@johnmo

Once you have the heat meter readings going in then hopefully you should be able to get the fully interactive read out (same as the heatpumpmonitor.org view) by clicking on 'Apps' and 'MyHeatpump' rather than having to look at the setup window. 

Admittedly all of mine was pre provisioned by OEM and installed by my installer when the heat pump went in so no setup required from me. Once the hardware was in and powered up it all worked straight out of the box. (As you already had the heat meter I imagine you'll need to get that data feed setup correct)

I did have a quick look at the OEM forums to see how to make the DHW flag work. Sounds quite simple if you're running a properly low flow temp heating circuit (e.g. UFH) as it could just look for flow temps higher than a threshold. Alternatively, looks like some are monitoring the 3 way valve position. 

I decided I wasn't going to worry about it in the end! 

I'm very happy with the level of detail I can get out of it, much nicer than just having the manufacturer's calculated SCOP and nothing else. Will allow monitoring for cycling etc. Just a shame that with accuracy comes cost - the heat meter in particular isn't cheap...

Thanks for above. Still waiting for the MBus communication card for the heat meter (due next Monday). So will be next week before I can play properly. But with the electric meter only and doing cooling I have already spotted room to improve. But could do with seeing the whole picture before making changes.

@johnmo I just realised you are going to be doing something similar to what I did, in hooking up a heat meter to my existing emonpi. Getting the two to talk together required a bit of tweaking, here is the thread I started on it with the solution. Hope you find it useful (or maybe hope not, if you manage to get then talking without a problem :-))

https://community.openenergymonitor.org/t/rusty-with-raspi-but-trying-to-set-up-mbus-to-read-sontex-789/23464

Posted by: @bontwoody

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@johnmo I just realised you are going to be doing something similar to what I did, in hooking up a heat meter to my existing emonpi. Getting the two to talk together required a bit of tweaking, here is the thread I started on it with the solution. Hope you find it useful (or maybe hope not, if you manage to get then talking without a problem :-))

https://community.openenergymonitor.org/t/rusty-with-raspi-but-trying-to-set-up-mbus-to-read-sontex-789/23464

Thanks

That's the monitoring all hooked up and appears to be working, just need the heat pump to start up to see what it does. It drops to 8 degs tonight so it should start up.

So heat pump ran a few cycles over night. Temp dropped to 9.5 degs.

Interesting is CoP when running average was just under 6, with the first run about 6.1. However due to averages and a CoP of zero or less due to no heat output and standby electric consumption when not running, the SCoP takes a hit and sits at around 4.5. so shoulder season (or rubbish September weather) and only a marginal heat requirement you take a SCoP hit. What the monitoring does allow is to make fine tweeks to see what really occurs. So far I have reduced compressor overrun temp by 0.3 Deg, this shortened run time, but more importantly reduced max flow temperature so gave a 0.3 uplift in CoP. It should also reduce the time between compressor cycles.

@lucia Back to finances! 
we are at the very beginning of the control journey all to reduce electricity bills. For us the key question is when and how to charge our battery.

We could choose to use Ovo’s heat pump tariff (15p at present) since we have a Vaillant pump being fitted, and at present it only works with Vaillant. But that isn’t optimal for us since we are a heavy electric user outside of a heat pump, and only the heat pump consumption is at the low price everything else is at std. With that tariff we would have no benefit of a battery since we can’t charge it at a low rate, and that would be a problem for us.

We have chosen Octopus Cosy for now, and are controlling it through the web based Octopus R&D app (free and took minutes in total to set up). But it only works for batteries with an available API (GivEnergy for us and I believe Growatt(?)).

At present the low rate on Cosy is 11p so 8 hrs of our ashp will be charged at that. Then we use what the battery has in stored charge and when that is depleted we are on the day or even peak rate.

I have modified Michael de Podesta’s spreadsheet from https://protonsforbreakfast.wordpress.com/2023/11/01/heat-pumps-cop-envy-is-pointless/ to take account of our house characteristics, electrical loads and battery size and concluded that our average  cost per kWh is ~25% more than the Cosy low rate. MdeP has done a smashing job of working out the distribution of UK temperatures and hence impact on SCOP for different house thermal characteristics. 

The key to all of this post is a battery that you can control via an API. No Python coding needed!

Been getting some useful feedback from the monitoring system.

The monitoring system monitors all electric inputs, so controller, circulation pump, valves and heat pump etc.

I can set the the circulation pump in several modes and have found just leaving it to run, works out best and only a few Watts more than other modes. While in standby the flow rate reduces down considerably.

Mild weather running - very low heat requirement

Prior to installing the monitoring equipment

heat pump run time was around 30 to 40 mins, CoP was around 6 to 6.5. The off period was several hours. Intuitively you would think this is best, but the standby time (CoP around zero) overwhelms the good CoP, so the daily CoP is closer to the 3.4 with only 1x DHW Cylinder heat.

Some playing with setting to reduce run time to close to 10 to 14 mins has almost no effect on CoP while running, but because you are adding less heat, the heat pump restarts sooner. The more equalised run time results in a CoP 23% better (while being 2 degs cooler outside), so have managed to get it up to 4.4 this including 2x DHW cylinder heating. CoP of 4.4 is made up of 3.68 for DHW and 6.37 for space heating.

Still a work in progress, but moving things in the right direction.

Good info @johnmo Are you using a calculation to achieve the COP or does the equipment do it for you? What is the total current for the ashp+pump? What is the standby current?

 The App gives you the CoP data, you can see instantaneously CoP, it uses a CT clamp on the 3 port valve to detect when it's seeing DHW heating and it logs the different CoP for DHW and central heating. It also shows a SCoP for each day, week month etc.

Standby with circulation pump running is 53W and without 35W

Screenshots - run from an hour ago. And a days data with a bit of messing about on behalf.

Got the cycles to about 15 min on and 30 to 40 mins off. But although giving a decent CoP the energy used was high, because I believe the quality of heat delivered was poor. To much heating a bulk of water, pipes etc with little meaningful heat delivered to the floor.

Have set to run without weather compensation for now.

@johnmo I did consider asking if you had found overall heat demand / electric usage had increased when you had reduced the cycle time but increased overall "on" time (despite overall COP improvements) when you first posted it - but couldn't work out how to phrase it without coming across negative/unhelpful. Everything I've been looking at for my own unit seems to have people chasing the longest possible cycle times (albeit in peak heating season).

For me I'm only really currently interested in the "while running" figures on my own installation at the moment as the unit is predominantly in standby, and that's a reported standby electricity usage of ~10W. 

At 35 W standby I can see how the "off" periods will impact the daily figure. 

As this will be our first winter (unit installed in May) its still hard to let our old habits die, as such only DHW runs at the moment. Finding the internal temperature is only really dipping to between 18C and 19C when we have a day or two of all day drizzle and gloom. Will be interested to see how the forecasted dips to single digits overnight later this week will impact things!

Recently switched onto Octopus Cosy as it does feel like the summer has ended! I'm holding off for now switching on the weather compensation (which I will want to fine tune when I have some proper heating demand) and have set ours to run in Vaillant's "expanded mode" where it only comes on as called for by the controller acting as a thermostat and it then modifies the weather compensation curve depending on how far away from the target temperature it is reading.

It'll be interesting to see how long I can get away with just running some heat in during the 3x cheap periods this tariff provides!  Although the ability for truly scientific experiments might be limited by how the willing test subjects family react...