Electric wet CH - yes roll your eyes!

matelodave

Cardew said:

Gerry1 said:

Cardew said:

Gerry1 said:

Ectophile said:

Doug86 said:

It's a shame. I considered everything else with this house except properly investigating the heating. I simply took it for granted that electric boilers were cheaper, were 100% efficient and required next to no maintenance thereby evening out the cheaper cost of gas. I figured it would be more expensive for sure but not to this degree.

A heat pump system costs a fortune to install, but has an "efficiency" around 300 to 400%.

Is there any evidence of a COP over 3.0 or more ever being achieved in reality?

Unfortunately the links to the detailed trial reports no longer work.

That's because a lot more work was done.

Try this instead: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/606818/DECC_RHPP_161214_Final_Report_v1-13.pdf

Thanks. I will get round to looking at in detail later, but a quick skim appears to show that you will be lucky to get a system COP of 3.0.

Incidentally this is a different trial to the EST trial I referenced in the my thread. In fact this later report makes reference to the earlier EST trial.

I've just had a read and it does look as though 2.5-3 is about right but it does depend on how it's installed, how its configured and how they are used together with people's lifestyles.

It seems to be very difficult, if not impossible to get definitive data when people actually use them in real life rather than when they are tested and evaluated under laboratory like conditions. People are unpredictable. We don't all do the same thing, we've all got different expectations and attitudes and so it's not easy to correlate one person's experience with another.

Some people understand how to use them and others don't, can't or won't and each of us has our own opinion on what a comfortable temperature may be both for heat and hot water. It would require a proper long term study (at least five years) with literally hundreds of parameters being measured and evaluated and properly controlled. Much more detailed data on both internal, external temperatures and control settings (room by room, hour by hour day by day) rather than just power in versus heat out would be required. Who's going to want to fund this?

Cardew

matelodave said:

Cardew said:

Gerry1 said:

Cardew said:

Gerry1 said:

Ectophile said:

Doug86 said:

It's a shame. I considered everything else with this house except properly investigating the heating. I simply took it for granted that electric boilers were cheaper, were 100% efficient and required next to no maintenance thereby evening out the cheaper cost of gas. I figured it would be more expensive for sure but not to this degree.

A heat pump system costs a fortune to install, but has an "efficiency" around 300 to 400%.

Is there any evidence of a COP over 3.0 or more ever being achieved in reality?

Unfortunately the links to the detailed trial reports no longer work.

That's because a lot more work was done.

Try this instead: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/606818/DECC_RHPP_161214_Final_Report_v1-13.pdf

Thanks. I will get round to looking at in detail later, but a quick skim appears to show that you will be lucky to get a system COP of 3.0.

Incidentally this is a different trial to the EST trial I referenced in the my thread. In fact this later report makes reference to the earlier EST trial.

I've just had a read and it does look as though 2.5-3 is about right but it does depend on how it's installed, how its configured and how they are used together with people's lifestyles.

Agreed.

As MCS is involved, and some are installed in rental properties, I suspect a lot were new build properties at the time of the investigation??

I can believe a system COP of 2.5 - 3.0 is perfectly possible with underfloor heating and a high standard of insulation. However there are some 20 million existing properties in UK and retro-fitting an ASHP is an altogether different proposition; as EST found out in their trial where the system COP was considerably lower.

Understandably these trials/investigations cannot take into account what might be termed 'equivilence'. By that I mean that a heat pump with low water temperatures to achieve a high COP has to run very long periods even 24/7. Not so with gas/oil CH where water temperature can be 80+C and warm up the property quickly.

So if you take an example where a heat pump uses, say, 5,000kWh and with a high COP of 3.0 produces 15,000kWh. With oil/gas CH the heating can be off during the day when the occupants are out, and during the night when the occupants are in bed, and come on say 30 minutes before they return/get up.   

Doug86

molerat said:

I suspect 3500 kWh is way under estimating.  That is just above the average for non electric heating.  Anyway, Neon Reef are currently offering 13.619p/kWh and 11.66p/day for your post code which comes out at £519 per year compared to SP standard of 16.908p/23.07p which comes out at £676.  A 12 mth fix with Neon Reef is only a fraction more expensive at 13.664/kWh. At 10000 kWh you would save £366 per year against SP standard rate. That current estimated 2900/600 at your current tariff is costing you at least £599 without adding the standing charge and maybe VAT as well.

Okay so i'll probably just add an extra load of kWh. I'd have to do some maths to try and work out if E7 or straight tarrf is the better option for me. The immersion gets 2 hours every morning on off peak and I suppose were I to stick the heating on for 2 hours aswell during that time it would also get the benefit of the off peak. That will leave about 3 or 4 hours of heating in the late afternoon/evening on the day tariff and even more on weekends. On the current SP tariff that's something like £7 a day on a work day and even more on a weekend.