Anyone familiar with the Valiant Sine boilers?

[Stu_M]

Just had some building work done today and after lifting the floor found a leaking water pipe which feeds the boiler. Problem is since this discovery our boiler has dropped a bit of pressure in the past couple of hours. Topped it up to just above the red line (0.75) and she's not happy to fire up anymore when we open a tap? Pressure was down to just over 0.5 and certainly not dry. Phoned to get our usual guy out and he's not there anymore. So it's back to engineers who don't understand how she works and want to concentrate instead on the hard sell. Yep, I know, I know, she's an old boiler! But we have no trouble - incredibly reliable, quiet and efficient. TBH neighbours who did swap to condensing are always having breakdowns, some are now on their 3rd W-B in 10yrs, and many get left without heating in winter when the pipe freezes up, hence just not ready for giving up on the old girl yet (she's been very well maintained too).

So does anyone know if there is an adjustment/setting I can do to get her firing for hot water again (vaguely remember good engineer uses a screwdriver to adjust something on one of the water pipes which is involved in the firing when we open the tap)? The new engineer was already booked to replace the LPG pipe whilst the floor is up (seems sensible given it's been wrapped and near the corroded water pipe and is not looking too good itself). So they'll be here to give her a look over if we can't get her going ourselves, but really not confident they'll know how to deal with her.

 

[Agile]

I cannot think of any reason why the boiler would not work if the pressure only went down to 0.5 bar.

I suspect it went lower and the overheat stat has tripped out.

Tony

 

[Stu_M]

Hi Tony, do you think the reading is reliable or could is it possible to have dropped lower than it read?

 

[Agile]

The very fine tubes to boiler pressure gauges often block.

But I have not seen your boiler.

Tony

 

[Stu_M]

OK, thanks. Will mention that to the engineer tomorrow. Have got the manual and service manual out so will go and locate the reset to see if it is a simple solution...

 

[Agile]

Its a bit fiddly to reset but you could do it yourself if you have a suitable long tool.

Tony

 

[Stu_M]

OK, can't see a reset??? and nothing referred to in the manual. it just describes how to change it

 

[algas]

the overheat re set is the black rubber tit in the middle of the two screws C8

 

[Stu_M]

Thanks just found it as you posted. Sadly nothing doing... thinking the vibration taking up the concrete around the pipes has upset things properly.

 

[algas]

have you tried the air vent top lhs heat ex

 

[Agile]

As I recall you cannot access that without removing the cover which is not a DIY job.

But if the info provided is correct then the pressure has not been allowed to go to zero so there should be nmo air in it anyway.

But you could check the cap on the auto air vent just behind the pump is just loose. To prevent leaking they are often done up tight.

Tony

 

[Stu_M]

Turned the power off to it, wriggled some of the contacts (noticed the vibration of a builders chisel hammer to take the concrete up over the pipes had dislodged the pilot start wire so it has obviously had a really good rattling), killed the pilot flame and re-lit no issues (that problem solved), found something about the pin on the differential valve (on flow chart 4 of the manual) so switched the heating switch off and on a good few times. The old girl then roared to life as soon as we flicked the power back on to her. Put the housing back on went to turn the tap on not firing up again??? Only thing we are not sure about is if the red power light has always flickered or if this is an new issue. Basically going to need the engineer to be prepared to test electronics I think, seems to be something loose or sticking...

 

[Stu_M]

Well engineer has been and he doesn't do LPG anymore Pity because he seems very good. However he quickly sorted the pipework feeding the boiler. Then he turned the LPG back on, refitted the housing and lit the pilot. Flicked the heating on and she fired up first time no issue. He says all he has done is pressed the kill switch and then relit and fitted the housing. He wonders if there is a switch sticking or binding on the housing which has meant it was pressed in? Still pretty curious as to why she flipped out, especially in case the issue recurrs.

Also if anyone knows a good engineer to service her (due again Feb) in the South Lake District area then please can you let me know. Have the name of one guy to phone, but we tried him as soon as we got the service reminder from the old company and was told our regular engineer had left... just goes through to voicemail and no reply to messages left.

 

[Agile]

It does sound as if you did let the pressure go down too low and air got into boiler.

I really don't know why regular checking of the pressure is such a problem for some people.

On your model it helps to alternate demand for CH and DHW to encourage any air to be dispersed to the rads and removed by the auto air vent if the cap is loose.

These are old boilers and regularly using the buttons on the front to kill and restart the pilot helps to keep the contacts clean.

Tony

 

[Stu_M]

Hi Tony, firstly thank-you for all your help, this is Stu's wife he's now left an gone back to work. The boiler has just gone off again. I went downstairs and the black needle was on the red line rather than above it. Filled it back up to where I have been shown before by our regular service guy. It's back firing up. It did make quite a loud gurgling sound so I am wondering if you are right about air being in it. Also not sure why we have 2 taps underneath it on that pipe had to open both as both were shut. Should I just leave it alone now and monitor the dial?