Just over 2 weeks since my gas boiler swapped out and a Vaillant Arotherm+ 7kW put in its place.
At the moment I’m interested in what’s going on with the hot water cycles, and whether the emonhp kit is reporting ok.
Today’s DHW cycle looks like this, and I don’t understand why the return temp is sometimes higher than the flow temp. It’s as if there are a few false starts when heating up water. And then something strange happening from 12:13 onwards too. Is this usual?
Return temperature is initially higher as warm water from cylinder coil is “flushed out” by colder water from heat pump
Flowrate ceases being measured later in the cycle due to dissolved air in the system
1 Like
Is it a problem for there to be dissolved air in the system?
Air in the system leading to erratic flow readings (and subsequent poor heat meter output into emoncms) is the most common of problems.
You’ve gotta get that air out of the system.
Ok, thanks. Had seen other thread, but wasn’t clear whether it was same problem. Had noticed gaps in indoor temperature sensor every DHW heating cycle before, but not the gap in heat being reported.
Will let installer know and try bleeding radiators after next anti-legionella cycle - might be tomorrow afternoon. Starting at top of house. Then top up pressure. Pretty sure we started with 2.2 a week ago, and now it’s dropped to 2.1.
Update:
Rather than starting with bleeding radiators, and on advice of installer have opened the auto airvent on the hot water side of the diverter valve (it was leaking a bit occasionally), and he has talked me through putting the whole system in an air purge cycle over the phone.
Will leave auto airvent open until after tomorrow night’s anti-legionella 60 degree cycle. And then if I have time will bleed radiators Wed morning.
1 Like
Thanks @SianiAnni let us know how you get on with it, hopefully this will clear, it can be a bit tricky sometimes to get all the air out.
The heat metering is still misbehaving, but I think only on the DHW cycle, so I’m disregarding the heat generated data for the time being, but I wonder if anyone else is seeing this kind of semi-regular glitch?
The electricity metering is detecting small amounts up to 100W, not every day, but it nearly always happens sometime between 11am and midday.
The DHW cycle is scheduled for 12-3. There have been a couple of days in August (4th, 7th) when the DHW cycle hasn’t run at all.
I thought initially perhaps it was down to using hot water, but a couple of times it has happened when the house is empty, and also sometimes when I know I’ve not been near a hot water tap.
Any ideas? Could it be heat meter related?
Hi Sian,
I’ve had a look at your data, and it looks like there’s still air in the system which is causing the heat meter to throw an error during a DHW cycle:
We’ve recently published a guide on the best practices for removing air from a new heating system: https://docs.openenergymonitor.org/heatpumps/removing_air.html
Thanks Glyn. Will take a look at this, and see what the next thing might be to try 
Do you think the little late morning glitches are anything to do with air in the system? Where the arrows point in the first screenshot?
Sitting at my desk I just heard a clunking noise coming from the ‘plant cupboard’ and the glitch is showing on the graph.
Yes if you can hear clunking or gargling noises this is a very clear indication that there’s air still in the system. The errors with the heat metering are certainly due to air in the system.
1 Like