Agreed, I want to create specific info pages on each heatpump make and model and work out a way to pull in datasheet heat pump capacity data into that. Given that the badge does not usually reflect the actual capacity.
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Yes sure, will add that in!
Wouldn’t it be useful if there were an organisation that certified heat pumps; including the capacities at various outdoor/indoor conditions in addition to an estimated sCOP for a particular climate zone; and made that readily available to all and sundry.
You could run it as a nonprofit and call it a certification scheme.
Perhaps it could even fund projects to establish what the heat losses of buildings really were and provide other such design guidance to assist people deploying heat pumps.
Perhaps only give grant funding for heat pumps with true and certified performance figures; installed in line with that sizing guidance?
Naaah. Stupid idea. It’ll never catch on.
Give all the money to a self serving cabal and leave it to the enthusiasts to pick up the pieces afterwards. 
This is a great piece of work @TrystanLea. I always used to joke that MCS used the heat losses with the ruddy windows open… without realising that this was quite literally true!
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it does feel like we’re missing something important in this industry. There’s an opportunity for more of a research and evidence driven rapid feedback loop to design, specification and guidance. The passivhaus institute seem to have been quite successful in this regard in the building fabric space with a successful system for quality control, product certification, high quality design tool etc.
I won’t pretend to know a lot about what goes on in certification bodies, I need to learn more on that topic and we should probably keep this thread to the topic of heatpump monitor development 
Sorry - will keep on topic
I think I replied to the wrong thread too (that was meant for the CO2 thread)
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Work in progress: An improved measured heat demand tool intended for exploring the question of over-sizing and impact or lack thereof on performance (I will do another post on this soon).
- Work out measured heat loss (or really heat demand as it included DHW demand).
- Auto fit line of best fit, manually adjust as required
- New datasheet max heat output for heat pump field available in the main form (I’ve entered all the Vaillant datasheet capacities so far)
- Hover over datapoints on chart to see more information about each data point.
https://heatpumpmonitor.org/heatloss?id=46
This tool can be accessed from system view page:
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A good example of a high performing Vaillant which is arguably oversized, but without a performance penalty?:
https://heatpumpmonitor.org/heatloss?id=139
not that it would have made sense to select a smaller vaillant, given that the 3.5 kW unit has the same compressor as the 5kW…
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Can Compare button be added to the system page, which automatically selects it, allowing users to add another system to compare to it?
Maybe the Histogram page too.
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Maybe once I’ve recovered from the work involved in building the above 
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‘Oversize’ may become more common as the heating requirement becomes a smaller portion of the demand, due to warmer weather and/or better building fabric. I sized our unit (5KW) on the time taken to (re)heat a tank of hot water (without an additional immersion heater) -that being the larger of the two demands. Based just on the heat requirements we could have gone a size down. The cycling, as we have come in to the shoulder months has noticeably impacted the efficiency, but it may also have had the same effect on the smaller unit (as both have the same minimum continuous power output). A small gain in the DHW efficiency may outweigh a slight loss in space heating efficiency…
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I’ve added the links to the other tools and improved the performance on mobile of the new heat demand tool.
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Looks really good Trystan.
I’ve tried this on my heat pump (Farnham, Surrey, Daikin Altherma, 11kw) which I know is very oversized. But I don’t get any data. Does it require me to add some extra details somewhere? I couldn’t work it out.
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The heat loss tool requires room temperature data
Thanks Glyn. Obvious when you say it.
I don’t have internal temperature sensors logged in the system. Can I add a time-series in manually to make this work?
My house is always within 0.5C of 20.5C, so I could just put in a record of 20.5C or it would be handy to have an over-ride in the tool to be able to add a fixed room temperature? I get the purest view that it’s a bit of a bodge, but someone estimating their heat loss they would have a good idea whether temperature in their own property has been maintained 24/7.
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Yes good idea, I will add this in.
Another minor update to the tool, it’s now possible to edit capacity figures that set the lines on the graph directly in the tool rather than having to switch between the form and the tool.
I’ve also added an option to provide a ‘max capacity test result’ which may be different from ‘datasheet capacity’. E.g @ColinS’s 11kW Daikin which we believe can’t reliably deliver more than 7.8 kW during heavy defrost conditions, having the option to include this line illustrates that the data sheet values are in question at least. (Link to data: ASHP sizing for Freezing Conditions - #63 by TrystanLea)
Ultimately I’d like to move test results like this to a heatpump make/model specific page, with a link to the period under which the test was performed so that those interested can double check the test.
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The max capacity test result line should probably be called ‘Be careful designing for accurate heat loss above this line’.
Interestingly the East Midlands 11kW Daikin Altherma 3 gave 10.35 kW over ~6 hours at -4.8C outside here and it doesnt look maxed out… and the COP doesnt look low enough for a booster heater to be on?? interesting result @ColinS
https://emoncms.org/app/view?name=Altherma&readkey=dfb6fbf82b5eb4f396ba1e8acb146d66&mode=power&start=1705541700&end=1705564785&cool=1
Or 10 kW over 3 hours here at -2.5C https://emoncms.org/app/view?name=Altherma&readkey=dfb6fbf82b5eb4f396ba1e8acb146d66&mode=power&start=1705628330&end=1705639070&cop=1&carnot=0.441
Hi Trystan,
That 11kW Daikin is not an Altherma 3 Monobloc like Colin’s.
It is a hydro split system.
They can’t be compared to each other like that?
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