What is the next step for HeatpumpMonitor?

Hardware Heatpump
1

@glyn.hudson and I are thinking through the next steps for HeatpumpMonitor.org and without prompting too much based on our own thoughts, we wanted to just ask on here first what are others thoughts on where we are with the project at this point, just over 3 1/2 years after @Timbones helped us launch the site back in November 2022 Introducing HeatpumpMonitor.org - a public dashboard of heat pump performance.

How do we best support heat pump adoption over the next few years?

What are the interesting questions?

How did you last use HeatpumpMonitor.org and what was the most useful thing you gained from it?

Perhaps the answer is also different from the perspective of installers and home owners.

Reflections and suggestions welcome!

2

Might it be possible to include features which encourage more monitoring of air-to-air heat pump installations?

No doubt the current heatwave - and the expectation of similar or worse heatwaves in the future - will lead to increased installations of ‘air conditioning’ systems.

In some ways this increased take-up could be considered A Good Thing, since these are still ‘heat pumps’ and can be used for (supplementary?) heating in cold weather - and I’m not hearing anyone claim that “air conditioning doesn’t work” so one outcome might be increased confidence in heat pump technology.

However, if there are a lot of poor-quality installations of poor-quality devices, that might lead to reduced confidence in heat pumps - or at least in the affordability of their running costs.

The recent thread started by @SarahH highlighted that we don’t have much real-world data for air-to-air systems, so it’s difficult to weigh up the pros and cons of the various options.

Questions it would be great to be able to answer include:

  • Are the ‘premium’ brands worth the extra cost, especially if systems are only used for a few weeks a year (and so efficiency and reliability are not as critical)?
    • For example, are the controllers in the premium systems ‘better’?
  • Is it preferable to have one External unit driving multiple Internal units, or to have Internal and External units paired 1:1 (typically leading to multiple External units being required)?
  • How does the efficiency in Heating mode compare with the efficiency in Cooling mode?
  • Is performance maintained over the life of the installation?
    • For example, is on-site-terminated refrigerant pipework more prone to leaks than the factory-terminated pipework in air-to-water heat pumps?
  • If someone has both an air-to-water heat pump (for heating and hot water) and an air-to-air heat pump (for ‘air conditioning’), what are the pros and cons of using either or both systems for heating?
    • Are there implications for right-sizing an air-to-water heat pump if there’s also an air-to-air heat pump available for supplementary heating?

I guess the big challenge is metering the heat output from these systems, since it’s not simply a case of fitting a third-party heat meter.

3

Thanks @dMb, that’s a good idea, @John_Ewbank has been doing good work on air-2-air monitoring that could contribute to this:

4

Are the ‘premium’ brands worth the extra cost, especially if systems are only used for a few weeks a year, meaning efficiency and reliability are not as critical?

Well, that depends. Most brands have different product ranges. For example, Panasonic has low-end, mid-range, and high-end models, but their high-end range has issues with temperature sensor location and modulation. So a high-end Panasonic unit is not necessarily great.

Conversely, Mitsubishi’s high-end MSZ-LN range has excellent temperature modulation, and the 3.5 kW unit can modulate very well. The 2.5 kW unit is less good in this respect, it has a different compressor and can’t modulate as low.

Many units have issues hitting the heating setpoint because the temperature sensor is often located in the internal head. Sometimes it is in the intake airstream, such as with Panasonic, which can cause issues.

I would always advise getting a unit that either allows for an optional wall-mounted controller with an inbuilt temperature sensor, or can operate with an external temperature sensor. Not all wall-mounted controllers have sensors in them.

All Midea units have a “follow me” function, which uses the temperature sensor embedded in the remote control. Most other brands do not have that. So Midea is a cheaper brand with a useful bit of technology.

For example, are the controllers in the premium systems ‘better’?

For the most part, yes: they operate better, but this is not true of all premium units. The unit most people seem most satisfied with is the Daikin Stylish, which is also one of the more expensive units.

I have no idea about LG or Fujitsu units. They are popular for cooling and cheap, but does that make them good for heating? I don’t know.

Is it preferable to have one external unit driving multiple internal units, or to have internal and external units paired 1:1, typically leading to multiple external units being required?

It depends what you are trying to achieve, and on the modulation of the multi-split or single-split system. Cost-wise, it will probably be similar.

How does the efficiency in heating mode compare with the efficiency in cooling mode?

From the unit I monitor, heating efficiency looks pretty good, at around a SCOP of 4.

The SCOP figures on the datasheets are not particularly accurate from what I’m told. The manufacturers can game the test by running at high fan speeds, so if you get a budget unit with a small heat exchanger the SCOP will be worse than what is listed.

It is a bit different from A2W in the respect that with A2W you can upgrade the emitters to get great results, with A2A you can boost the fan speed on your unit which might be noisy.

I’m part of a team putting a unit into the Salford Energy House soon, so that should provide more answers on this.

Is performance maintained over the life of the installation?

Yes, as long as you keep the heat exchangers clean.

For example, is on-site-terminated refrigerant pipework more prone to leaks than the factory-terminated pipework in air-to-water heat pumps?

It does not appear so. Sometimes you can get leaks, but these are relatively uncommon when the work is done by people who know what they are doing.

If someone has both an air-to-water heat pump for heating and hot water, and an air-to-air heat pump for air conditioning, what are the pros and cons of using either or both systems for heating?

I think they should be used together to help lower the flow temperature for the air-to-water heat pump, but the controls for this are not really there yet.

Are there implications for right-sizing an air-to-water heat pump if there is also an air-to-air heat pump available for supplementary heating?

You could undersize your air-to-water heat pump. My main idea was that you could avoid radiator upgrades. For example, if you are marginal on radiator output with an air-to-water heat pump, you could use air-to-air in some rooms to supplement the heat.

There are not good controls for doing this at the moment, so it is something you would have to figure out.

5

Thanks @John_Ewbank

Looking forward to seeing the results of this!

6

Thanks John (and thanks Trystan for looping John into this thread and posting those links to John’s existing posts).

I’ve had a NIBE GSHP heating my House since it was built in 2016 but last year I had a Daikin multi-split air-to-air system installed into a new, separate Workshop building. The Workshop doesn’t need stored hot water and is used intermittently (and unpredictably) so air-to-air was the obvious choice for heating - with the ability to deliver cooling too being a free bonus.

I’ve got an M-Bus electricity meter on the supply to the Outdoor unit but so far I’ve not looked at any further monitoring (apart from logging room temperatures). I’d not considered correlating Energy Consumption with Degree Hours but your “What uses more Electricity… ?” post shows even that can provide useful insight without adding further instrumentation to the system.

Your replies to my questions confirm that if we had a good range of air-to-air systems reporting into heatpumpmonitor we’d be better placed to understand how well manufacturers’ datasheets compare with real-world operating conditions and some of the pros and cons of different makes and models.

7

I use the ‘Visit A Heat Pump’ website, aiming to assist others in making the heat pump transition. For folk who seem more technically aware I introduce the Heat Pump Monitor website, pointing out heat pumps installed in properties just like theirs. Hoping to build confidence. But for a newbie / non-techie, the site is a bit daunting. The ‘System View’ page is useful ie. the property summary. I wonder this page could hold / link to some form of ‘user story’, something that makes that households heat pump experience come to life ? Humans like stories :slightly_smiling_face:

8

Thanks @SteveW

Agreed

I like that idea!

9

Would be interested to hear what people here think of the following, do you agree with this assessment?

  1. We have now for sometime succeeded in a key original goal of HeatpumpMonitor.org which was to highlight that well designed, installed and commissioned heat pump systems can deliver much better performance in terms of SCOP/SPF than historic trials.

  2. A second goal to find the state of the art in terms of performance has also I think largely been achieved. We know the best air source systems can just edge over an SPF H4 of 5.0 and the best ground source systems around 6.0.

  3. When we assess the reason for lower performance in historic trials such as Electrification of Heat, these were not for the most part low disruption installations that balanced capex against opex, they were often relatively expensive and included radiator, pipework and cylinder upgrades. They also used the same generation of heat pumps that show much better performance in the HeatpumpMonitor.org dataset. The clearest reason from looking at the detailed monitoring data from these systems was a lack of control optimisation - likely made more challenging by over-complicated system designs: buffers, poorly balanced low loss headers, zoning, 3rd party stats and excessive over-sizing (~2-3x vs accurate heatloss).

  4. The principles of good system design are now more widely understood:

    • Keep things simple with open loop designs where applicable (this both helps reduce installation cost and helps improve performance - avoided distortion and extra pumping power).
    • Avoid excessive over-sizing (e.g 2-3x) with accurate heat loss calculations (in particular realistic air change rates) - while taking into account real world max outputs, re-badged units and available modulation range.
    • Control settings optimisation (e.g tuning of weather compensation to reflect actual heat loss or use of automatic optimsation e.g havenwise, homely).

  5. When these principles are applied it’s possible to get the best performance for a given design flow temperature, whether that’s a very low temperature system at 35-40C hitting SPF 4+ or an install that re-uses existing radiators and cylinders at higher design flow temperatures 50-55C with SPF 3-4. Even the low disruption high temperature installs are beating the lower performance results from the earlier trials - thanks to simple design and optimised control.

  6. Solving the issue of over-inflated heat loss calculations together with the wider temperature range of R290 heat pumps has opened up a much wider range of existing systems to low disruption installations - this is what makes the various zero/low disrupt models possible (e.g the approach being championed more recently by Heat Geek). From a heat decarbonisation perspective this shift helps address two large barriers to adoption: upfront cost and the level of disruption, reducing those helps more people adopt heat pumps.

So I think the interesting question now is not necessarily how we can get the best performance in an absolute sense, but how we get the right balance between upfront cost and running costs and make the most of the chosen level of disruption and resulting design flow temp in retrofit installations. This also ties in of course to co-benefits with tariffs and home solar and batteries.

Practically for HeatpumpMonitor.org I think this means moving away from the current front page which opens straight on the Top of the Scops leader-board view toward a more varied front page that is more focused on answering this question of balancing upfront cost and running cost, highlighting a wider range of what is possible: systems that achieve both maximum optimisation on particular tariffs and standard levels of optimisation, systems which perform well on a whole lifetime system cost basis alongside SPF performance alone.

It would be great to get more data the installation cost of systems on HeatpumpMonitor, we could also encourage submission of systems and highlight those systems that do focus more on the lower capex side of the equation or focus more on time of use optimisation or co-benefit with solar and batteries.

It would also be good to consider what the impact is of changes to the spark gap over time (favourable or not) and the impact on system longevity if the race to lower capex results in corners being cut that result in lower system water quality and therefore earlier than otherwise replacement.

The un-subsidised economics of air-to-water heat pump retrofits in the UK is very challenging (e.g What are the co-benefits of Solar, Battery, HP, EV, Tariff? - #41 by TrystanLea) whichever way you look at it and adoption is still much lower than where it needs to be for heat decarbonisation despite the currently generous subsidy levels. Perhaps this is where alternatives such as air-2-air comes in, perhaps bought initially for summer cooling in heat waves but then used to reduce gas consumption in a hybrid configuration in the winter too.

Anyway, that post got a bit longer than I intended. Reflections welcome. Is this a broadly accurate assessment? What have I missed?

10

Nice summary, @TrystanLea.

I think your point about reversible A2A supplementary heating (echoed recently by @dMb) is well made. Knowing what I know now, and with ever hotter summers, I would probably have bought a smaller A2W base-load HP for winter heating than I did, but added an A2A split unit to boost the heating in the critical room - the living room - and (in reverse) cooling the living room - and maybe others - during heat waves. The supplemental A2A heating would also have partially overcome my living room radiator limits (already as large as practically/aesthetically possible).

I don’t recall much discussion about the potential benefits of split A2A for supplementary heating (and cooling if required) in the OEM introductory material for beginners - maybe we should consider a guidance paper, maybe from the “new user learnings” perpsective as suggested by @SteveW?

11

Thanks @SarahH that’s a great point about using A2A as a hybrid with A2W! Perhaps there is also a route where households move first to A2A hybrid with a gas boiler and then swap out the boiler for an A2W later. The other option for cooling of course is to do cooling with a hydronic fan coil on a single A2W..

12

For sure, but they’d have to be patient. My local A2A installer just told me that he’s getting 200+ enquiries PER DAY for split unit ACs, and he’s not even compiling any new quotations for the next 3 months. If I was a few decades younger I would be enrolling for F-gas certification training - then setting up my A2A installation business - right now!

13

Some more thoughts on how the HPM website might assist someone transition to a heat pump. I’m thinking of someone who is around Early Adopter->Early Majority, focusing on their need to build confidence, that a heat pump will work for them in their property … an acceptable level of cost, time, disruption, learning/complexity. These needs could be addressed with quantitive and qualitative data.

Mr Early uses a new HPM feature which lists nearby properties and/or properties like his … e.g. within 100 miles of , ,

For the properties returned Mr Early can see, for example,

- Property detail : Semi-detached, insulation level, Age, other

- Prior Heating System : Condensing Gas Combi

- Installation summary: heat pump type/size, 4 rad changes, new cylinder, no pipework, 3 day install, householder comments

- Installation cost:

- Running cost: using a standard eg. 25p rate

- Living with the system: householder comment. Comfort eg. ‘Constant, even temperature, more comfortable than gas heating’. Operating eg. ‘We chose Havenwise which makes running the hp easy’

Getting this data maybe a challenge but I imagine that behind all those SPF > 3.x installs on HPM are lots of happy heat pump owners who could convey a very positive picture.

14

Just in time to not need f gas anymore :sweat_smile: .

15

Could you do domestic hot water leg as the cheaper entry point.

Stick-on DHW cylinder monitoring kit (flow temp at coil in/out, just two cheap surface thermistors, no flow meter at all, using known cylinder volume and a temp-rise integral) should be good enough to estimate DHW-only COP, which is a much lower barrier to entry than full system monitoring and would dramatically widen the funnel of people contributing some data rather than none?

16

The gas team, the boiler manufacturers protecting forty years of installed base, the columnists who’ve never read a SCOP figure in their life they have not been debating heat pumps. They have been working them over, and we have been responding with politeness.

Heat pumps wont be adopted by being right. Being right was never going to be enough, because being right quietly loses to being wrong loudly, every single time.

So get loud! The data is real, its right there, and it is the one thing they cant make up. Every dodgy installer hiding a bad commission, every tabloid running a £4,000-bill story from a system that was never set up properly, every gas line about heat pumps not working in this country all of it goes away the moment it meets a verifiable, individually attributable, public number. So stop being polite!

Make comparison data shareable, competitive, and a little bit ruthless, because FOMO has built more behaviour change in a year than ten years of patient public information.

IMO heat pumps are the only side in this playing nice.

17

Trystan, Good Evening.

I have the money and have several times entered your web site and thought: OK I’m just going to order up a system and get going. But I have found the technical language used incomprehensible. I find I have no idea what I need to monitor my system and I leave with the message: this is not for you!

I am modestly technically competent (PhD in experimental physics: 40 years experience in a lab: and I am still a world-leading expert in temperature measurement) but every time I have tried to go shopping on your site I have left defeated.

What might be the next step for heat pump monitor? Make it easier to select a package of products that will achieve a particular end that a customer might be interested in. .

Best wishes

Michael

18

@Swwils love that! haha definitely something I could learn from there!

@MdeP the Michael de Podesta (https://protonsforbreakfast.wordpress.com/) good to hear from you again and thanks for your reflections on this! For you what was the end that you were interested in - or might still be interested in?

19

Seconded. (and did this…but not the next step on account of the city wanting to compulsory purchase my house and bulldoze it…)

Aside from cooling a nice thing about the a2a units is that unlike a2w on radiators, where you have this horrible dynamic of the radiator temperatures wanting to go through the roof just as the outdoor temperatures drop, the a2a units typically keep a modest coil temperature and crank up the fan to increase the power output of the indoor units.

They also have a higher COP in very mild heating conditions as you’re doing a lot less shoving around of water etc.

Using this as a band-aid to get away with smaller heat pumps would be good.

Caveats?

Planning Taxes

The MCS “union” has been granted a monopoly* on permitted development for A2W heat pumps in the UK by DESNZ. If you install an a2a unit first then you’ve used up your “one” outdoor unit and can no longer install an A2W heat pump under permitted development. You’ll have to pay far more in “planning tax” than the a2a was worth.

*In addition to ensuring that only MCS contractors can install heat pumps under permitted development; DESNZ actively stepped in to actively prevent commercial competition from Flexi-Orb in 2025 by blocking them from all Clean Heat subsidies such as BUS. David Capper was the Senior Responsible Officer personally accountable for having made both the decision to permit MCS a monopoly on Permitted Development AND the decision to ban Flexi Orb from all Clean Heat subsidies on the back of a couple of meetings with his buddies from MCS (public record) and the justification that in principle it was possible to offer even worse consumer protection than MCS does and nobody else should be permitted to try this.

Stratification

For heating you want the head downstairs in the living room. For cooling you want it upstairs in the bedrooms or at least on the landing. Bungalows are easy. Houses are harder to make the “but it does heating and cooling in a single unit” argument.

Hot Water / Dehumidification

Air to (hot water) cylinders are worthy of more attention. Many newer UK houses are rarely properly ventilated. Ventilating properly and recovering the heat from exhaust air is arguably a good thing. Having the option to flip the exhaust into “recirculate AND dehumidify” mode for a cylinder in an upstairs location is a real bonus. The dehumidification is the biggest win for AC. Our AC gets set to 24C and “dry” mode when it’s hot and sticky out. 24C and dry is perfectly pleasant. 23C and dry is chilly!

Trades

There are the Open Energy Monitor/ Heat Geek type installers. Then there are all the other monkeys. Monkeys can install water based heating systems; use the appearance of wet patches to identify leaks; rely on cleanable strainers to catch all of the dirt and swarf that are introduced when installing the unit. Pull the same tricks with refrigerant based systems and they’ll be forever kinking lines / leaking flares / introducing muck into systems that are not tolerant of this and will fail as a consequence.

Theft

Scrap copper is up at €10k/tonne these days. Sanctions for criminality are not meaningful. Put expensive, very readily man-carryable, things outside in less affluent areas and they’ll walk a lot more often than heat pumps currently do.

Parting Thought
Bungalows - get installing splits and a2w cylinders yesterday.

General purpose cooling - I think high quality portable splits / window units probably have their place for reasons of being installable by monkeys / safely stashable when not in use / bring movable to your next rental / not being a permanent installation that attracts “paperwork taxes / union barrier” the same way that others do / not needing variations to leases that the flats who suffer the most from overheating will be plagued with if wanting a proper split.

20

Thanks @SteveW these are great ideas and I agree is probably the right way to go on the front page. An easier way of finding the type of systems that most interest the visitor.