Saunier Duval boiler pressure gauge shooting up to the red!

[jasonwicks]

Hi, can anyone tell me why the pressure gauge on my saunier duval thema F23E boiler shoots up to over 3 in the red then cuts out completely, it has been working fine for last 4 years, no problems, it came on ok by timer yesterday, did its business till mid day, but when i went to flick it on constant in afternoon, it fired up ok, but then cut out after few mins, i noticed gauge was very high, and unit was hot, pressure goes down again to around 1.5, then it triesto fire up again, but pressure shoots up to 3, then turns off.
any ideas anyone,
many thanks
jason

 

[Agile]

Be aware that anything called a Saunier Duval will not be liked by any gas engineer.

Your only salvation is that Homeserve and British Gas do not have the ability to refuse to work on them as an independent does!

Your problem is at the simplest that the expansion vessel is not operating correctly! You can read all about it in the FAQ on this site.

Having said that I dont see any reason why a high pressure should actually stop the boiler from working so there may be another problem as well.

As an independent I rarely have the misfortune to work on them although I am aware that they seem very similar to the GlowWorm boilers.

I went to a S-D boiler last week with water spurting out of a hole in the plastic right hand hydraulic block which was a simple case of a faulty injection moulding.

Tony

 

[jasonwicks]

hi , the boiler does turn off completely once the pressure reaches the highest point in the red, then once its cooled down a little it turns back on for only about a minute before turning off again cos pressure has shot up again,, one other thing i forgot to mention, is that none of the radiators are even luke warm not even the one right next to the cupboard where the boiler is,
so could the pump be faulty as well as expansion vessel, ??

 

[kwakbiker]

you,ll probably find that the hose connecting the expansion vessel to the block is chocked,depending on the location of the boiler (i.e. next to adjacent wall etc ) it is a simple enough job to do

 

[jasonwicks]

im really a complete novice at all this, technical words like chocked and next to the block mean nothing im afraid, i couldnt locate the expansion vessel if i tried, thanks anyway,

 

[Boilerhe1p]

you,ll probably find that the hose connecting the expansion vessel to the block is chocked,depending on the location of the boiler (i.e. next to adjacent wall etc ) it is a simple enough job to do

What he said^^ or it may just want pumping up but yes that wouldn't cause the boiler to cut out sounds like its also overheating which your right is either a weak pump .. A blocked gauze filter in the flow or return isolation valve or a system blockage.. Also could be temp sensors if there wet pocket may be dirty.

 

[picasso]

Any particular reason your dragging up old posts, if they aint fixed by now they aint gonna be.

 

[swbjackson]

Probably working up to a massive spam fest.

 

[diyplumber1980]

I'm no expert but went on a job with a boiler engineer a while back and they had the same problem. The pressure would shoot upto to 3bar, then drop down. then fill up to 3, then suddenly drop.

It was dumping water out of the overflow/safely valve pipe.

Turns out the fault was with the silver filling loop. The home owner decided to top up his heating, but in doing, when he thought he had closed the valve, the valve had not shut. So the water would keep flowing, push pressure up to 3 bar then drop again. The fix was done by simple changing the filling loop and iso valve. cost about 7 quid for the loop. Engineer charged a wopping £85 labour for a 2 minute job.

 

[Agile]

Would have been simpler just to close the filling valve!

 

[diyplumber1980]

Would have been simpler just to close the filling valve!

lol no the actual valve was faulty, even though it was in closed position, it was still letting water through. This is why I always say never touch anything to do with the boiler/heating. even messing with the filling loop can cause problems.