What is the real story around heat pumps?

[Siwastaja]

Then we are at 3500 EUR investment which is only for hot water, not for heating.

Normally, sensible people would get air-to-water heatpump to heat both the house, and DHW. For hot water only, quite obviously it will not make any sense, unless you are running a public bath.

[NiHaoMike]

Yeah someone in the neighborhood was buying wood for cooking in the garden and that sort of things, and I was seriously questioning his sanity when he told me how much it cost.

Wood for cooking is often for a specific flavor, that factor alone makes the specific kind of wood far more expensive than general purpose firewood.

Normally, sensible people would get air-to-water heatpump to heat both the house, and DHW. For hot water only, quite obviously it will not make any sense, unless you are running a public bath.

For just hot water, a much smaller and cheaper heat pump will do.

[tszaboo]

Then we are at 3500 EUR investment which is only for hot water, not for heating.

Normally, sensible people would get air-to-water heatpump to heat both the house, and DHW. For hot water only, quite obviously it will not make any sense, unless you are running a public bath.

We already talked about that. That starts at 12K for the equipment, new floor, new paint + finish for the walls, several months installation time, entirely new heating system. That ballpark 50K, not 3.5K. The one for 3.5K doesn't even support heating.

[Siwastaja]

Then we are at 3500 EUR investment which is only for hot water, not for heating.

Normally, sensible people would get air-to-water heatpump to heat both the house, and DHW. For hot water only, quite obviously it will not make any sense, unless you are running a public bath.

We already talked about that. That starts at 12K for the equipment, new floor, new paint + finish for the walls, several months installation time, entirely new heating system. That ballpark 50K, not 3.5K. The one for 3.5K doesn't even support heating.

This is one weird discussion. One can easily miss the fact that you are here just trolling, and accidentally take you seriously, like I did. It is unfruitful to discuss a case where a product which is completely unsuitable for your use case and just throw around ridiculous numbers when you force-fit it. Why stop at 50k, why not ten thousand million trillion billion? In reality, you just should do something else and not even consider air-to-water heatpump for your case.

People usually assume you are being sensible and honest, and don't want to read tens of pages of wall-of-text to find something that shows you were not. From now on, you are ignored by me on this thread so the mistake won't happen again.

[coppice]

Yeah someone in the neighborhood was buying wood for cooking in the garden and that sort of things, and I was seriously questioning his sanity when he told me how much it cost.

Wood for cooking is often for a specific flavor, that factor alone makes the specific kind of wood far more expensive than general purpose firewood.

This can be true, but it often feels like they are using the most bizarre wood for no good reason. Like the use of mesquite for barbeques in Arizona. Mesquite is a tree that grows in the desert, and has very dense hard wood. Growing in the desert, you can imagine how long it takes to grow big enough to be harvested, and tossed on the fire.

[peter-h]

I have not read the whole thread but here is my two cents based on seeing many installations, and running my own air to water one.

The claimed COP turns to ***t in conditions where evaporator icing is possible, which is basically anytime the humidity is above about 50%, which is most of the time The pump then has to go into reverse cycle to thaw it, which is ridiculous.

The COP is poor in ambient temp anywhere near 0C.

The output temp is not great (thermodynamically, pushing heat up the hill is hard) so you really need underfloor heating. Radiators need to be pretty large otherwise and here in the UK you can forget it if you want to achieve +21C inside with -8C outside, with radiators.

Heat pumps work great with a ground source (borehole, or a long buried pipe) but you still want underfloor heating.

Having it outdoors corrodes it nicely and produces a fairly short life (under 10 years). This is again where ground source is good because the pump is naturally indoors.

The bigger ones, say over 5kW claimed output, are better (more reliable) with a 3 phase compressor.

[nctnico]

In reality, you just should do something else and not even consider air-to-water heatpump for your case.

True. You have to keep in mind though that 'something else' is easier said than done. In the NL a large number of people are stuck with homes which are not suitable for any kind of heatpump because the insulation is insufficient and it is financially not viable to upgrade the home as it would come down to rebuilding the home from scratch. The only alternatives there are to replace natural gas, are district heating or hydrogen (as a replacement for natural gas).

[Siwastaja]

The claimed COP turns to ***t in conditions where evaporator icing is possible, which is basically anytime the humidity is above about 50%, which is most of the time The pump then has to go into reverse cycle to thaw it, which is ridiculous.

This is weird, because just today we have witnessed some very British weather: the whole day has been +1degC and RH exactly 100% + thick fog.

Number of defrost cycles between 7am and 7pm (right now) is: 2. For example, the previous run cycle:
Started at 15:32
Defrosted at 17:06
Finished defrosting at 17:11
Running at minimum power, reached upper temperature setpoint at 18:01 and stopped

There is nothing "ridiculous" in defrosting. It's completely normal, it's a feature, not a bug. Did you actually measure or otherwise verify it's causing a problem? Or do you just "feel" it is "ridiculous"?

During the last 24 hours, 19.136kWh has been consumed by the heatpump. The heat as required by the house, to maintain +22degC indoors, at this weather, is approximately 50kWh/24hrs based on earlier calculations and tests. Additionally, the heatpump pre-heats domestic hot water, amount of which is hard to exactly say, but we have a 1.5 year old poo generator who needs butt washing and stuff like that, so with two showers, some dishwashing etc. I would quickly guesstimate at least 10kWh worth of hot water preheating took place. Therefore, COP would be around 60kWh/19.1kWh = 3.14.

Manufacturer test reports, which honestly says it ignores defrosting, and thus probably also ignores the bottom tray heater, and which also ignores water pump, which I do include in my numbers, states COP = 3.95 in similar conditions. Once you add water pump, it's down to 3.55. Once you add bottom tray heater, it's down to 3.09, nearly exact match with my estimate. This means the heatpump is doing excellent job with defrosts ending up with the same COP than in dry tests (which is unsurprising, if you read my previous longer post about it); and one could improve the heatpump, not by magically removing need for defrosting by dehumidifying the whole planet, nor by improving defrosting decision algorithms, but by more intelligently controlling the bottom tray heater, which is something I haven't done yet; I have not modified the thing at all.

Does your system work, and have you measured the consumption to verify there is a problem? Or is this again some feeling mumbo jumbo?

here in the UK you can forget it if you want to achieve +21C inside with -8C outside, with radiators.

Also this is obvious bullshit, there is nothing special in UK climate at -8C compared to e.g. Finnish climate at -8C, RH varies between 85-100% anyway at that point. -8C and +21C is completely normal everyday operating point for me, and yes, with radiators, albeit admittedly swapped for larger sizes than original.

[Siwastaja]

In reality, you just should do something else and not even consider air-to-water heatpump for your case.

True. You have to keep in mind though that 'something else' is easier said than done. In the NL a large number of people are stuck with homes which are not suitable for any kind of heatpump because the insulation is insufficient and it is financially not viable to upgrade the home as it would come down to rebuilding the home from scratch. The only alternatives there are to replace natural gas, are district heating or hydrogen (as a replacement for natural gas).

Air source heatpumps are quite acceptable for poorly insulated houses, they are e.g. used in traditional Japanese houses basically made out of thin wood frame and paper. You just keep the thing switched off when not present, and turn it on when you are there. It blows warm air towards you and heats up the air in the room pretty quickly. COP is very good because the condenser can run at low temperature, especially when you coldstart the heating. Of course a lot of energy is wasted with poor insulation, but this is wasted with any form of heating and therefore high COP is of high importance.

Ground source or air-to-water heatpumps indeed do not work too well (this is probably what you mean) in such cases unless you install water fan coil units, replicating the behavior of the simple air-to-air units for much higher cost; if there are radiators at all in such poorly insulated houses, they require high temperatures that can be only provided by burning something in a boiler.

[tszaboo]

Then we are at 3500 EUR investment which is only for hot water, not for heating.

Normally, sensible people would get air-to-water heatpump to heat both the house, and DHW. For hot water only, quite obviously it will not make any sense, unless you are running a public bath.

We already talked about that. That starts at 12K for the equipment, new floor, new paint + finish for the walls, several months installation time, entirely new heating system. That ballpark 50K, not 3.5K. The one for 3.5K doesn't even support heating.

This is one weird discussion. One can easily miss the fact that you are here just trolling, and accidentally take you seriously, like I did. It is unfruitful to discuss a case where a product which is completely unsuitable for your use case and just throw around ridiculous numbers when you force-fit it. Why stop at 50k, why not ten thousand million trillion billion? In reality, you just should do something else and not even consider air-to-water heatpump for your case.

People usually assume you are being sensible and honest, and don't want to read tens of pages of wall-of-text to find something that shows you were not. From now on, you are ignored by me on this thread so the mistake won't happen again.

Are you serious? Let's just take a ballpark installation for a 120 sqm house. I'm going to look up prices for you. New floor, 40EUR/SQM, installation costs 10-20 EUR depending where, let's cut the middle at 15 EUR/SQM. So floor is 6600 EUR. Painting the entire house, 2-3 days of work for 2 people, 3000 EUR. Pray that you don't need a new kitchen.
Floor heating installation cost: 7800EUR +2500EUR https://www.reddit.com/r/Netherlands/comments/18mrkba/under_floor_heating_cost/
Disconnecting district heating: 4200 EUR (Not a joke)
Removing every furniture, storage for the duration of the work, moving back: 2x1500 EUR for moving, Storage few hundred EUR. Again, pray that SO doesn't get creative and decides to buy new furniture.
Actual heat pump 9500 EUR. You get back 20-30% as subsidy. Juppy je, that's as much as the VAT. : https://www.klimate.nl/panasonic-kit-wxc09h3e8-lucht-water-warmtepomp-singlesplit.html
Heatpump installation cost: 2300EUR. https://cv-kosten.nl/warmtepomp/ (De prijsopbouw van de installatie van je warmtepomp)
Again, going with my neighbor's example, if you are lucky, you can organize the entire thing in two months time. Because their agenda is usually completely full.
Total listed here was 36000 EUR. You know what, it's not 50000 EUR, though I probably left out a few things. That calculation was for the ground source heatpump.
And no, I cannot "just install larger radiators", they are sized for 70-80C district heating, and it's completely unsuitable for low temperature heatpumps.

[Siwastaja]

And no, I cannot "just install larger radiators", they are sized for 70-80C district heating, and it's completely unsuitable for low temperature heatpumps.

Yes yes yes, we heard you already, your house is not suitable for air-to-water heatpump retrofit, we got it. I could come up with a calculation how expensive it would be to run natural gas heating on the Moon, including the work to build a pipeline from NL to the Moon, and then just throw around the number of ten gazillion megagillions in every thread, but I prefer not to. Now please can you just go away wasting our time, thank you.

[tszaboo]

And no, I cannot "just install larger radiators", they are sized for 70-80C district heating, and it's completely unsuitable for low temperature heatpumps.

Yes yes yes, we heard you already, your house is not suitable for air-to-water heatpump retrofit, we got it. I could come up with a calculation how expensive it would be to run natural gas heating on the Moon, including the work to build a pipeline from NL to the Moon, and then just throw around the number of ten gazillion megagillions in every thread, but I prefer not to. Now please can you just go away wasting our time, thank you.

Yes, because brushing off issues like the OP's issue (who is btw from the Netherlands) is the right solution. And houses are built everywhere like the Finnish standard, because we all get -40C in the winter. But that's ok, because you can just tell everyone that it's only 500 EUR. One size fits all!

[Siwastaja]

Yes, because brushing off issues like the OP's issue (who is btw from the Netherlands)

.. whose house is in France and it DOES have underfloor heating lack of which you are complaining about so your game is now exposed, you did not care about helping the OP the slightest bit, you did not even read any of the OP's posts unlike me and others. You are here just trolling and spoon feeding your own case disguised as some sort of advice for others. Now enjoy the actual ignore list because it seems I can't resist replying to dishonest people like you.

[nctnico]

In reality, you just should do something else and not even consider air-to-water heatpump for your case.

True. You have to keep in mind though that 'something else' is easier said than done. In the NL a large number of people are stuck with homes which are not suitable for any kind of heatpump because the insulation is insufficient and it is financially not viable to upgrade the home as it would come down to rebuilding the home from scratch. The only alternatives there are to replace natural gas, are district heating or hydrogen (as a replacement for natural gas).

Air source heatpumps are quite acceptable for poorly insulated houses, they are e.g. used in traditional Japanese houses basically made out of thin wood frame and paper. You just keep the thing switched off when not present, and turn it on when you are there. It blows warm air towards you and heats up the air in the room pretty quickly. COP is very good because the condenser can run at low temperature, especially when you coldstart the heating. Of course a lot of energy is wasted with poor insulation, but this is wasted with any form of heating and therefore high COP is of high importance.

That is not going to work. One of the reasons you really need to heat a home thouroughly is to keep moisture under control to avoid issues with mold.

[Siwastaja]

That is not going to work. One of the reasons you really need to heat a home thouroughly is to keep moisture under control to avoid issues with mold.

It is not "going" anything, it is how millions and millions of people actually live. Complete shutdown of heating is maybe a slight exaggeration, but the level is definitely adjusted based on being present or not, and poorly insulated houses with little thermal mass cool down and heat up quickly. Remember, when people are not present, also water vapor is not being produced by breathing etc. And these poorly insulated houses are not also very windproof, so they naturally ventilate. For mold control anyway fairly small temperature differences are sufficient, such as 5-6degC as studied at Tampere University of Technology where I attended too, so if it's say 0degC outdoors you don't need to heat to +20 to keep the mold out. All that is needed is to reduce RH% to somewhere below 75% and that happens with a few degrees of difference under all conditions. "Keep dry" systems are basically constant power heaters.

This style of living is unintuitive for those who are used to having more thermal mass and good insulation - and heating which is kept to provide constant temperature. Also the control strategies to produce savings are totally different. We can easily cut the whole heating for 2-3 hours without much effect on room temperature here for savings with hourly spot prices, but we really don't do fast adjustments on per-room basis. In a poorly insulated paper house, it's the exact opposite; it would be ridiculous to use the lower cost hours to proactively heat up rooms where no one is present, but in a glasswool insulated house with inner brick walls it totally makes sense.

[tszaboo]

Yes, because brushing off issues like the OP's issue (who is btw from the Netherlands)

.. whose house is in France and it DOES have underfloor heating lack of which you are complaining about so your game is now exposed, you did not care about helping the OP the slightest bit, you did not even read any of the OP's posts unlike me and others. You are here just trolling and spoon feeding your own case disguised as some sort of advice for others. Now enjoy the actual ignore list because it seems I can't resist replying to dishonest people like you.

Oh no, I've been find out. I'm actually paid by big gas(?) and big district heating. Not someone who was actually interested in this technology, until I've been presented the shortcomings of the technology and calculated the costs of it for myself about a year and a half ago. And didn't see one particular post in 15 pages filled with wall of text. I clearly have an agenda here, good thing you have it all figured out.

[pcprogrammer]

Yes, because brushing off issues like the OP's issue (who is btw from the Netherlands)

.. whose house is in France and it DOES have underfloor heating lack of which you are complaining about so your game is now exposed, you did not care about helping the OP the slightest bit, you did not even read any of the OP's posts unlike me and others. You are here just trolling and spoon feeding your own case disguised as some sort of advice for others. Now enjoy the actual ignore list because it seems I can't resist replying to dishonest people like you.

 

You got to love a good fight.

Still waiting for the second set of quotes. I'm very curious as to what they are going to offer for air to water in terms of output power, and what the price will be for the complete job.

What I know so far is that they mainly use Mitsubishi Electric for air to water with split units, so the pipes running to the outside unit hold the refrigerant and not the central heating water. This means they have to fill it with the gas themselves. In France there is a certification for heat pump installers called "Qualipac" and "certifRGE" so there is some reassurance that the ones we invited are not telling total porkies. 

Also keen to see which brand they will offer for the geothermal system.

If they do a proper job and really perform calculations on the house based on what we told them about insulation and the measurements they did it should be in range with my own findings based on previous energy usage.

For the geothermal a big portion of the expenses are the drilling of the holes. Unfortunately not a lot of companies around here do that kind of work.

We just have to wait and see what they come up with.

[Siwastaja]

Panasonic also makes some quite decent air-to-water heatpumps, both monoblocks and splits. They do more conservative ratings than most others on the market so you basically know that unit rated for x kW nameplate thermal also provides it even at -15degC or so, making them more cost-effective than they first appear compared to the Chinese ones. I'm happy with my Chinese thing though but Panasonic was on my list of options and not much more expensive if at all. I believe they are somewhat cheaper than Mitsubishi Electric but not sure.

[pcprogrammer]

The bigger ones, say over 5kW claimed output, are better (more reliable) with a 3 phase compressor.

Is there a difference in life expectancy and reliability between tri phase and single phase models?

For what I have seen of the De Dietrich models there is no difference in price between them. Don't know about other brands.

[coppice]

Panasonic also makes some quite decent air-to-water heatpumps, both monoblocks and splits. They do more conservative ratings than most others on the market so you basically know that unit rated for x kW nameplate thermal also provides it even at -15degC or so, making them more cost-effective than they first appear compared to the Chinese ones. I'm happy with my Chinese thing though but Panasonic was on my list of options and not much more expensive if at all. I believe they are somewhat cheaper than Mitsubishi Electric but not sure.

My experience has been that Panasonic units are OK when new, but don't offer the lifetime of a Mitsubishi or Daikin. Which Chinese unit do you have? Some are really sophisticated, and high performance, which some are still pretty crude. People like Gree have put serious effort into making world class heat pumps, but that doesn't say much about their lifetimes. They don't have the kind of long track record of Mitsubishi or Daikin.

[coppice]

The bigger ones, say over 5kW claimed output, are better (more reliable) with a 3 phase compressor.

Is there a difference in life expectancy and reliability between tri phase and single phase models?

For what I have seen of the De Dietrich models there is no difference in price between them. Don't know about other brands.

Unless you have a bargain basement heat pump, why would three or single phase power make any difference? They are all inverter driven these days. Is this single vs 3 phase issue related to old heat pumps? I can definitely see a three phase induction motor giving better results.

[nctnico]

The bigger ones, say over 5kW claimed output, are better (more reliable) with a 3 phase compressor.

Is there a difference in life expectancy and reliability between tri phase and single phase models?

I think the difference expressed is between on/off compressor versus variable frequency inverter driven compressors. Nowadays you will want an inverter driven heatpump as these are quieter under light loads. Also make sure to buy a unit with a rotary compressor as these produce way less vibrations.

The outdoor unit I have from Panasonic has both and it sits on a sloped roof with a wooden construction. I have to listen very carefully to hear it from directly under the roof. But I have to say that I mounted it on extra shock absorbers.

[tszaboo]

Still waiting for the second set of quotes. I'm very curious as to what they are going to offer for air to water in terms of output power, and what the price will be for the complete job.

Reading through your situ., I think the air to water heatpump probably makes the most sense. Especially since you have most of your house prepared for it.

[Someone]

The bigger ones, say over 5kW claimed output, are better (more reliable) with a 3 phase compressor.

Is there a difference in life expectancy and reliability between tri phase and single phase models?

I know someone with an older 3-phase unit that was destroyed during a phase drop, but modern inverter units probably dont have that vulnerability.

[tom66]

Pretty much every heat pump now, even with a single phase input, will be using a three phase compressor because they will use an brushless or induction motor and inverter to drive that motor.  That will probably be immune to losing a phase (will likely cause the unit to shut off though if it has any monitoring of the AC line.)