Mitsubishi Ecodan Controller

System

This discussion was created from comments split from: Mitsubishi Ecodan. Hot water but not heating. Help!.

Pec123

My Controller has gone 31/08/25 I have no idea when they are coming:

I am writing to report concerns about Mitsubishi Electric UK’s aftercare support for their Ecodan air source heat pump systems. I believe their conduct may warrant investigation by Trading Standards.

I have experienced:

•     Repeated delays in appointments

•     Poor communication and lack of follow-up

•     Difficulty accessing qualified engineers for repairs

•     A complete absence of support

These issues have caused significant stress due to no hot water and no heating. I have made multiple attempts to resolve the matter directly with Mitsubishi Electric UK, but have received no satisfactory response.

I believe this may constitute unfair trading practices and a failure to deliver services as advertised. I am requesting that Trading Standards investigate whether Mitsubishi Electric UK is in breach of consumer protection laws.

Spoonie_Turtle

Pec123 said:

My Controller has gone 31/08/25 I have no idea when they are coming:

When you say the controller has gone, do you mean it's lost connection?  If you have a thing on the wall with a wifi symbol on it near your cylinder, you might be able to press it to reset - but I can't get in our cupboard to show you a picture of ours, and I can't be 100% certain.  But the person who came out last time our controller disconnected, just did that.  (Thankfully at the Housing Association's expense, would have been SO annoyed if we'd had to pay for something we could have easily done if there were any instruction manual anywhere instead of everything saying ~contact your installer~ 🙄)  HOWEVER I can't remember if we still had hot water, I just know we were cold. 

matelodave

Pec123 said:

My Controller has gone 31/08/25 I have no idea when they are coming:

I am writing to report concerns about Mitsubishi Electric UK’s aftercare support for their Ecodan air source heat pump systems. I believe their conduct may warrant investigation by Trading Standards.

I have experienced:

•     Repeated delays in appointments

•     Poor communication and lack of follow-up

•     Difficulty accessing qualified engineers for repairs

•     A complete absence of support

These issues have caused significant stress due to no hot water and no heating. I have made multiple attempts to resolve the matter directly with Mitsubishi Electric UK, but have received no satisfactory response.

I believe this may constitute unfair trading practices and a failure to deliver services as advertised. I am requesting that Trading Standards investigate whether Mitsubishi Electric UK is in breach of consumer protection laws.

I'm not sure that spamming multiple threads is going to get you very far especially if you want a reply as any comments will get spread all over the place. 

TBH we don't really want a rant against the supplier/manufacturer sent all over the forum just because you feel aggrieved. There's not a lot we can do about it and its not going to help you or anyone else sort out the problem

If you have a problem, then open your own thread outlining the situation (preferably without all the emotion) and you might get some useful comments to help you solve it.

Pec123

matelodave said:

Pec123 said:

My Controller has gone 31/08/25 I have no idea when they are coming:

I am writing to report concerns about Mitsubishi Electric UK’s aftercare support for their Ecodan air source heat pump systems. I believe their conduct may warrant investigation by Trading Standards.

I have experienced:

•     Repeated delays in appointments

•     Poor communication and lack of follow-up

•     Difficulty accessing qualified engineers for repairs

•     A complete absence of support

These issues have caused significant stress due to no hot water and no heating. I have made multiple attempts to resolve the matter directly with Mitsubishi Electric UK, but have received no satisfactory response.

I believe this may constitute unfair trading practices and a failure to deliver services as advertised. I am requesting that Trading Standards investigate whether Mitsubishi Electric UK is in breach of consumer protection laws.

I'm not sure that spamming multiple threads is going to get you very far especially if you want a reply as any comments will get spread all over the place. 

TBH we don't really want a rant against the supplier/manufacturer sent all over the forum just because you feel aggrieved. There's not a lot we can do about it and its not going to help you or anyone else sort out the problem

If you have a problem, then open your own thread outlining the situation (preferably without all the emotion) and you might get some useful comments to help you solve it.

The thing is they are still marketing it and people need to know that some people have quoted months until it was fixed, they have a very bad problem at the moment getting engineers. They are spending all the money advertising and shows when there are a lot of people in the same situation no money spent on their diamond service warranty. Not worth the money it is printed on. I could not believe it until I have just read all the reviews. Now I am worried I won't have heating through the winter months. Nobody cares.

MSE_Stephen

@Pec123 We've split this into a new thread for you.

Pec123

I’ve been dealing with a nightmare situation involving my #Mitsubishi #Ecodan air source heat pump. No hot water, no heating, and their support team keeps fobbing me off.

I’ve tried calling, emailing, and even escalating—but nothing. I’m now considering reporting them to Trading Standards.

Has anyone else had similar issues? Any advice on how to push for repairs or compensation?

Let’s share experiences and help each other out. This can’t be normal.

NedS

Pec123 said:

I’ve been dealing with a nightmare situation involving my #Mitsubishi #Ecodan air source heat pump. No hot water, no heating, and their support team keeps fobbing me off.

I’ve tried calling, emailing, and even escalating—but nothing. I’m now considering reporting them to Trading Standards.

Has anyone else had similar issues? Any advice on how to push for repairs or compensation?

Let’s share experiences and help each other out. This can’t be normal.

What did your installer say? That would be my first port of call and I'd expect them to deal with the manufacturer for any warranty claim.

Pec123

Installer said out of warranty sorry. Long story short. Paid £309 for a field report from #Mitsubishi:

"System: 8.5kW heat pump connected to a Telford Tempest cylinder with third-party pump and zone valves

• Issue: Main-RC was blank; system not functioning

🧪 Inspection Findings

• Main-RC was being used as the thermostat

• Surge protection device indicators were green

• Heat pump connected to B32 RCBO; immersion to B16 RCBO

• Loose cable in airing cupboard taped at the end — needs securing in a junction box

• FTC box had a fuse cover incorrectly fitted

• Immersion heater is 16A but wired through a 13A fused spur — needs upgrading

• Rotary isolator was broken and incorrectly fed from above — requires replacement and correct installation

• Fuses F1 and F2 inside the heat pump were blown — replaced

✅ Works Carried Out

• Continuity testing of all system cables — all passed

• Reassembled and tested rotary isolator and control board — passed

• Verified correct voltages and polarity at S1, S2, S3 terminals

• System successfully booted after isolating third-party components

🔁 Recommendations for Follow-Up

• Replace or test:

• Heating zone valve (OUT13)

• Hot water zone valve (OUT4)

• Third-party pump

• Two zone valve heads

• Upgrade immersion heater switch from 13A to 16A

• Install a new rotary isolator, fed from below

• Secure loose cable in airing cupboard into a junction box"

Contacted Installer who are not happy with Field Report because they disagree with the following:

"Upgrading the immersion heater switch from 13A to 16A can work with your house wiring if the existing cable is rated to safely carry the higher current. Here's what you need to consider:

⚡ Electrical Compatibility Checklist

• Cable Rating: The cable feeding the immersion heater must be rated for at least 16 amps. Typically, this means:

• 2.5mm² cable is suitable for up to 20A depending on installation method and length.

• If your current cable is 1.5mm², it may not be safe for 16A and would need upgrading.

• Circuit Protection: Your report shows the immersion supply is protected by a B16 RCBO, which matches a 16A load. That’s good—but the fused spur is only 13A, which is undersized for a 16A immersion.

• Switch Type: You’ll need a 16A rated switch or isolator, not a standard 13A fused spur. These are available as:

• Unfused 20A DP switches

• 16A rotary isolators

• Dedicated immersion heater switches

• Installation Method: If the cable runs through insulation or is clipped directly, its current-carrying capacity may be reduced. An electrician should verify this.

✅ Recommendation

Before upgrading, have a qualified electrician:

• Inspect the cable size and route

• Confirm the cable can handle 16A safely

• Replace the 13A fused spur with a suitable 16A switch

This ensures compliance with wiring regulations (BS 7671) and avoids overheating or fire risk."

The original installer is coming round to check his work and to do the remedial work according to the field report and get the system up and running as it had done since Nov. 2023. Installer hoping to get us a refund for £309 call out fee from Mitsubishi Ecodan. This leaves me wondering if our system will be safe (if installer disagrees upgrading the immersion heater switch from 13A to 16A) 

QrizB

Pec123 said:

This leaves me wondering if our system will be safe (if installer disagrees upgrading the immersion heater switch from 13A to 16A) 

It would be unusual to have a 4kW immersion heater that required a 16A supply.

Most UK domestic immersion heaters are 3kW and are correctly supplied by a 13A fused spur.

Pec123

This is the installers reply:
Please see attached photo of an equivalent immersion heater as fitted to your cylinder, from the label you can see its rated at 3kw at 240 volts or 2.7kw at 230 volts from this we can calculate the amperage of the immersion.

 

To calculate amperage, you use the below calculation and from Mitsubishi’s report we know you have 242 volts.

 

Watts divided by voltage= amps

 

3000 watts / 242 v = 12.4 amps

 

Based on this the 13 amp fused spur is more than sufficient for the immersion heater fitted furthermore had the immersion had exceeded its 13 amp rating the fuse within the 13 amp fused spur would have blown leaving