Is that actually closed cell insulation designed for outdoor use or ordinary internal insulation,  If its the latter it all needs to be stripped off and replaced with the correct stuff.

@jamespa 

I told that it is Primary Pro insulation which is suitable for external use as supplied by HeatGeeks.

https://primarypro.co.uk

My installer has just got back to me to say that the manufacturer is aware of the problem  (which is due to insulation shrinkage not pipe expansion) and that they advocate re-sealing each joint with a tube of their sealant.

My installer has a different view. I am now being told that as the insulation shrinkage has now taken place a better solution is to cutout the affected areas; compress and insert foam plugs which are slightly longer than the gaps needing filling along with copious amounts of sealant. 

I am also not sure that short plugs ( as per the photos) are a good idea when insulation is liable to shrink after installation.

Posted by: @l8again

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My installer has a different view. I am now being told that as the insulation shrinkage has now taken place a better solution is to cutout the affected areas; compress and insert foam plugs which are slightly longer than the gaps needing filling along with copious amounts of sealan

The key issue is that no gaps must appear after the remedial work is done.

A gap would allow ingress of rainwater between the insulation and the pipe. That will absorb heat energy and deposit on the ground outside the house!

I hadn't realised that Primary Pro would shrink post-manufacture. I wonder whether the rate of shrinkage is affected by high temperatures or whether it's merely the elasticity of the material which reduces the fibre lengths over time.

I've used Solar Thermal pipe insulation outside and haven't noticed any shrinkage there.
I tape the joins rather than use a mastic. Perhaps that's what prevents gaps opening between lengths.

Posted by: @l8again

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I told that it is Primary Pro insulation which is suitable for external use as supplied by HeatGeeks.

If that's Primary Pro, it's been appallingly installed.

@david-s can you please advise on what this homeowner's installing is saying?

Posted by: @l8again

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My ASHP was installed 6 weeks ago. I have just noticed that a number of the external insulation joints have failed. My first thought was this was down to the recent heat wave but I suspect that it is more likely due to copper pipe expansion during the HW cylinder disinfection cycle. I have asked my installer to return to site to make appropriate repairs.

Is the repair just a case of

more mastic or is there something missing from the design which might mean that this is a recurring problem?

 

Can you send us a picture of the whole pipe length, I think there is a lack of clips and the pipe has dropped, I am not sure the insulation shrinks that much but it will bunch at the top and drop at the bottom if it scales the whole house to the roof?

If the pipe only rises up a meter then it will not be that and I would then say the insulation was cut short but pulled together slightly and sealed, I have used this product a lot and it is very robust and we do not have any installation that have shrunk over months or hot or cold weather.

When we install our Primary Pro we cut 2020mm of insulation to fit a 2000 length of pipe 10mm for every meter to cover expansion and contraction, pipework over the same distance. The approximate expansion of copper 28mm rising from 20DegC to 60DegC is about 1.4mm over a 2m length, your gaps are the 10mm I am allowing on our installations. Also the special sealant they use is not mastic it is something else like a rubber, its very hard to pull it apart and it stretches more than 3mm so again this would cover the expansion. 

I would check if the pipe dropped 1st, might have might not have. 

I would be interested in the end result so we all installers can be aware of any product defects.

Just to add to this, it is a very easy fix so I don't think anything to worry, if you live in Kent I would be happy to come and fix it for free as long as I can video it for learning materials.

@ashp-bobba The vertical pipe rise from the heat pump is about 2M to just above the back door. I cannot see any other broken butt joints or stress points. 

Looking again at the two vertical pipes, it looks to me that the installer’s apprentice has elected to use two very short insulation plugs. Personally, I might have cutback the insulation and gone for longer plugs. It also looks as if very little mastic has been used to secure the butt joints. This looks like a simple apprentice error to me which was not picked up on inspection.

The installer responded quickly and he will return to site to make good. I am confident that second time around he will make sure that all the joints are secure.

@l8again Perfect, it happens and they need to be able to try to learn, as long as you are supported its no harm done.