Solved

Hot water and heating control with my Mitsubishi Ecodan Air-Source Heat Pump (ASHP)?

  • 25 October 2021
  • 81 replies
  • 13979 views


Show first post

81 replies

Just a little update on our noise issues, Hafod Renewables came back, this time with 2 different engineers who told me they actually subbed out the install to a plumber.  Within an hour they had improved the lagging outside and given me a guided tour of the Eco Dan Settings.

Both water pumps were set to run at 5 (max) and now with them both set to 3 the noise level is greatly reduced and their is no whoosh of water when they start, so we aren’t woken when anti freeze kicks in (he also dropped the anti freeze temp to 3 from 5). We have a large 11.2 kw ASHP for our 4 bed house but he said a smaller 8 kw ASHP would need to run at 5 to keep a 3 bed house warm.

The water tank was incorrectly set as medium size when we have a large which has 2 temperature sensors not one like the medium.  This sorted the issue with a huge temp drop which didn’t cause the water to come on.  So pretty much all sorted and happy now thanks.

I do have one other question about insurance cover.  I’ve just had a weird conversation with my contents insurer who told me a gas boiler and presumably a ASHP is covered under buildings insurance because its fixed to the house and wouldn’t fall out if the house was turned upside down (their analogy not mine).

So did anyone else let their insurer know they now have a heat pump or was it the buildings or contents insurer?

Userlevel 7
Badge +4

No, we didn't tell our insurer about our heat pump. Any installed equipment will be automatically covered under your buildings insurance.

Userlevel 4
Badge +2

@christianedward what size hot water tank do you have? I’m wondering if mine has also been set up only using the bottom thermostat

@christianedward what size hot water tank do you have? I’m wondering if mine has also been set up only using the bottom thermostat

The water tank is a large which has 2 temperature sensors not 1 like the medium.

The controller was set to work with a medium so didn't heat the water when expected or possibly just showed the wrong temp on the screen leading us to think it should be heating when it wasn't.

Hi, does this look normal to you guys. Our hot water drops considerably within a few minutes of running our mixer shower.  Any help would be great. Thanks 

 

Userlevel 7

Hi @Oz182uk - thanks for posting this. 

 

Do you have an air source heat pump? Can you tell us a little bit more about your home set up and the issue, and I’ll know which members may be able to help...

Badge

Hi,

 

i am not sure if anyone can help with our mitsubishi ashp.

We moved in 2020 (new build) did not get shown how to use heating system. I have watched you tube videos but they are too general and do not really give me enough information.

 

I have ‘set it up’ best i can but feel were using a-lot of electricity but the house feels cold.  
We are 2 bed semi detached, underfloor heating downstairs, radiators upstairs and have thermostats in each room.

I have also contacted mitsubishi but they just sent me a general guide which didnt really help at all.

Thank you! 

Userlevel 7
Badge +1

Hey @haze146 !

Sure thing. Let me see if @M.isterW is around as I think he can figure this out better than I can.

Bear with us!

Userlevel 7
Badge +4

The first thing to do, if you haven't already, is find Heat Geek on YouTube and watch their videos on heat pumps. You're looking for videos about zoning, weather compensation and running at lowest flow temperature. While you're there it's also worth checking out what they have to say about hot water temperatures. I think @juliamc had a link to an article they wrote on the subject.

Userlevel 7
Badge +2

Possibly this one about legionella ? But all their articles are very informative. 
https://www.heatgeek.com/hot-water-temperature-scalding-and-legionella/

Userlevel 7
Badge +4

How are you running the system at the moment?

Badge

The outdoor install isn't much better with bare sections, gaps and gaping on the bends.

Should I try and get the installer back to sort these issues?

 

The pipe lagging should have no gaps but also it should be painted with Armaflex UV paint to prevent it degrading in the sunlight. The other problem which may cause a board fault in the future is that they’ve run the power cables into the top of the switch. Over time if the water seal degrades and a neutral fault occurs it will be an expensive call out for new circuit boards.

It’s summer here and hot; so haven’t used the underfloor heating since April.

Yesterday we had no hot water when we turned hot taps on. It’s was reading 16 degrees.

System automatically goes to immersion but doesn’t heat up either.

Turned U/F heating on and that works fine.

Had an electrician out tonight and he checked voltage over pump - none - checked spur and fuse has gone!

He then checked pump (attached to tank) and no voltage going to it - so where would supply be coming from?

Could it be a problem with the circuit board attached to tank?

Managed to get the immersion to turn on to get some hot water - but obviously not an ideal solution…..

EDIT: it’s the 14kw product

Userlevel 7
Badge +2

@M.isterW our resident ecodan owner ! Any thoughts ?

Userlevel 7
Badge +4

I'm no expert but it sounds like either a fault with the controller or the circulation pump.

 

Have you tried turning the water on from the FTC controller and Melcloud?

Userlevel 7

@Caroline2000 just to confirm, the electrician confirmed that the fuse (where is the fuse in a heat pump?) had gone. So it needs replacing does it? He also confirmed no power to the pump? How is the underfloor heating working if the pump has no electricity?

A heat pump needs an electric source. There are 2 13A spurs…..one has just melted! The U/F heating and DHW are on 2 different loops, hence one is affected and the other not

 

I'm no expert but it sounds like either a fault with the controller or the circulation pump.

 

Have you tried turning the water on from the FTC controller and Melcloud?

We don’t have Melcloud. We have now got hot water but it’s using the immersion only to heat which isn’t ideal

Userlevel 1

Did you find the solution to this problem? If so tell us

Our electrician friend has bypassed the fuse/spur - still amped via fuse box in garage so safe. Allowing immersion to come on. He thought the pump must be broken but he’s said it’s a very simple Groundfos CIL2 pump so shouldn’t be an issue. He thinks that the pump wasn’t kicking in as the temp was below the settings we had set for when it would heat water (he thinks maybe to protect airsource during very cold weather)

The water temp is now above this minimum level (thanks to the immersion working) and it seems to have kicked the air source unit/pump attached to tank into action.

We are keeping our fingers crossed as an issue with the FTC would be very expensive to fix!

Userlevel 7
Badge +4

It sounds like the fuse that's blown was for the immersion heater, not the heat pump. I would get a proper electrician to fix it because bypassing it is potentially dangerous.

 

Heat pumps don't have a minimum water temperature below which they won't switch on. That would make no sense as it would stop the heat pump reheating the cylinder if you used all the hot water. I'm pleased it's now working but I wonder if there was a problem with your settings.

Obviously it needs fixing - we need a new spur switch/fuse which is getting done today.

The friend is a qualified electrician, qualified to work on high voltage installations off shore as well - so trust he knows what he’s doing!

We have had this system since 2019 and got the most part works fine. Biggest gripe is the cost to run it…..£6000 a year at the moment - hopefully a drop in electricity prices will help 

Our settings were to heat water once it dropped around 20 degrees from target temperature 

Userlevel 7
Badge +2

Yikes, unless you have a huge house heated to tropical temps that’s far more than it should be. Sounds like there’s something not set up right. Are you still in touch with the installer ? Do you know what COP you’re getting?

If you describe your system components and settings here there are a number of heat pump owners keen to help improve the performance for you. It may be just a few settings that can be altered.

It’s the heating that is the biggest cost, specifically the wet underfloor heating downstairs.

When electricity was 13p/unit the summer months were around £60/month.

The original installer came out a few times, but said it was fine…then seemed to go AWOL/MIA…..got some advice from a forum to fiddle around with the compensation curve - that helped a bit; but the increase in electricity price pretty much tripled/quadrupled the cost.

Where do I find the COP…I do recall having this at the start…now we just try not to think about altering settings as it was driving us crackers!

House is quite big, but it’s never tropical…..just about warm enough in winter to get by!

Once I get the fuse/pump sorted I’ll post our settings and see if it can be improved.

It sounds like the fuse that's blown was for the immersion heater, not the heat pump. I would get a proper electrician to fix it because bypassing it is potentially dangerous.

 

Heat pumps don't have a minimum water temperature below which they won't switch on. That would make no sense as it would stop the heat pump reheating the cylinder if you used all the hot water. I'm pleased it's now working but I wonder if there was a problem with your settings.

Just to add…when I refer to the pump, Im taking about the small pump device attached to the mixing tank…not the ASHP outside.

Reply