Gravity fed 308k Rayburn Back Boiler Leaking?

[dilligaf76]

I have a gravity fed Rayburn 308k model with a back boiler that appears to be leaking water as the base of the Rayburn is very wet and rusty. It's not coming from the fittings on the outside so it must be the internal tank.

I cannot see how to get to it though, some models appear to have a side plate but this one doesn't and the only other way I could see is to take off the whole top but that looks like its not design to come off?

Any help would be great please...

 

[Exedon]

Top of easy
First disconnect flue
Take of 4 chrome screw caps ( they unscrew ) sometimes a hammer and screwdriver job replacements are available.
Under chrome caps are conical shaped nuts with screwdriver head (very large screwdriver required)
Soak with penetrating oil remove 4 nuts lift of top.
Replacement rayburn heat exchangers can be eye watering expensive often making job not worth doing.
Try Harworth heating for spares .
By the way that remote fire valve couldn't be in a more useless place if you tried. Needs a 90c type fitted next to burner.

 

[dilligaf76]

Thank you for that info. I managed to get the whole top off with your help and eventually with a struggle I got the boiler out. On inspection and pressurising the boiler as best as I could with a hose pipe and blocking the outlet it appeared to be fine and given the type metal there was no way it would rust to the point of leaking.
So I have been scratching my head trying figure out why the whole bottom of the Rayburn was wet with rust all the way around it. The only thing I can think is one of the fittings on the outside of the Rayburn to the boiler was leaking prior and that the water must have run along the pipe back inside the Rayburn.
I could be missing something but I cannot see for the life of me what else could have happened!

 

[Exedon]

The original fitted boiler in the 308 was stainless steel (though I have known them leak)
It should have a gravity only circulation to a hot water cylinder I think one small towel rail could be run as well.
Only way to be absolutely certain of boiler is to put a proper hydraulic water test on it say 3bar.
What was the new section of copper on flow installed for?

 

[dilligaf76]

Oh yes that's right it was stainless steel. I will have to try and rig up something better then to test it as to get more pressure and maybe spray some soapy water over it and look for bubbles.

And yes it is indeed a gravity circulation only type heating with one small radiator in the bathroom and the hot water cylinder. I fitted a new section of pipe because the old was leaking on the joint which is the return as you probably know and although I cleaned it as best as I could and using flux the new solder just wouldn't take properly so I cut a piece out and soldered on some new.

This cured the leak but again I was thinking as the Rayburn has been off for quite sometime given the time of the year and where it had been leaking before on that old joint water may have run back through inside the Rayburn and down the side of the boiler gradually making all the insulation wet to the point a pool of water had settled at the bottom of it.
Before the Rayburn was turned off for the summer I am guessing that previous leak was drying out enough as to not make it very noticeable wet on the bottom of it.

This is my theory but of course I can tell you know a lot more than me and I am thankful for your time and help. I forgot to ask about the sensor for the remote fire valve that's on the wall, should I move it then?

 

[Exedon]

First fire valve sensor should be in front of burner as near to door as it will go there was originally a clip on bottom plate
Make sure fire valve is rated at 90°C it's marked on valve.
It's not possible that rain has been getting down flue is it?
I've seen it happen on straight flues with no rain cap.

 

[dilligaf76]

Okay cool. Good question, I cleaned the flue recently through the access panel too with some rods and brush attached to a drill and although there was carbon and soot build up it appeared dry, of course I renewed the fire gasket as well when I had finished.
I also checked outside and visually looked at the cap and it looks to be in place and intact…

 

[Exedon]

Just a case of monitoring it maybe try to get a decent test on boiler if OK reinstall and fill up.
I would be tempted to give it a few days before patching any fire cement up in cooker.
Then bring it up to temperature nice and slowly.

 

[dilligaf76]

Will do and I'll try and remember to let you know what happens when I get round to doing it, might not be for a few weeks yet. For now though thanks again for your time and all your help you've made life just that little bit easier

 

[dilligaf76]

Just a case of monitoring it maybe try to get a decent test on boiler if OK reinstall and fill up.
I would be tempted to give it a few days before patching any fire cement up in cooker.
Then bring it up to temperature nice and slowly.

Hi again, haven't put the Rayburn back together yet but I have found that the boiler was leaking after all through the welded seams when it was under pressure, I'm glad I checked it again.

Luckily through a friend of a friend I had one made from stainless steel for £200 which is a lot cheaper than I could get one for online. They did re weld the original one but noticed some more hair line cracks. They of course pressure tested the new boiler before handing it back to me, the welding was absolutely brilliant.

So hopefully once I reinstall it everything should be as it should. Here's the photo of the new boiler I had made, oh and thanks again for all your help

 

[Exedon]

Thanks for update that looks a nice bit of fabrication
When its all back together slowly bring it up to temperature as soon as you can less chance of fire cement cracking.
Plus don't forget to sort that fire valve.