Help ////// I have a Vaillant Sine 18 T3 and everything has been ok up untill 2 weeks ago i noticed when we have the hot tap running slow the boiler doesnt fire up like before. When i put the heating on the boiler fires as normal and the taps work ok, and also when i turn a tap on full and the boiler fires up without the heating on if then i turn the cold tap on to mix the boiler turns off. Would Appreciate any help at all thx
Vaillant Sine 18 T3
- Thread starter OKKA
- Start date
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Diaphragm in the water section is the first thing to check. Probably stretched or maybe a small hole.
I seem to be one of the very few who will still repair these boilers.
But part of the problem is that they are very fault tolerant and most of those I see have multiple faults.
For example the failed diaphragm can be effectively bypassed by activating the hot water preheat facility ( if that is still working ).
BG still have a few on their cover but if they fail they quote the lack of spare parts as an excuse for not repairing them.
Tony Glazier
But part of the problem is that they are very fault tolerant and most of those I see have multiple faults.
For example the failed diaphragm can be effectively bypassed by activating the hot water preheat facility ( if that is still working ).
BG still have a few on their cover but if they fail they quote the lack of spare parts as an excuse for not repairing them.
Tony Glazier
Thx for the reply lads i will try the Diaphram ..... I do know a little about boilers but wanted to see some replys ..... I will take the boiler pressure down to zero and unscrew the diaphram body to release the two pipes that are connected, then take appart so if theres a little hole or its streched that may be the problem ...... Right will post back when i have ordered a new one .........
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This is great when DIY ers r on it 
U don't need to release pressure that's the heating side ! An by sounds of it ur gonna remove the 2 pipes from bottom of divertor valve! No diaphragm there lol! Try the water valve underneath!
U don't need to release pressure that's the heating side ! An by sounds of it ur gonna remove the 2 pipes from bottom of divertor valve! No diaphragm there lol! Try the water valve underneath!
Dony worry, he knows all about boilers!
One wonders in that case why he needed to ask here!
I have to say it had not crossed my mind that it was the diverter valve that he was going to open to replace the diaphragm.
Tony
Thanks for spoiling my fun... was looking forward to the return post...
"do vVaillant sell drysuits as part of the service kit"
"do vVaillant sell drysuits as part of the service kit"
Lads i ask on here because there are so many faults that it could be .... the part i was refering to was the differential valve the one in front of the gas valve. It has two pipes that run to above the pump, that has a diaphram in it.
So i need to check the diaphram in the water section and when i say i know a little i mean just the basics thats why im asking for help. No one knows it all .........
So i need to check the diaphram in the water section and when i say i know a little i mean just the basics thats why im asking for help. No one knows it all .........
Eh on the vcw s me an 831 do know it all
N
namsag
Between me and my brother we know absolutely everything about anything.
Ask me something
Ask me something
A clue namsag?
All sorted didnt need a rain jacket ...... Thx 45yearsagasman for your advice well pleased it was the Diaphram in the water section £6.00 and all done. As for the 3 numptys Bunnyman, youllneverguess, Agile go swivel on a u bend you was no help at all ........
I was not intending to help you.
You had already said that you know all about boilers so clearly did not need further help.
You had even devised a method of changing the DHW diaphragm with only undoing two pipes that had escaped me.
You had already said that you know all about boilers so clearly did not need further help.
You had even devised a method of changing the DHW diaphragm with only undoing two pipes that had escaped me.
Okka u get forums a bad name **** off an drown urself idiot!
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