Radiators Inflated Like a Balloon - Dodgy PRV?

[ACOperson]

Hello all,

I'm a fitter with a question is regarding a PRV.

We fitted a new Worcester Compact 30si for a family in early Feb 2014. Been working OK ever since, save for customer noticing a long delay in the heating kicking back in if someone runs a tap etc so after I visited to check the external controls etc I called Bosch and booked an engineer visit. PCB I thought.

BTW: I've been to this place about 3 times following installation for other unrelated things and as always I checked the boiler quickly to make sure it looked ok (pressure, temperatures etc) - always fine.

Worcester sent someone who (apparently) reduced / removed the heating delay facility on the board, she also changed the MT10 internal timer and then said she thought my wireless room stat was also somehow at fault (despite the stat being operationsl). God knows what else she did to the boiler but it was left working and away she went. The customers summary of the visit smacked of an engineer who was out of her depth and just carrying out random work...

Anyway, approx 34 hours later the customer heard banging, water coming through living room ceiling, noticed two approx 20 year old steel rads had swollen up like balloons ready to pop! Turned off system.

When I got there the boiler pressure was at 3 bar, PRV dripping but only slightly. External screwdriver-slot type Filling loop left very slightly open. I had a think about it all and I guess that if the Worcester engineer had refilled, and effectively overpressurised to +3 bar at night when street mains pressure rises then the expansion vessel becomes useless, however the PRV should have kicked in and done its job. I twisted the PRV and when used manually its fine. What I could not test at the time was its calibration (whether it activates properly at over 3 bar) as I had no way of putting +3 bar in at that time of day.

I think that a faulty spring in the PRV could have led to this. If spring is too stiff then maybe it would not activate? Its def not blocked as I managed to open it by hand.

I saw a similar thread here from 2008:

//www.diynot.com/forums/viewtopic.php?t=134919&start=0#.Uyd8nBHeVWE.email

Lots of differing opinions there...Rads on my customers job look the same as in above thread

 

[Dan Robinson]

Not looked at the link, but 20 year old steel panel rads can give way.

We have T's&C's on our website and estimates to protect us from sh1itty systems.

Could be a dodgy PRV on the boiler. Seen them at 4 bar and dry as a bone - relatively new boilers too.

 

[ACOperson]

Yes granted, old rads can give way, but these have been pressurised for 20 years (old boiler was also a combi) with no trouble.

System had also been working safely (although not necessarily very well) in the month or so that the boiler had been installed for prior to the Worcester engineer's visit.

Also strange that 2 radiators would give way at the exact same time. Has to be more to it than just crappy old radiators - boiler safety systems should have kicked in well before this.

One of the radiators reminded me of a time I saw a hot water bottle bursting competition on late night TV - contestants were trying to inflate & burst hot water bottles by blowing into them!

 

[FiremanT]

Are they old Servowarm radiators?

 

[ACOperson]

Not that I can see. Just 25-30 year old panel rads same as you see all over the place in old houses. Mixture of single & doubles. No markings / name anywhere.

Like I say: I accept the rads are old, but too much of a coincidence that this has happened only a few hours after Worcester's visit.

 

[ACOperson]

Summary of my Email to Bosch tech / Service last night:

************************************************************

I attended the above address last night following a report of a water leak from two radiators. On arrival I found two radiators which had expanded due to what must have been a massive overpressurisation , one of which had leaked and has caused damage to a ceiling.

These are radiators which although old were materially sound and fully operational until this event. Just to clarify: These are steel panel radiators which have been warped and ‘inflated’ almost to the point of bursting – one can only be thankful that such a catastrophe did not happen as it could have caused severe damage to property and potentially physical harm to the occupants of the house. In all my years as a heating engineer I have never seen anything like this.


Please see below for a timeline of the events & relevant information surrounding this boiler:

Worcester 30si Compact

Comprehensive Timeline of Events:

• 10/02/2014: Boiler installed to existing pressurised system (previous combi was approx 18 years old) commissioned & benchmarked. System including all radiators inspected and tested. Left operational by myself. System pressure at 1 bar.

• 12/02/2014: Further visit made to property. Boiler inspected – all operational and no issues. System pressure at 1 bar.

• 04/03/2014: Further visit made as customer had complained about intermittent heating – heating turns on, reaches temperature and then turns off for excessive period so house cools too much. External controls checked and passed by myself. Question raised regarding central heating delay duration. Spoke to Worcester technical who although slightly unsure of correct delay time advised to book service visit if event continues. All other boiler functions eg hot water ok. System pressure at 1 bar.

• 15/03/2014 – approx. 13:00 : Further complaint from customer, heating still intermittent and so Worcester service visit booked in for same day. Worcester engineer attends, as I understand it her works included:

1. Replacement of MT10 clock.
2. Adjusting heating delay period to 1 minute.
3. Questionmark over boiler pressure: Did she adjust system pressure in any way? This is very important and needs to be ascertained.

• 16/03/2014 – approx. 21:00: Customer hears a great deal of noise from radiators in front of house on both ground floor and first floor. Investigates to fing first floor radiator leaking which has caused severe damage to ceiling below. Notices that 2 radiators have swollen up and appear ready to burst. Heating switched off. Emergency engineer attends to make safe and stop leak. Boiler left switched off. Two radiators in question have suffered catastrophic damage and will need to be replaced. Ceiling downstairs will need to be redecorated. Boiler PRV has been turned to test and it does work, however it is unknown whether the spring calibration is correct to discharge at 3 bar automatically – this will be very important to establish.

It is very important to know whether or not the Worcester service engineer increased the system pressure in any way, as it will be key to knowing what has caused this major problem.

Regarding the technicalities of this problem: As an experienced engineer I know that a combination of the boiler’s expansion vessel and pressure relief valve should stop this situation from ever happening. One could hypothesize the following event could have led to this happening:

• Worcester engineer visits. Either overpressurises the system or leaves filling tap open accidentally.
• System reaches high pressure (eg 2.5-3 bar)
• Heating kicks in, expansion volume of system is now way in excess of expansion vessel capacity due to overpressurisation.
• PRV does not activate due to manufacturing defect / incorrect spring loading.
• System pressurises well in excess of 3 bar and causes damage to radiators.

The above is purely a hypothesis but it is a scenario that is theoretically possible at least.

This matter needs to be escalated immediately to the highest point of the Bosch service department, the Worcester engineer should be interviewed and asked about the above. I will make it clear: Prior to her visit there were no pressure problems ever reported on this system, and I know that those radiators were not damaged in such a way before this weekend as I saw them all with my own eyes in February and March 4th at my last visit.
**********************************************************

 

[Gasguru]

.....External screwdriver-slot type Filling loop left very slightly open.

Just a thought...fit a quality approved filling loop with two valves and take the loop off

Bet your loop doesn't comply with the water regs and Worcester will quite rightly tell you to to do one.

One of my bug bears that installers fit or leave cheap illegal filling loops that cause so many pressure problems.

Your T&Cs should cover old rads.

 

[ACOperson]

Um excuse me but who says this filling loop is not wras approved?


http://www.directheatingsupplies.co...spx?agid=586&gclid=CP7AyMXXnL0CFcfKtAodlEgA0A

I will also reiterate: I was not the last person to work on the boiler. Worcester were. If you are blaming me for leaving the filling loop open in at start of Feb when this was installed - how on earth did the Worcester engineer miss the fact that the gauge was all the way over to maximum? She was there the day before the rads blew and in front of the boiler for 40 mins.

Let me guess, you work for Worcester or another manufacturer - their sole mandate seems to be to stitch up the installer wherever possible nowadays...

 

[Gasguru]

It's still a carp filling loop...you seriously expecting a customer to use a screwdriver and set the slots exactly perpendicular to the pipe?

I'm not blaming you for leaving the loop open, I'm saying it's all too easy to leave the valves open.

Did you leave it disconnected when you last left the property, or did you disconnect and cap the valve ends?

I don't work for Worcester, I'm an independent. Worcester have some dross "engineers" working for them...I've seen the "quality" of some of the fixed price repairs.

The rads are old and the spot welding has failed or perhaps they were old Servowarm rads. Regardess of the pressure being up at 3 bar (or a shade more) it was on the cards they would fail at somepoint.

FWIW most of the boiler manufacturers don't give a t**s about the customers/installers but then neither do most installers care about installing boilers properly.

 

[ACOperson]

The customers on this job have never and will never use the filling loop. They are very old and will always call me out to do such things. Equally they would not have used a Worcester filling key or a filling loop with hand turn valves on it either, trying to explain things like this to some people over the phone can be impossible so I just tell elderly customers that I will take care of that side of things for them.

I left the filling system the way it should be, all off and disconnected etc, however as I wasn't the last one in it is obvious to me that it has been overpressurised by someone else - that someone has to have been the manufacturers engineer as she was there the day previous to this disaster. If she didn't overpressurise it herself then she missed the fact it was at massive pressure and she has left herself open to criticism and possibly blame.

With ref to it being a carp filling loop - that is your opinion and frankly not of my concern here. It had WRAS on the packet, and it complies with the MI (page 10 figure 2). That is all that really matters.

Its fine and well saying that the rads would fail at some point, I wouldn't deny that they are old - however it should be obvious to you that the customer is looking for someone to blame here, I do not accept that person should be me. Two rads rads failed by blowing up like balloons at the same time, both had been operational and pressurised for approx 18 years with no massive failures, this happened one day after WB were there - who would you look to blame for that f you were looking to apportion blame?

Your sweeping comments about the quality of installers and manufacturers engineers are nether here nor there, I only posted this to ask for any comment on the boiler itself and why the PRV did not kick in. 3 bar did not do this to the radiators, would have been way in excess of 3 bar to cause such damage. All I can think of is the factory putting the wrong spring in the PRV - one for a much higher pressure valve eg a mains pressure reducing valve etc. The PRV was not mechanically blocked - I know this as it can be operated by hand.

Also as an update Worcester visited today, apparently their person said they were happy that we had done the installation correctly. Not sure if this was put in writing...Their service department is conducting an investigation which will be concluded tomorrow.

PS: I do actually have a disclaimer in my t&c's about existing pipe and fittings. It will be invoked if the rads are to blame, I do not feel that anyone will have a valid claim against my company in all of this despite whether or not they would like to blame me. I'm just trying to understand what has happened here and help my clients as much as I can following this catastrophe.

PPS: It must be wonderful in whatever location you work in by the way Gasguru, obviously customers growing on trees, no problems from difficult clients questioning all materials used or competitor engineers to steal your customers by undercutting your price. I live and work in London in what is probably the most difficult place to be self employed doing this work - we are walking a tightrope between using the best possible materials and installation practices and actually winning enough jobs to keep a roof over our heads. Every job I quote for there are 3/4 other guys quoting, some amazingly shoddy workers too - but the client only ever seems to look at the bottom line until they have had their fingers burned a few times. Every other day I hear potential customers telling me that their other quotes include a powerflush but that it will only take the installer 2 hours to do, why am I charging £50 to fit service valves on the system etc etc.

 

[Nige F]

Would the house be in a town a few miles North of Eastbourne

 

[stardanny]

How do you know it was Worcester engineer? Could it be customer who turn up and overpressuring it, in order to get free radiators? Long shot but never know....

Daniel.

 

[ACOperson]

Nige: No was London.

Daniel: Not these people. Either way, they couldn't have known PRV wasn't going to activate...

 

[oilboffin]

NIce one hashish Worcester have some right dogey ads working
For them

 

[Nige F]

Nige: No was London.

Daniel: Not these people. Either way, they couldn't have known PRV wasn't going to activate...

That makes @ least 2 occurences then