Happy New Year to you too.  Good numbers for your size of house.  Our December was 970 for heating and HW for a similar sized place. 

When it's very cold does the ASHP maintain the room temp you want?  What was your highest consumption/lowest temp in December?  (can't see the detail in the ss)

Your 'other' consumption seems quite high compared to your heating and HW. 

Hi Kev,

From what I can see the highest daily electricity consumption by the heat pump inc DHW was 42kwh (39 for CH, 3 for DHW). All the individual months data is in the desperate sheets in the document . 

• I forgot to mention, our base load is high due to an EV being charged at home. 
• The unit always managed to reach required temps in the house, albeit with it running flat out for longer periods. 
• We still haven’t reached the point where the unit is running at a lower load all the time, it still starts stops a fair bit. 
• the learning curve with this is steep. 

How does our system compare to others out there? 

ATB. 

Drew 

Posted by: @drew-pa

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Hi Kev,

From what I can see the highest daily electricity consumption by the heat pump inc DHW was 42kwh (39 for CH, 3 for DHW). All the individual months data is in the desperate sheets in the document . 

• I forgot to mention, our base load is high due to an EV being charged at home. 
• The unit always managed to reach required temps in the house, albeit with it running flat out for longer periods. 
• We still haven’t reached the point where the unit is running at a lower load all the time, it still starts stops a fair bit. 
• the learning curve with this is steep. 

How does our system compare to others out there? 

ATB. 

Drew 

All the months except December are there?

My ASHP will run constantly if it's between about 2 degrees and 9 degrees outside.  Below 2 it can defrost maybe once an hour and above 9 it cycles (switches on and off) twice an hour or so. 

Do you know if your thermostats are causing the starts and stops or is it the flow temp target being met?

@drew-pa, a good collection of data. Thank you for sharing. Your consumption numbers are quite low, which is good, but it would be good to know what your target temperature is across the house and, like Kev says, to know whether that temperature has been hit. 

A bit trickier, but very helpful, is to have the average daily ambient temperature (or a low and a max) for each day to see how the heat pump copes when things get really chilly (and how chilly it got). For me, that's a very useful reference point to understand at what temperatures our heat pump loses significant efficiency and whether we can supplement that with a log fire for a few hours, for example. The software for our heat pump gives a daily temperature average for each day it collects data. That would be very interesting to see, but a bit of hassle to do manually.

@editor 

it’s good to hear we are heading in the right direction.  

• target temps - upstairs 19c constant - downstairs 20c constant. 
• upstairs is controlled by the Vaillant  controller, presently in the hall, soon to be in the coldest room.  All valves wide open now.
• Down stairs has Vaillant controller, but this is redundant at present.  Presently running the whole downstairs off one of the rooms(zones) controllers. All zone heads disconnected so effectively running a single zone.  All other controllers set low enough so as not to call for heat.
• would like to reinstate the Vaillant controller, but as far as I am aware it won’t call for the UFH pump to turn on so this is the reason we are using the UFH room controller.
• All temps have been hit. Albeit with higher loads on the heat pump. We have never had a situation yet where the heat pump hadn’t reached a required temp.
• I am intrigued regarding the outside temps.  We can see it in the Vaillant controller, but it’s not logged.  There must be a website I can pull historical data for the area for analysis purposes. I have a list of improvement suggestions to email Vaillant, let’s see what they say.
• We have a 6kw solar PV coming in the next few months along with a battery so fingers crossed that will drop costs.
• @kev I’m sure it’s the controller that’s shutting down, not the flow temps if that makes sense.  Downstairs it’s a room temp controller we are using, upstairs it’s the Vaillant controller operating to a set point of 19c.

hope that makes some more sense.

What is the size of your house?

I have only been collecting numbers for a short while but it looks like my total consumption for December was almost identical to yours at 762 kWh, for a three-bedroom house in southern England. 

However the system was not set up properly with weather compensation for some of that period. Based on more recent days when the weather was milder it looks like it should be about 500-550 kWh for January, barring any more cold snaps. 

@bob77 

Our house is circa 180m2.  3 story 5 bed plus office in the attic/3rd floor.  

@drew-pa 

Visual Crossing and Time and Date websites both do historical weather data.

If u like numbers as u say u will love all the data from visual crossing. 😀 

Posted by: @sand

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@drew-pa 

Visual Crossing and Time and Date websites both do historical weather data.

If u like numbers as u say u will love all the data from visual crossing

Another valuable source of weather data is the Met Office's WOW website:

https://wow.metoffice.gov.uk/

You have to sign up (free) but then you get access to very detailed local weather data. Just find an observation station near you and you can download data in csv format until you are blue in the face. The one I use has observations every few minutes, these can be converted into hourly obs using pivot tables.   

@editor 

it’s been very noticeable this last week. The temp has risen by a couple of degrees, and the consumption has dropped again.  The efficiency of our unit seems a lot greater around the present temps (circa 5-6c).  I will get all the data merged into one data set and then present it to show the findings.  

From what I can see at present

• Our unit is a little smaller than it should ideally be.
• the efficiency dropped massively when the temp got to -2/-4c. Adjusted curves slightly to try and improve efficiency. 
• So far, we have never not reached desired temp.
• Think I’ve found a solution so that the Vaillant control system will be able to control the UFH pump on and off. Work in progress.
• looking forward to getting our solar PV/batteries in the coming months.
• really enjoying the forum, great work by all involved.  Thank you.  

Drew 

@drew-pa. At risk of sounding like one of the Four Yorkshiremen, I dream of a monthly consumption like that, 760kWh - you were lucky!  
I live in a c100yr old four bed detached in the Cairngorms, around 175m2, solid stone walls and suspended floors. Never going to be a passivhaus it's true but we've installed secondary glazing throughout and are zealously chasing out draughts to try and improve matters and we've a C-rated EPC (79 score). We've 2 x 12kW Samsung heat pumps operating on a master and slave basis.

During December we managed to consume an eye-watering 2536kWh, with a daily peak of around 130kWh, that's around twice a typical daily figure for November or over the last week. Obviously not sustainable. I ended up switching the slave heat pump off as I'm not convinced it's adding much value - the controller shows its output temp consistently some 6° C lower than the master (so presumably just lowering the buffer tank temperature) and heat power generated is recorded as virtually zero which may be a measurement issue. Neither unit gets anywhere near their WC set point. 

Like you I've seen a significant improvement in efficiency over the last few days as temperatures have risen to 3-4°C or so. Nevertheless I'm far from convinced the system is set up optimally and I'm currently waiting for a visit from the installer and Joules. I'm not holding my breath. 

Simon