With the recent talk of the Vaillant Arotherm 7kW not quite meeting expectations of output versus spec, I had already ruled it out as I suspect my heat loss is somewhere in this region. I am in the early stages of moving to a HP having run the calcs through Heatpunk, I am hovering around the 7kW mark, though this is for relatively low air changes and “normal” room temps - I suspect that with a BUS calc it would come in way over (this might determine whether to go down that road or not)
Anyway, I digress - the Samsung 8kW Gen7 R290 looks like it could be a contender and considering it’s £1k cheaper than the Vaillant, looks good on paper. I am now seeing a handful on heatpump monitor however - does anyone have any other data or experience? Glancing around @SarahH appears to be the Samsung MVP
Thanks I had already been looking around those graphs and noted that on some of the coldest days in Jan most appear to be peaking at “badge” ratings (8.5 - 9kW for very short periods at full chat) rather than averaging those outputs which is essentially what the debate around the Vaillant was if I understood the thread? I guess I’m asking anyone that has one or has installed one whether the reality is matching the specs and if on those -6C days they maintained the inside temps? I’m also curious about idle power when doing nothing - are these glitches in the readings or are they using 200W every now and again for circulation for example? My current “background” use varies from 50W to 350W if nothing is running versus if say the fridge and freezer are both cycling, which also factors into my battery sizing - if a HP starts sucking that up while delivering no heat then that sort of bothers me!
Looking around this forum, it’s clear that pretty much all brands of ASHP struggle to achieve their rated outputs in ‘perfect storm’ UK freezing winter conditions.
I would choose the Vaillant over Samsung; mainly down to the ‘energy integral’ based control algorithm which eliminates short-cycling in warmer weather, the controls/app are superior, and the UK parts and support network actually functions.
But not sure how relevant mine is to your question. I have the 8KW unit but the heat loss tool on HPM suggests my heat loss is more like 4.5kw.
I also used Heatpunk and used realistic room temps and low air changes and it came out to 5.4 KW. My installer calculated 6 KW.
The 200W usage when below freezing is the resistive heater in the base, it turns on occasionally to make sure the condensate doesn’t build up as ice. There is also the occasional firing up of the circulating pump to prevent the water in the pipes from freezing, but this only draws around 60W.
While I’m happy enough with my Samsung, I dont think I could recommend them to friends and family members.
I have a Homely controller, which helps alot by adding an element of load compensation (which the Samsung lacks). The controls for cycling are also frustrating, I have some settings on my controller that help with this, but others don’t have these settings. Your milage may vary.
My installer went on the Samsung training course as he hadn’t done one before, and he’s said he won’t do a other. They’re now stipulating that installers with inline backup heaters in case the unit breaks down and they need to prevent the water from freezing, even if anti freeze valves are fittted. This adds cost and complexity for something that should ultimately never be needed.
I’d recommend the Vaillant, Viessman or Mitsubishi to friends and family. All great units and all compatible with Ovo heat pump plus, which charges 15p/kwh for HP usage. Ive been averaging 20.4p for the last 30 days and because the Homely controller is trying to optimise for the Octopus Cosy tariff, my COP has been lower than others at just 3.19. Though it has been very cold.
Thank you - that is a really helpful set of information which ordinarily I’d have been none-the-wiser to - on reflection what it tells me is that, particularly with HPs, though that has been the case with other things (my £7k waste treatment plant as an example!) is that whilst on paper something may tick the spec boxes, the day-to-day reality may not match the experience unless someone that has first hand experience can share that knowledge!
(Wikipedia: “(MVP) is a version of a product with just enough features to be usable”) Yup, that sounds like me…
When it comes to selecting a heat pump, YMMV (to quote our Leader), depending upon your expectations and requirements, and the relevance of the information available to you for making a decision:
I only have direct experience with the HTQ Series. For a wider perspective on comparative heat pump performance, I would refer you to our CNCc (Chief Number Crunchers) @TrystanLea and @Timbones – few manufacturers have evaded their incisive scrutiny.
HTQs are unusual in that they feature a 2-stage compressor (vapour injection circuit), so any observations I make on controller algorithms may not be relevant to Gen 7s (which I think are single-stage compression).
I’m pretty confident that Samsungs (at least HTQs) will achieve at least nameplate heat duty over the full operating window. A quick glance at the (8kW HTQ) published window…
…shows that Samsung expect at least 8kW at all LWTs and ambient temperatures (apart from below -25degC). Why am I confident? Well 1) the same compressor is used in all HTQ units (8/12/14kW) so at the smaller end there is plenty of spare capacity under the bonnet, and 2) my measurements strongly suggest that this table applies just at synchronous compressor inverter frequency (50Hz), whereas in reality the inverter is quite capable of over 55Hz if the controller requests it – I have often observed heat duties well over 10kW on my 8kW unit, including on cold days – see example below.
Your selection of ASHP may partly depend on how you plan to operate it. Many owners strive for the best possible CoP, and run “low and slow” (compressor trundling along at low speed 24h/day at the lowest LWT consistent with a warm house). Others (like me) look for the minimum operating cost. In my case this seems to be switching the heat pump off for 10h/day (using a large setback), and tolerating a high energy use for an hour or so each morning as the whole system warms up again. I’ve concluded that this is partly down to reduced night-time heat loss, and partly down to compressor efficiency – in my case the BEP occurs at or close to synchronous inverter frequency, and falls off quite significantly at lower compressor speeds, so by running my HTQ flat out for 1-2 hours or two I get a lower energy consumption than running it at 50% speed for 3-4 hours (whilst obtaining the same energy of course).
Unfortunately, so far as I know, none of the heat pump manufacturers publish their compressor performance curves (i.e. head versus throughput for several speeds), so the only way of establishing optimum economics is to reverse engineer them (which is tricky without Outdoor Unit monitoring), or trying different operating strategies and watching what happens at your electricity meter.
I can answer your question about heat output on cold days with a good recent example (10/01/25, when ambient was -5degC min overnight, 0degC max daytime, fairly high humidity – that’s about as bad as it gets, here in balmy Wiltshire). The maximum HTQ output I recorded was 10.6kW when ambient was -2degC, LWT was 47degC, inverter frequency 51Hz, Outdoor Unit power consumption approx 2.7kW). At these temperatures, the Capacity Table above shows 8.0kW duty, 2.8kW energy required, so I seem to have beaten that by some margin. My total household electrical consumption that day (and that’s including electric cooking, appliances, lighting etc., and a defrost cycle – something I rarely see on the HTQ thanks to its economiser circuit) was 34.2kWh – about £7 at my standard tariff. If that’s the worst day of the year, then that’s something I can live with. (It also suggests that it would be difficult to justify much in the way of @glyn.hudson 's OEM kit…)
As to background power consumption, apart from the evaporator fan (around 100W) and circulating pump(s) (maybe 70W each), my Outdoor Unit monitor has entries for (compressor) base heater (which @Jakey notes is 200W when active) and PHE heater (no data on this). I’ve never noticed these heaters showing as operating on the monitor display, but I don’t watch it all the time.
Things I like about the HTQ are:
Wide range of robust and energy-minimising controller algorithms
Flexible controller user inputs
So far (20 months operation) flawless operation
Approachable Samsung Technical Helpline (even if they are constrained from answering some questions probably due the Head Office concerns for their technical assets)
Things I’d worry about:
Operating manuals are hard to understand/interpret without lots of effort
One or two problematic algorithms (like the one that swipes energy from your DHW tank for hourly frost prevention cycles when it’s cold, and the one that only allows the same DHW times every day, even if you only want to heat DHW 2-3 times each week)
Other makers publish lots more operating data than Samsung
Small user base, so lots more forum expertise with other makes
In summary, if you do go for a Samsung, and if (like me) you are cursed with an enquiring mind, you should be prepared to sometimes feel like the man who, with eyes tight closed and fingers in his ears, is gingerly stepping across a minefield…
I was thinking Most Valuable Player rather than Minimum Viable Product
A lot to take in there - thank you - I will digest all of that - eek!
Finding an installer who is also on the same page of my inquisitive need to control everything is also a factor - I’ve had a couple go “radio silent” on me the moment I mentioned I’ve started running the calcs into Heatpunk - one wants £350+VAT to do a survey before taking it off the cost of the install - I am inclined to go self-install at this rate…
I chose a wonderful installer (by chance), but when after commissioning I asked about controller settings, he replied “Ah yes - FSVs. I’ve set them all up, so you won’t ever need to touch them”.
I still wonder whether my wearing a skirt and heels may have influenced his response …
Good luck with your research - let us know what you choose, and why .
I’ve not been particularly impressed with the data I’ve seen from Gen 7 systems, my Gen 6 works well but Vaillant units are much easier to control and setup. The Samsung controller and software algorithms are not nearly as good as Vaillant. If sized correctly Vaillants are very good heat pumps. Samsung systems can work well, but almost never do out of the box.
I have first hand experience of installing and living with both Samsung and Vaillant systems.
Mine’s the Gen 7 installed in Margate. It performs well when the temperature is >5C but performance drops significantly in the 1-3C band with a defrost sometimes every 45 minutes.
I installed in in early November and the monitoring started to work in early December. Up until Christmas it had an SPF of 4.6 and then it really dropped with the near freezing temperatures. The Vaillant heat pumps appear to have performed much better in the -3C to 3C temperature band.
I plan to install a Homely, but I haven’t got around to it yet and I think it might be good to leave it running on the Samsung controls for this winter, so that I can compare the Homely next year against the Samsung baseline.
We are currently installing a 5kw Vaillant on another job and we’ll monitor that, so it will be interesting to see how that compares.
Thank you @glyn.hudson and @Henry_Pelly - again all very useful first hand experience being shared.
I haven’t had much more time this week to delve deeper - a quick search of R290 units of a similar spec and the Mitsubishi isn’t that widely available, nor can I find much useful data. Midea was another contender so I emailed them a sales guys wanted to “pass my details to a partner” to which I said “no” just share the details with me - no answer.
The other one I found was by Grant - they now do an Aerona R290 and their documentation looks pretty good - there are also a couple of systems on HPM, but I couldn’t find any details on where to actually buy one** or the pricing*! I have a feeling they work directly with installers only…which bothers me too as it’s far from transparent IMO.
Ergh, I hate stuff like this sometimes, especially when it’s a significant investment of money and time - but on the other hand it’s a immense learning experience
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