The architect said to me that we'll never fully recoup our costs of putting the hat on the house. To which I replied that we don't always to things for economic reasons, and just do them because they are the right thing to do. My only regret was going with a Rheem heat-pump water heater in this mix. It does not perform well at all. With hindsight I would have looked for a way to perhaps have water heating integrated with our air heat-pump system. There is a company called Arctic that has those systems. Also with regard to heat-pump water heater, out big problem is that a hydronic floor heating system (installed when we were on gas) is now constantly drawing off heat from our tank. I'd like to find a small standalone unit to handle floor hydronic heating separate from my main water heating.

belter 3y ago
How noisy is it? I heard of people installing them, and getting complaints from the neighbors.
- WirelessGigabit 3y ago
  They're as noisy as an AC. So here in Arizona no one cares. But in Belgium this was an issue as they run more in winter and in winter sound travels further.
  - belter 3y ago
    Uhmm...I see a problem for countries where you have wall to wall connected urban environments...If all 60 connected houses on a street, install external heat pumps, it will add up.
    - toothrot 3y ago
      Turns out cities are loud! In NYC, at least, heat pumps are far more quiet than the endless window unit A/C's, or larger traditional A/C's, in my experience. Outdoor noise is less of an issue in the winter in big cities because windows are closed.
      - wussboy 3y ago
        Most of the noise in cities is cars. One idiot on a Harley drowns out a warehouse of heat pumps
      - belter 3y ago
        Sounds like an installation can be really tricky or you will end up with something like this: https://youtu.be/1rKNT7-42J0?t=1510 https://youtu.be/1rKNT7-42J0?t=1510
  - cduzz 3y ago
    Just installed heat pump systems (daikin) this december. The exterior unit is basically silent even when there was a cold snap (below freezing but not northern alaska cold). I suspect an interior air source heat pump hot water heater, being smaller, will be noisier, and likely less efficient. I'd love to switch my 240v/30a water heater to use a 120v/20a service, but will wait a bit longer for the technology to mature. Ideally it'd have the heat collection part outside.
  - triceratops 3y ago
    In the winter everyone has their triple-paned windows closed. Is noise that much of a problem?
    - wussboy 3y ago
      Is triple pane common in Belgium? It’s not in the UK (as far as I recollect) and they’re colder than Belgium
      - WirelessGigabit 3y ago
        I built a house in 2014 there. Triple pane. Pointless. You never recoup the cost.
- jillesvangurp 3y ago
  Depends on the installer. A lot of noise results from units that are not properly mounted or mounted at a slight engine. The fan then starts getting more noisy and wears out earlier. There are other problems to not installing units properly.
- switch007 3y ago
  Also, when talking about noise it's important to talk about frequency. If they produce low frequency noise, that can be far more irritating. Shutting the windows won't help much
kingnothing 3y ago
What problems are you seeing with your water heater? I’ve had one for about a year and have been pretty happy with it after learning I needed to schedule high demand times of day. It is a bit louder than I’d like but it’s not horrible.
Aurornis 3y ago
> The architect said to me that we'll never fully recoup our costs of putting the hat on the house. Your architect is almost certainly right. I would bet that most of your improvements came from fixing the drafts, with the insulation providing a marginal improvement on top of that. I’ve also dealt with insulating old homes, but I did draft fixes, wall insulation, and attic/roof insulation at different stages. The draft fixes provided the most improvement, followed by attic/roof insulation. Insulating walls had much less effect than I anticipated. In friends’ houses I’ve used my thermal camera (which I didn’t have back then) and it’s easy to see where the heat or cold is coming in during weather extremes. These days I’d recommend anyone start with the thermal camera view before deciding where to spend money on insulation.
- pjc50 3y ago
  Thermal cameras have got really cheap: I found one on Aliexpress for less than £150, that plugs into a smartphone.
  - dotancohen 3y ago
    Have you tried it, though? Is it any good?
- mpaepper 3y ago
  What kind of thermal camera do you recommend and what price range?
  - andrewblossom 3y ago
    I bought a Topdon TC001 a year ago that in my experience is significantly more responsive and higher resolution than similarly priced FLIR or other name brand options at that price point. It appears there are even more low cost options now.
    - MobiusHorizons 3y ago
      I find it rather interesting that companies like FLIR are limited by regulation (I believe US export bans) from selling IR cameras with greater than 9fps. there is also a resolution cap but I forget what it is off-hand. Strangely enough this doesn't stop US citizens from purchasing higher performing cameras from non-US companies. I think technology has come down significantly in price over the last few years and you can now get smartphone attached versions like infiray for a few hundred bucks.
jbjbjbjb 3y ago
On the payback period, that’s probably just outlay divided by energy savings. I’m sure you’d get more enjoyment from a more comfortable house and the next owner will appreciate the modernisation too so those need to be factored into the investment appraisal. I doubt the architect puts such a miserly lens on the other projects they’re involved in.
- jillesvangurp 3y ago
  This is actually becoming an important point. In parts of the world where energy ratings matter, they have an impact on house value as well. They unlock incentives, etc. A house that is up to modern standards is simply worth more because any new owner does not have to do expensive renovations to modernize. In the Netherlands house flipping is pretty common. Buy something old, modernize it, live in it a few years and make a profit. The lower energy cost is both a nice bonus and a key selling point.
mecameron 3y ago
> The architect said to me that we'll never fully recoup our costs of putting the hat on the house. To which I replied that we don't always to things for economic reasons, and just do them because they are the right thing to do. I am so frustrated with this analysis and sentiment when it comes to environmental investment. I understand that looking at it with a financial lens can and should be done to inform what we do, and it would be great if a project just paid for itself, but you look at all the other things we spend money on and the same calculus is not used. People don't buy the cheapest car, house, clothing, or food they could possibly get by with, or analyze the marginal cost of moving up or down the possible price tiers available to them with only the financial payback as a guide. Yet we constantly hear the refrain that you shouldn't spend a given amount of money on solar, house improvements, appliances, etc. that might be better for the environment if the payback isn't somehow positive with a 10-20 year payback period. I've constantly had to work with contractors to let them know that I still want to pay for the marginal costs associated with investment even knowing that the marginal financial benefit is smaller. For instance, with solar panels in less than ideal locations, tri-pane windows, etc. I have disposable income, and I think the world is trouble for the 8+ billion humans inhabiting it, so I think it's worthwhile that I would spend some of that to make it marginally better even if that means I don't have a positive financial return.
- jancsika 3y ago
  > so I think it's worthwhile that I would spend some of that to make it marginally better even if that means I don't have a positive financial return. Your action is going to make close to 0% difference for the 8+ billion humans inhabiting the planet. So from a practical standpoint, you've failed, but that practical failure makes it clear that the gesture has pure symbolic value for you. And since that symbolic value stands in stark contrast to incessantly chasing positive financial returns: task failed successfully. Congratulations!
  - toomuchtodo 3y ago
    From a practical standpoint, they have valued their energy savings closer to what the true cost of carbon emissions are (remember, most carbon emitters are in no way paying the true cost of their emissions [1]; this externality dumping continues with wild abandon). You're arguing systems and scale. This person is simply early in the adoption curve. Consider what will happen when this happens more broadly. As the climate situation becomes more dire [2], the price of carbon emissions per ton will rise and the willingness to prioritize energy savings and carbon emission reductions should increase regardless of fiat return. Physical system outcomes are distinct from magic number in database goes up. But sure, if you're already poor and have nothing [3], this won't matter to you and your life trajectory is already mostly locked in today. As nullstyle mentions, we need to compound in the positive outcome direction, and those decisions are being made today. [1] https://www.nature.com/articles/s41586-022-05224-9 https://www.nature.com/articles/s41586-022-05224-9 [2] https://www.npr.org/2024/04/09/1243595924/march-world-hottest-on-record https://www.npr.org/2024/04/09/1243595924/march-world-hottes... [3] https://ourworldindata.org/poverty https://ourworldindata.org/poverty
mataug 3y ago
> My only regret was going with a Rheem heat-pump water heater in this mix. It does not perform well at all. Heat-pump water heater's performance depends a lot on where its installed and the airflow+heat available. If the water heater is undersized or if there isn't enough heat in the air, it would perform worse than a standard gas/electric water heater. Mine is installed in a closet under the stairs, which is not ideal, but as long as I keep the water heater in eco mode, and keep closet door slightly open, it works good enough for our usecase. Our annual water heating costs went down from ~$500 to ~$100 after switching to the heat pump water heater.
- usrusr 3y ago
  As in the cold end of the heat pump is inside the heated area of the house? That feels very weird. On the other hand with heat pumps, stacking multiple stages strategy isn't necessarily a bad thing! All inefficiencies are not really losses but merely resistive heating contributions (unless their heat escapes to the final cold sink aka outside) and in the end the real question is which configuration is good in terms of capex and maintenance. In an environment where getting rid of humidity is a concern (mold!), a "cold end inside" heat pump for water might even double as a dehumidifier, with water condensing on the cold end sent to the sewers, contributing a little energy in the process.
  - sf_rob 3y ago
    That's not uncommon and is even beneficial in warmer climates. It will be parasitic in winter (even if externally vented) and symbiotic in summer.
loceng 3y ago
Have you ever monitored the air quality levels in various rooms? Curious if getting rid of those drafts may be unknowingly affecting your health in other areas.
- doctorhandshake 3y ago
  My understanding is that any house that isn’t built ‘tight’ by today’s standards will have a fast enough ACH that you don’t need to worry about ventilation as you would with a tight house. And only a ‘deep energy retrofit’ of an older house would result in tightness like that, so ERV and MUA etc are not necessary. Local code, build detail, and age of house are factors, YMMV, but this isn’t a problem you’d cause by accident with anything but a very invasive retrofit.
  - amluto 3y ago
    Mechanical ventilation is not necessary in a drafty house, but it’s still very nice to have. Bonus points for a well-filtered system. (None of the major brands will sell you a system that is well filtered out of the box. But it’s straightforward, if rather space consuming, to put a monstrous filter with effectively zero pressure loss in series with the system.) Bonus points for taking advantage of a balanced ventilation system’s ability to continuously extract air from stinky areas, e.g. bathrooms. Even more bonus points for avoiding negative pressure due to conventional bathroom exhaust, which can defeat stack effect-based exhaust from non-power-vented combustion appliances, which are, for some reason, still legal. (Seriously, WTF. There’s a straightforward design that could safely created a forced draft even with legacy leaky ductwork: put the fan on the exterior vent terminal, so the duct is under negative pressure. The wiring could be fished through the existing duct using class 2 / SELV wiring with high-temperature insulation. A pressure or airflow-sensing interlock in the appliance could prevent gas flow if the fan stops working. Sadly, I’ve never heard of a system remotely resembling this. The choices appear to be stack effect (category I or II) but basically crossing fingers and hoping the pressure works out) or positive-pressure sealed but not tested “category III” or “category IV” pipes and crossing fingers and hoping that the pipes are actually airtight.)
ip26 3y ago
Drain water heat recovery seems like the best efficiency boost for water heating. Completely passive, 60% extra heat energy. At least for cold climates. Heat pump water heater might be phenomenal in a Phoenix garage.
- _JamesA_ 3y ago
  A heat pump water heater seems phenomenal to me in an Austin attic. And I use the cold air generated to cool a wiring/server closet. Win/win.
rayiner 3y ago
There’s a couple of big problems with the heat-pump industry in the U.S. First, people get their advice about HVAC from the tradespeople, who are way behind the curve on heat-pump technology. Second, and relatedly, the trusted American HVAC brands are far behind China and Japan and Europe on heat pump technology, especially cold-weather capable inverter units. I had our heat pumps replaced here in Maryland in 2019-2020 with mid-range Amana (rebranded Daikin) units. Decent efficiency, but output drops to half at 10F. The guys who recommended the system, a trusted local business, didn’t even tell me about that. Even in Maryland that means waking up to a cold house several weeks out of the year. That means we needed to keep our oil-based backup heat in place, which is a huge expense to maintain. (Also, our HVAC guys didn’t know that the communicating Daikin units can’t control external auxiliary heat, so they just left things with no backup heat whatsoever.) After educating myself about this, I wish we had installed one of those Chinese inverter based units, like the Gree Flexx. But if I asked my HVAC guy about that they’d stare back blankly. And the folks who do know what they’re doing can charge whatever they want. The price of getting a mini-split installed here is several times the price of the unit. The $16,000 we spent just a few years ago for two condensers and air handlers looks downright cheap compared to what it would cost today. Regarding your floor, we have a similar situation with radiant heat in our basement slab. I’ve been looking to ditch our oil boiler, but there’s basically no heat pump options that are widely available. (I don’t want to install some imported Chinese air to water heat pump that the local guys can’t fix.) With heating oil prices being over $4, though, I’m looking at just biting the bullet and installing an electric boiler, which is at least something I could probably fix myself.
- mrb 3y ago
  I feel you. The lack of knowledge among American tradespeople is infuriating. As soon as you deviate slightly from the brands of furnaces they have been installing for decades, they don't know anything.
danans 3y ago
> The architect said to me that we'll never fully recoup our costs of putting the hat on the house. That's only true if value your added comfort at a very low price. The problem is that it is hard to put a value on the comfort of a house, either while living in it, or while selling it. Hotels, however, do it all the time, but it's easier since they are in the business of selling comfort at various levels.
- ihaveajob 3y ago
  That's right. I remember a local "electrification festival" where some vendors and city officials teamed up to explain the various options. One of the most common questions was "will this lower by bill"? And the most memorable answer by a vendor was "probably now, but you won't have to be wearing that coat in your living room". Which hit home because at the time we had a drafty house with poor heat distribution.
1123581321 3y ago
That's a shame about the Rheem. Ours has been overperforming my financial model in the standard eco mode. We do have an advantage in that it sits out in the open in the unfinished part of the basement, which runs slightly warm in the winter due to a ductwork problem. No venting was necessary. It's definitely challenging to find trades who have both the knowledge and interest to innovate relative to standard HVAC installations in the area.
GenerWork 3y ago
>My only regret was going with a Rheem heat-pump water heater in this mix. It does not perform well at all. Sorry to hear that. My Rheem heat-pump water heater works fantastically, although I do live in a hot climate so that could be why.
mechagodzilla 3y ago
Wait - you have a HPWH connected to a hydronic floor system? That's an extremely inappropriate setup - the heatpump on a rheem is probably like ~4000 BTU/hr, and it's pulling the heat from the conditioned space, then you're drawing it off and pumping it back into the space via the floor. If you don't have an air-to-water heatpump and don't want fossil fuels, just use an electric boiler.
- _spduchamp 3y ago
  I know! It is definitely something i need to fix. I just havent found the right thing to handle the hydronics separate from our water heating.
Merad 3y ago
I think the biggest hurdle to heat pump adoption (at least in North America) is likely to be that it provides an experience that simply isn't as good as a gas furnace. On a chilly morning the air coming out of the vents just isn't that warm and it may take hours to bring the house up to temp, whereas gas puts out pleasantly warm air immediately and can quickly warm the house even on the coldest days. When it's truly cold (like < 20F) the heat pump will run continuously and struggle to maintain temp. Don't misunderstand, the heat pump is certainly _good enough_, but people typically don't pick the "good enough" experience over the "better" experience when the better option is available and they can afford it. For reference I've lived in NC and TN near the mountains where heat pumps are pretty standard. I imagine we don't get the ultra high efficiency cold weather heat pump units that would be used up north, but they also get much colder temps than us. Several of the houses I've lived in have been recent construction (2008 and 2018), so well insulated and reasonably new & efficient heat pumps. For the last 2 years I've been in a house with gas, and it's just so damned pleasant... I know on paper that heat pump is better, but I really don't want to give up that furnace.
- antisthenes 3y ago
  > I think the biggest hurdle to heat pump adoption (at least in North America) > When it's truly cold (like < 20F) the heat pump will run continuously and struggle to maintain temp. Luckily, pretty much the entire Western and Eastern Coastal areas, it doesn't actually get that cold on a regular basis, except a few days in the winter. The US is actually in an incredibly advantageous geographical position for at least 60% of households to be on heatpumps, as opposed to, say, Finland/Canada/Russia etc.
  - napoleongl 3y ago
    Meanwhile it was estimated that half of Swedish houses were equipped with heat pumps in 2016. That number has certainly not gone down since given the steep rise in electricity costs we’ve had since. Many houses have been converted from horribly inefficient direct electric heating to heat pumps.
- Mvandenbergh 3y ago

belter 3y ago

How noisy is it? I heard of people installing them, and getting complaints from the neighbors.

WirelessGigabit 3y ago
They're as noisy as an AC. So here in Arizona no one cares. But in Belgium this was an issue as they run more in winter and in winter sound travels further.
- belter 3y ago
  Uhmm...I see a problem for countries where you have wall to wall connected urban environments...If all 60 connected houses on a street, install external heat pumps, it will add up.
  - toothrot 3y ago
    Turns out cities are loud! In NYC, at least, heat pumps are far more quiet than the endless window unit A/C's, or larger traditional A/C's, in my experience. Outdoor noise is less of an issue in the winter in big cities because windows are closed.
    - wussboy 3y ago
      Most of the noise in cities is cars. One idiot on a Harley drowns out a warehouse of heat pumps
    - belter 3y ago
      Sounds like an installation can be really tricky or you will end up with something like this: https://youtu.be/1rKNT7-42J0?t=1510 https://youtu.be/1rKNT7-42J0?t=1510
- cduzz 3y ago
  Just installed heat pump systems (daikin) this december. The exterior unit is basically silent even when there was a cold snap (below freezing but not northern alaska cold). I suspect an interior air source heat pump hot water heater, being smaller, will be noisier, and likely less efficient. I'd love to switch my 240v/30a water heater to use a 120v/20a service, but will wait a bit longer for the technology to mature. Ideally it'd have the heat collection part outside.
- triceratops 3y ago
  In the winter everyone has their triple-paned windows closed. Is noise that much of a problem?
  - wussboy 3y ago
    Is triple pane common in Belgium? It’s not in the UK (as far as I recollect) and they’re colder than Belgium
    - WirelessGigabit 3y ago
      I built a house in 2014 there. Triple pane. Pointless. You never recoup the cost.
jillesvangurp 3y ago
Depends on the installer. A lot of noise results from units that are not properly mounted or mounted at a slight engine. The fan then starts getting more noisy and wears out earlier. There are other problems to not installing units properly.
switch007 3y ago
Also, when talking about noise it's important to talk about frequency. If they produce low frequency noise, that can be far more irritating. Shutting the windows won't help much

kingnothing 3y ago

What problems are you seeing with your water heater? I’ve had one for about a year and have been pretty happy with it after learning I needed to schedule high demand times of day. It is a bit louder than I’d like but it’s not horrible.

Aurornis 3y ago

> The architect said to me that we'll never fully recoup our costs of putting the hat on the house. Your architect is almost certainly right. I would bet that most of your improvements came from fixing the drafts, with the insulation providing a marginal improvement on top of that. I’ve also dealt with insulating old homes, but I did draft fixes, wall insulation, and attic/roof insulation at different stages. The draft fixes provided the most improvement, followed by attic/roof insulation. Insulating walls had much less effect than I anticipated. In friends’ houses I’ve used my thermal camera (which I didn’t have back then) and it’s easy to see where the heat or cold is coming in during weather extremes. These days I’d recommend anyone start with the thermal camera view before deciding where to spend money on insulation.

pjc50 3y ago
Thermal cameras have got really cheap: I found one on Aliexpress for less than £150, that plugs into a smartphone.
- dotancohen 3y ago
  Have you tried it, though? Is it any good?
mpaepper 3y ago
What kind of thermal camera do you recommend and what price range?
- andrewblossom 3y ago
  I bought a Topdon TC001 a year ago that in my experience is significantly more responsive and higher resolution than similarly priced FLIR or other name brand options at that price point. It appears there are even more low cost options now.
  - MobiusHorizons 3y ago
    I find it rather interesting that companies like FLIR are limited by regulation (I believe US export bans) from selling IR cameras with greater than 9fps. there is also a resolution cap but I forget what it is off-hand. Strangely enough this doesn't stop US citizens from purchasing higher performing cameras from non-US companies. I think technology has come down significantly in price over the last few years and you can now get smartphone attached versions like infiray for a few hundred bucks.

jbjbjbjb 3y ago

On the payback period, that’s probably just outlay divided by energy savings. I’m sure you’d get more enjoyment from a more comfortable house and the next owner will appreciate the modernisation too so those need to be factored into the investment appraisal. I doubt the architect puts such a miserly lens on the other projects they’re involved in.

jillesvangurp 3y ago
This is actually becoming an important point. In parts of the world where energy ratings matter, they have an impact on house value as well. They unlock incentives, etc. A house that is up to modern standards is simply worth more because any new owner does not have to do expensive renovations to modernize. In the Netherlands house flipping is pretty common. Buy something old, modernize it, live in it a few years and make a profit. The lower energy cost is both a nice bonus and a key selling point.

mecameron 3y ago

> The architect said to me that we'll never fully recoup our costs of putting the hat on the house. To which I replied that we don't always to things for economic reasons, and just do them because they are the right thing to do. I am so frustrated with this analysis and sentiment when it comes to environmental investment. I understand that looking at it with a financial lens can and should be done to inform what we do, and it would be great if a project just paid for itself, but you look at all the other things we spend money on and the same calculus is not used. People don't buy the cheapest car, house, clothing, or food they could possibly get by with, or analyze the marginal cost of moving up or down the possible price tiers available to them with only the financial payback as a guide. Yet we constantly hear the refrain that you shouldn't spend a given amount of money on solar, house improvements, appliances, etc. that might be better for the environment if the payback isn't somehow positive with a 10-20 year payback period. I've constantly had to work with contractors to let them know that I still want to pay for the marginal costs associated with investment even knowing that the marginal financial benefit is smaller. For instance, with solar panels in less than ideal locations, tri-pane windows, etc. I have disposable income, and I think the world is trouble for the 8+ billion humans inhabiting it, so I think it's worthwhile that I would spend some of that to make it marginally better even if that means I don't have a positive financial return.

jancsika 3y ago
> so I think it's worthwhile that I would spend some of that to make it marginally better even if that means I don't have a positive financial return. Your action is going to make close to 0% difference for the 8+ billion humans inhabiting the planet. So from a practical standpoint, you've failed, but that practical failure makes it clear that the gesture has pure symbolic value for you. And since that symbolic value stands in stark contrast to incessantly chasing positive financial returns: task failed successfully. Congratulations!
- toomuchtodo 3y ago
  From a practical standpoint, they have valued their energy savings closer to what the true cost of carbon emissions are (remember, most carbon emitters are in no way paying the true cost of their emissions [1]; this externality dumping continues with wild abandon). You're arguing systems and scale. This person is simply early in the adoption curve. Consider what will happen when this happens more broadly. As the climate situation becomes more dire [2], the price of carbon emissions per ton will rise and the willingness to prioritize energy savings and carbon emission reductions should increase regardless of fiat return. Physical system outcomes are distinct from magic number in database goes up. But sure, if you're already poor and have nothing [3], this won't matter to you and your life trajectory is already mostly locked in today. As nullstyle mentions, we need to compound in the positive outcome direction, and those decisions are being made today. [1] https://www.nature.com/articles/s41586-022-05224-9 https://www.nature.com/articles/s41586-022-05224-9 [2] https://www.npr.org/2024/04/09/1243595924/march-world-hottest-on-record https://www.npr.org/2024/04/09/1243595924/march-world-hottes... [3] https://ourworldindata.org/poverty https://ourworldindata.org/poverty

mataug 3y ago

> My only regret was going with a Rheem heat-pump water heater in this mix. It does not perform well at all. Heat-pump water heater's performance depends a lot on where its installed and the airflow+heat available. If the water heater is undersized or if there isn't enough heat in the air, it would perform worse than a standard gas/electric water heater. Mine is installed in a closet under the stairs, which is not ideal, but as long as I keep the water heater in eco mode, and keep closet door slightly open, it works good enough for our usecase. Our annual water heating costs went down from ~$500 to ~$100 after switching to the heat pump water heater.

usrusr 3y ago
As in the cold end of the heat pump is inside the heated area of the house? That feels very weird. On the other hand with heat pumps, stacking multiple stages strategy isn't necessarily a bad thing! All inefficiencies are not really losses but merely resistive heating contributions (unless their heat escapes to the final cold sink aka outside) and in the end the real question is which configuration is good in terms of capex and maintenance. In an environment where getting rid of humidity is a concern (mold!), a "cold end inside" heat pump for water might even double as a dehumidifier, with water condensing on the cold end sent to the sewers, contributing a little energy in the process.
- sf_rob 3y ago
  That's not uncommon and is even beneficial in warmer climates. It will be parasitic in winter (even if externally vented) and symbiotic in summer.

loceng 3y ago

Have you ever monitored the air quality levels in various rooms? Curious if getting rid of those drafts may be unknowingly affecting your health in other areas.

doctorhandshake 3y ago
My understanding is that any house that isn’t built ‘tight’ by today’s standards will have a fast enough ACH that you don’t need to worry about ventilation as you would with a tight house. And only a ‘deep energy retrofit’ of an older house would result in tightness like that, so ERV and MUA etc are not necessary. Local code, build detail, and age of house are factors, YMMV, but this isn’t a problem you’d cause by accident with anything but a very invasive retrofit.
- amluto 3y ago
  Mechanical ventilation is not necessary in a drafty house, but it’s still very nice to have. Bonus points for a well-filtered system. (None of the major brands will sell you a system that is well filtered out of the box. But it’s straightforward, if rather space consuming, to put a monstrous filter with effectively zero pressure loss in series with the system.) Bonus points for taking advantage of a balanced ventilation system’s ability to continuously extract air from stinky areas, e.g. bathrooms. Even more bonus points for avoiding negative pressure due to conventional bathroom exhaust, which can defeat stack effect-based exhaust from non-power-vented combustion appliances, which are, for some reason, still legal. (Seriously, WTF. There’s a straightforward design that could safely created a forced draft even with legacy leaky ductwork: put the fan on the exterior vent terminal, so the duct is under negative pressure. The wiring could be fished through the existing duct using class 2 / SELV wiring with high-temperature insulation. A pressure or airflow-sensing interlock in the appliance could prevent gas flow if the fan stops working. Sadly, I’ve never heard of a system remotely resembling this. The choices appear to be stack effect (category I or II) but basically crossing fingers and hoping the pressure works out) or positive-pressure sealed but not tested “category III” or “category IV” pipes and crossing fingers and hoping that the pipes are actually airtight.)

ip26 3y ago

Drain water heat recovery seems like the best efficiency boost for water heating. Completely passive, 60% extra heat energy. At least for cold climates. Heat pump water heater might be phenomenal in a Phoenix garage.

_JamesA_ 3y ago
A heat pump water heater seems phenomenal to me in an Austin attic. And I use the cold air generated to cool a wiring/server closet. Win/win.

rayiner 3y ago

There’s a couple of big problems with the heat-pump industry in the U.S. First, people get their advice about HVAC from the tradespeople, who are way behind the curve on heat-pump technology. Second, and relatedly, the trusted American HVAC brands are far behind China and Japan and Europe on heat pump technology, especially cold-weather capable inverter units. I had our heat pumps replaced here in Maryland in 2019-2020 with mid-range Amana (rebranded Daikin) units. Decent efficiency, but output drops to half at 10F. The guys who recommended the system, a trusted local business, didn’t even tell me about that. Even in Maryland that means waking up to a cold house several weeks out of the year. That means we needed to keep our oil-based backup heat in place, which is a huge expense to maintain. (Also, our HVAC guys didn’t know that the communicating Daikin units can’t control external auxiliary heat, so they just left things with no backup heat whatsoever.) After educating myself about this, I wish we had installed one of those Chinese inverter based units, like the Gree Flexx. But if I asked my HVAC guy about that they’d stare back blankly. And the folks who do know what they’re doing can charge whatever they want. The price of getting a mini-split installed here is several times the price of the unit. The $16,000 we spent just a few years ago for two condensers and air handlers looks downright cheap compared to what it would cost today. Regarding your floor, we have a similar situation with radiant heat in our basement slab. I’ve been looking to ditch our oil boiler, but there’s basically no heat pump options that are widely available. (I don’t want to install some imported Chinese air to water heat pump that the local guys can’t fix.) With heating oil prices being over $4, though, I’m looking at just biting the bullet and installing an electric boiler, which is at least something I could probably fix myself.

mrb 3y ago
I feel you. The lack of knowledge among American tradespeople is infuriating. As soon as you deviate slightly from the brands of furnaces they have been installing for decades, they don't know anything.

danans 3y ago

> The architect said to me that we'll never fully recoup our costs of putting the hat on the house. That's only true if value your added comfort at a very low price. The problem is that it is hard to put a value on the comfort of a house, either while living in it, or while selling it. Hotels, however, do it all the time, but it's easier since they are in the business of selling comfort at various levels.

ihaveajob 3y ago
That's right. I remember a local "electrification festival" where some vendors and city officials teamed up to explain the various options. One of the most common questions was "will this lower by bill"? And the most memorable answer by a vendor was "probably now, but you won't have to be wearing that coat in your living room". Which hit home because at the time we had a drafty house with poor heat distribution.

1123581321 3y ago

That's a shame about the Rheem. Ours has been overperforming my financial model in the standard eco mode. We do have an advantage in that it sits out in the open in the unfinished part of the basement, which runs slightly warm in the winter due to a ductwork problem. No venting was necessary. It's definitely challenging to find trades who have both the knowledge and interest to innovate relative to standard HVAC installations in the area.

GenerWork 3y ago

>My only regret was going with a Rheem heat-pump water heater in this mix. It does not perform well at all. Sorry to hear that. My Rheem heat-pump water heater works fantastically, although I do live in a hot climate so that could be why.

mechagodzilla 3y ago

Wait - you have a HPWH connected to a hydronic floor system? That's an extremely inappropriate setup - the heatpump on a rheem is probably like ~4000 BTU/hr, and it's pulling the heat from the conditioned space, then you're drawing it off and pumping it back into the space via the floor. If you don't have an air-to-water heatpump and don't want fossil fuels, just use an electric boiler.

_spduchamp 3y ago
I know! It is definitely something i need to fix. I just havent found the right thing to handle the hydronics separate from our water heating.

Merad 3y ago

I think the biggest hurdle to heat pump adoption (at least in North America) is likely to be that it provides an experience that simply isn't as good as a gas furnace. On a chilly morning the air coming out of the vents just isn't that warm and it may take hours to bring the house up to temp, whereas gas puts out pleasantly warm air immediately and can quickly warm the house even on the coldest days. When it's truly cold (like < 20F) the heat pump will run continuously and struggle to maintain temp. Don't misunderstand, the heat pump is certainly _good enough_, but people typically don't pick the "good enough" experience over the "better" experience when the better option is available and they can afford it. For reference I've lived in NC and TN near the mountains where heat pumps are pretty standard. I imagine we don't get the ultra high efficiency cold weather heat pump units that would be used up north, but they also get much colder temps than us. Several of the houses I've lived in have been recent construction (2008 and 2018), so well insulated and reasonably new & efficient heat pumps. For the last 2 years I've been in a house with gas, and it's just so damned pleasant... I know on paper that heat pump is better, but I really don't want to give up that furnace.

antisthenes 3y ago
> I think the biggest hurdle to heat pump adoption (at least in North America) > When it's truly cold (like < 20F) the heat pump will run continuously and struggle to maintain temp. Luckily, pretty much the entire Western and Eastern Coastal areas, it doesn't actually get that cold on a regular basis, except a few days in the winter. The US is actually in an incredibly advantageous geographical position for at least 60% of households to be on heatpumps, as opposed to, say, Finland/Canada/Russia etc.
- napoleongl 3y ago
  Meanwhile it was estimated that half of Swedish houses were equipped with heat pumps in 2016. That number has certainly not gone down since given the steep rise in electricity costs we’ve had since. Many houses have been converted from horribly inefficient direct electric heating to heat pumps.
Mvandenbergh 3y ago