Heat pumps (air source)

[Franz316]

All the posts about heat pumps that I could find in the "Russia invades Ukraine" thread in P&N have been moved here. This thread was actually started by Atari2600 with post #22.
admin allisolm

Germany really dropped the ball the last two decades becoming so dependent on Russian fossil fuels. They should have begun transitioning to electric heat pumps many years ago.

 

[Dman8777]

Germany really dropped the ball the last two decades becoming so dependent on Russian fossil fuels. They should have begun transitioning to electric heat pumps many years ago.

I know a lot of people here in Germany who have built houses in the last ~10 years. They almost all have a solar system on the roof and heat pumps for heating. These systems are subsidized by the government to various degrees depending on the current administration. Generally, they can heat the house and cover ~50% of the electricity costs when averaged over the course of a year, which is a pretty good deal imo. There's always the issue of low energy production / high energy demand in the winter though. The current battery systems available definitely aren't capable of aleviating this issue yet.

The problem in Germany is that a lot of people live in apartments or older houses, where adding such systems is cost-prohibitive or not possible at all. In the apartment complex where I live, we have been trying to get a solar system approved for years without any success. That was before the invasion of Ukraine though. Maybe at our next condo association meeting we'll have more luck. I have a feeling the invasion will result in a lot of projects here being pushed through the approval phases more quickly. We need to be setting up wind mills everywhere possible, which is something that has previously been subject to lots of red tape.

 

[pmv]

I know a lot of people here in Germany who have built houses in the last ~10 years. They almost all have a solar system on the roof and heat pumps for heating. These systems are subsidized by the government to various degrees depending on the current administration. Generally, they can heat the house and cover ~50% of the electricity costs when averaged over the course of a year, which is a pretty good deal imo. There's always the issue of low energy production / high energy demand in the winter though. The current battery systems available definitely aren't capable of aleviating this issue yet.

The problem in Germany is that a lot of people live in apartments or older houses, where adding such systems is cost-prohibitive or not possible at all. In the apartment complex where I live, we have been trying to get a solar system approved for years without any success. That was before the invasion of Ukraine though. Maybe at our next condo association meeting we'll have more luck. I have a feeling the invasion will result in a lot of projects here being pushed through the approval phases more quickly. We need to be setting up wind mills everywhere possible, which is something that has previously been subject to lots of red tape.

Same for much of the UK. It's why I get irritated at those who push "micro solar" systems, and the idea of subsidising them - they are all very well for those who are wealthy enough to have large houses with lots of roof-space per person, plus the money for the initial capital outlay. In inner city areas people live in flats, and have very little roof-space per person.
Plus the freehold system means putting solar on such buildings would be the responsibility of the freeholder - the same freeholders who are extremely reluctant to pay out for even the removal of potentially lethal flammable cladding. Often the freeholder is the local council, who can take decades to get round to even basic repairs, there's no way I can see them getting their act together for things like heat pumps or solar panels.
Hence subsidising solar (through a levy on everyone else's fuel bill - the way they tend to want to do it) just works out as subsidising the already-well-off at the expense of poorer people.

(Can heat pumps be used on flats/apartments? I had the impression they needed plenty of land, but there are air-based versions, no? I don't know if those would be usable for apartments/flats? They seem to me to be like an Air Conditioner unit running backwards - is that basically it?)

 

[K1052]

(Can heat pumps be used on flats/apartments? I had the impression they needed plenty of land, but there are air-based versions, no? I don't know if those would be usable for apartments/flats? They seem to me to be like an Air Conditioner unit running backwards - is that basically it?)

Air source heat pumps have been a thing for decades at least. You can get mini-split versions too which seems to be a more popular form factor for A/C in Europe from what I recall. People would stick them on roofs, balconies, or just hang on the side of the building. Heating performance used to kind of suck but in recent years there have been significant improvements.

Random example from Spain where they mostly seem to mount condensers on the building exterior

 

[Captante]

Both videos are a good watch.

 

[Zorba]

Same for much of the UK. It's why I get irritated at those who push "micro solar" systems, and the idea of subsidising them - they are all very well for those who are wealthy enough to have large houses with lots of roof-space per person, plus the money for the initial capital outlay. In inner city areas people live in flats, and have very little roof-space per person.
Plus the freehold system means putting solar on such buildings would be the responsibility of the freeholder - the same freeholders who are extremely reluctant to pay out for even the removal of potentially lethal flammable cladding. Often the freeholder is the local council, who can take decades to get round to even basic repairs, there's no way I can see them getting their act together for things like heat pumps or solar panels.
Hence subsidising solar (through a levy on everyone else's fuel bill - the way they tend to want to do it) just works out as subsidising the already-well-off at the expense of poorer people.

(Can heat pumps be used on flats/apartments? I had the impression they needed plenty of land, but there are air-based versions, no? I don't know if those would be usable for apartments/flats? They seem to me to be like an Air Conditioner unit running backwards - is that basically it?)

The vast majority of heat pumps are air to air, just a normal AC ran backwards. It's literally the same equipment with a reversing valve installed.

They do lose their efficiency in environments below freezing or with a lot of moisture in the air.

Heat pumps should also be used in electric cars.

 

[Zorba]

Air source heat pumps have been a thing for decades at least. You can get mini-split versions too which seems to be a more popular form factor for A/C in Europe from what I recall. People would stick them on roofs, balconies, or just hang on the side of the building. Heating performance used to kind of suck but in recent years there have been significant improvements.

Random example from Spain where they mostly seem to mount condensers on the building exterior

View attachment 59824

The biggest issue with that setup is in heat mode you get condensation on the outdoor coil, which would drip on everything below of no drip pan was installed.

 

[hal2kilo]

The vast majority of heat pumps are air to air, just a normal AC ran backwards. It's literally the same equipment with a reversing valve installed.

They do lose their efficiency in environments below freezing or with a lot of moisture in the air.

Heat pumps should also be used in electric cars.

They even have heat pump dryers now. My electric company was pushing them with a deal last year.

 

[pmv]

The vast majority of heat pumps are air to air, just a normal AC ran backwards. It's literally the same equipment with a reversing valve installed.

I really don't understand any of this stuff. If heat-pumps are like AC, how do they help with energy conservation? AC is a big consumer of electricity, and here (and maybe for much of Europe?) that electricity tends to be produced from gas anyway. What's the big selling-point of heat pumps? If they take electricity to run, where's the saving?

Solar seems promising, but does it not require scarce mineral resources (that have to be dug out of the ground with corresponding environmental cost) to produce them, ergo would it not be more efficient to use those that exist in lower-latitude countries that get more sun? Or are solar panels much more widely available now than they used to be, so it's worth using them even at Northern latitudes?

(Also, could the same unit be used for AC in summer and run as a heat-pump in winter?)

Most of all though there seems a massive problem of inertia with actually getting housing stock improved, because of the complications of how ownership works. As I say, local councils are utterly hopeless at actually maintaining the housing stock they are responsible for, even when it costs them money in the long run to not do maintenance. Things like solar and heat pumps or even basic insulation seem likely to be entirely beyond their capacity to manage.

 

[Fenixgoon]

I really don't understand any of this stuff. If heat-pumps are like AC, how do they help with energy conservation? AC is a big consumer of electricity, and here (and maybe for much of Europe?) that electricity tends to be produced from gas anyway. What's the big selling-point of heat pumps? If they take electricity to run, where's the saving?

Solar seems promising, but does it not require scarce mineral resources (that have to be dug out of the ground with corresponding environmental cost) to produce them, ergo would it not be more efficient to use those that exist in lower-latitude countries that get more sun? Or are solar panels much more widely available now than they used to be, so it's worth using them even at Northern latitudes?

(Also, could the same unit be used for AC in summer and run as a heat-pump in winter?)

Most of all though there seems a massive problem of inertia with actually getting housing stock improved, because of the complications of how ownership works. As I say, local councils are utterly hopeless at actually maintaining the housing stock they are responsible for, even when it costs them money in the long run to not do maintenance. Things like solar and heat pumps or even basic insulation seem likely to be entirely beyond their capacity to manage.

Electricity generation, even by gas, is still more energy-efficient than gas distribution and heating house-by-house.

 

[pmv]

Electricity generation, even by gas, is still more energy-efficient than gas distribution and heating house-by-house.

That surprises me. I don't really know but generally had the impression that the opposite was the case. Certainly those who have to heat their homes with electric fires tend to have much, much, larger bills than if they had gas fire heating. Likewise electric cookers are more expensive to run than gas ones. Seems logical given that to use electricity for heating requires an additional stage, of conversion from gas to electric, at the power plants, and that's going to involve a loss of efficiency.

Unless the point is that a heat-pump uses much less electricity per joule of heat produced than, say, an electric fire? Because it's getting more heat out of the air (or ground) than it's using in electricity? And that this gain more than makes up for the waste of the conversion process at the power plant?

 

[K1052]

Unless the point is that a heat-pump uses much less electricity per joule of heat produced than, say, an electric fire? Because it's getting more heat out of the air (or ground) than it's using in electricity? And that this gain more than makes up for the waste of the conversion process at the power plant?

This is it precisely. Heat pumps are way way way more efficient than electric resistance heating.

 

[[DHT]Osiris]

That surprises me. I don't really know but generally had the impression that the opposite was the case. Certainly those who have to heat their homes with electric fires tend to have much, much, larger bills than if they had gas fire heating. Likewise electric cookers are more expensive to run than gas ones. Seems logical given that to use electricity for heating requires an additional stage, of conversion from gas to electric, at the power plants, and that's going to involve a loss of efficiency.

Unless the point is that a heat-pump uses much less electricity per joule of heat produced than, say, an electric fire? Because it's getting more heat out of the air (or ground) than it's using in electricity? And that this gain more than makes up for the waste of the conversion process at the power plant?

Here you go, plenty of other comparison sites available.

Fuel Comparison Calculator

Compares cost and CO2 emisssions for various fuels

www.chinetco.com

 

[pmv]

Here you go, plenty of other comparison sites available.

Fuel Comparison Calculator

Compares cost and CO2 emisssions for various fuels

www.chinetco.com

Interesting. Heat pumps definitely seem worth investing in, on those figures. Though given the complications of how housing stock is managed and owned it really needs concerted action by government to ensure it actually happens.

I notice it also rates "wood burners" highly, but the problem with that is the massive amount of localised particulate pollution they create.

‘Eco’ wood stoves emit 750 times more pollution than an HGV, study shows

Only ecodesign stoves can be legally sold from 2022 – but experts say the standard is shockingly weak

www.theguardian.com

Wood burners emit more particle pollution than traffic, UK data shows

Revised government data estimates a lower proportion of pollution comes from wood stoves but they remain a ‘major contributor’

www.theguardian.com

Avoid using wood burning stoves if possible, warn health experts

Charity calls for people to use alternative, less polluting heating and cooking options if they can

www.theguardian.com

Wood burners cause nearly half of urban air pollution cancer risk – study

Exclusive: Wood smoke is a bigger cancer risk than pollution from vehicles, finds Athens analysis

www.theguardian.com

Surprised how well coal scores on a purely cost-basis - but I think the CO2 emissions are greater even than for gas.

 

[hal2kilo]

Interesting. Heat pumps definitely seem worth investing in, on those figures. Though given the complications of how housing stock is managed and owned it really needs concerted action by government to ensure it actually happens.

I notice it also rates "wood burners" highly, but the problem with that is the massive amount of localised particulate pollution they create.

‘Eco’ wood stoves emit 750 times more pollution than an HGV, study shows

Only ecodesign stoves can be legally sold from 2022 – but experts say the standard is shockingly weak

www.theguardian.com

Wood burners emit more particle pollution than traffic, UK data shows

Revised government data estimates a lower proportion of pollution comes from wood stoves but they remain a ‘major contributor’

www.theguardian.com

Avoid using wood burning stoves if possible, warn health experts

Charity calls for people to use alternative, less polluting heating and cooking options if they can

www.theguardian.com

Wood burners cause nearly half of urban air pollution cancer risk – study

Exclusive: Wood smoke is a bigger cancer risk than pollution from vehicles, finds Athens analysis

www.theguardian.com

Surprised how well coal scores on a purely cost-basis - but I think the CO2 emissions are greater even than for gas.

Also carves up eastern American hardwood forests. It's renewable you know. But, sustainable?

 

[Atari2600]

(Can heat pumps be used on flats/apartments? I had the impression they needed plenty of land, but there are air-based versions, no? I don't know if those would be usable for apartments/flats? They seem to me to be like an Air Conditioner unit running backwards - is that basically it?)

All well and good. But they kinda stop working <3 deg C.

The external Hx will freeze up any water vapour in the air and swiftly clog.

I suppose you could run heating elements though it to try and stop that, and accept the crap performance when its freezing - but not exactly the magic bullet many in the media purport.

 

[[DHT]Osiris]

Interesting. Heat pumps definitely seem worth investing in, on those figures. Though given the complications of how housing stock is managed and owned it really needs concerted action by government to ensure it actually happens.

I notice it also rates "wood burners" highly, but the problem with that is the massive amount of localised particulate pollution they create.

‘Eco’ wood stoves emit 750 times more pollution than an HGV, study shows

Only ecodesign stoves can be legally sold from 2022 – but experts say the standard is shockingly weak

www.theguardian.com

Wood burners emit more particle pollution than traffic, UK data shows

Revised government data estimates a lower proportion of pollution comes from wood stoves but they remain a ‘major contributor’

www.theguardian.com

Avoid using wood burning stoves if possible, warn health experts

Charity calls for people to use alternative, less polluting heating and cooking options if they can

www.theguardian.com

Wood burners cause nearly half of urban air pollution cancer risk – study

Exclusive: Wood smoke is a bigger cancer risk than pollution from vehicles, finds Athens analysis

www.theguardian.com

Surprised how well coal scores on a purely cost-basis - but I think the CO2 emissions are greater even than for gas.

Wood burners are cheap/efficient for btu's, but yeah there's health concerns. Wood pellets are much better (we have one, love it). More efficient, and better for the environment.

 

[[DHT]Osiris]

All well and good. But they kinda stop working <3 deg C.

The external Hx will freeze up any water vapour in the air and swiftly clog.

I suppose you could run heating elements though it to try and stop that, and accept the crap performance when its freezing - but not exactly the magic bullet many in the media purport.

They do? Our heat pump ran like a champ all winter.

 

[dank69]

All well and good. But they kinda stop working <3 deg C.

The external Hx will freeze up any water vapour in the air and swiftly clog.

I suppose you could run heating elements though it to try and stop that, and accept the crap performance when its freezing - but not exactly the magic bullet many in the media purport.

You just reverse the cycle for a few minutes to thaw the condensation.

 

[Brainonska511]

The biggest issue with that setup is in heat mode you get condensation on the outdoor coil, which would drip on everything below of no drip pan was installed.

I feel like that is a pretty trivial problem to solve.

The vast majority of heat pumps are air to air, just a normal AC ran backwards. It's literally the same equipment with a reversing valve installed.

They do lose their efficiency in environments below freezing or with a lot of moisture in the air.

Heat pumps should also be used in electric cars.

The TechnologyConnections guy points out that there are heat pumps that still retain good efficiency well below freezing. You could easily cover 95% of the year for many people in the US and Europe with existing heat pump technologies, and cover the rarer extremely cold day with some back-up traditional electric heating

 

[repoman0]

My heat pump system works just fine for heat 100% of the year in Boston * shrug *. It certainly draws more power the larger the delta T it has to overcome meaning it’s pretty expensive to run in the middle of the winter, but I haven’t found the lower limit yet. And it’s very cheap to cool the house in the summer since a comfortable temp difference is usually only 10-15 degrees F. Modern systems are very good and at this point I wouldn’t choose anything else.

 

[Atari2600]

So, I'd always been told that when temps approach freezing, the COP approaches 1.

Due to ice formation on the external Hx forcing either direct heating or reverse cycling (i.e. sucking heat out of your house to melt the ice).

Has anyone actually measured their power draw for summer vs. winter?

 

[NutBucket]

That's generally the rule of thumb. I've noticed modern heat pumps will usually have thermistors to measure outside air temp and coil temps so they cycle properly before freezing up.
I think there are more advanced units that can operate efficiently at even lower temps but I do not know what the differences are.

 

[Zorba]

It really depends on the amount of moisture in the air. Below freezing the air is generally pretty dry most days. As the coil freezes up and loses performance the system will reserve for a few minutes and generally kick on the aux heat to make the refrigerant hotter for the the ice melting.

I believe newer units have designed their coils to help prevent ice build up as well.

At the end of the day, you just lose some efficiency but not all of it. You also lose some efficiency as it gets colder out because there is less heat to move into the house. Just like AC loses efficiency as it gets hotter outside.

 

[Meghan54]

I feel like that is a pretty trivial problem to solve.

The TechnologyConnections guy points out that there are heat pumps that still retain good efficiency well below freezing. You could easily cover 95% of the year for many people in the US and Europe with existing heat pump technologies, and cover the rarer extremely cold day with some back-up traditional electric heating

Our 25 y.o. Trane heat pump does very well until it hits in the low 20's F. It has built-in resistance backup heating...labeled "emerg. heat."

Has a defrost cycle, too.

I'll deal with it being elect. in the winter vs. having gas...nice to have until it's not.