Wor 28cdi rsf

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12 Aug 2006
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Location
Hertfordshire
Country
United Kingdom
When heating off and hot water tap turned on fully after 7 secs loud banging from boiler. The pressure gauge needle goes all the way round (like a rev counter) then back to position while banging occurs. Also have noticed loss of pressure on the gauge in the morning.
Any ides anyone, much appreciated....
 
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Serious problem. Best find a competent boiler engineer to sort it out.
 
Sounds like no air left in the expansion vessel!

Tony
 
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what a nightmare !!!!! Tried to put air in the expansion vessel and the position of the nipple valve to hook onto was in an impossible postion. 10 mm pipe in the way of valve, thought it was just a non pressure bleed pipe so pulled out the u pin holding it in place lifted the pipe and then waterfall city started, tried to put the pipe back as quick as poss then rubber o ring broke (so no seal). Shut down system turn off main and hunt o ring in 3 plumbers shop which none had the same o ring just something close to it so had to put 2 thin o rings together, put it all back together fired it up and the banging has subsided a bit and pressure is holding....time will tell.

Seperate prob now when pressurising system, put T bar in undo grey knob allow pressure to 2 bar turn off knob and now when I try to take 'T' bar out it leaks warm water, so I have to leave t bar in, any ideas what to do.

Thanks by the way on everyone's comments/advice so far much appreciated.........
 
manonamission said:
Thanks by the way on everyone's comments/advice so far much appreciated.........
......and much ignored! We said get a professional in and you try to DIY. We don't just say these things for fun, although in your case I will allow myself a bit of a smirk. :evil:
 
point taken chrishutt, had made enquires with the plumber who fitted boiler to take a look at it, he can only make it at end of the week so did the best I could but a proffesional will be taking over
 
Whoops, you need to drain down and undo the pipe first, I usually take pressure out of the prv and replce the head afterwards.
 
have been told by Worcester tech support that it is likely to be the water to water heat exchanger, because of noise when hot water sounds like the water not going thru quickly enough. I live in hard water area and boiler been in 7 years now. Tech support says can be taken off put into a solution to descale or replace, how long does this take a fitter to do ?
 
manonamission said:
have been told by Worcester tech support that it is likely to be the water to water heat exchanger, because of noise when hot water sounds like the water not going thru quickly enough. I live in hard water area and boiler been in 7 years now. Tech support says can be taken off put into a solution to descale or replace, how long does this take a fitter to do ?

To replace should be no more than an hours labour charge.
 
If your 7 seconds is correct then it wont be the heat exchanger 7 seconds is far too quick. I f the pump isn't running that would give you an overheat in or around 7 secs, if the ch overheats or just shuts down then its prob the pump but if the ch is fine then it could be the pcb. If the heat ex was scaled up the problem would tend to get worse over a period of time not just suddenly start. I have worked on the CDi since it was a prototype and have seen a lot since. The bad news is you may have stuffed up the expansion vess charge and as it would only have given a problem on ch anyway it should have been left alone. the dripping filling loop is easy to replaced but is prob just a tight tap or the non return valve a bit bunged up, both easy to fix when drained down (2 mins)
 
Bought heat exchanger (£90) and got plumber to fit it (£100). Filling loop fine no leaks now so no need to replace it. But banging still there. The banging only happens for a short while when hot tap is turned on then stops, pressure levels off water hot and all is good. Turn off tap leave for 5 mins and the same happens. Put the central heating on let it circulate and then hot water on and no noise.

Any ideas anyone? My plumber thinks it could be a lazy pump for the first few seconds when turning hot tap on then correctly circulates so the banging stops and pressure is fine, or could be a thermister sender switch.
 

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