Hi @jonathans 

The weather has been colder recently, so you should expect warmer radiators.

Where is your SensoComfort controller located? Is the controller or a wireless sensor in the main living area?

For expanded control to work correctly, the temperature sensor must be located, and measuring the temperature, within the main body of the building. If this is not the case then you will only be able to use weather compensation control.

Posted by: @jonathans

I have another question, this time about TRVs. I've seen many of the more technically minded posters saying that the TRVs should be left fully open, and that's what I've done until now. I'm guessing this is to prevent prematurely shutting the heat pump off by increasing the return temperature too quickly.

 

However, I'm tempted to try adjusting the TRVs (all mechanical, none are smart TRVs) as a way to lower temps in the rooms where I'm overshooting the temperature and thereby raise temps in rooms where the pump is slightly undershooting the desired temp. Is this just a bad idea?

 

The only internal temp data the heat pump gets is from our sensoCOMFORT controller, which is located in the room we use most (and which very consistently hits the desired temperature & stops there). So as far as the heat pump knows, it's doing a great job of hitting the desired temps.

 

The heat shifts around the house reasonably well, so none of our rooms are sweltering or freezing. Still, I wondered whether the TRVs are of any use here or if I would be better off just leaving them alone.

 

 

Hi Jonathans,

TRV's are used to control the water flow through a radiator and therefore can limit the output heat energy from the radiator. A TRV should therefore, rather crudely, control the temperature within a room.

Since you state that the temperature in the room where your controller is located, is being kept fairly constant, then it would indicate that the control system is working correctly and should not require any further adjustment.

In the rooms where the temperature is above the desired level you could use the TRV's to reduce the temperature to the desired level.

In the rooms where you are failing to achieve the desired temperature, you should check that both the TRV is fully open and also the lockshield valve at the other end of the radiator is fully open. If you still cannot achieve the desired temperature in all the rooms, then you would need to locate your controller in the coldest room, and then regulate the other rooms to the desired temperature. Remember to only close in valves when it is absolutely necessary, to ensure that you are getting the maximum amount of heat energy out of the heat emitters.

Just to be clear heat curves has nothing to do with the type of heat generator..I have gas boilers with heat curves on UFH as low as 0.1

Hi folks,

Here are some charts showing how things have progressed since the end of November (the data immediately after my mid-November commissioning had a big Storm Arwen-shaped hole in it). My various tweaks to the heat curve and weather compensation have yielded about a 30-35% increase in COP, which is very pleasing. Energy use is a little harder to compare but the trend is generally lower, and less spiky.

Notable dates in the data are:

Dec 27: I redid all of the external pipe insulation*
Dec 29: heat curve changed from 1.2 to 0.8
Jan 4th: adaptive mode switched on (weather compensation)
Jan 10th: heat curve changed down to 0.6**

I'm now trying an experiment with the heat curve at 0.6 and adaptive mode off, because that's a permutation we've not tried yet.

-Jonathan

* The installers didn't do the greatest job w/ that -- the outdoor insulation was EPDM (good), but it had tightly-applied zip ties squeezing it and causing gaps (bad), corners were not mitred well (bad), and wall thickness was either 15mm or 19mm (bad). I replaced it with 25mm-wall EPDM, and all joints and corners are taped and well closed. This alteration was inspired by an Ovo Energy thread (link), I think @hydros is a contributor to the information there and their pictures and @transparent's words were very helpful.

** Actually running with more like 0.7, which is what adaptive mode was setting

@jonathans Hi Jonathan, I've also got an Arotherm Plus 12kw, Sensocomfort, in a windy, exposed part of Scotland and use Home Assistant to monitor. I've got my heat curve down to 0.35 and averaging around 30kw per day use over the past couple of weeks. What're you using to monitor the COP? I've installed the VR921 gateway, Aqara temp sensors and a HA integrated energy monitor and I'm quite keen to improve the reporting.

@jonathans good spot. I did contribute to that post over on the OVO forum. I was initially a causality of a poor installer but after a lot of to and fro with the trial coordinator a new installer was appointed and a lot changed on my system, including the insulation. 

It looks like you are getting decent and predictable COP out of your system now. On your two graphs the second one, with ave temperature, the trace looks identical to COP in the first trace. I know they will correlate well but might be worth double checking you’ve picked up the right data. Could just be my eyes of course. 

@colin

All I'm doing to monitor COP is taking daily readings from the sensoCOMFORT for power consumed and environmental yield, then doing the maths on that. At some point I want to add an OpenEnergyMonitor device to report that data (& more) for me automatically. https://guide.openenergymonitor.org/applications/heatpump/

@hydros

Good spot with the graphs. I must have messed up the data ranges when I was updating the date range this morning. All good now and thanks for pointing that out.

Correct data below:

@jonathans How did you get on with expanded? I'm working my way through each setting with a HC of .4 currently, we're still getting solar gain so I'm tempted to sit with expanded for now then move to inactive once the really cold weather kicks in. Lots of differing opinion on whether expanded ultimately saves money or not.

@jwilliams89 We're quite satisfied with the performance we get from expanded and haven't seen any reason to tweak things further. It's settled on a HC of around 0.65, with only slight variance up or down.

Ramblings of a retired Sapper

@jonathans we have 2x6.5 aroTHERMs working together. On installation i was told just to run the system as set. Like you I am on the east coast in what was a 2 bed random rubble cottage 300 feet up overlooking the North Sea in Fife.we have over 40 yrs extended and upgraded but basically 4/5 bedrooms on about 1 level.

to put my comments below into perspective a few details and costs

prior to removing our LPG boiler in 2021 our costings were

£125 pm ELEC

£137 pmLPG

£65 pm )on ave) seasoned wood for wood burner our main heat source

£327 total each month this was before the massive jump in Elec/LPG

our wet CH system was installed in 1983 was micro bore and ready to be ripped out as we had a lot of trouble with rads blocking slow etc. due to the high cost of LPG we didnt run the central heating very often simply using a big wood burner 24/7 and the boiler for hot water, cooking was elec oven and gas hob

having just retired we were looking at future proofing the house and up grade the EPC so we looked at heat pumps and engaged a firm to install what was decided would be a 13kW heat pump. As we were fighting to complete to allow us to get the monthly payments available then there was a shortage of our size heat pumps hence getting the 2 smaller ones. - in the end a rush to complete which failed as we never did hit the time line and failed to get the payments  - not the end of the world as they reduced the payments to take into account the £7500 grant.

moving forward our total electric costings are £325 pm. 

However this covers the cost of recharging our EV and also allows for the power needed yo heat my wifes chalet office with an Air2air heat pump (in my day when it was my office the cost was ave £110pm

in addition and most importantly our house runs at 19.5/20 fall back 18 degrees (except the rear room which is 16.5 as we cannot fit in a large enough radiator due to a fully shelved library which I'm not going to move!

the original costs given were in the good old days when elec was 14.5 per unit!!

so i recon that I am about £1500 per year better off my property is constantly warm - i have 300 ltrs of piping hot water on constant demand and i have a new wet system well installed and working.

what I cannot get my head round is COP heat curve etc, having the for the last 20  working yrs we owned our own property management/letting agency in St Andrews I am not daft but i really cannot be bothered fiddling around tweaking this and that to scrape up a penny here or there. The system cost a chunk of  capital which as I am saving £1500 pc will clear itself in another 9 years but as it was capital i am just rebuilding it (or being honest investing it in cruises!!) rather than fiddle around inside the system i decided that I would look at the other end and try and drop the cost of the power being used

I therefore investigated ground based solar panels using one of my contractors who designed and installed  an 8kW solar panel system plus 9kW battery systemin the front field south facing, this was done with a interest free loan from the scottish govt and after allowing for the monthly payments we are currently making an average monthly  profit of £32 pm so basically covers one of my monthly DDMs to the utility company and once paid off i will be making an average of £103 pm (on .23p per unit)

Finally if you have follow this long ramble we engaged a professional EPC company (i used that term deliberately ) to have a new EPC written. It took her over 3 hrs do do a full check including checking all the double glazing units etc. the result was that we moved from a mid D to an upper B. This has a big advantage should we decide to ever move, if they ever get round to changing the model for EPCs which discriminate against heat pumps we could even hit an A  rate. Not bad for a 200 yr old random rubble cottage which those anti the system will tell you cannot be heated by ASHP