Odd behaviour when hitting strong man on Daikin Hot Water Boost

JustinUK · 2024-05-11T17:35:05.981Z

I’m hoping to get the heating engineer out again to check this 3 way valve.

JustinUK · 2024-05-11T17:41:08.944Z

I tried to get tank up to 62 degrees this afternoon for legionella cycle.

Seems it cut out at 52 degrees and would not go any further.

Had to use the Eddi to get it up to 62 degrees by scheduling a boost session.

All happened around 1.30pm - 4pm today
https://emoncms.org/app/view?name=MyHeatpump&readkey=bd99c02f463c065f0f7184a5c2eccadc

JustinUK · 2024-05-11T18:48:47.898Z

Now that schedule is taken away. How do I schedule in the legionella cycle. They disconnected it at the immersion at the heatpump I believe so that the Eddi could control the immersion. Told it’s not possible for both to be connected at the same time. Though I am hearing different if the relay board is fitted to the eddi which I am trying to get them to do for me along with fitting the PT1000 sensors at same point the Daiken controller is using and again at the top of the tank. Along with the M5Stack M5StickC Plus to get data into home assistant.

I can no longer see the schedule, assume what was scheduled is no longer going to work now anyway. e.g. I put 2 hours at comfort level when rates on agile were lower this afternoon to do legionella heat up.

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ColinS · 2024-05-12T07:06:11.814Z

If the heat pump cant control the immersion then it cannot get to 60c for the legionella cycle. The HPmax temp ie without the immersion, is around 50 to 55c depending on the outside temp. So you have to depend on the eddi to get you to 60c now.

Using recycle only was just a way to simplify your operation to see how it is really working, and see if it is only cutting in when the tank temp drops by 10c. Its hard to advise further without a continuous plot of hw tank temp…
Can you check the position of the flow/heat meter …it shoukd be in the flow line between the heat pump and the 3 way valve?

Timbones · 2024-05-12T07:40:59.580Z

ColinS:

Can you check the position of the flow/heat meter …it should be in the flow line between the heat pump and the 3 way valve?

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

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

Timbones · 2024-05-12T07:44:39.945Z

marco has some advice for dealing with trapped air:

DHW cycle interpretation please Applications

It happens because unlike radiators there is nowhere for the air to hide (top of rads) and because it is hotter (more air dissolves out of water the hotter you get it). What can you try? Remove the air The system needs to be bled properly. Heat the tank HOT, then heat the radiators HOT, then flush all the air into the radiators by alternating between heating and hot water (heat pump off, pump on, cycle the diveter), and bleed the air from the radiators. Design it more robust to air Mounti…

ColinS · 2024-05-12T08:08:33.895Z

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??

Timbones · 2024-05-12T08:19:49.116Z

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.

TrystanLea:

This is a known issue. Ultrasonic heat meters are very sensitive to air in the system and will not report a heat value if air is interfering with the reading. Your heat pump will be producing heat, this is just a heat meter issue!

It would be worth making sure that your system pressure is above 1.5 bar and to go around the radiators bleeding any air that may be present. Do you also have a bleed valve on the hot water cylinder coil?

See this topic in particular:

Kamstrup Multical 403 Erratic flow readings Heatpump

Glyn and I have been going through the data here from the system we have access to to try and work out how prevalent this issue is. It does seem that it’s affecting a larger number of kamstrup units than we thought. 50% of kamstrup systems are not showing the issue, 22% of systems did show the issue early on but the issue has now resolved and 28% of systems still appear to show the issue to varying degrees. The Sontex systems do not appear to have this particular issue, at least not visibly, …

JustinUK · 2024-05-12T08:46:19.643Z

Hoping one of these show it

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Timbones · 2024-05-12T08:54:44.953Z

JustinUK:

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.

JustinUK · 2024-05-12T09:08:55.574Z

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?

JustinUK · 2024-05-12T17:07:49.154Z

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

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

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So surprised there is spike in heat just now.

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ColinS · 2024-05-12T18:08:35.979Z

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

ColinS · 2024-05-12T18:26:00.279Z

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.

JustinUK · 2024-05-12T18:47:24.170Z

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.

JustinUK · 2024-05-13T07:41:00.219Z

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

Timbones · 2024-05-13T07:49:44.982Z

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°

JustinUK · 2024-05-13T08:21:07.793Z

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

ColinS · 2024-05-13T19:20:24.480Z

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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…

KnightPhoenix · 2024-06-09T23:23:51.339Z

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.