I’m running my Ecodan on identical flow rates as reported by FTC, but (indirect*) numbers from my heat meter suggest it’s more like 15 and 21 l/min. There’s glycol in my system, and I wonder if the Sika isn’t calibrated for that?
(*I’m inverting the maths to get the flow rate from the measured heat, SHC and dT)
Not quite the same symptoms as yours, but my unit had a wobble on Jan 20th, where the DHW kept stopping for some reason.
13:28 - compressor stops, CH pump switches on instead yet 3-port valve is still on DHW
13:36 - I turn it off-and-on-again, DHW resumes
13:56 - happens again: compressor stops, switches to CH pump, yet valve on DHW
14:00 - I increase pump speed from 4 to 5, DHW cycle resumes properly
No immersion. This is the only time I’ve ever seen this happen, and it’s not happened since. It feels like it was objecting to the low flow rate, but I have no idea if that’s the cause, or it just got confused.
It’s being services in 3 weeks. Will keep an eye on the flow rates after then.
We don’t have glycol in ours, is there some configuration in the FTC settings to let it know if there is or isn’t Glycol? AFAIK the OSM heat meter is set up to assume no Glycol.
I’ve just remembered that the OSM heat meter is on the return and the Sika flow meter is on the flow, just after the pump. Could that change anything? Can’t see how it would have that much of an affect.
My Sika is on the return just before the primary pump, on the pre-plumbed cylinder. The Sontex is also on the return, some way downstream of the pump. Unfortunately I’m not able to read flow directly off the heat meter, as it’s inaccessible.
I think the FTC6 wont let you disable the flow switch… I learnt this the hard way once, and Mitsi technical said… FTC5 is switchable, FTC6 not. It sort of makes sense… If the flow rate stops, or is very low, the system should shut down.
I don’t know that the flow meter is actually causing any problems it’s just going to be hard to convince Mitsubishi that the problem with my hot water cycles isn’t down to flow rate unless the flow they can see in MelCloud is right.
I don’t think it does and I didn’t think it was one of the things in the json model but it was one of the items in the cab file the employee was able to access.
Good point John, I hadn’t thought that the FTC6 could be different in this regard. My experience and reading is with regards FTC5 systems.
I don’t have flow switches installed. I do have flow meters installed on both my Ecodan FTC5 systems and when I first inherited the systems one of them had the flow meter disabled via the dip switch.
Sorry, I used the wrong word. I meant flow-sensor, not switch. The flow rate is on ‘running information’ code 540… you would expect it to be readable on the melcloud facility
@Timbones is your primary pump pulling water through the system rather than pushing? Is that normal and are there any advantages to having it on the return rather than flow?
I’ve just tried changing the angle of the Sika flow meter to see if that makes any difference. It didn’t.
Flow rates only ever seems to be about 12 l/m on low pump settings, 13 l/m in mid setting and 14 l/s on high.
The meter is straight after the pump so I’m wondering if that’s the issue.
Depends which way you look at it - it’s pushing water out to the heat pump. I guess this is “normal” as that’s how the pre-plumbed cylinder comes (with LLH). I don’t know if it matters which side the pump is.
It could be that the meter is affected by turbulence from the pump, but I don’t know.
Well after a bit more prodding and poking something I have done has improved things.
Not sure for certain but I removed the cable from the flow meter, causing the FTC to error, then plugged it back in and reset at the main controller.
Now it is giving the correct value, maybe done 1-2 l/m on what the OSM flow rate is.
I’ll keep an eye on it but leave it for a bit. There is some cold weather coming up so if my bad DHW cycles are going to happen again it is likely then. I can then get Mitsubishi to take a look again.
P.S. Annoyingly the Mitsubishi person looking at my data yesterday on MelCloud means my pymelcloud script can’t connect as it is being throttled.
So now I have sorted my FTC6 connected flow meter Mitsubishi support can see the correct values.
Their suggestion to fix the problem was to up the flow rate to 24 L/min.
Not sure why it would need to be right at the highest supported flow rate but thought I better give it a go to prove it wasn’t that.
Unsurprisingly the same pattern of flow temp collapsing to the same as return temp and eventually resorting to immersion is happening.
So I have asked them to explain what else could be wrong.
Since our Ecodan 8.5kW (Emoncms - app view) was installed in the summer we have been running without a hall radiator.
The old panel (no fins) radiator was obviously not going to be up to the job so I removed it and we bought a 600x1200 vertical type 22 radiator that then sat on its side waiting to be plumbed in.
So this has meant we’ve been running with reduced emitter output but to make matters worse our FTC6 main controller is in the hall meaning it would be running things hotter and seeing the effects of heating up later as this would have to spread from the other ground floor rooms.
As of 22nd/23rd of Feb I finally got the rad installed. Although I then had to replumb it after realising the installer had put the wrong coloured handles on the shut offs I connected to so the flow and return were the wrong way around (now fixed). I’ve also been messing around with balancing and replumbing our kitchen plinth heaters since then.
It looks like there has been some effect on the running of the system although it is a bit hard to tell as installing the radiator coincided with a significant drop in outdoor temperature.
However I’m a bit disappointed the improvement in our system hasn’t been more significant.
I’m at a bit of a loss as to what is now holding it back.
Is the heat pump too large, it seems to start cycling as soon as its trying to hit a flow temperature of 40C or less?
Is the hallway still too cold (need to insulate under the suspended floor) so the controller keeps the flow high?
Although I’m sure our emitters are still to small (especially those that are in play at any given time due to the bedroom TRVs closing down, all other rads are fully open)?
Do I need to balance better (maybe controlling the system pump to try to keep a ΔT of 5K or getting better lockshield valves especially on the towel rads)?
Could some of the settings be improved, especially the Auto Adapt ones?
Do I need to leave Auto Adapt longer to get to know the changed system (I’m not sure over how long it adapts for or if it is more reactive to the current conditions)?
Something else?
I’m never expecting my SCOP to be amazing as it is a heat pump added into an existing system but at the same time I would have thought it would stand a fairly good chance of being higher than it currently is as the fundamentals of the system don’t seem to be too bad.
Wousers here’s a good one Emoncms - app view!
Looks like they must have at least double the (in play) emitters that we do.
They have a very high flow rate but again I assume that’s because the emitters are dumping a huge amount of heat.
