First year of ASHP power use

[Post and beam]

4th October marks the first full year of occupation of our new build. The heat pump has recorded 2650kWh for a cost of £703. This is taken straight from the Vaillant app and yes i know that some believe it to be potentially less than accurate. But ours is a very simple system so i am inclined to go with it unless i discover a reason not to. We have no gas supply so that is all of our heating and hot water.  Happy with this.

Now i need to try to get an accurate idea of what Octopus recorded for everything.

Edited 19 hours ago by Post and beam
Spelling

[JohnMo]

Usage is pretty similar to ours when were doing DHW also.  But not bad for heating and cooling.  Now you have that information maybe worth comparing other tariffs and see how they work out as I assume the £703 is based on a standard tariff and has no solar (battery?) input.

[SteamyTea]

25 minutes ago, Post and beam said:

The heat pump has recorded 2650kWh for a cost of £703

703[£] / 2650 [kWh] = 26.5p/kWh

 

Something does not seem right there.

[Post and beam]

1 hour ago, SteamyTea said:

Something does not seem right there.

Why?

1 hour ago, JohnMo said:

for heating and cooling

Heating & hot water. I cut the cooling fraction out.

[SteamyTea]

1 hour ago, Post and beam said:

Why

It suggests a CoP of 1.

Cost me about half that on E7, storage heaters and an immersion heater.

[marshian]

1 minute ago, SteamyTea said:

It suggests a CoP of 1.

Cost me about half that on E7, storage heaters and an immersion heater.

I think @Post and beam was declaring the electric consumption of the heat pump rather than the heat generated (which would work out as a cop of 1)

 

@Post and beam if you are pulling usage data out of Octopus it can be a bit flakey - I've reverted to the old consumption page because it doesn't have missing data as often as the current consumption data extract

[Post and beam]

OK guys i get what you mean. Apologies.

So, that 2650 kWh is what the Vaillant app records as energy consumed. For a generated 12119. so a SCOP of 4.56

[Post and beam]

As it happens our total electricity use since the board was made live is exactly 6100 kWh as of 2 hours ago. This includes the couple of months prior to us actually moving in full time. so there will be a little consumption not accounted for elsewhere. Small amount, i dont think it changes the figures enough to care.

[SteamyTea]

4 minutes ago, Post and beam said:

SCOP of 4.56

That's better.

[JohnMo]

40 minutes ago, Post and beam said:

generated 12119. so a SCOP of 4.56

CoP sounds good, but heat generated how does that compare to your design energy usage? If 12,000kWh is correct all good. But I thought your house was near Passivhaus standards, so maybe high depending on house size and hot water usage.

[marshian]

42 minutes ago, Post and beam said:

As it happens our total electricity use since the board was made live is exactly 6100 kWh as of 2 hours ago. This includes the couple of months prior to us actually moving in full time. so there will be a little consumption not accounted for elsewhere. Small amount, i dont think it changes the figures enough to care.

 

6100 - ASHP usage of 2650 is 3450 Electric used by other appliances so that's a little over the average but then so are we at around 3600 (2 people in 4 bed house with a reasonable level of tech/convenience)

 

The scop is good too!!! 

 

Edited 15 hours ago by marshian
typo

[ProDave]

If you  are looking for comparisons, My rolling 12 months usage for ASHP  is 1200kWh in heating mode and 700kWh for hot water.

 

That's electrical power into the heat pump.  Measured with a dual rate electricity meter (old dumb E7 electricity meter)

 

No idea of COP my heat pump has nothing to measure output power of even how to estimate it.

[Post and beam]

14 hours ago, JohnMo said:

But I thought your house was near Passivhaus standards, so maybe high depending on house size and hot water usage.

No, i wanted it to be prior to starting but i never planned for it to be. I just wanted to build as good a house as i could arrange. My ACH of 1.4 for example is a slight disappointment as i wanted to get below 1.

House is 201 sq metres by the way.

[JohnMo]

 

9 minutes ago, Post and beam said:

No, i wanted it to be prior to starting but i never planned for it to be. I just wanted to build as good a house as i could arrange. My ACH of 1.4 for example is a slight disappointment as i wanted to get below 1.

House is 201 sq metres by the way.

In that case the overall heat usage may be a little high.  We are similar sized building but a single storey with very poor form factor, loads of glazing and on looking at only the heating and including DHW we are good bit below your quoted heat output (around 2000kWh). Plus your weather is much better than our based on location, so should really be way lower than ours. CoP is great, but maybe how the heat is used could be refined a little. 

 

Are you rooms or areas heated more than needed, is the heat pump cycling more than needed?  Cycle length has big influence on heat developed and CoP.  Depending on cycle length 1 to 2 mins will lead to rubbish CoP and a lot of heat developed, but not much delivered - not sure you here.  But 10 to 15 runs will give a good CoP but the heat developed could be higher than the house needs as some is wasted.  Your Vaillant heat pump has a few tools to help, as you can use a mode that counts deg minutes, this allows long run times and long off times but delivery the correct amount of heat, so if not switched on it may be worthwhile.