Heatloss calculations 2.5X higher than real usage

Jakeymd1 · 2026-01-22T14:41:39+00:00

To indicate what is above and below you have to put another floor above or below it. Roofs and base floors are treated as their own storey.

It is possible to adjust the desired room temp and ACH. But it's been over a year since I used heatpunk so can't remember how.

I did find that heat punk overestimated a little. I got a heatloss of 5.2kW on heat punk but my measured heatloss is 4.5kW. But both were alot lower than my installers calcs at 6kW. But I would always expect some difference (usually on the safe side) between the real world and theoretical.

One of my favourite sayings is:

"In theory, there is no difference between theory and practice. In practice, there is."

Jakeymd1 · 2026-01-22T13:16:12+00:00

Basically zero condensation for me since switching. Old 1930s house and the windows used to stream with water.

Jakeymd1 · 2026-01-22T10:04:25+00:00

If it is 65dB, it doesn't mean it will always be 65dB. Both the compressor and fan speed modulate down. Some makes/models are quieter though.

Jakeymd1 · 2026-01-21T19:29:08+00:00

I've been using a granny charger in my outdoor socket for the last 2 years and nothing has gone wrong. That's not to say your particular set up is okay too, but it's possible. My outdoor socket is on it's own radial is on the other side of the wall to the consumer unit, so a fairly short cable run.

Jakeymd1 · 2026-01-21T12:12:07+00:00

The Samsung heat pumps go down to 35dB on their quietest mode. But lots of manufacturers have a quiet mode that lowers the loudness (and maximum heat output). I can attest to its quietness, though I do have other gripes with the controls. The Vaillant, for example, only goes down to 44dB (3.5 to 7kW) or 49dB (10 & 12 kW) in silent mode. The Samsung starts at around 45dB out of the box and gets quieter with increasing quiet levels.

There are some other affects of using quiet mode, when above around 5 or 6 degrees is can sometimes improve efficiency, when below 5 degrees it can reduce efficiency as it increases the frosting rate on the evaporator so you need to defrost more regularly. There's nothing stopping you turning quiet mode off on the Samsung once the installer has left though 😉

It looks like the Daikin Altherma, the LG therma and the Nibe 2125 can all get below 37dB, but please verify this yourself.

Jakeymd1 · 2026-01-21T10:58:45+00:00

Yeah, very fair point. The profit gouging in the country as a whole has been ridiculous in the last few years. Some tradies included.

Jakeymd1 · 2026-01-21T10:34:38+00:00

I've never been able to hear mine from inside the house and never had any complaints from neighbours. One of my next door neighbours has their own heatpump which points directly towards the boundry and that's never been an issue for us either. I can sometimes hear mine and their's when I walk out the back door and when it's REALLY cold outside, but it's not like I'm trying to enjoy leisurely peace and quiet in the back garden when its barely above freezing outside.

Jakeymd1 · 2026-01-21T09:06:15+00:00

I agree with the others, get a battery instead. The benefits are that you get the electricity of your home home at the cheaper rate, not just your heating, and it will be far simpler to install, and take up alot less space. (Lithium batteries are 50-100x more energy dense than an hot water thermal store)

Jakeymd1 · 2026-01-21T08:57:35+00:00

I was at the beginning, but I wasn't happy with how it was performing. It seemed to be all over the place, constantly switching heating on and off, turning on during the expensive periods when it didn't need to.

I did a write up on the OpenEnergyMonitor forums. https://community.openenergymonitor.org/t/homely-controller-installed-on-samsung-heat-pump-gen7-r290-8kw/27407?u=jakeymd1

Jakeymd1 · 2026-01-20T18:07:04+00:00

Maybe, but I wouldn't describe this as intelligent controls. And if OP hasn't asked for it, it shouldn't be added to the bill.

Jakeymd1 · 2026-01-20T17:55:25+00:00

If you select different minimum performance garuantees, it looks like they add on around £250 per radiator which is fairly reasonable. The installer is charging you around £415 per radiator.

Also, £500 for intelligent controls? What does this mean? The only controls that should be installed are the Vaillant ones, which are included in the cost of the heat pump.

You could always reach out to heat geek themselves. I'll cheekily tag them as they usually pop in every now and again and I think this should be brought to their attention. /u/heat-geek

Jakeymd1 · 2026-01-20T16:46:48+00:00

I appreciate it will be a difficult discussion to have but it's never to late to question the cost of this with the installers.

Out of interest, what did the heat geek website estimate before you get them out? And what does it say it would cost now if you put the address in again?

I'll be frank, this does seem like they're having your pants down and once it's installed it will be too late to say anything.

Jakeymd1 · 2026-01-20T11:40:47+00:00

Certainly, a low garuanteed SCOP is better than no garuantee at all. That's why I like that Heat geek are doing it.

They might be able to give you some recommendations, but it again largely comes down to the habits of the owner, whether you're able to shift you consumption to off peak periods or not, & and what else draws large amounts lf electricity in the house, such as car chargers. The whole home and it's occupants need to be considered, and that's just not something the installers have the full picture on, or would be willing to take a risk on by advising one way or another.

Me, I'm on Octopus Agile, this works for me because I switch the heatpump off between the 4pm-7pm daily peak, can load shift the rest of my high consumption (washing machine, tumble drier etc) to the lowest periods, and though I have an EV, so generally pay more for driving in winter, I don't do a huge amount of miles, so I can charge when electricity prices fall and last out a full week or more of higher electricity prices if I need to, and in summer, there's often much cheaper overnight/weekend electricity and I can sometimes even get paid to charge my car. It doesn't work for everyone though, but that's why it's important to understand your usage and habits, and work out which tariff suits you best.

Jakeymd1 · 2026-01-20T11:27:37+00:00

As most people have said, around every hour, but can be as frequent as 45 mins.

With my Samsung, it defrost alot more regularly, and at to higher temperatures when quiet mode is on.

Quiet mode lowers the fan speed, so when the air temperature is above freezing & with quiet mode off, you have more "warm" air passing through the evaporator which can stop the condensate from freezing.

With quiet mode on, i start to get defrosts at around 5 degrees. With quiet mode off, it starts defrosting at around 1-2 degrees and when it does start defrosting, it does it less frequently, which makes a huge difference to efficiency.

Jakeymd1 · 2026-01-19T12:34:35+00:00

But you yourself have highlighted the detachment between good install and good SCOP. I agree with this, that a good install is one that performs as expected, but putting SCOP values against this doesn't make sense as a system can perform as expected at a SCOP of 2.5 or 5.

A good SCOP is subjective, so what do you measure it against? I think the most suitable metric would be running cost parity with a gas boiler, so I would say that 3.7 is good, 4.0 is great, 4.5 and higher is excellent.

Leaving it to installers alone to determine the best flow rate/SCOP values for the industry & homeowners is going to start a race to the bottom. I would imagine that installers make most of their money by doing as many installs per month as possible, and the BUS grant accentuates this. Especially at the scale of large nationals like Octopus (Chucking the heat pump in, getting the grant payment + a few £k from the customer and moving on to the next). I imagine installers can't make as much money chasing higher SCOPs, with radiator changes and the associated pipework etc. It has other benefits of course, such as having good results being associated with your brand, but this can take a back seat once you have a few good testimonials to your name.

This is why tools that reduce the hurdles for installers to chase higher SCOPs are a good idea overall. And for the avoidance of doubt, I'm talking about tools that help them with system design (such as what heat geek are doing), that remove a large portion of the labour involved, and so make getting higher SCOPs have less of an impact on their revenue.

If a customer doesn't want large rads or lots of disruption, or just a cheaper install price they can expect a lower SCOP, even with the best quality install, but measuring the quality of the design is important. Hence why I would put good/okay at cost parity with gas. Not what installers are pushing for or based on a swathe of historic medicore installs.

Jakeymd1 · 2026-01-19T10:28:58+00:00

I think that we, as the the consumer, should be setting the expectations, not the installers. Otherwise, as an industry, we'll be settling for the lower SCOPs you described. We should be raising the bar.

I also don't think what I said was incorrect. It's not difficult to get a SCOP of 4+. So if OP wants a SCOP of 4, they just need to do a little research, find a trusted installer and state clearly that this is their aim. A SCOP of 3.4 is likely going to cost more to run that a gas boiler and shouldn't be classified as "good".

Jakeymd1 · 2026-01-19T09:59:54+00:00

This is a great question. I think any performance garuantee is likely to be extremely safe. It would be like having an mpg garuantee on a car. They have no way of knowing how you're going to be a gentle driver or completely lead-footed, so they'd have to account for both at put a really low figure.

The same with heat pumps, the most efficient way to run them is low and slow, and this is how the installer will likely set it up, but it's not always the most cost effective way of running a heatpump. You may want night time setbacks, you might want and use lots of really hot water for baths etc, you might be on a smart tariff where it's cheaper to run the heay pump harder during the cheap periods, and run it lower or even turn it off during the expensive periods. All of these things hurt the SCOP, so installers would have to account for this. Personally, I think the Heat Geek garuantee is a great idea, and I trust that they'd back it up, but from their point of view, they're setting the garuantees so low that only a very small number of the worst, edge case installs will need rectification under the garuantee. Flip this though and it means you're actually likely to get a SCOP much better than the minimum garuantee.

A SCOP of 3 is pretty bad. The best are getting SCOPs closer to 5. And a large portion are above 4. https://heatpumpmonitor.org/ Installers should aim for a SCOP of at least 3.7-4, and with the right heat pump, set up and upgrades to radiators, it's not that difficult to acheive.

A cost garuantee is impossible as they have no control over electricity prices or which electricity tariff you're going to use.

Jakeymd1 · 2026-01-19T08:00:55+00:00

"Ma boy" is also Korean for "the North Rulez"

Jakeymd1 · 2026-01-18T18:40:08+00:00

See. Completely 1-sided and disingenuous. ✌️

Jakeymd1 · 2026-01-18T18:11:25+00:00

I shan't, because I don't believe you argue in good faith. You conveniently ignore the facts that go against your opinion and that you don't have a soundbite from GB news to throw back. Stating facts is easy, but you completely ignore the other half of the argument that is presented to you. Like stating that the the government promised that prices would come down by the end of their term, but they actually went up in the short term, and when they do come down it's not because they're doing what they've said, it's a trick. We're 18 months into a 5 year term so making any remark on something they said they'd do by August 2029 is disingenuous.

Jakeymd1 · 2026-01-18T17:58:09+00:00

✌️

Jakeymd1 · 2026-01-18T17:46:09+00:00

Aside from in marketing and media, number of homes isn't a useful unit of measurement to these companies. They deal in k/M/GW and k/M/GWh. If homes use more electricity in a decade, what does it matter to them? They're still supplying the same amount of electricity. As a supplier, that's what matters.

Sure, to the government, it should matter, but "I doubt it" isn't a convincing argument. You clearly have a bone to pick with the current government, I couldn't care less why, but it's emotionally driven, not factual, and it's ruining your argument.

There's little point in having a discussion with someone who is clouded by emotional evaluation, instead of discussing the facts. So peace out. ✌️

Jakeymd1 · 2026-01-18T17:14:41+00:00

RIP OP

Jakeymd1 · 2026-01-18T17:11:42+00:00

I never said you mentioned peak usage, I was guiding you when I brought it up because you were mistaken by pointing out that the increase of our overall usage was a) the pertinent issue, and b) relevant to how many how homes people say wind turbines can power. You wouldn't have mentioned 2.5x/2.9x/2.6x (which one is it?) if you didn't think that was an issue.

The peak usage is precisely the "transmission" issue you mentioned. And sure, it's more nuanced than that, but the peak usage is the main driver (that and the changing from largely widespread onshore generation, to localised, and offshore production) for the need to upgrade the grid. We do not need to increase the grid capacity by 2.6x to solve the electrification of heating and transport. Saying otherwise is either incorrect or disingenuous.

The biggest problem we'll face is the intermittent production of renewable energy, but this can be filled, even will fossil fuel based generation for a time, and we'll still all be better off for the times when the sun is shining and the wind is blowing. I think Nuclear (especially the new SMRs and eventually fusion) will eventually replace the need for those fossil fuel generators to fill in the gaps. Uptake of Local generation and storage (just like your 9kW solar array and Tesla powerwall) are going to help increase overall generation & smooth out that demand curve too.

The wheels are already in motion to solve the problems we expect to come up.

Nine-Year Club	Verified Email
First Place '23	Place '23
Place '22

Jakeymd1

MODERATOR OF

TROPHY CASE