The heat loss calculation was 12KW, since when we have improved insulation 

Our House is a 4 bedroom detached house on two storeys, built in about 1920. The floor area is about  240 sq metres, so quite big

a. On the basis of the Ecodan recommendations following a heat loss study, we have up graded all our radiators

b. We have replaced doors and windows so that all our doors and windows are now double glazed

c. We have put new thicker insulation in our loft

c. We have put throttles in our chimneys

d. Our radiators were rebalanced last week

e. We have set weather compensation so that flow temperature is at the recommended level

f. The heat loss study confirmed that our 14 kw is big enough to heat our. House and compensate for the heat loss

G. The system was serviced in December, when the filters were cleaned.

My web researches don’t suggest any other explanation for poor efficiency so can any one come up with new ideas?  Failing that I don’t know what to do short of taking our heat pump out and starting again with an efficient combi boiler

This is much harder now! A few questions:

Are you letting WC control room temperature or are you using thermostats; either Mitsubishi or 3rd party?  Is the ASHP running all the time or is off/cooler some of the time 

What sort of flow temps do you have at, say 0 and 5 degrees outside? 

Are you including HW in your numbers?  If so, how hot and do you use a lot?

Do you have different zones in the house that are on and off at different times, or do you use TRVs a lot?

Do you have a buffer or low loss header?

I have a 14kW Ecodan and my January COP for heating and HW is about 3.1 so far. 2.3 is a bit low but it depends how you are using it.

Oh @kev-m you star you 😘🤣

@dotty9943 I’m glad you’re on the up 👍

I was fed up of Derek getting all the plaudits, this is just the start for me!! 😆 

I am devastated. 😪 

It would appear the 'peasant's are revolting', but then they always have been. Have you been 'eating cake' again? 😋 

d. Our radiators were rebalanced last week

Who re-balanced the radiators? Was it done using the lockshield valves? Do you have any TRV's fitted?

e. We have set weather compensation so that flow temperature is at the recommended level

What are the settings of the WC curve?

f. The heat loss study confirmed that our 14 kw is big enough to heat our. House and compensate for the heat loss

What are the heat loss calculations for your home? What type and size is your home?

My web researches don’t suggest any other explanation for poor efficiency so can any one come up with new ideas?  Failing that I don’t know what to do short of taking our heat pump out and starting again with an efficient combi boiler

Low efficiency can be caused by incorrect WC settings, also using on - off type thermostats. Having a buffer tank, low loss header or plate heat exchanger can also have a detrimental affect. Do you have any of the above installed?

@dotty9943 I’m glad you’re on the up 👍

I was fed up of Derek getting all the plaudits, this is just the start for me!! 😆 

a. On the basis of the Ecodan recommendations following a heat loss study, we have up graded all our radiators

b. We have replaced doors and windows so that all our doors and windows are now double glazed

c. We have put new thicker insulation in our loft

c. We have put throttles in our chimneys

d. Our radiators were rebalanced last week

e. We have set weather compensation so that flow temperature is at the recommended level

f. The heat loss study confirmed that our 14 kw is big enough to heat our. House and compensate for the heat loss

G. The system was serviced in December, when the filters were cleaned.

My web researches don’t suggest any other explanation for poor efficiency so can any one come up with new ideas?  Failing that I don’t know what to do short of taking our heat pump out and starting again with an efficient combi boiler

@dotty9943 I’m glad you’re on the up 👍