ASHP to Avoid from October 2022

No_No_No_Yes

Hello everyone, this is my first post here.

I am applying for a new ASHP under the Green Home Grant (UK) and wondered what brands to avoid.

If you have a new ASHP installed recently under the grant, do you have a say in what it will be installed?  Including HW cylinder and possible radiators too.

Does the installer just fit whatever he/she feels is OK or right for the property?.
The big worry is that the installation won't be ideal for the type of property.  Would I get to see the surveyor's report?

Thanks in advance for your reply.

Spoonie_Turtle

I'm afraid I can't actually answer any of your questions, but whatever model is recommended (or if you're given a choice between any), do a search to see what their realistic vampire load is.

Last month I discovered ours apparently uses 1-2kWh/day 'for heating' when there's literally no heating on, 0kWh output … 50kWh it says it used in August, flipping August with an actual heatwave (I am still cheesed off).  We had no choice in it at all - Housing Association - but now I know to keep an eye on it and maybe even turn it off altogether in summer, only turning it on for a few hours for hot water every couple of days.

What's your current heating/hot water setup?

shinytop

No_No_No_Yes said:

Hello everyone, this is my first post here.

I am applying for a new ASHP under the Green Home Grant (UK) and wondered what brands to avoid.

If you have a new ASHP installed recently under the grant, do you have a say in what it will be installed?  Including HW cylinder and possible radiators too.

Does the installer just fit whatever he/she feels is OK or right for the property?.
The big worry is that the installation won't be ideal for the type of property.  Would I get to see the surveyor's report?

Thanks in advance for your reply.

Getting a good ASHP setup is mostly about design, not brand.  It's far, far more important to use a good designer and installer who designs a system for your house and needs.  Like cars nowadays, the main brands are all good; there are no real lemons.  

Which brand you get will be influenced by which designer/installer you choose due to experience, whether they are partners with any suppliers and also what is available. You can ask for a specific brand but you might not get it.

If you go ahead with a company you can definitely see the report/heat loss calculation/design as it's part of what you are paying for.  Most companies will ask you to pay for this if you don't go ahead though; it's a lot of work for them.   

Reed_Richards

I have a heat pump (LG) and spend time reading about them.  I'm not aware of any manufacturer with a really bad reputation.  Some models have a "vampire load", as explained by @Spoonie_Turtle and that's probably worth trying to avoid as other models don't and don't seem to suffer at all as a consequence.  Almost all heat pumps these days have Weather Compensation, which helps you run the heat pump more economically, but it's worth verifying that your proposed heat pump has this feature.  And i agree with @shinytop that design is really important.

No_No_No_Yes

Sorry for the late reply... I never got notification for the above posts and just found out about it because I logged back in.

The surveyor report states a 10 KWH Midea pump, not sure if it has the "vampire load" or how bad it will be.
I have read the report and I can see issues with it.  It mention for a kitchen radiator to be fitted but the only place that can a source of heating can be located it would be under the base unit, on the skirting section.  there is a heating device that can be installed on the CH pipes and a small fan built in can dissipate the heat, but the installer refuses to install that under the grant.

Then I discovered that the pipework run from the monoblock pump to the HW cylinder is at least 17m and not 10m as per surveyor's measurements.  Then the location of pump would have the pipework run across my side gate and the installer again refuses to put the pipework underground (this would be not more than 3m run).  I assumed that he would be be digging a soak-away under the pump location, if that's the case then it wouldn't be much work for burying the 2 pipes so to clear the gate's opening. 

It feels like the installer is not that interested on the job.  I asked to come to the property to discuss the system and installation but has yet, he has not agreed a he has been too busy.    Not a good start for sure.  I am too worried about the system under-performing.  The heat loss data shows that the system would perform at a scop of 3.86 at a temperature of -2C.  Is this good?

Now, back on finding out how to get notifications from this forum.

Reed_Richards

No_No_No_Yes said:

The heat loss data shows that the system would perform at a scop of 3.86 at a temperature of -2C.  Is this good?

SCOP is Seasonal Coefficient of Performance, so it's a sort of average for the year not related to any particular outside temperature.  My heat pump, installed two years ago, was sized to provide sufficient heat at -4.7 C outside, a temperature that was calculated to be exceeded 99.6% of the time; could that be where your -2 C comes from?

The SCOP will depend heavily on the maximum output water temperature for heating that your heat pump is specified to use.  Without knowing what temperature that is it is impossible to say if 3.86 is good or bad.  

Spoonie_Turtle

Our COP has never reached 3, but then we had no say in the process (Housing Association decided to install it) and no tuition how best to use it - even the owner's handbook basically says 'your installer has set it up, you don't need to know or change any of the settings' which is complete codswallop, they set it up so we'd always have hot water and heating, not for it to be efficient.

Re notifications, click on the notifications bell and in the top right-hand corner the 3 sliders symbol will take you to notification settings.

No_No_No_Yes

I have just realised that the SCOP I wrote on the previous post is wrong it should read 3.78 so here is an extract from the survey given.  Hopefully it makes sense to you.

Reed_Richards

I think the survey is indicating that your heat pump has enough capacity to heat your house and hot water provided the outside temperature is -2.5 C or greater.  The output water temperature is 50 C in which case I think a SCOP of 3.78 is good, I am only promised 3.2 for the same output water temperature.

Should you pay a bit more for a heat pump with a larger output capacity that would still keep you warm enough in colder conditions?  That's a difficult question to answer.  Your heat pump loses output power between 7.5 C and 2,5 C (approx.) which (to me) implies a loss of efficiency.  Is that the same with all models?  What modulation range can your heat pump achieve?  An installer who is not very interested is unlikely to want to help you answer such questions. 

No_No_No_Yes

The reply I got with regards to efficiency at lower temperatures such as -7C or -10C was, "it will still work but not as efficient".
No recommendations for a larger pump.

Someone mentioned that if the pump is too big, that, will be inefficient too.  It seems that a balance needs to be struck in order to be efficient.
Two thing for sure, I don't want inefficiency, and a want to reduce my heating bills, otherwise I'll stay with my old gas boiler, at least it will keep me warm.

Reed_Richards

No_No_No_Yes said:

Someone mentioned that if the pump is too big, that, will be inefficient too. 

There are two aspects to efficiency.  There is the actual efficiency, which will depend on the difference between the outside air temperature and the output water temperature.  Then there is the "performance efficiency" which is the percentage of the theoretical maximum that is achieved for a given temperature difference.  I read somewhere that heat pumps tend to achieve their best performance efficiency when operating at about half their maximum output.  So maybe you take the mean outside temperature duding the coldest months of the year and size you heat pump such that at that outside temperature it would be running at half power to keep your house warm enough?

I have no idea if this suggestion is right or misguided.  I don't believe there are many people (in the UK) who really know how to right-size a heat pump.  I'm certainly not one of them.