ASHP heating issues...
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ASHP heating issues / error code - advice very much appreciated

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Active Member Member
22 kWhs
Joined: 6 months ago
Posts: 1
Topic starter  

Good Morning,

I'm a new member to this forum after stumbling across it in my panic the last few weeks.

I moved into a shared ownership flat just over a year ago, I have a Mitsubishi Ecodan ASHP installed alongside a 200L indirect cylinder.

I noticed 3/4 weeks ago that I had a water at the base of my cylinder, which turns out there was a crack at the top of the stainless steel inner tank and it was running down the inside of the casing. New cylinder therefore needed.

Contacted the housing association that is the other half of my shared ownership, they would have nothing to do with advising engineers etc to assist with the installation and informed me I just needed to get some gas certified to install a new cylinder. After many a tear at the unexpected cost of this, my dad is an electrician and has a plumber he works closely with, we spent a about 2 weeks researching the best cylinder to replace it with so that existing pipework/connections didn't need to be changed too much and installed it.

Since the installation of the new cylinder my ASHP is not heating my flat or hot water. It is running and everything appears that it should be working, but my radiators don't get any heat to them at all. The immersion side of the cylinder works fine, so I have hot water that way. We have bled everything, and been running the ASHP on and off for a week now but still no heat. My dad and the plumber have tried everything but to no avail. Last night I had an error show up on the display of "check error 01"

I can't find any error codes like that on the Mitsubishi error code checker.

I'm just desperate to get some heat in my home, but really cannot afford to keep having all these different engineers come out to my home when I couldn't afford a new cylinder in the first place. What's even more frustrating is the lack of care of the housing assocation that own the other 50% when they have engineers they use for their rented properties. But because I am not a commercial entity they will not come and look/do work for me.

I just wondered if anyone had had any similar issues or had an idea of what the error code could be?

Any help/advise would be greatly appreciated.

Illustrious Member Moderator
13737 kWhs
Veteran Expert
Joined: 3 years ago
Posts: 4168

Welcome to the forum.

I cannot see an error 01 in the manual for an Ecodan, which may or may not be relevant.

When you say the heat pump is running, do you mean the compressor and fan? Have you checked the water pumps?

Some photos of your system may be helpful.


This post was modified 2 months ago by Mars

Reputable Member Member
2741 kWhs
Joined: 1 year ago
Posts: 149

Stab in the dark, might it be error P1?  This is the system lost thermistor value error. It can be reset in the settings -


Illustrious Member Admin
17018 kWhs
Joined: 3 years ago
Posts: 2341

@em_19 did you ever resolve this error?

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