Any Boiler Experts on the forum (or someone who's worked on one before)

[Most Easterly Pandas]

Hi guys,

I've a 10 year oil oil fired combi boiler. Massive thing it is!

Anyway we had it serviced a few months back, and was advised that the Diaphragm on the expansion vessel has perforated and will fail completely eventually.

Upon asking what will happen if its left we were told it'll cause the boiler to over heat and trip, which is has done, once before this diagnosis, and twice since.

So last night it tripped, and a reset didn't resolve it, so I went about draining the vessel of the water which has bypassed the diaphragm.

Basically looks like it'll need changing sooner rather than later, now never afraid to try things myself it looks easy enough to do DIY - literally take the pipe from the boiler off of the old vessel, and attach it to the replacement.

However I've a feeling this would then result it the whole (all 9 radiators (some double sized) draining out through this pipe. Does anyone know if this is correct? And if so what the correct method of changing the vessel is.

Cheers,

Jon.

 

[PuntoHowTo]

You should have a tap some where at the lowest point of the heating system near the bottom of a down stairs radiator, to drain the system down before you do any work on it, should prevent the problem you describe

 

[Andy Monty]

Removing the cover (on most boilers) is an offence unless your a Gas safe registered gas engineer as the cover is classed as a combustion seal.

even a oven door seal is classed as a combustion seal



You can get a pipe freezing kit which gives you 15 mins or so before it begins to leak

eg

http://www.screwfix.com/p/rothenberger-tradesmans-pipe-freezing-kit/95208
http://www.screwfix.com/p/arctic-pipe-freezing-kit-425ml/20183

 

[PuntoHowTo]

Removing the cover (on most boilers) is an offence unless your a Gas safe registered gas engineer as the cover is classed as a combustion seal.

even a oven door seal is classed as a combustion seal

I believe oil fired boilers are covered under a different set of rules. You have Oftec engineers for installation but repairs can be carried out by anyone, oil isn't easy to ignite and it very obvious when leaking you could argue its no different to doing your own maintenance on a diesel engined car

 

[Andy Monty]

Im blaming speed reading MEP's post....... :devil:

 

[Most Easterly Pandas]

You should have a tap some where at the lowest point of the heating system near the bottom of a down stairs radiator, to drain the system down before you do any work on it, should prevent the problem you describe

Having had a good look on youtube, like you say should be a drain point somewhere to enable the system to be drained and then allow me to change the vessel.

Removing the cover (on most boilers) is an offence unless your a Gas safe registered gas engineer as the cover is classed as a combustion seal.

even a oven door seal is classed as a combustion seal



You can get a pipe freezing kit which gives you 15 mins or so before it begins to leak

eg

http://www.screwfix.com/p/rothenberger-tradesmans-pipe-freezing-kit/95208
http://www.screwfix.com/p/arctic-pipe-freezing-kit-425ml/20183

Cheers for those links Andy. Luckily, regardless of if those rules apply or not, the door / cover which is removed to gain access to the vessel is the same one to gain access to the on/off control and temp dials, so I'd assume different to a 'main boiler cover' which would be governed by said laws.

That said, its only as its oil, and a simple thing I'm considering doing it myself. I would be staying well away if Gas!

 

[2668GRIFFIN]

let off the pressure in the system,turn all the rads off at there valves,you will only get a small amount of water discharge, unscrew the vessel,and replace with a new one,inflate to about 1 bar of pressure.
turn the rad valves back on pressurise the system via filling loop,start up boiler and bleed out the air.
done
luigi

 

[Big Black Stilo]

Removing the cover (on most boilers) is an offence unless your a Gas safe registered gas engineer as the cover is classed as a combustion seal.

oops.....

i have done work on my boiler, not knowing this, but only on the water side of the boiler, not touching anything gas (self bleed valve leak, expansion vessel re pressurise)

if anything went on its gas system i wouldnt mess with it, i'd call someone in.

Anyways as said, somewhere on the system there will be a drain point. you can stratigically close radiators to minimise loss, however if you draining it, might as well drain it and get rid of any sludge build up in the rads. I recently changed two rads upstairs in my house, the heating system hadnt been drained for at least 5 years so instead of isolating each rad, i drained the system and got rid of some nasty cack out the downstairs rad where the drain point is.

now all is well and a lot toastier than previously

 

[Andy Monty]

oops.....

i have done work on my boiler, not knowing this, but only on the water side of the boiler, not touching anything gas (self bleed valve leak, expansion vessel re pressurise)

if anything went on its gas system i wouldnt mess with it, i'd call someone in.

Anyways as said, somewhere on the system there will be a drain point. you can stratigically close radiators to minimise loss, however if you draining it, might as well drain it and get rid of any sludge build up in the rads. I recently changed two rads upstairs in my house, the heating system hadnt been drained for at least 5 years so instead of isolating each rad, i drained the system and got rid of some nasty cack out the downstairs rad where the drain point is.

now all is well and a lot toastier than previously

well i replaced a oven door seal the other day our local gas man said you can't get a seal for that its discontinued..... 30 seconds on google... 2 mins trying to remember paypal password and 48 hours later it arrived......


had visions of having to strip the oven down to fit it.... bloody thing was a push fit once the old seal had been picked / broken out...

(nb it was then checked by a gas safe man who replaced our hot water tank and immersion heater since it went bang the other day)

 

[EvoStevo]

Did you get it fixed?

I have replaced several diaphragms in combi boilers over many years, they are only about < £5 and common to many models.

Replacement is just a case of drain down, remove the assembly, unscrew all around and take out the existing diaphragm. AT this point it helps to take a photo of how it comes out so that you can refer to it when reassembling. Refill, bleed the rads and enjoy the hot water.

 

[Most Easterly Pandas]

Did you get it fixed?

I have replaced several diaphragms in combi boilers over many years, they are only about < £5 and common to many models.

Replacement is just a case of drain down, remove the assembly, unscrew all around and take out the existing diaphragm. AT this point it helps to take a photo of how it comes out so that you can refer to it when reassembling. Refill, bleed the rads and enjoy the hot water.

Not touched it since as we've been away since christmas eve and won't be home until new year. I believe the vessel on our is sealed. I'll take some pictures and see what you think.