Boiler works intermittently

[RodgerA]

Hi

I'm after the benefit of your experience, before I go on wild gooses chases.

The system is new to me, its an old Thorn Olympic 38/50CF with 5 rads downstairs and 4 upstairs. From searching this forum I think its gravity fed HW, since I can only find one 2 way valve.
So far I have managed to unsludge the radiators with Sentinel X400, good stuff that.
The micro switch on the 2 way valve was not connected to anything! It now has a live and connects to the room thermostat, which now works!
The timer had an intermittent fault because the cover wasn't on properly.

So I am getting there. My remaining problem is that the boiler doesnt always fire up. When it fails to fire, I can feel the pump running and hear the fan, and I definately have 240v to the boiler (I measured it). If you turn the mains supply on and off this will sometimes fire it up. When it does fire up it sometimes has a woolly flame for a short while. Once it is running the flame looks nice and blue, boiler is quiet and works well.

Searching this forum makes me think it is a "sticking" gas valve, which I guess would effectively write the boiler off.

I would appreciate your advice on anything else I could test.

Just noticed that the pilot light flame isn't vertical its about 30 degrees from the vertical, should it be like this? Worth changing the thermocouple?

Many thanks

 

[HERTS P&D]

Get it serviced!

Andy

 

[Agile]

Does this old boiler really have a fan?

No DIYer should be opening or touching the inside of the boiler!

Tony

 

[matt1e]

Get it serviced!

Andy

Is the way forward

 

[dcawkwell]

Gas valve solenoid. Would be my guess.

 

[RodgerA]

Thanks for taking the time to reply. Appreciated. Shame that the solenoid seems integral to the valve, but even the whole valve seems available at a price thats worth doing. I will find someone local to fit it. Thanks again.

 

[Agile]

Better to diagnose the fault first!

 

[RodgerA]

Well I will of course take the pro's advice, I'm just trying to minimize my costs, like most people I guess.
I sthere anything you think I should check first?
Thankyou.

 

[Mikefromlondon]

On many boilers if you play around with the room stat, the boiler has a so called anti-cycling delay, and this delay gets cancelled when you turn mains off, i.e. the delay resets, so make sure this intermittent problem is not because you are trying to test the boiler from firing each time you turn up the room stat dial, it won't respond immediately as you would expect.

The delay is there to stop a boiler from firing too many times in a short period, so as to stop it from becoming a nuisance. So this may be worth considering before you decide to call an engineer, in any case, if it has not been serviced for quite some time, then worth calling someone to give it a good clean up and service.

 

[Dan Robinson]

This boiler has none of that.

I suggest you keep schtum.

 

[RodgerA]

Thanks Mike, I take your advice onboard. I think I am in "doubt" mode because the thermostat wasn't connected and there was a problem with the timer programmer front case not fitted properly. Also when I looked at the wiring there was a blue wire from the timer to the earth on the boiler, which freaked me a bit. Whoever installed it used two lots of 2 core instead of one 3 core from timer to boiler!

Apparently it has been serviced annually, but I can't find any stickers etc to that effect. I wil give it some more time, now the other problems are sorted. Understand the point about the delay. You don't want the boiler firing because someone opened the back door for two seconds, a kind of damping effect.
Thanks again.

 

[Mikefromlondon]

This boiler has none of that.

I suggest you keep schtum.

There is no need to behave like a 20 yr old jealous kid!

 

[Dan Robinson]

I'm a fair bit older than 20.

Why do you insist on giving out BS advise?

 

[CBF]

This boiler has none of that.

I suggest you keep schtum.

There is no need to behave like a 20 yr old jealous kid!

Dan is spot on, you are posting about boiler issues when you are neither a RGI or know what you are talking about, which could lead to you giving incorrect or dangerious advice

 

[Mikefromlondon]

This boiler has none of that.

I suggest you keep schtum.

There is no need to behave like a 20 yr old jealous kid!

Dan is spot on, you are posting about boiler issues when you are neither a RGI or know what you are talking about, which could lead to you giving incorrect or dangerious advice

Where does it say that you have to be an RGI to offer sound advice, and my advice was no BS, why do you say I don't know what I am talking about, may be you don't know what anti-cycling delay is then.