@martin53, that sounds like a plan. There's never a "right" system; only one that's "right for you" and you can't find it without starting somewhere. Everything you say makes sense and, like @editor, I'll be interested to hear how you get on.

You did mention about energy companies signalling lower carbon intensity through their TOU price points. There have been a few discussions on this forum about the correlation between half-hourly price and carbon intensity (particularly this thread), and we haven't yet managed to find a good answer; there may or may not be a correlation but any correlation appears to be relatively weak if it does exist. Nonetheless, since you're one of the early adopters of Havenwise and they are listening to you quite closely I'm sure any feedback you might give about how important carbon intensity may be to you would help influence the extent to which they incorporate that factor into their software (after all, the carbon intensity figures are always available via another API and so could easily be gathered if there's a good reason for Havenwise to do so).

A follow-up that may be better in another forum but relevant to new ashp install: when you switch to electric TOU tariff and have your gas meter removed to avoid the standing charge then you seem to lose access to downloading historic gas consumption data. This is both on my Hugo app and Octopus "My Energy" page of my account.

Both say they will look into this and you can get monthly data from Octopus statements but transcribing is a pain and I want weekly, daily or even more data for future comparisons. I'll report back in case it helps.

Very early days on Havenwise but interesting to note that my cop has dropped from 4.2-4.3 in days before started to 3.2-3.4 now. This is seen to be due to the pump working harder in low cost period to bridge the higher cost ones.

HOWEVER, the average cost of electricity used (on Cosy tariff) has fallen from 21.5 to 19p per kWh and this is for total household not just heat pump. Outside trmperates have not change much at around 6-10 deg average. Cycling frequency has not changed.

Shows that cop is a useful initial measure of how well the system has been designed and set up but, at least for me, total electricity cost for ASHP and whole house to achieve the desired comfort level is the real measure of efficiency/efficacy.

A further thought. The 21.5p per kWh was with my attempt to optimise using Cosy tariff by scheduling heating to favour low cost periods. The 19p figure is when the Havenwise algorithm took over. So algorithm beats human (well, at least me) under similar conditions and same tariff.

Perhaps real test or comparison will likely be pence/kWh/°C ∆T for full year to allow for milder or more severe winter. I can generate this for past year (pre-ashp) and also for coming winter.

This will give me comparison of gas heating versus ASHP on Cosy/HW. Would have been good to generate ASHP with Cosy/manual control to see HW benefit over me alone but was keen to try HW.

I will report back in the Spring. Cheers.

Posted by: @martin53

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Perhaps real test or comparison will likely be pence/kWh/°C ∆T for full year to allow for milder or more severe winter. I can generate this for past year (pre-ashp) and also for coming winter.

This will give me comparison of gas heating versus ASHP on Cosy/HW. Would have been good to generate ASHP with Cosy/manual control to see HW benefit over me alone but was keen to try HW.

I will report back in the Spring. Cheers.

For a true comparison we need to account also for changes in electricity price as well as variations in severity of winter.  The question then becomes, how to normalise for changes in electricity prices.

Perhaps the measure is something like

Pence per degree day / OFGEM price cap price per unit.

This is going to be a rather small number so a bit meaningless to many!

I am assuming of course that there are no material changes in the 'target' IAT

This is more complex than it first appears!

@jamespa On top of which, maybe one should make allowances for: inflation, RPI, possible raise/drop in wages/pension, abandonment of WFA, I suspect that the CROSA factor (cube root of sod-all) might be factored in to cover all the above😉 Cynically, Toodles.

@jamespa hi James, you are right about internal temperature as I may have tended to increase the setting to enjoy the comfort (and convince my wife). An example of the Jevons paradox perhaps.

I was going to apply current gas and electricity standard variable pricing in my area to the kWh numbers (plus allocated standing charge across kWh used in the period considered) as I am trying to compare what the difference would have been under current weather and pricing with gas, ASHP/Cosy/me and ASHP/Cosy/HW.

Of course I could have gone onto a fixed term price tariff but there are only so many options I can look at.

Using price/kWh/delta T does not consider that more kWh could used by gas or ashp to hit the temperature setting so I will also look at total cost per delta T but I'll collect the data first.

First defrost cycle of the new heating season (LWT drops below RWT):

Note also how the 60min trailing COP drops from about four 12 hours earlier to about two. My heat pump does not like outside air temps a bit above zero. However, despite the OAT falling to two degrees, the inside air temp stayed constant.  

Has anyone done a self install of homely ?

or self installed  a planet device (I also couldn’t really find reviews )

They both look simple to install but seems behind installer login etc

Posted by: @pie_eater

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Has anyone done a self install of homely ?

or self installed  a planet device (I also couldn’t really find reviews )

They both look simple to install but seems behind installer login etc

In the case of homely, if you download the installer app you can see what it needs you to do software-wise, and they have a video or two on their youtube that shows how you wire in the modbus connections- I've not done it myself, but it looks rather straightforward, not much harder than wiring a three pin plug. On the software end you just enter the address (so it knows the local weather it should be looking up), the heat pump model, the capacity of the DHW tank, the min/max flow settings. I think that's about it. It does need a compatible heatpump of course.

Which Shelley? Shelly EM and a clamp? Or what?

To monitor power (as that's all you can do with Shelley no?).

I'm asking because there may be a 'Black Friday' [🙄] deal.