Very happy with my heat pump installation in Northants from Clean Spark Renewables Ltd (YourEnergy).

Ecodan 11.2, 250L tank, 25L Buffer, all new rads.

Accomodating, punctual, clean. No complaints at all.

Heat Pumps ..................What a Sad industry.

"Happy with a Heat Pump installation"...............I would wait a wee bit .

I was "Happy " during November 2022............then December came ,  my Heat pump producing Large Rectangular Clouds with spectacular bills!

I have , however, been contemplating my experiences with the innumerable  plumbers,  used, or exploited  as "service Engineers " by their  "Installers".

Most of the visiting Plumbers said that they "had No confidence in the Heat Pump Technology itself and would not , themselves, fit a Heat Pump in their own home ".

Most Heat Pump servicing seems to consist in "Slagging OFF " everybody else, or , at least finding someone else to blame.....

What a Sad industry.

Agree, it's early days and of course not using the heating in anger.

Nevertheless, I do feel confident that all will be well.

I'll let you know!

Posted by: @richard24738

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Ecodan 11.2, 250L tank, 25L Buffer, all new rads.

I hope and presume the buffer is plumbed as a 2 port volumiser in the return.  If not you are likely going to want it replumbed. Otherwise it sounds sound.

JamesPA: The installers specified the buffer (4 port not a volumiser in the return) and, to be frank, I have seen arguements both for and against.

I will just have to see how it goes.

Anything I should look out for in the MELCloud reports which would indicate an issue?

@richard24738 I have a Daikin monobloc 8kW ASHP and when the pipework arrives in the airing cupboard, it first meets with an LLH which I have set using the secondary pump speed to match the flow temperatures within about 0.2 degrees C. Our system usually achieves a COP of 4 plus and sometimes I check and find it has achieved 5.25 or better - so an LLH isn’t always bad news! Regards, Toodles.

Posted by: @richard24738

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JamesPA: The installers specified the buffer (4 port not a volumiser in the return) and, to be frank, I have seen arguements both for and against.

I will just have to see how it goes.

Anything I should look out for in the MELCloud reports which would indicate an issue?

Measure, if you can, the temperature drop from flow in to flow out.  For every degree you are losing 2-3 PC in efficiency.

Unless you have a secondary heat source or something else odd, there are no arguments 'for' which survive a rigorous analysis asfaik  That doesn't mean it's definitely a problem, just that, unless your install has something unusual about it, it's not a solution to anything that cannot be better solved another way.

Presumably you have 2 pumps one either side of the llh (25l is too small really to be called a buffer)

@jamespa Unfortunatley, I don't have a means to measure degree in and out unless you mean the MELCloud graph "Internal Temps" which has "Flow Temp" and "Return Temp".

Most of the time there is nothing as the pump has mainly switched itself off except for the hot water session and a few occasions when the temp has dipped.

Yes, there are two pumps in the loft; one before the "buffer" and one after.

@toodles Thanks. Always interesting to read your comments.

It's of course early days, but from a cost perspective, nothing unexpected compared to last year with a gas boiler.

Posted by: @richard24738

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@jamespa Unfortunatley, I don't have a means to measure degree in and out unless you mean the MELCloud graph "Internal Temps" which has "Flow Temp" and "Return Temp".

Most of the time there is nothing as the pump has mainly switched itself off except for the hot water session and a few occasions when the temp has dipped.

Yes, there are two pumps in the loft; one before the "buffer" and one after.

Flow temp and return temp aren't what you want, you want the temperature of the flow into the buffer from the heat pump (which should equal flow temp) and the temperature of the flow out of the buffer towards the emitters (which the heat pump doesn't measure).  You may well find, when its doing space heating, that the latter is 5C lower than the former, which inevitably equates to a 10-15% reduction in system efficiency (ie a 10-15% increase in your electricity bill).  This may or may not matter to you.

If you haven't seen anything abnormal I wouldn't worry.  However if, once the heating season starts (and particularly when its really cold), you aren't getting warm enough or are seeing larger bills than you would expect then feel free to post here and ask for suggestions.  You ideally need to post the system diagram and the heat loss calcs, both of which your installer should have given you (and if they haven't now is the time to ask!).  The Mitsubishi 11.2 has a very solid reputation so you have good kit, and as all rads have been replaced the system is presumably designed for a low is flow temp so should give good performance.  Its unfortunate that many installers are still fitting either an LLH or a buffer when none is needed, the rationale (if there is one) is often linked more to installer convenience than system performance/customer convenience.  As @toodles says, it may not matter, but there are definitely installations reported here where the unnecessary presence of an LLH/buffer is clearly causing problems.

Please bear in mind that heat pumps should generally be operated low and slow.  Weather compensation, no TRVs (or at least no TRVs downstairs/TRVs set 2C above the desired temperature), room thermostat set 1-2C above the desired room temp, no or minimal zoning is generally the way to go, typically with 24*7 operation (certainly in the coldest season) or only a modest night time setback to spread the load over a long period, allowing flow temperature to be reduced to the minimum possible.  As your installation was completed in summer your installer wont have been able to adjust the WC curve particularly accurately (you cant blame the installer for that!), you may want to tweak it when winter comes.  Apologies if you already know this.

@jamespa Thank you for your detailed response.

I may have to start a new thread at some point with my questions!

With regard to the Flow and Return Temp measurement, would this require some extra kit in the form of meters and a plumber to fit or would it be simply something to temporarily attach to the pipework?

The "buffer" is plumbed so the top 2 are in and out from the heat pump (primary flow think that's the term) and the return from the rads via the bottom two. 

The installer set up the Ecodan as "Auto Adapt" with a wifi control unit downstairs. My understanding is that the Auto adapt takes little or no notice of the WC Curve or possibly adjusts it automatically.

All programming is done on the master FTC which is on the wall outside the airing cupboard. Set Temperature is reduced by 2 degrees overnight.

All TRV's are open except the one in the master bedroom which is set to 3 to set a maximum. No zoning.

Posted by: @richard24738

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@jamespa Thank you for your detailed response.

I may have to start a new thread at some point with my questions!

With regard to the Flow and Return Temp measurement, would this require some extra kit in the form of meters and a plumber to fit or would it be simply something to temporarily attach to the pipework?

The "buffer" is plumbed so the top 2 are in and out from the heat pump (primary flow think that's the term) and the return from the rads via the bottom two. 

The installer set up the Ecodan as "Auto Adapt" with a wifi control unit downstairs. My understanding is that the Auto adapt takes little or no notice of the WC Curve or possibly adjusts it automatically.

All programming is done on the master FTC which is on the wall outside the airing cupboard. Set Temperature is reduced by 2 degrees overnight.

All TRV's are open except the one in the master bedroom which is set to 3 to set a maximum. No zoning.

Other than the buffer that all sounds very sensible indeed - which makes it even more curious that the buffer is fitted at all.  Did the installer give any reason?  Anyway never mind, it shouldn't be difficult to bypass the secondary pump and the buffer (or turn the latter into a 2 port volumiser) if it proves necessary, or leave it if its all working well!  

My understand is that the auto adapt uses the set WC curve as a starting point then tweaks from there.  Others report good results.  I don't think the algorithm is published but, judging by what others have said, it should do the job.

re the temp measurement you just need a suitable thermocouple/meter which you strap temporarily but securely onto the pipe (under the insulation of course and, if you have some, with some heat conductive paste).  Many multi meters have thermocouple inputs or you can buy cheap ones easily, here for example are two for £9, each with two sensors (so one of these could do both measurements, with the two you can measure all 4 ports on your buffer simultaneously!) .  These need a power supply/battery but I expect you can get ones with an integral battery compartment also.