Yes I will share the installation photos - Dropbox
This is a 4kW Daiken Heatpump and 250L hot water tank, The Heat Pump pipes go into the garage at the side of the heat pump by the side door, then straight above into the cupboard where the hot water tank is in a cupboard upstairs above the garage.
I can see from this imageâŚ
âŚthat they have used a standard 28mm Honeywell Home diverter valve with the cylinder. In one of your other posts with this YouTube linkâŚ
âŚI could see on the heat meter that the flow rate was 1238 litres / hour, which exceeds the maximum capacity of that valve.
I would say this is some of your issue. This diverter valve would be suitable for the applicationâŚ
I just asked the Octopus engineer this question seem itâs not going to cause a problem.
No offence to the Octopus engineer, but he wonât know any of this information. I train installers on this stuff and consult on heating systems and hydronic design so I do know a bit more than the average fitter.
Indeed. Also plausible but I donât think it fits the symptoms.
Heat meter is three parts:
One of the probes is usually fitted into the flow sensing element
If the installer had fitted the flow sensing element on the return line from space heating, with the return temperature probe inside it; with the supply temperature probe in the supply line from the heat pump; you could get the situation where thereâs temperature showing AND compressor power being used but no flowrate.
This chart is a classic âas the temperature increases the water canât hold as much dissolved air and once bubbles start to form it trips out the ultrasonic sensing elementsâ format. Works OK up to space heating type temperatures but as soon as you start to finish the hot water off it throws codes and ceases measuring flowrate. (meters are configured for fiscal billing so err on the side of ânopeâ rather than âIâll try to guessâ)
It sounds like it isnât the cause of the sounds but it is an issue for performance monitoring.
What about the head office full of engineers and their own climate chambers and heat pump designs preparing these designs / kits for their installers to use? 
(rhetorical question - itâs fairly nuts for them to be using undersized valves given the number of installations under the belt)
Edit: equally if it really is only a 4 kW unit; does it need 1200 litres/hour or can that be usefully dialled back and the noise issue resolved with a few tweaks of the heat pump controls?
Totally agree. Iâm a big fan of Henryâs Law too. 
If you look how they have piped this up itâs not surprising this is happening with the heat meter on the return just after the connection tee where the space heating and DHW returns meet.
Lots of these systems are running DT3, so if the system had been running DT5 at 4KW then at best you would get away with it. As I said in my video, personally I donât think these valves are suitable (especially for mass heat pump adoption), as the fitters setting up the systems just arenât aware of the limitations of the components they are using, nor capable of the fine tuning necessary.
When itâs running a dhw program, look in I/O mask and take a note of the pump pwm %⌠it will likely be on 100.
Also, have a look in user mask and see what the deltaT itâs set for.
What size of Invertech?
Heating system designers/engineers will be though.
Running an installation business with lots of (minimally trained) surveyors and (minimally trained) installers; whilst relying on relatively few (trained) heating system designers/engineers at head office to write the right recipes/kit up appropriate parts - as Octopus do - youâd have thought theyâd avoid such basic boo boos via the recipes.
Perhaps theyâre just that penny pinching on the details they think itâs worth the saving of the cheap valve.
Sadly this isnât my experience and I have been part of many projects where the finer details have been overlooked by the designers including big manufacturers like Vaillant.
Differential shut-off pressures of motorised valves is a good example of this, where designers have seen that the valve has a Kv/Kvs value of say 8.6 and assume it can automatically deliver 8600 litres per hour, without fully appreciating the maximum shut-off pressure is much lower than the 100 kPa the Kv/Kvs value was generated with.
The V4044C is not much different in cost to the VC Series valve, but the application difference is night and day.
Looking at the installation photos @JustinUK has shown, the installation isnât terrible, but there are some very clear hydronic design faults including the position of the heat meter.
A (trained) engineer will do the sums/read the manuals.
A (minimally trained) installer/designer reading from a recipe by others will not be expected to.
The point I was hinting as is that Octopus et al are delegating too much work to insufficiently trained people. They should hire more folks who have been taught by folks such as yourself, kimbo betty, heat geek etc. But management wants to pay 30-50% less than market rate and keep their staff sufficiently untrained that they donât know enough to be able to strike out on their own/get poached by others; with predictable results.
Do some Vaillant units have sufficient residual head to force valves open? IIRC it was only 40-50 kPa residual head at the rated flow on those.
Others (especially name plate only de-ratings) have some jock off pumps with 120 kPa etc at rated flow. Potentially useful but should be used with caution for sure. Anything over 40 is liable to have cheapo radiator valves singing if nothing elseâŚ
Some of the Heat Geeks are designing open loop systems with ultra low system pressure losses, which means the residual head is generally more than usual. On a heat pump like the aroTHERM (where the pump seems to target a theoretical flow rate), you can see this is leading to system wide DT3âs on most of these systems on OEM and the designers had designed these systems for DT5.
A few of the side effects have been excessive radiator valve noise, etc, etc. It doesnât really help, when you have one Resideo/Honeywell manual states the 1"/28mm V4044C has a max shut-off pressure of 21 kPa another states 55 kPa?
curious you do not put these things on your lines to prevent water hammer
I was always taught to design things out correctly rather than add things to mask the actual issues.
Auto air bleeds like the one you have shown are only really any good at aiding with initial filling of the system, but can actually cause air ingress if they are left live in the system after this is done (especially when placed on the negative side of the pump/circulator).
With a heat pump you are better to use a microbubble separator on the flow (standard practice) or a vacuum degasser (best practice).
All extra costs Octopus probably donât want to pay for but more info about the degasser we sell/use is here - https://www.servitec-mini.com/
How long do you think youâd need to leave a!n actively powered unit fitted do degas a residential install of 250 litres or so?
never had problems with mine. it being installed for many years . mine is installed just after the pump on the top of an inverted âTâ that acts as an air trap. and it runs continuously when you charge the lines you hear air after 24 hrs it usually quiet. but will bubble for weeks of months before all the air is gone completely out of the system
Couple of weeks? All depends on the size of the vacuum degasser.
I was always taught to fit an isolator under them and isolate once the initial fill and commissioning was complete. As yours is on the positive side, it will cause less issues. All the systems I have designed and commissioned, the bulk of the air is gone after commissioning and the microbubble separator or the vacuum degasser can then left to remove the rest.
I have a vacuum degasser on mine, and my system is live here - HeatpumpMonitor.org
Going to move the heat pump
And fit a 28mm deaerator too
Drain out the system and refill it
Put more inhibitor in
Do you think that will fix it?
Ok they did a few more things today as well as drain the system out, as got the water hammer noises when the engineer was here which stumped him
Turned down pressure at the main tap to 2.5 bars
put on a few bits and pieces, donât ask me what they do I have no idea.
R&D are monitoring it, so am I - if there are any problems they will replace the expansion vessel on the tank.
More bits and pieces pics.
Filled it up with 3 of these
Deaerator fitted
Moved the heat pump
Fitted a few new bits and pieces in here and pressure guages
Do the charts look any better?
https://emoncms.org/app/view?name=MyHeatpump&readkey=bd99c02f463c065f0f7184a5c2eccadc
