Heat Pump - KwZ usage through the roof

michaels

We have similar floor area (174sqm) and just scrape a B EPC (extended 30s semi). 

When we heated with gas (high efficiency condensing boiler with weather comp) we used about 20Mwh per year just for heat and hot water.  WE are big users of hot water, currently we use immersion and about 20kh per day year round, so probably 13mwh for heat to about 21c for the whole house. 

WE are now doing heating with a very inefficient heat pump set up and using about 44kwh on a 1c day, probably would have been about 120kwh of gas.  Overall we will use about 20mwh of electricity a year, 7Mwh for hot water, 4Mwh for heating, 5Mwh for EV miles leaving 4Mwh for everything else.

Reason our bills are not mad is that we have a TOU tariff and V2H using up to 100kwh of car battery for time shifting.

Reed_Richards

JEdelman said:

An update on this. Sadly, despite some minor works from the installer (two larger rads and some silicon over exposed areas) we remain in the same boat. On cold weather days we are burning through £26 worth of electricity and the temperature upstairs fails to get to 17C with barely any heat coming from the radiators. Our usage per year for the heat pump alone is 9,138.37 kWh. The installer says this is not excessive and that the upstairs should not be set above 18C (it's currently set at 21C during the day). Google tells us that the usage is more than double what it should be. Any thoughts or inspiration welcome.

My heat pump was installed to MCS standards.  For the purposes of my heat loss calculations, bedrooms were assumed to be at 18 C, halls and kitchen at 18 C, living areas at 21 C and bathrooms at 22 C.  I assume these are standard temperatures.  But that's not to say you can't set your own temperatures to suit your needs.  The heat loss calculations are based on an outside temperature which is exceeded 99.6% of the time, -3.8 C in my case.  In principle if it's colder than that outside then my heat pump will not have sufficient output to keep my house to its specified temperatures.  In practice it easily can; my heat loss must have been overestimated.

My heat pump has used 60 kWh of electricity on a very cold day but my average usage over the year is 15 kWh per day for heating and hot water.
   

QrizB

I can't help but think that, barring a major system malfunction or design/installation shortfall, this problem should be solvable by careful measurement and record-keeping over a period of days or weeks.

If it was mine I'd be monitoring power drawn, energy consumed, heat produced and temperatures achieved on a regular basis.

@matt_drummer has a box of tricks from Open Energy Monitor (?) that does most of this for him. Matt, what did your monitoring system cost and is it something a novice could use?

matelodave

Have shufti here - https://shop.openenergymonitor.com/level-3-heat-pump-monitoring-bundle-emonhp/. It can work out quite expensive if you want to do a proper job

matt_drummer

QrizB said:

I can't help but think that, barring a major system malfunction or design/installation shortfall, this problem should be solvable by careful measurement and record-keeping over a period of days or weeks.

If it was mine I'd be monitoring power drawn, energy consumed, heat produced and temperatures achieved on a regular basis.

@matt_drummer has a box of tricks from Open Energy Monitor (?) that does most of this for him. Matt, what did your monitoring system cost and is it something a novice could use?

It was around £800 plus an electrician for half a day. I did the plumbing.

The £800 includes ten years of monitoring so over it's lifetime about £10 a month.

The heat meter will need replacing some time after ten years but it's a DIY job and the monitoring is maybe £1 a month thereafter.

I am a novice. so yes, a novice could use it.

It is just data that is presented on a graph that enables you to see in real time the effects of any changes you make, I would be lost without it.