vaillant vcw sine 18 t3w

[Aleboy564]

Hi. I've recently moved house. The boiler is a vaillant vcw sine 18 t3w. It was installed in 86.
Ive so far worked out it has a immediate hot water switch and an instant hot water. When switched to the instant and you turn the tap on no hot water comes.
On the immediate it seems to heat the water the boiler holds then I'd say 50% of the time it not fire so cold water comes out after around 20 seconds.
Also te boiler seems to run and no flame present. I can make it stop by running a hot tap.
Any ideas? I'm trying to figure out wether to struggle on and save for a new boiler or put money into it. All reviews I've read say this is a very good boiler!
Any help woud be appreciated. Thank you

 

[Dan Robinson]

you have one of the finest boilers of our time. but it needs a certain kind of looking after.

i will direct a couple of the Bunny boys to your thread who will hopefully help you more than i dare.

 

[gaspro1981]

Sounds like the diaphragm or the micro switch on the water section is goosed

 

[Aleboy564]

Thank you for the boiler compliment. I have British gas homecare. Do you think they'd fix it? Or just try sell me a new one?

 

[The831Bunny]

When you do run hot water, does the pipe on the far left get hot?

 

[Aleboy564]

No, just ran hot and the second from left was warm. I noticed boiler fired up for about 5 secs then shut off. Even though hot tap was still on.
I can still hear the boiler motor/pump now even though hot is off and there's no flame if that makes sense.

 

[The831Bunny]

Ok, next questions. With the centre switch OFF, can you hear a click when you turn the hot tap on?

Then put the centre switch on and the pre-heat switch (right switch) on. Put the heating switch (left) off. The boiler should fire and turn off after 2-3 minutes of pre heating the hot water. The pipe on the far left should not get hot, but the pump should stop running. Have a check and report back.

I'll reply in the morning.

 

[mcmoby69]

DHW heat exchanger blocked and overheating?

does it fire again when it has cooled down or need resetting?


sorry, but im not a bunny boy! there will be someone else more use than me along soon!

 

[Aleboy564]

I really appreciate all your help!!
I couldn't hear a click with the centre off. Would I hear it over the sound of the water?
Then as you described, boiler fired for a min then turned off fine. But when I run hot water it doesn't fire again so water goes cold.
Just a side note, but when the boiler works, it works perfect. Mrs can be in the shower for what seems like an eternity. No probs. and gas bill shows I'm not using an excessive amount.

 

[Aleboy564]

As an extra to my last, when. Turned the hot on the pump/motor came on but no flame.

 

[Dan Robinson]

first thing tomorrow - tell BG to fook right off. find someone local - maybe ex Vaillant/Group Service who will care for the boiler. it is what i do for all my customers with these thst have a breakdown- luckily i have just the chap in London.

 

[bell824]

you have one of the top men on this forum to guide you through this831bunny was born and bred on these machines and his advice is final on this one bud!
hope all is well and you can save this beast as she is a creation of wonder

 

[ChrisR]

If you have free BG cover it's worth trying them. They should still have some guys who know these beasts really well. Or have they all left now?
I have a T3 in my shed , waiting for the day when I properly find out how the bloody thing works. I know it will never happen.

 

[bell824]

lol chris i am a bunny and have just got to grasp with the thermo/combi compact range, no chance of me fully understanding the sine range now

 

[Dan Robinson]

If you have free BG cover it's worth trying them. They should still have some guys who know these beasts really well. Or have they all left now?
I have a T3 in my shed , waiting for the day when I properly find out how the bloody thing works. I know it will never happen.

When I saw the thread title, my first thoughts were that if the thing was being changed to let me come and take it off the wall carefully - then I saw his location