@derek-m I have absolutely no way of knowing without the manual. I can only assume weather compensation has been set up. I don’t want to mess with it as is unfamiliar to me.

@kev-m I suppose that’s a fair point.

@editor that’s disappointing. If the case then I suppose it’s trying to make the best of what she has been given.

@bontwoody, she could pursue other avenues. They will be time consuming and probably massively frustrating, and if she’s lucky would result in a smaller pump being fitted.

@editor thanks Mars. I’ve pointed her to this page so she can ask you directly if she wants to try. 

I’ve also emailed you about a potential heat pump review. 

regards Mark

@bontwoody clearly it doesn't sound like any optimisation , handover or proper control setup has been done. and if its not being monitored nobody will know what its actually doing. That surely needs to be priority #1 that she should insist that this company does, immediately.

At least, with your local knowledge, you've been able to help at an early stage so hopefully it'll not run at high cost for too long.

@editor the issue as you say with the big units is how much input power does it drop by when output power reduces. on the big units the "fixed cost" doesn't drop off as much so it ends up not being worth running lower as the input power still says high. Then its all about how much over the house minimum heat loss the heat pump minimum sensible output is, how does it behave when cycling etc. 

what the options are: have a read of some of the discussions on openenergymonitor with respect to 9kw daikins (which are a de-rated 16, so the down modulation behaviour is that of a 16). there are documented cases now of octopus having put in a 9 based on overestimated property heat loss, the owner proving awful performance in mild weather, and then octopus swapping it for an 8 (which is a whole physical size smaller so modulates down a lot lower).

there's one Acond N user on HPM , check the stats, it's producing over 6kw regularly. Its low point on mild days (that I can find) is not as low as the plated number. Of course I don't know how its being controlled though. might be worth asking them?

@iancalderbank I saw that Acond user on the site but couldn’t see a way of contacting them unfortunately. I think it would be useful

@bontwoody one of my "feature requests" for HPM, a way to get from system to person. some want anonymised of course but most are open. however if you search the forum you will find this I think thats the owner.

@iancalderbank Thanks thats really useful

I have now had a reply from the company regarding my questions of the sizing of the heat pump. I think there answers are incorrect and would appreciate some second opinions on my answers. Thanks in advance:

Thank you for this information. Just to be clear my concerns are to do with the correct sizing, installation and handover of the system. Running costs while being of primary concern to Helen **** are a consequence of the other decisions made and are not part of my questions. However enabling her to be able to schedule when the heat pump is active would obviously impact them greatly, therefore a comprehensive handover is long overdue.

Any criticisms I make will be based on empirical data and Helen’s customer experience.

Something that I have not been able to find yet in your documentation is the value of the design flow temperature at -3°C. I would be grateful if you would state what this value is. I am assuming that it will lie between 35 and 55 °C, which luckily are the two lines on the graphs you have supplied.

Sizing

“To deliver the building heat load calculated at 5.8Kw plus the anticipated 1.2kw for the additional room which has long external walls and no heated space above requires 7kw at -3°.”

The 1.2 kW heat load for the possible (not certain) extension is a maximum figure and could be as low as 600W depending on construction. Therefore the total heat load is between 6.4 kW and 7 kW at -3C

“The smaller Pro N unit maximum capacity at -3° is less than 5Kw.”

Looking at the PRO-N graph you supplied, at an outdoor temperature of -3°C the range of Heating Capacity is between 6.8kW (at 35°C flow) and 6.2kW (at 55°C flow). Why do you assert its maximum capacity is 5 kW?

“The output range of the installed Pro R unit is 3.1Kw -18.2Kw, at the design flow temperature at -3° maximum output is 9Kw.”

Looking at the PRO-R graph you supplied, at an outdoor temperature of -3°C the range of Heating Capacity is between 14.7kW (at 35°C flow) and 13.2kW (at 55°C flow). Far in excess of your assertion of 9kW and far in excess of the heating demands of the property.

So in summary this does not answer my questions as to your choice of heat pump. In my view you should have selected a heat pump with a more appropriate output at the flow temperature you have designed the system for and not just inserted the next size up that you happen to have in stock.

Given Helen’s repeated pleas that she prefers rooms cool (18°C), the revised output of the PRO-N and the closeness of its output to the buildings requirements even with the possible extension, I believe the PRO-N would have been a much better choice.

Installation

As per my initial comments in a previous email, I believe the pipe insulation to be substandard on the pipe joints. I also think the siting of the heat pump to be sub-optimal in its distance from the house. This is I believe a consequence of erroneously selecting the much larger heat pump model. Again selecting the PRO-N model would have improved the position of the heat pump close to the house.

Handover

Helen has been given no proper instruction, or manual as to how to use her heat pump. She was warned to leave it on 24/7 and believed in fact that it could not be turned off. Consequently her running costs are very high. At this time no date has been arranged for her to have this handover. While I understand that you prefer to wait until an internet connection is made it would have at least been possible for her to turn it off at the wall control unit had she had some basic instruction.

@derek-m

@kev-m 

@iancalderbank

if you have time could you please look at my reply in the post above and give me your opinions. Either I've got this totally wrong or they have or they are being deceitful. Thank you Mark

Posted by: @bontwoody

↑

@derek-m

@kev-m 

@iancalderbank

if you have time could you please look at my reply in the post above and give me your opinions. Either I've got this totally wrong or they have or they are being deceitful. Thank you Mark

Based upon the available information, I would say your assessment looks to be correct.

One thing that I learned many years ago is that people can make their mouths say whatever they wish. 😋