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I finished building my house this year and moved in back in June.  I’ve been using my air source heat pump for heating and water and not really thought anything about it until I noticed my electricity bills.  I’m spending about £13 a day on electricity and decided I need to learn how to most efficiently run my airsource and heating schedule. 

 

There really isn’t much information online about this.  So I’m really hope someone here will be able to help me please. 

 

Thank you

 

My set up is as follows:

 

Mitsubishi Electric Ecodan PUHZ-HW140VHA2 14kW air-source heat pump

Mitsubishi Electric EHPT25X-UKHCW 250 litre water tank

Mitsubishi Electric FTC5 Ecodan Controller PAC-IF062B-E

Heatmiser Streamline controllers in each room

 

House:

 

New build house.  Largely open plan downstairs.  Does have some large window walls in the entrance hall which we would lose a bit of heat through.

Floor coverings: upstairs is carpet and low tog underlay.  Carpet is thick, but we kept the total tog below the recommended amount (my memory is hazy, possibly 2.5 tog?)  Downstairs we have 12mm thick laminate.

 

Underfloor heating upstairs and down

 

Current schedules:

 

Ecodan controller set to run at 18degrees continuously. 

3 main living rooms (open plan kitchen, dining and lounge) set to 21 degrees between 5am-8.30am and then 16 degrees, then on again at 4pm for a couple of hours at 21, then back to 16

All other rooms in the house:  Heatmiser contollers set to Frost protection mode (set to between 10degrees and 15 degrees)

Hot water is heated from 6-7am and then half an hour in the afternoon 3-3:30pm.  Hot water seems to heat to41degrees now – although it used to be higher (could it be the compensation curve?  Not sure if that changes DHW temp)

 

I think my hot water only heats when scheduled to heat on the Ecodan controller – I though it might be using the immersion heater.  From what I can work out, i don’t think the underfloor heating results in the water heating at all unless the immersion heater turns on.

 

Hot water costs:

October    158 kWh    £34.74
November    228 kWh    £50.13
December (<19th)    164 kWh    £36.06
 

Heating costs:

October    164 kWh    £36.06
November    621 kWh    £136.54
December (<19th)    491 kWh    £107.96
 

Temperatures

 

The room temp on the thermometers seems to average around between 15 and 17 degrees.  Which I feel is too low.  We do have a wood burning stove which we have been using to heat the downstairs rooms to a more reasonable temp (gets up to 21-23 when this is running)

 

COP values

 

According to my MSC certificate we should get 3.48 COP.    I reckon we’re getting the following:

December 2021 <19th    2.348
November 2021    2.377
October to December 19th    2.179
 

If anyone can help with any advice that would be very much appreciated.  Thank you very much

Hello and Welcome to the the OVO online community, @PNorman!

 

Great question to ask about how to get the best out of your Air-Source Heat pump - You’re seeking the really important green tech success we love to see here!

 

Just going to tag in a few of our forum regulars who have a similar Heat pump set-up as I’m sure they’ll have some valuable advice to share - @sylm_2000, @Speps, @James_N, @M.isterW 

 

We’ve also had a similar discussion here before that you might find helpful to check out:
 

 

 

Welcome to the forum, you have an excellent set-up and future proof! 

Assume you have a recent new build so the walls and insulation are relatively new?

I noticed the ASHP took almost 2-3 days to return to a reasonable COP when we returned back after 4 weeks holidays recently. This proves the principle “set it right, leave it on and forget about it”.

Mine would be a first winter season however my data is diluted with V2G exports and part PV generation so can’t comment on your usage however I would say COP above 3 to 3.5 is pretty good and real life acceptable. Winters it will take a dip and recover in the summer/autumn so on average over the year you’d be okay.

I am no expert but a few things spring to mind.

1. Underfloor heating takes much longer to heat up and cool down generally than radiators so i am not sure the schedule you have set is going to work. 

2. Be good to know the square meters of your house to compare with others. 

3. Probably best to think in terms of kWh used rather than cost initially as posters will be on a wide variety of rates.

4. For November you used 849 kWh, so 28.3 kWh a day. Be interesting to compare this to the other Ecodan users in comparable properties. 

5. On the post from Jess there is a link to a post about the 3 different heating modes for the Ecodan. Do you know which one you are currently using? 

 

Hi @PNorman,

I have a similar set up to you. As has been posted above, the biggest thing that stands out to me are the many temp changes you have set up. My thermostat is set at 21C for the day, then drops to 19 or 19.5 at night. 

Just to give you an idea how slow my system is at changing temp, I was away last week, and it took 28 hours to get the house from 14C to 19C

Are you also using the temperature gradient? THis means the flow temp is adjusted depending on how cold it is outside. The colder it gets, the warmer the the heating system runs (but the less efficient it is)

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