What's your monthly SCOP

Magnitio

https://forums.moneysavingexpert.com/discussion/comment/82067315#Comment_82067315

I tried lower temperatures, but by the evening the water wasn't quite hot enough for our needs. Decided it would be better to use a slightly higher target temperature than to reheat during the day.

NedS

https://forums.moneysavingexpert.com/discussion/comment/82067435#Comment_82067435

Yes, it's a balancing act. We started at a recommended temperature and then fine turned downward until the point where it's just hot enough for us. Everyone's use is different, so you find what works for you, as you have done.

It's always more efficient to reheat from cold than to top up, so reheating once per day (or when empty) is generally more efficient. We reheat in the afternoon from solar, at the warmest part of the day which is most efficient for us. For those on a cheap overnight EV tariff, heating overnight at cheaper electricity prices should more than offset any efficiency gained from warmer afternoon temperatures.

Magnitio

Turned the heating on yesterday just to check it out. Reported a COP of 6 with outside temp of 11C and flow of 30C. Probably about as good as it gets. Average COP for DHW so far is 4.89 heating overnight mostly to 50C with the odd increase to 60 when there is free electricity available.

akwexavante

Is this COP of 6 just for heating only?

I'm assuming the COP of 4.89 doesn't include the disinfection cycle? If it does then this is very good.

Magnitio

https://forums.moneysavingexpert.com/discussion/comment/82163465#Comment_82163465

That is for heating only in very favourable circumstances. Will be interesting to see how it manages in colder weather.

I don't run disinfection cycles. 50 degrees is sufficient with a good turnover of water in the tank. I do heat up to 60 when there is free electricity, which is quite often currently.

akwexavante

My own experience is that my COP improves the more the heating is on which makes sense. In summer my COP is very low because of the disinfection cycle that my system will not allow me to disable every week. Once a week is far too often, once a month would be better.

So your overall COP is 5.45 which is also very good. My worst month is July at 1.7 and my best month is February at 3.7 for a system which should have a COP of between 3 and 4. A rolling yearly average of 3.3 which i'm hoping will improve after changing a little pipework this summer.

NedS

I don't mean to gloat, but with COPs in the 5-6 range this time of year, a heat pump is so much cheaper to run than a gas or oil boiler.

This winter is going to be really painful for those who have not yet switched to a heat pump.

Meanwhile, we've locked in electricity at 14p/kWh on Cosy fixed, and with a SCOP of around 4 we will be heating the house at around 3.5p/kWh this winter.

MWT

https://forums.moneysavingexpert.com/discussion/comment/82168044#Comment_82168044

That's not gloating, that is just a great example of an accessible tariff that doesn't require anything more than the heat-pump to enable you to beat the cost of gas.

Gloating would be using my numbers based on a large home battery, solar and an EV giving access to IOG at 3.8p/kWh and a SCOP of 4 so under 1p/lWh… No idea what next year will bring but for this winter I'm good. :)

NedS

https://forums.moneysavingexpert.com/discussion/comment/82172056#Comment_82172056

Nice.

We are hoping to add an EV, but with our winter usage, I'd need 3 x PW3's to last 18h of peak rate usage, and the cost of adding two expansion packs makes that unviable.

I've yet to figure out what the best strategy is for an EV and a heat pump. We are either charging the car at 14p on Cosy or we run out of battery and end up heating the house at 37p day rate on IOG.

MWT

https://forums.moneysavingexpert.com/discussion/comment/82172114#Comment_82172114

You'd need to look at your mileage and hence charging frequency to figure out what would work best.

For us, we have 2xPW3 and it would make no sense to try and cover 100% of the heating requirement on battery by adding an expansion pack, but we can cover the vast majority of the heating demand except on the coldest days and the lower kWh cost on IOG easily results in a lower average than we could get on Cosy.

Even then, IOG can often deliver day-time slots as well so in that case the battery would still be able to cover all the heating requirements, not guaranteed though of course.

Similarly Cosy would make no sense year-round with the lower rate available on IOG.

Also if seriously considering more than 2xPW you have to factor in the new regulations regarding battery location which have a big impact once you go over 40kWh.