worcester-bosch high pressure.

[keel]

If I pressure up boiler when off to 1 bar,when system fires up pressure rises to approx4.5 bar and prv opens to vent off pressure. when system next shuts down pressure is approx 0.4bar. system still works but water not so hot. CH seems OK. Tried changing prv but problem still the same. Any ideas/solutions appreciated. Thanks

 

[Soggy_weetabix]

Expansion vessel failure, read the posts and re-pressurise or replace.

David

 

[Nickthedentist]

Totally agree with David

The expansion vessel is a big metal container, usually red, fitted with a valve like you'd find on a car tyre.

Press in the valve's plunger briefly and you should hear a bit of air (or inert gas) hissing out. But you'll probably get nothing, or a face full of hot water (usually black )

Replacement is quite easy - genuine/OEM parts available on the web, full instructions in the Installation/Servicing Guide You need to isolate the rads and drain down the boiler itself. Don't forget that if the EV is full of water it will be heavier than you expect.

I'm just a dentist who likes a bit of DIY, but I managed to sort mine (Worcester 240RSF) in about an hour and it's been fine ever since

Nick.

 

[ollski]

Replacement is quite easy

Not in every case Nick....not by a long chalk.

 

[Nickthedentist]

Replacement is quite easy

Not in every case Nick....not by a long chalk.

Oh well Obviously I was very lucky with mine

Cheers.

 

[ollski]

worcesters are often pretty good, but there's many a boiler that needs to be completely removed from the wall to permit replacement.

 

[ricardo111]

BEFORE CHECKING THE EXPANSION VESSEL, CHECK THE FILLING LOOP TO SEE IF IT IS PARTIALLY IN `ON` POSITION. SOME ARE BUILT-IN TO THE BOILER UNDERNEATH ON LEFT HAND SIDE WITH A BIG WHITE PLASTIC REMOVABLE KEY THING, OR YOUR EXTERNAL FILLING LOOP-CHROME FLEXIBLE MAY BE LETTING BY. DISCONNECT IT, AND SEE IF IT STILL DRIPS WHEN IN THE OFF POSITION.
OTHER THAN THAT, CHECK EXPANSION VESSEL, AND IF IT IS OK, ASSUMING YOUR MODEL HAS GOT A SECONDARY HEAT EXCHANGER (SOME DONT) THEN IT MUST BE WHERE THE COLD MAINS IS PASSING ACROSS INTO THE HEATING CIRCUIT THROUGH THE PLATE HEAT EXCHANGER. I HAVE COME ACROSS THIS A SMALL NUMBER OF TIMES. IF IT IS THE CASE, YOU WILL HAVE TO GET A REPAIR DONE.