Sunamp failure - NOW FIXED!

[Jeremy Harris]

39 minutes ago, TerryE said:

 

What happened to your idea of anti-PCM bund?

 

All prepared!  I managed to quickly Sikaflex a bit of plastic angle along the rear, to seal the bit I wouldn't be able to get at, and got the installer to fit the new unit slightly further out.  All I need to do now is add the other three sides, the plan is to just bond and screw some boards around the edges of the bit of varnished marine ply that the unit is sat on.  I'm pretty sure this will catch any PCM leak, should I be unlucky enough to experience another one.  I'm also going to seal up that hole in the floor, when I replace the damaged carpet tiles around the unit (I still have a load of spares left over from fitting them, it's good to hoard stuff sometimes!).

 

Sunamp have definitely made some significant changes to the way their control system works.  The original unit I had just went through an initial commissioning stage on first power on where it clacked the contactor on and off repeatedly for around 20 minutes.  This new one smoothly modulated the power at a rate of increase of around 150W per minute during that initial stage.  No doubt this is a fair bit more benign in terms of the way the PCM initially melts around the element.

 

I can't really fault Sunamp, unless I was being really picky.  They agreed to change the unit on Tuesday and by just after 16:00 on Thursday the job was completed.  That's pretty good service in my view.

 

 

[Jeremy Harris]

34 minutes ago, Russdl said:

@Jeremy Harris that’s excellent news, let’s hope the current model has some subtle modifications to prevent a repeat failure!
 

We’ve got a few years left on our warranty and I’ll be paying closer attention to our Sunamp in the future. It’s kind of easy to forget it’s there as it quietly goes about doing its thing (or quietly spilling its guts). 

Out of interest are they going to fix the damage caused to the house or have they swerved that one?

 

 

To be fair, I didn't ask them to fix the damage.  The flooring damage is a ten minute job, as I have a part-box of left-over carpet tiles I can use.  The plasterer was around earlier and having had a good look can't see any damage or reason to pull the ceiling down and replace it, so I'm just going to make good the surface and try repainting it, perhaps with a coat of some sort of stopper/sealer first.  It's not a large area, so not worth getting a decorator in.  I can't see any build up of crystalline PCM in the ceiling void, it looks almost as if the felt of the carpet tiles has worked as a sort of crude filter to leave most of the crystals behind.

[Conor]

Would you consider installing the next one in some sort of bund? I've a drain in my plant room I case something goes pop someday.

[ProDave]

Did the plumber make any changes to the plumbing like different or extra expansion vessels, pressure reducing valves, over pressure valves etc?

[Jeremy Harris]

42 minutes ago, Conor said:

Would you consider installing the next one in some sort of bund? I've a drain in my plant room I case something goes pop someday.

 

 

Yes, I've already sorted how to do this.  The Sunamp sits on top of a bit of 19mm varnished marine ply.  I've sealed along the back with a bit of Sikaflexed plastic angle to the panelling behind.  The plan is to add three sides to the edges of the ply to form a bund to limit the flow of anything that may leak (although I sincerely hope it doesn't!).

[Jeremy Harris]

22 minutes ago, ProDave said:

Did the plumber make any changes to the plumbing like different or extra expansion vessels, pressure reducing valves, over pressure valves etc?

 

None at all.  He checked the pressure regulating valve, checked the 100 litre accumulator sat almost next to the the thing and checked the incoming pressure from the well pump and, quite sensibly, concluded that there was zero risk of the supply going over the upper pressure limit.  He did also say that he'd never seen a failure caused by supply over-pressure, he reckoned leaks were most often down to poor workmanship during installation.

 

He reckoned most failures were electrical or poor installation workmanship, with a strong view that the latter was the cause of a fair few.  PCM leaks weren't high on the list of things that happen, especially with the newer models, according to his view.  The pipe work has been simplified on the new unit, too.  It doesn't have two sets of heat exchanger pipes, just one set, which makes installation a bit simpler for electric-only installations, like ours.

 

Most impressive takeaway from today was just how awesome the Zonzini stair climber was.  Instead of me sweating away for hours with a sack truck, ropes and a tirfor winch to get the thing upstairs, the motorised Zonzoni just drove straight in the door and up the stairs in a couple of minutes!  Having seen it working I'd no hesitate to just hire one if I ever needed to move anything hefty.  I reckon I could have very easily got a new unit in and the old unit out using one of these, and really it's the heavy lifting that is the hardest part of the job, the rest is pretty straightforward.

[joe90]

Gosh, Jeremy I have been away and didn’t see this. So glad to hear that. your about but not about your problem. I have quoted you so many times. 

Edited yesterday at 19:19 by joe90

[saveasteading]

21 minutes ago, Jeremy Harris said:

how awesome the Zonzini stair climber was.  Instead of me sweating away for hours

I hadn't heard of this. So have looked it up.

Is it the "simpler" version that is a trolley then has carterpillar tracks for stairs?

I dont suppose it goes up a loft ladder though?

[Jeremy Harris]

Just now, saveasteading said:

I hadn't heard of this. So have looked it up.

Is it the "simpler" version that is a trolley then has carterpillar tracks for stairs?

I dont suppose it goes up a loft ladder though?

 

The one they used didn't have tracks, but motorised wheels and moving step things that grabbed each stair and lifted the wheels up the next step.  It also had a motorised lift platform, which made getting the heavy box out of the back of a van easy, it's a bit like a mini-forklift.

 

It definitely wouldn't go up a ladder though, I'm afraid!

[Roger440]

Welcome back

 

Good news on the resolution.

[Jeremy Harris]

@Nickfromwales,

 

Out of curiosity I had a good look at the sensor string in our failed unit, to see if it had moved.  Easy to determine that it hadn't, as there's no form of gland at the top of the dip tube on our old unit and the cable was folded over where it had been under the insulation, so would have been physically restrained from moving upwards.  I pulled the sensor string out to check, and it looked undamaged, same as when it went in from what I can remember.  I also had a look to see if there was somewhere obvious that the PCM had leaked from but couldn't see anything.  The filling plug (which I had thought might be a blow-off point) looked fine, in fact the area at that end of the cell looked pretty dry, as did the pipe entry points into the top of the cell.

 

If I had to guess, based on the fact that the PCM had pushed up around the edges and leaked out around the pipe entry points (but not obviously out of the cover over the heating element terminals) my suspicion would be that the casing might have cracked, perhaps somewhere close to the top corner, at the pipe entry end somewhere.  The PCM looked to have pushed up between the cell case side and the VIP panels in that area.

 

Doesn't really make anything any clearer, I'm afraid.  All that seems fairly certain is that this failure wasn't caused by anything on the water side, there was zero evidence of any water leakage at all, so I suspect the concerns I expressed earlier about some sort of over-pressure event almost certainly had nothing at all to do with it.

 

Very annoying not being able to understand the exact cause of the failure, both because I'm too damned curious for my own good, and always want to know WHY stuff happens, but also because it'd be reassuring to better understand these things, perhaps even to find ways to reduce the risk of it happening again.

 

Guess I'll just have to accept that it is what it is.

[Nickfromwales]

1 hour ago, Jeremy Harris said:

Out of curiosity I had a good look at the sensor string in our failed unit, to see if it had moved.  Easy to determine that it hadn't, as there's no form of gland at the top of the dip tube on our old unit and the cable was folded over where it had been under the insulation, so would have been physically restrained from moving upwards.  I pulled the sensor string out to check, and it looked undamaged, same as when it went in from what I can remember.  I also had a look to see if there was somewhere obvious that the PCM had leaked from but couldn't see anything.  The filling plug (which I had thought might be a blow-off point) looked fine, in fact the area at that end of the cell looked pretty dry, as did the pipe entry points into the top of the cell.

 

Great to hear you didn't have to suffer a 13 week delay like the lady I mentioned, so that's a result considering previous track records!!

 

SA's own chap sent me in this direction for diagnosing multiples of other failed units, and it was indeed the culprit; I think units pre/immediately post Covid were the worst ones tbh, so not sure about their current reliability, but I guess only time (or people raising their hands on somewhere as prominent as Buildhub) will tell. These things certainly grew organically, frustratingly for the client, by them falling down and then being picked back up again with various 'remedies'.

 

I can only hope that there are not others out there who got the cold shoulder or simply completely ignored as per my own direct experiences....but as there is now a network of installers then I guess turnarounds for these warranty claims have improved somewhat. I remain curious if your standing here, and the mention on the forum of this episode, has not played a part in your resolution (given how they treated an ex-employee and at least 2 members of this forum very differently in identical circumstances).

 

People evolve, companies improve, so this offers a glimmer of hope to some, but is a complete kick in the teeth for others.

 

Bottom line here is, I am very happy that you, Jeremy, are back in good order with a great outcome, as you deserve it from your loyalty and honesty. You detail things very well, which will help / has already helped many people I am sure.

[TerryE]

10 hours ago, Jeremy Harris said:

The plasterer was around earlier and having had a good look can't see any damage or reason to pull the ceiling down and replace it, so I'm just going to make good the surface and try repainting it, perhaps with a coat of some sort of stopper/sealer first. 

 

If you can't get a decent consistent finish then you might need to paper the ceiling with lining paper to get a decent uniform base for painting. 

[SteamyTea]

7 hours ago, Jeremy Harris said:

my suspicion would be that the casing might have cracked, perhaps somewhere close to the top corner, at the pipe entry end somewhere

Could it be differential expansion/contraction if different materials over time?

Some materials age and become more brittle.

[Russdl]

@SteamyTea that’s something I’d considered.
 

We know some people have had issues with their Sunamps bulging (ours is perhaps a little plumper around the middle than when it was delivered, but not obviously so). Does the PCM expand and contract or just expand. If it is expansion and contraction then that may well cause a crack in the PCM containment vessel. 

[SteamyTea]

5 minutes ago, Russdl said:

Does the PCM expand and contract or just expand

As it changes phase between liquid and solid, it will change volume.  I am not sure by how much.

 

(water is strange when it crystallises and between 273 to 277K)

[Jeremy Harris]

3 hours ago, Russdl said:

@SteamyTea that’s something I’d considered.
 

We know some people have had issues with their Sunamps bulging (ours is perhaps a little plumper around the middle than when it was delivered, but not obviously so). Does the PCM expand and contract or just expand. If it is expansion and contraction then that may well cause a crack in the PCM containment vessel. 

 

It could well be something like that, or just something relating to the manufacture of the casings, perhaps. As de Havilland tragically found out in the 1950's, squar'ish shapes do not tolerate fatigue cycling anywhere near as well as round'ish shapes.  The stresses in corners are always a lot greater than in the same material under the same forces that doesn't have corners.  It took loads of testing in a massive water tank at Farnborough to discover why the early Comets were breaking up in flight, as no one had considered the impact of stress concentrations at the corners of rectangular openings in the pressure hull.

[Pocster]

2 minutes ago, Jeremy Harris said:

 

It could well be something like that, or just something relating to the manufacture of the casings, perhaps.  As de Havilland tragically found out in the 1950's, squar'ish shapes do not tolerate fatigue cycling anywhere near as well as round'ish shapes.  The stresses in corners are always a lot greater than in the same material under the same forces that doesn't have corners.  It took loads of testing in a massive water tank at Farnborough to discover why the early Comets were breaking up in flight, as no one had considered the impact of stress concentrations at the corners of rectangular openings in the pressure hull.

Is this why doughnuts are round not square ? 🤔

[ProDave]

Good news about the replacement and good service by SA.

 

Hopefully the changes to the start up sequence mean they have learned from failures and it will be more reliable, but the only real solution to prevent failure of the PCM vessel is a stronger PCM vessel.  Is there any kind of vent on the actual PCM containment vessel, something to vent pressure if by chance some of it did reach it's boiling point?

[Jeremy Harris]

47 minutes ago, ProDave said:

Good news about the replacement and good service by SA.

 

Hopefully the changes to the start up sequence mean they have learned from failures and it will be more reliable, but the only real solution to prevent failure of the PCM vessel is a stronger PCM vessel.  Is there any kind of vent on the actual PCM containment vessel, something to vent pressure if by chance some of it did reach it's boiling point?

 

I believe that the design has probably changed quite a lot, and I have a strong suspicion that the heating element is something very different to the original immersion heater design, because of that slow ramp up in power on cold start.  There's no power modulation in the control box, it seems to use a relay to turn the power on and off to the heating element.  In our old UniQ that relay directly switched power to immersion heating elements in the base.  This is what the start up power looked like, from first cold start, showing the ramp (the dip is where we turned the bypass switch off on the Eddi and switched to the one hour boost, so the power was off for a short time):

 

 

This wasn't anything to do with the Eddi, as the first part of that ramp was with the Eddi off (the bypass switch was on) and the second part is with the Eddi on, in boost mode.  This means there must be some sort of heating element control going on outwith the stuff in the control box itself (because that clearly only turns the supply on and off to the heater).  There has to be a good reason for Sunamp having made this change, I'm sure.  I don't think that it's a coincidence that some early models, with a resettable thermal trip next to the heating elements in the base (our old one had this) had some issues with that trip operating and turning the unit off.  When the contactor in the control box failed on our first unit the advice from Sunamp was to check and reset that trip (which hadn't operated, the contactor had just mechanically broken internally).

 

As for a vent, then I believe that the filling plug may do double duty as an over-pressure vent, although I can't be sure.  It was fine on our old unit, the leak seemed to be at the other end somewhere.  This again makes me think that the cause of our leak may just have been a failure in the casing somewhere, perhaps a latent manufacturing defect or even (as was mentioned by the installer) possible transit damage.  Our unit did have a very rough ride during delivery.  I reported this to Sunamp, with photos, at the time, as the pallet had been broken by a forklift and the unit may well have fallen over, as there was damage to the top of the casing, where the pipe entry cut outs are, plus the lid was damaged with a force so great that one of the lid securing screw rivnuts was ripped out (I fitted a new rivnut to fix this).  These were the damage photos taken at the time, with the wrecked pallet it arrived on, the dented case and the ripped out rivnut hole:

 

 

 

 

At the time, Sunamp didn't believe that there had been internal damage, but in the light of what the installer said yesterday about the care they now take when transporting and lifting units into place it has made me wonder whether or not there may have been some slight damage internally that has taken years to turn into a leak.  The more I think about it the more believable I think this scenario may be.  The sheer weight of these things does mean that if one was to fall over during delivery then it seems quite possible that this might cause internal damage.

 

I think it's quite possible that some of the other cases of failure may be related to possible transit damage, thinking about it.  It ties in with the way they are now delivered, if my experience yesterday is typical, where a great deal of care is taken to transport these things carefully, at every stage of their journey. 

 

My original UniQ unit arrived via a standard pallet service, and had clearly been subject to some fairly rough treatment along the way.  Just to get it off the truck was a challenge, and with the damage to the pallet I had to transfer it to a spare timber pallet at the truck in order to be able to get it to our front door.  I seem to remember Sunamp saying they were going to speak with the transport company and look at using more robust pallets at the time.  Is it a coincidence that the end of my old unit that got a knock is the same end as the leak has appeared?

[Russdl]

An interesting theory regarding the transit damage leading to the PCM failure Jeremy and gives me a glimmer of hope that mine may survive as it was in good order when it arrived - as far as I could see…

 

That slow heat up is interesting as well. 

 

 

[Nickfromwales]

6 hours ago, SteamyTea said:

Could it be differential expansion/contraction if different materials over time?

Some materials age and become more brittle.

The main issue is (was?) that the case is manufactured as 2 parts, and the break is where they have to be plastic welded together. I’d throw a £20 on that being where these fail, as it’s about 9/10th’s of the way up the case not at the top; ergo they’re in the dynamic section where movement is continuous.

 

These things began to look like they were 3 months pregnant after installing and cycling a few times, where they heat up, get loose, and slump into their final resting position. A bit like when you get out of work and take your tie off and loosen your top button. Just too much weight in a flexible plastic box, particularly if that’s been bean-counted too; more reasonable argument for how these early failures have occurred.

[Nickfromwales]

Always handy to have a few of these ‘remnants’ at the side of the shed lol. 
 

@Jeremy Harris, note the blue cable gland I mentioned for securing the thermistor string, or not as the case may be.
 

 

Ignore the random cardboard box at the bottom. I’d just had a coffee and a chocolate croissant and didn’t feel

much like bending over to remove it. ☕️ 🥐 😋 

[Nickfromwales]

The orange do-dah is what they refer to as the 1 way breather, or that’s what it was called, item 6 in the MIs I found online. 
I referred to it as the PCM PRV earlier in the thread (sorry for the confusion).

That’s how the goop gets evacuated if it all goes nuclear.

[Nickfromwales]

The heat exchanger gets installed into the empty cell, the molten PCM gets poured in up to the fill up line (?) and then the difficulty starts methinks.
 

How that gets sealed / welded shut successfully these days is unknown to me, but it was simply with a hand-held BFO soldering iron looking thing ( back in the day when I was standing right there watching the process) and I found it quite interesting to watch how this was actually being ‘done’…”manually”. 🫤. 
 

Hopefully a clever robot is doing this these days 🤞or a fusion weld wire or something. Or maybe they now have more guys and more irons.