Mitsubishi Ecodan 11kw Defrosting Issue.
Hello, i am new here and also a newbie on air to water heat pumps.
I recently bought a Ecodan / Zubadan split system manufactured 2019 and installed 2021, it was too cheap (500€) so i could not help my-self from buying it and try to get it working. Outside unit is Zubadan PUHZ-SHW112YAA with the pre plumbed inside unit EHST20C-YM9CR2.UK.
I installed it in June and found lots of small problems, outside unit dip switches configured wrong and also some settings in the FTC5 controller that made it run really inefficiently, when i first got it running the COP was about 2.0 or worse even tho it was summer and warm weather. Then made some changes to the settings and got the COP up to about 3.2 and that was not too bad, now when the weather has become colder the real problem started to show.
When the outside temperature gets below 0 degrees C the defrosting seems to have some weird issue. I saw that the unit had frost on it so i waited until a defrost cycle started and it worked fine, but then when it got even colder to about -4 to -6 degrees it defrosted many times every day and i noticed that the defrost cycle is much to short so it just starts to melt the ice then stops and resume with the heating causing the unit to freeze completely in a day or two.
My first guess to the problem would be the 4-way valve but i really cant see how that could be the issue when it clearly do go in to defrost mode but mostly seem to "finish" the cycle in well under 10 minutes which seem to be a very short defrost cycle.
So now with the colder weather the outside unit is frozen and the COP goes down under 2 and won't completely defrost until the ambient temperatures are just below 0
Here are some Melcloud and SD card graphs.
Could this be a sensor problem or something else? Grateful for any advice on this issue.
And greetings from Finland.
I had a problem with my ecodan unit freezing up having to literally put a hot air gun on Christmas Eve at 10pm 2 years ago.
Took various engineers over a month to sort out.
Low and behold after all the headaches it mounted to a dodgy temperature sensor mounted at the outside or the outside unit at the rear.
Basically it was sending the wrong signal.
good luck
@westkent Thank you for the info, this was exactly what i was thinking about. i have a Beamex temperature calibrator and a dry well temperature generator at hand so i will check the service manual what kind of thermistors they use and then check the temperature curve and compare with the manual. Best to check them all as they seem prone to failure / drifting.
I did not have the time to check the thermistors Yesterday but i am now almost certain that's the problem. I enabled the cooling function on the heat pump and manually "defrosted" the unit by cooling the home. Worked great, had it on about 12 minutes and all the ice was gone.
At least the 4 way valve should be ok, worst case there is low refrigerant but would not bet on that as the pump both heat and cool very good.
Also i noticed that when using weather compensation i got really bad COP, then when using room auto adapt i got much better COP which also points to the outside unit thermistors.
This weekend i will test ALL thermistors and hopefully find a faulty one.
@thundermink can you give us an update on your tests?
Pre-order: The Ultimate Guide to Heat Pumps
Subscribe and follow our Homeowners’ Q&A heat pump podcast
@editor Sorry for the slow reply, it looks like a happy new year to me. 4 days ago it was a bit warmer so i got to start trouble shooting a bit more, i noticed that if i completely shut down the system the LEV electronic expansion valves open fully, then the unit defrosted ok for a while so and i started thinking if it is the valves that skip some steps causing the defrosting issue over time when the valves misses steps and is in the wrong position.
I removed the valve heads and noticed one was not fully in place and another one was stuck to the valve body so i sprayed some wd40 to loosen it and then cleaned the stepper motor coils, also the cables was zip tied to the copper tubing and the cable shrink seemed to have shrinked and caused very much tension on the valves wich also can have been why one of the valves was rotated out of place, 4 days now and no problem, it has not been too cold yet but it is now -4 degrees C and i have not seen any frosting what so ever on the outside unit. Also the COP is much better so it seems that this has worked. Still need to wait and see how it behave the coming days as colder weather is on its way (friday forcast -11)
Hopefully the system will work 100% for the rest of this winter 🙂
-
Ecodan consuming 100kwh per day in new build!!!
3 weeks ago
-
Efficiency Concerns on newly installed Mitsubishi Ecodan 8.5kW
3 months ago
-
Ecodan 11.2kw Wireless thermostat drop outs
4 months ago
-
Mitsubishi Ecodan System Pressure Changes - An Issue or Expected ?
4 months ago
-
Transforming a Derbyshire Property into an Energy-Efficient Haven
5 months ago
Currently viewing this topic 1 guest.
- 26 Forums
- 2,118 Topics
- 46.6 K Posts
- 85 Online
- 4,523 Members
Latest Posts
-
RE: Double or Triple Glazed Windows?
If you get windows replaced, then I think it's well wor...
By robl , 12 minutes ago
-
RE: Help me keep the faith with my air source heat pump installation
They could hang a secondary CU off the existing ASHP MC...
By JamesPa , 56 minutes ago
-
-
RE: Heat Pump Books For Beginners – Bodge Buster & From Zero To Heat Pump Hero
@topher you’re more than welcome to, yes. I’ll send you...
By Mars , 19 hours ago
-
RE: Fitting new shower valve ..........
I’ve never taken a chance when fiddling and changing ou...
By Mars , 19 hours ago
-
You should contact the council and report the unsatisfa...
By JamesPa , 23 hours ago
-
RE: Benefits of an extra horizontal loop for GSHP
I would deffo install an additional slinky run, especia...
By Transparent , 1 day ago
-
RE: Say hello and introduce yourself
@editor fab - thanks Mars, and keep up the great work o...
By normpang , 1 day ago
-
RE: Compressor and Evaporator Stratification
@trebor12345 So I think the 1st zigzag section shows so...
By ASHP-BOBBA , 2 days ago
-
RE: Is this just haze or something more?
@majordennisbloodnok I was giving a talk to primary sch...
By Toodles , 2 days ago
-
RE: Tesla Powerwall – More of a ‘Luxury’ Than an ROI Winner!
We had our Tesla Powerwall 3 (and Gateway) installed ea...
By Old_Scientist , 2 days ago
-
Indeed. With a battery its presumably the battery con...
By JamesPa , 2 days ago
-
RE: No-code, plug-and-play monitoring for your heat pump
To update an ESP device using ESPHome in Home Assistant...
By Grantmethestrength , 3 days ago
-
RE: The good, the bad and the not that great – my heat pump installation
Said I would pop back with a update. Only Mr Jesus h...
By Burtis , 6 days ago
-
RE: Buffers, hot water and cooling
Thats presumably heat pump DT, what about radiator DT a...
By JamesPa , 6 days ago
-
RE: Who's your electricity provider and what's your tariff?
@chandykris Exactly the same here. We now have 13.5kWh ...
By Old_Scientist , 6 days ago
-
RE: Wood burner with ASHP - direct air?
This depends on the size of your wood burner and size/t...
By Lucia , 7 days ago
-
RE: Difficult positioning of air source heat pump
@rikiarn It's a not a buffer it's a volumiser which is ...
By Lucia , 7 days ago
-
RE: Is your heat pump insured?
To make things clear, lots of insurance companies cover...
By Lucia , 7 days ago
-
RE: Boxt Heat Pump Installation Experience
@adrian any updates since installation? How is it perfo...
By Ashfp , 1 week ago