New emonHP install with strange readings

I have had an ecodan installed and am getting the installers to put in emonHP bundle monitoring equipment.
They still have to come back and install the electric meters but they have the heat meter already installed.
Our first proper DHW cycle was recorded by this but I am confused by the output (below):

As you can see it looks like the HP is heating hot water from 02:00 (as scheduled) until just before 03:30 based on the flow and return temperatures. However although the power readings look correct at the beginning of the cycle they then seem to go weird, spike and then drop to zero at about 02:15.

Can anyone explain what might be happening?
I have a PUZ-WA85VAA and got the Kamstrup Multical 403 (up to 11kW) Heat Meter as part of the bundle.
The heat meter is installed on the Return with the arrows pointing in the direction of the heat pump.
The temperature probe on the Flow is in a Tee.

Additional information that may or may not be useful…
My wife says she heard creaking and cracking noises like our radiators and pipes were warming up at around roughly 03:30. This would match up with the end of the DWH cycle so I assume when the hot water was up to temperature the 3 port valve was switched and extra heat still in the circuit between the HP and valve circulated through the rads. It looks like this was picked up by the heat meter.

It looks like the heat meter not correctly measuring the flow. There can be a number of things which can cause this:

  • Low system pressure, try increasing to 2 bar
  • Air in the system
  • Sub optimal heat meter installation location

The heat meter should be installed on a straight pipe run away from sources or turbulence caused by valves, pipe fittings and pumps. It should also be installed so that liquid flows horizontally through the meter or upwards through the meter, not downwards. Could you share a photo of the installation location?

Here’s the emonHP installation guide which include manufactures instructions regarding the heat meter installation.

Thanks Glyn,
I think it may have been air or pressure related. I bleed the system when the 3 port was back to heating and increased the pressure back to 2.
This was the DHW cycle last night.

I’ll keep an eye on it but looks like it is working.

Great! That looks much better, out of interest what was the pressure? Over the coming weeks keep bleeding the system to try and make sure all the air has been purged.

This is my latest DHW run from last night (still waiting for electric meters to be installed):

Are spikes normal when the output has dropped in the later stages of the cycle? Feels like there may be some air trapped in the system but not sure why this would only happen at the lower output as surely the flow of water won’t have changed just the amount of heat transferred to it in the outdoor unit.

It also seems quite common to have that large single spike at the start. That and the initial fluctuations could be when the pump starts the water in the coil still being warm from the water tank. Will that effect my COP values once I have Input energy being monitored.

I’ve been watching our DHW runs since I had the electricity meter installed about 1 1/2 weeks ago.
My readings mostly make sense but I’m still a little confused by a few things.

Here is a DHW run from this morning:

I realise that the strangeness at the start is when the pump starts running there will be a warm bit of water in the coil in the tank and this goes around a few times messing with the flow and return temperature sensors. I assume this cancels our and doesn’t effect energy readings over time.

The next most immediately obvious thing is that towards the end of the cycle things get a bit more spikey with the flow rate and related to this the power output. It looks like he pump stops a few times as zero flow is read and one huge spike upwards. Any idea what might be going on here. It can be seen in my earlier post as well but there are much fewer upward spikes now.

Lastly the values seem only to be changing once a minute for the flow rate and flow and return temps until this spikier phase (from 02:38) when they appear to change every 10 seconds. You can see this easiest with the temperatures going from the jagged steps to a more smooth line. I don’t know if one reason for not seeing the spikes until the last part is that the value is being averaged every minute until that point.
This behaviour appears to happen for every run of the heat pump.

This spikey flow rate readings towards to end of the DWH cycle are due to the heat meter incorrectly measuring the flow. See my previous post for a list of things which could cause this:

Out of interest, could you share a photo of your heat meter showing the location that it’s been installed on the pipework?

This is what a DHW run should look like

See below for a photo. Sorry for the mess, haven’t tidied up the wires yet.

According to the instructions it looks like it could be too close to the 90 degree bend before it on the return. There is a Tee directly after it as well for the bypass. The bypass looks to be set to 2 bar as is the pressure gauge at the expansion valve.

I’m just a bit confused as to why it goes a bit random at the same part of the heating cycle and that it looks like the data update frequency changes at the same point. Should the values on the graph be updating once a minute or once every 10 seconds?

What could change about the flow once it gets up to the higher temperatures that would change things as it all looks good up to that point?

Sounds similar to things I experienced with my Sharky meter, ie it only started to foul up during mid to latter parts of hot water runs.

Lots of detailed replies in that thread about what happens when water gets hotter with cavitation and other things.

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That all sounds very similar. The fact that it seems to happen at around 50 degrees on a DHW cycle.

But what I still don’t get is why is there a corresponding change in the behaviour of the data going from 1 minute steps to every 10 sec spikes?

I’ve run the system at 50 degrees and manually set the 3 port valve and manually switched back and forth for a while. How much air noise is normal? I could definitely hear a tinkle of air bubbles every so often and more air movement every time I switched between DHW and heating. Might leave the pump on its highest setting for a while and see if things improve if more air gets out.

Another question I have is would there be any auto air vents in the outdoor unit? Our cylinder, pump, heat meter, expansion vessel etc are all in our cellar with the ASHP at ground level height above this. Is there any way for air to escape if it ends up at the unit? If not wouldn’t this get pushed back around when it turns on?

I don’t think there is an AAV in the outdoor unit as you’re not really supposed to be poking about in there.

What about bleeding the rads? Especially those at the top of the house? Any air in those?

Looks like I may have made things worse, probably by dislodging some air yesterday.

This is last nights DHW run:

The output power goes to zero around 02:30 but also strangely the data points change from 1min stepped to every 10 seconds but this time change back again towards the end of the run (the area I’ve highlighted).

I really want to understand what is going on with this change in behaviour of the readings being shown from the heat meter for both flow and the temps. How often is normal for measurements recorded in EmonCMS with the emonHP bundle with the Kamstrup Multical 403 heat meter?

It doesn’t seem right that this would change even if there is also an issue with air in the system or turbulence from the plumbing set up. Do the raw data points from the meter get sent through to EmonCMS or is there any processing that goes on in the EmonHP first?

Do we know of another setup on the Heat Monitoring Dashboard that uses the same setup as me that I can have a look at to compare?

I’ll give them another bleed later but would have though air in the rads would be stuck there and unlikely to make its way back round the return.

Also currently there is no heating going which might be part of the problem as air will never really get much opportunity to get out of the DHW circuit to rads. Maybe once heating is needed air will make its way out over time.

Ah ha!

I think my problem (or one of them) might be that the flow meter has been fitted in the wrong orientation.

If I’m reading the instructions correctly I think it is upside down.

Although this diagram seems to contradict that…

4 posts were split to a new topic: Kamstrup Multical 403 Erratic flow readings

I’ve rotated the flow meter and only got a little wet.

However here is the latest run (note there was a shower part way through which is why the temps dropped a bit on the middle):

Thanks Andrew, will review this and @JohnT’s with Glyn in more detail. We do have systems with Kamstrup meters that are performing fine e.g Mytchett Heat Geek so the question is what is causing the difference? and how to resolve without so much trouble for yourselves.