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Mitsubishi Ecodan pipe width query

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(@cougarsmith)
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We have a Mitsubishi Ecodan in a new build home. It has worked OK with the odd system reset being involved and occasional low pressure but following a weekend away a month ago the temp had dropped a lot so we went to turn on the heating and it didn't work, flashing up an L9 fault.. we discovered that its low pressure.. when someone came to look from a reputable company he thought he should have sorted it, but couldn't understand why he kept getting an L9 code. He went to look at the fan outside and discovered that the pipe on the back of the fan unit going in to the house had a 40 ish cm section which was 15mm wide rather than the 28mm recommended. He was quite shocked and said that it shouldn't be there, and took photos. The company who installed it said that it should be 15mm and have washed their hands of it. Unfortunately we still don't have any heating (thankfully we had a log burner installed so that's proving to be a life saver at the moment) but w0ndered if there was such a thing as an independent assessor of work to help us if we have to go down the legal route to get this rectified. I have attached a photo showing the length of pipe in there at the moment.

heating1

 


   
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(@kev-m)
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Posted by: @cougarsmith

We have a Mitsubishi Ecodan in a new build home. It has worked OK with the odd system reset being involved and occasional low pressure but following a weekend away a month ago the temp had dropped a lot so we went to turn on the heating and it didn't work, flashing up an L9 fault.. we discovered that its low pressure.. when someone came to look from a reputable company he thought he should have sorted it, but couldn't understand why he kept getting an L9 code. He went to look at the fan outside and discovered that the pipe on the back of the fan unit going in to the house had a 40 ish cm section which was 15mm wide rather than the 28mm recommended. He was quite shocked and said that it shouldn't be there, and took photos. The company who installed it said that it should be 15mm and have washed their hands of it. Unfortunately we still don't have any heating (thankfully we had a log burner installed so that's proving to be a life saver at the moment) but w0ndered if there was such a thing as an independent assessor of work to help us if we have to go down the legal route to get this rectified. I have attached a photo showing the length of pipe in there at the moment.

heating1

 

15mm primary flow pipes will definitely cause problems.  There is a minimum flow rate depending on the size of the ASHP and it's unlikely that 15mm pipe would allow that.    

Have you tried approaching the builder?  This is such an obvious fault that it would be hard for them to fob you off. 

 


   
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(@cougarsmith)
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thanks very much for your info. I have approached the builders who seemed to have doubled down with the installers unfortunately. I am now trying to find an assessor who can independently come and look at the workmanship but its all a bit of a faff! thanks again!  


   
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(@derek-m)
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Posted by: @cougarsmith

thanks very much for your info. I have approached the builders who seemed to have doubled down with the installers unfortunately. I am now trying to find an assessor who can independently come and look at the workmanship but its all a bit of a faff! thanks again!  

If you look in the manual for your heat pump, it will probably specify the size and type of connections for the flow and return water pipes. I cannot really see from the photo, but I suspect that reduction pipe fittings must have been used in order to connect to the 15mm pipe. I would suggest that you ask whoever was responsible to explain why.

Also ask your installer for details of his indemnity insurance, since you may be able to make a claim via that route.

 


   
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(@iancalderbank)
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@cougarsmith wow. This takes the biscuit for stupid installer errors. The recommended pipe sizes for heat pump to cylinder connections from mitsubishi installation manual snipped below. these are implicitly the same pipes as those outside pipes you are looking at. depending on what size heat pump you have , the minimum is either 22mm or 28mm. Most installers would fit 28mm even if 22mm is enough. 15mm is simply nonsense.

image

there is also the MCS pipe sizing standard on page 20 of this

which states similar.

the table part way down https://www.heatgeek.com/does-my-pipework-need-upgrading-for-a-heat-pump-with-cheat-sheet/ tells you that 15mm pipe can only carry 2.75kw at DT5 (the normal DT for a heatpump). I assume your HP is significantly bigger than 2.75kw!

I would send the installer a letter stating that their installation is not compliant with either the Manufacturers installation guidelines, nor the MCS specifications (I assume they are a member of MCS?) with respect to this pipe sizing , and that you require immediate remediation of your install and give them a short time to comply (given that winters approaching).

what about the 3rd party who surveyed it and found these 15mm pipes? if they are suitably qualified they should be able to give you that formal "15mm isn't big enough" statement?

My octopus signup link https://share.octopus.energy/ebony-deer-230
210m2 house, Samsung 16kw Gen6 ASHP Self installed: Single circulation loop , PWM modulating pump.
My public ASHP stats: https://heatpumpmonitor.org/system/view?id=45
11.9kWp of PV
41kWh of Battery storage (3x Powerwall 2)
2x BEVs


   
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(@cougarsmith)
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Topic starter  

@iancalderbank Thanks so much for the information, it’s all very helpful. Thanks again.


   
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(@cougarsmith)
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Topic starter  

@iancalderbank i have attached photos of the pipe fittings now if that helps?

heating6
heating5

   
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(@george)
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I would also get them to improve the insulation on that exterior pipework as its looks pretty basic.

Mitsubishi Ecodan 14kw ASHP + 500l Cylinder


   
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(@iancalderbank)
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@cougarsmith so its obviously a bit hard to get scale, but using your finger as a guideline, that looks like 28mm coming through the wall (a good sign - implies its probably 28mm all the way on the other side of the wall) stepping down with two soldered reducers, from 28 to 22mm , then 22 to 15mm , in 2 steps on the exit of the elbow. then the other pic looks like a 15mm flexi hose, presumably that is going to the heat pump. Chances are on the other end of that hose, at input to the heat pump there will be a step up again back to 28mm, because the heat pump will have 28mm connectors.

you just need this replaced with 28mm all the way: that can be had everywhere. every plumber has stock of it in their van. 28mm flexis specifically designed for ASHP connections are available from the right heating merchants. I wonder if they bodged it using a 15mm flexi connector (commonly used for basin taps) they had lying around because they didn't have a proper 28mm ASHP flexi.

the flexi needs to be this https://www.bes.co.uk/flexible-hose-1-bsp-f-swivel-x-28mm-x-750mm-pair-25288/ or this 

https://www.screwfix.com/p/joule-cylinders-flexible-insulated-heat-pump-connection-pipe-28mm-x-28mm-x-300mm/741PG

and the insulation needs to be this https://midsummerwholesale.co.uk/buy/external-pipe-coverings/Primary_pro_28m_1_meter

 

the diagram on the BES page is a really clear overview actually. Also it should be insulated where it goes through the wall. but thats a 2nd stage issue at this point.

image

 

its so obviously wrong it makes my head hurt.

My octopus signup link https://share.octopus.energy/ebony-deer-230
210m2 house, Samsung 16kw Gen6 ASHP Self installed: Single circulation loop , PWM modulating pump.
My public ASHP stats: https://heatpumpmonitor.org/system/view?id=45
11.9kWp of PV
41kWh of Battery storage (3x Powerwall 2)
2x BEVs


   
Derek M reacted
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(@cougarsmith)
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Topic starter  

@iancalderbank thanks again, yes I can see this too now its been pointed out by yourself and others, as you can imagine, its frustrating that the installers are taking no responsibility and have even gone to the point of writing to us to tell us that they are 100% happy with the installation without having really looked at any evidence.


   
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(@iancalderbank)
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so its up to you, but because winter is going to start imminently , you could consider:

- getting a 3rd party to fix this.  The people who already inspected it would be the first ones I'd suggest you ask, because they've seen the system. Ask for a full explanation in writing of what they would propose to change / do. Post those details on here, we'll help you understand and vet them.

You'll have to pay for it, but its not a big job. that'll be your quickest "time to get a working heating system".

- Then sue your installer for the cost of the remediation. Make sure you involve every public body you can (MCS, Trading Standards) in this because they really do not have a leg to stand on.

My octopus signup link https://share.octopus.energy/ebony-deer-230
210m2 house, Samsung 16kw Gen6 ASHP Self installed: Single circulation loop , PWM modulating pump.
My public ASHP stats: https://heatpumpmonitor.org/system/view?id=45
11.9kWp of PV
41kWh of Battery storage (3x Powerwall 2)
2x BEVs


   
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