Odd behaviour when hitting strong man on Daikin Hot Water Boost

It looks to be on the return pipe, just after the two circuits rejoin, and before the mag filter.

Is there a way to bleed air out of the hot water circuit directly?

marco has some advice for dealing with trapped air:

What puzzles me though @Timbones is why the flow readings are zero for considerable periods when we know there is flow - wouldn’t you expect a lower and erratic reading with trapped air? but not zero??

The charts for this system match those from many others we’ve seen here with trapped air; it seems to be a common problem. The kamstrup in particular will report zero flow and an error code instead of a partial reading.

See this topic in particular:

Hoping one of these show it









Those pictures do not show the heat meter. It is actually positioned beneath the volumiser tank. See post #62.

1 Like

OK thank you, that’s in the garage then with the hot water cylinder directly above in a cupboard.

Colin do you need anything else or will the picture on post 62 do?

eddi came on earlier today to heat the tank during agile price drop as programmed.

So current temperature showing as 61 degrees on the tank and 26 degrees in the house, yes it’s toasty today :slight_smile:

So surprised there is spike in heat just now.

That’s not a heat spike from the HP but just your house and the piping getting warmer together as it warms up outside.

1 Like

The last time your HP heated the HW was at 14:20 yesterday. With the Eddi/solar doing all the work today then it has not needed to come on again. Taking it off schedule and just relying on reheat was the right thing to do and I would leave it at that for the moment. No point forcing a schedule heat up if the tank has been warmed by the solar. It seems to be working as planned.

Now the HP should only come on again once the tank temp has dropped by 10c below the rheat SP of 43, ie it drops to 33c… if you use no HW then that might take a couple of days without the sun shining or for much longer with sun shine. If you use a lot of HW then the HP might kick in earlier.

Even without the heat meter reading we can see it is working by seeing the flow and return temps rising. Generally the HW cycle runs at a fixed flow rate ( call that F) so we know it is putting heat into the tank = F x (flow temp - return temp) x constant . The fact that the return temp is lower than the flow temp proves that the tank is taking this heat and heating up (otherwise the flow and return temps would both be the same as the tank temp).

If you are not taking HW out of the tank and it runs reheats frequently then we can conclude that something else is drawing heat from the tank… and you will need to find out what that is.

At the moment though it seems to be working as planned! only the heat meter is not registering … and the solutions for that are detailed above by Tim and others.

2 Likes

Thank you Colin for all your help.

The Eddi should only come on with grid price drops below 3p kWh on agile. I turned off the solar diversion as it works best to export to grid at 15p per kWh

Eddi would have topped up the tank today but this is not showing on heat pump monitor

Going to ask Octopus to purge system of all air see if that helps otherwise I suspect the heat pump monitor needs replacing as they say they have faulty units.

Yes there was a temperature drop last night from around 60 degrees, to 40 degrees overnight. Seems somethings going on.

Was any hot water drawn through taps in that time?

Remember, the temperature sensor is usually at the bottom of the tank, so it doesn’t take much to make the tank appear to be colder when the water at the top is still likely to be close to 60°

1 Like

That’s a possibility, but would not have thought much water would have been used overnight by the other occupants.


Well the heat meter worked for half of the hw heat up this morning. If we can believe the data it was running at about 7.9kw for that 15 mins at a COP of 4.59 - which seems OK to me.

Over the whole time the HP was running it must have put in about 3kWh of heat. I’m guessing it responded to a temp drop after a few morning showers before 08:50.

Looking at this and a few previous cycles it seems that the heat meter stops measuring the flow once the flow temp gets much above 40c.

So it seems Ok - if you can get the air out of the system…

I had a similar thing. One important thing to check if Octopus have filled and drained the system multiple times is that they put the inhibitor into the system after the last full up.

I had the same with my Kamstrup meter and 1l of sentinel x100 fixed the issue after about a week with the AAV’s open to allow all the dissolved air to escape.