Saunier Duval Boiler problem

[badbaz]

Hi, I'm after for some advice on a pressure issue with my boiler.

It's a Saunier Duval Themaclassic F18E SB. When the heating switches on via timer the boiler won't fire because the pressure gauge is flashing showing only 1bar of pressure, the red light is also flashing. If I open the water supply valve the pressure rises and immediately the boiler fires up and will run all day.

Overnight, maybe over a couple of days the same problem occurs as the pressure drops too low. There is no sign of leaks, the radiators are all full and when bled only water comes out. It seems no matter how much I pressurise the system it drops back again and no heating!!

Thanks for looking.

 

[wards]

have you checked the prv?

 

[badbaz]

have you checked the prv?

if you mean pressure relief valve can you say where this is located and how I'd check it please?

 

[stevetheplumber]

you check the small overflow pipe that goes through the wall see if its dripping

 

[oldplumber]

pressurise your sytem to 1.5 bar, turn on the boiler and turn central heating upto max, monitor the pressure gauge and see what pressure it rises to. if it rises rapidly upto 3.5 bar you will then see the prv blowing off, and if this occurs you need to repressurise you expn vessel or if you see water coming out of he shraeder valve on the expn vssl you need to replace it as your diaphram has perforated.

 

[badbaz]

you check the small overflow pipe that goes through the wall see if its dripping

this pipe comes from the boiler?

if it is dripping what do I do, if I can do anything?

 

[fireblade]

It is possibly the flexible hose going to the expansion vessel in the boiler it is probably blocked thats what happens to my saunier

 

[badbaz]

It is possibly the flexible hose going to the expansion vessel in the boiler it is probably blocked thats what happens to my saunier

Is this easy to locate/identify? Cure?

 

[fireblade]

de presurise the boiler expansion vessel is inside boiler follow the braided hose to the hydroblock ther should be a clip onto the hydroblock undo clip put the end of the hose in a bucket and shove a piece of solder up the hose to unblock it and re assemble

 

[oldplumber]

Id try what i advised first before you decide to deconstruct your boiler, it may be you just need some air in the expansion vessel or may already have failed and need anew epn vssl.

Dont forget fireblade is a plumber and makes it sound easy, saunier joints/clips have a habit of cracking, so be careful and dont floof your pcb which will cost around £150 to replace just for parts. How do I know, only did one last month where someone had had a go at replace a leaky prv (without depressurising the boiler lol)

 

[fireblade]

Cheers oldplumber i sometimes forget its not that simple

 

[badbaz]

Guys, I very much appreciate your advice. You are experienced in these things and work with them every day. If i were to describe a job on your car to you, I have no doubt you could do it but when I described it to you then you'd say, hold on, a bit at a time!

Can you tell me which I should do first and how to go about it? Bare in mind the boiler isn't in front of me right now, I have any amount of tools available and I'm more than capable of following your instructions.

I can take pics if you need me to?

Cheers

 

[oldplumber]

go online, look up saunier duvals website, Removed a look for the installation instructions and pull them up. they will list step by step how to remove expn vessel. recharge it etc.

 

[badbaz]

go online, look up saunier duvals website, Removed a look for the installation instructions and pull them up. they will list step by step how to remove expn vessel. recharge it etc.

I'll give it a go thanks

 

[badbaz]

Thanks for the help - today I took off the braided hose and checked to see if blocked - not sure if it may have been just barely blocked - refitted and pumped up the expansion vessel which did have pressure to begin with but not sure how much!

Time will tell if it's a success!

Cheers