ECODAN , can I run just the heating without DHW?

Reed_Richards

It so happens that with my heat pump and my radiators I need the difference between the leaving water temperature and the room temperature to be about the same as the difference between the outside temperature and the room temperature.  So if I want my rooms to be 21 C and it's 1 C outside then I need my water temperature to be about 41 C.  So the regime that @MultiFuelBurner is using would not work for me if the outside temperature was less than about 7 C. 

Different properties will have different requirements.  My property used 33.66 kWh on 7/1, 33.81 kWh on 8/1 and 32.49 kWh on 9/1.  Daytime temperatures on those days were only just above 0 C.  Those are the only 3 days where my usage has been above 30 kWh in a day since I started making daily measurements on 17/12.  That's for heating and hot water and I have a 12 kW heat pump.

Any heat pump will use a lot of electricity when it's really cold outside but should make up for this in milder weather.  The colder it is outside the higher your water temperature will need to be to keep your house warm and the less you will benefit from any form of weather compensation.  Whether you should be horrified about using 52 kWh per day really depends on how much heat your property requires to keep it warm.  If you had an MCS installer you should have a figure for that. 

Swizz

Thanks for your help. Water turned off at the moment so we're using electric shower. Kept WC at what it was before in my last posts. I've looked at stats on melcloud and there have been times in last 7 days when it stopped, probably because of woodburner and being south facing with open plan upstairs.
The backup heaters I didn't know about..where are they please!
We can't afford £15 a day .,.should I change the settings?
Very grateful for your help

MultiFuelBurner

Could you share your melcloud stats?

Also people have asked in the thread for your EPC info on how much it recommends to heat your property  and what is size of your property?

To check your freeze stat settings watch this as if your anti freeze is low I would suggest having it set as default so when the temp outside is 5oC the system maintains a flow temp of 20oC round the whole system to stop it freezing up.

https://youtu.be/fA9mZicFSm4?si=wfemYVl5zOWKV41g

Reed_Richards

Don't panic!  You have been monitoring your daily use since last November, perhaps earlier.  And if you have had your heat pump for 7 years you know roughly how much electricity it uses in a year.  Most of that time your heat pump has not been using nearly so much electricity per day and it won't again as soon as the weather gets milder.  The last time you showed a weather compensation curve the maximum water temperature was 35 C.  If that works for you it should give you an excellent SCOP, that's the COP averaged over the year. 

You mention backup heaters.  My heat pump (not an Ecodan) does not have one and if installed they should not be used until it gets really cold out.    

Swizz

It's only in the last few months that we gave been properly running it low all the time. Before we just used it like a gas boiler as we didn't know any different. 
Ive put 2 comparison graphs up 
Last year, we just had it running on thermostat, and didn't leave it, this year, on all the time. I'm aware 5hdt this last month might have been colder than same period last year, so I've put in December from 22 and 2023 as I think they were similar.
T

Swizz

To summarise
Last year month to Jan 10.........121.8kwh
This year to Jan 10...........348.2kwh

Dec 22......88.6kwh
Dec 23......308kwh


This is heating only 
Massive difference

MultiFuelBurner

Swizz said:

To summarise
Last year month to Jan 10.........121.8kwh
This year to Jan 10...........348.2kwh

Dec 22......88.6kwh
Dec 23......308kwh


This is heating only 
Massive difference

But not 52kwh a day as you suggested.

As said earlier in this thread do what suits you if using it like a gas CH system works for you and saves you money and delivers the heat you want do that.

You said you were spending £15 a day and based on your graphs every at 30p kWh you are spending £3 a day on heating. Based on Dec 2023 figures 

If your electricity bill is £15 a day you have other issues in the house burning through electricity It isn't your heat pump.

Reed_Richards

Swizz said:

It's only in the last few months that we gave been properly running it low all the time. Before we just used it like a gas boiler as we didn't know any different. 

Well you say "properly running it low" but the effect seems to have been to make it a lot worse, using a lot more energy than this time last year.  So either your heat pump is going subtly wrong or it "doesn't like" the changes you have made and you need to go back to the way it was before, if you can.

Heat pumps are supposed to run most efficiently if you can get them to be on almost all of the time just making the water hot enough for your room heating.  But if it's too warm outside they won't be able to reduce their power output enough and they will cycle.  And if it's too cold outside they have to defrost regularly and will also cycle to do this.  So the range of outside temperatures where they can stay on all the time may be quite limited.

If you can recapture your original settings you might want to try those for a bit.  Alternatively you could copy @MultiFuelBurner and set a fixed leaving water temperature and see how low you can make that whilst still keeping your house warm enough.  But you'll have to keep track of the outside temperature because what works for 5 C outside might not work for 0 C outside.      

Swizz

Any suggestions for outward flow temp ...bearing in mind it's going to be very cold next week. 14 days at £15 a day , which is what it will be by end of next week a bit daunting...

Swizz

The 52kw a day has only been in last 4 days . I've carefully re read the helpful comments , and will raise the flow temperature, probably up it by +4