Glow worm 30SI Overheat problem

[jpbamford]

Hello,
I've a Glow worm 30SI which has failed with an F5 error code. On searching, I've found that the overheat sensor can be re-set, which I've done. This allowed the boiler to fire up briefly, but then the sensor tripped again.
Am I right is suspecting a failure in the pump in this case?
The boiler is over five years old.
Thanks for your suggestions; luckily its quite mild at the moment!

 

[Agile]

Poor flow can be pump or most often on that model sludge !

To those who like that make, should he be looking to the right of the pump?

Tony

 

[bell824]

tony,

would love to say i know what your inferring to but i can't mate.

but you quite rightly state the obvious and have answered the poters question, it is a circulation problem.

check the pump is turning check for sludge, as tony says.

 

[Agile]

I always know boilers from their insides with the cover off! Not from their type numbers in many cases.

There is an S-D boiler which has a filter just to the right of the pump on the left which obviously gets blocked. Its not very obvious that its there unless you are very familiar with the boiler. Many G-Ws are the same as the S-Ds.

Luckily I dont get called to many of the later G-Ws. Mostly the earlier Compacts etc.

Tony

 

[jpbamford]

Thanks very much for your swift replies.
I see from the schematic that there is a CH filter on the 30SI; I'll drain it down and fish out the filter tonight. Is there any specific procedure for cleaning it, please?

 

[bell824]

No set procedure other than to get it as clean as possible, also ensure the pump is moving though.

 

[jpbamford]

Ok. Filter cleared - yes fairly clogged with black crispy bits. Pump certainly seems to be running. Boiler fired up and ran for a few seconds before stopping again this time with an F14 code - another overheat code. That one seems to be recoverable as after a short time it started up again but then failed with F5 again.
Now I'm thinking that there might be a blockage in the manifold, perhaps - I am in a hard water area.
Is this a possibility?

 

[bell824]

does your heating system have an externall byepass fitted?
i.e a bridge between the flow and return.

Also as you say manifold i am guessing you mean 8/10mm supplys to your rads. If so how old is the system and was it flushed at install?

looks like you are going to be chasing a blockage and at least having that sytem chemical cleaned!

 

[Agile]

Hard tap water has no effect on heating systems.

The sludge is the products of corrosion of the insides of the rads!

Was the boiler filter where I described it and long and thin?

Tony

 

[jpbamford]

Sorry, wrong word - I meant heat exchanger not manifold.

Filter was located right next to the pump, accessed from below, and rather difficult to remove. It was long and finger-like black plastic and had narrow slotts arround it; the top most of which were filled in with black crispy residue. The rubber seal had orange rust arround it. I cleaned the filter and also up insude the chamber

The central heating system is about 30 years old, but at least half the rads have been replaced in the last 10. The Boiler is located right at the top of the system in the loft. I have an external pressure gauge so I know that the pressure is good, but I have a very slow leak somewhere - I need to top up the system every 6-8 months when the pressure drops below 1bar. I only add a very small amount! The boiler was repaired due to a faulty pressure release valve about 18 months ago.

Thanks again for you help.