Swapping out a DHW heat exchanger

[ianmcd]

Yes, A selection pack of washers, 1/2 and 3/4 should suffice.

The plate heat exchanger doesnt use washers

 

[gasbanni]

The plate heat exchanger doesnt use washers

Quite right but get the boiler specific o rings for the plate to plate.......when you go to get them go with the gc no of the boiler from the data badge ....plus open all the hot taps and the shower if it's a mixer and drape a black plastic bag over the back plastic cover over the control board electrics.
Spirit of salts will also do the job, a little silicone grease on the o rings will help too.

 

[mattylad]

There are also videos on youtube from RGI's doing this that you can watch to learn from.

 

[MJN]

Is it advisable to fit new washers when refitting if so are they a standard size- it would be better to get them prior to removal?

Yes, and get a pack of o-rings too if my experience with what is admittedly a different make/model (WB 24CDi) is anything to go by as there's nothing worse than putting everything back together again and standing back to admire your handiwork than seeing a weeping joint right in the bowels of the boiler... Washers are arguably not quite so bad but o-rings deform over time and once disturbed can struggle to reseat. They will likely come pre-lubricated but a small amount of silicone grease can also help and also make them last longer too.

Edit: Apologies @gasbanni; didn't see your post but now see I've just regurgitated what you'd already said!

 

[Stringman_uk]

Many thanks guys, I am able to buy a pack of 10 from wolseley for the sum of £13 ! but can get them today.
One final question.
I know i have to isolate the mains feed to the boiler ( at the boiler) and switch the lowest hot tap on. with the exception of the bathroom sink all taps are mixer, so switch them to full hot should i expect them to run dry or will there be an element of cold running through? Just preparing myself as to what to expect.
Thanks in advance

 

[ianmcd]

Many thanks guys, I am able to buy a pack of 10 from wolseley for the sum of £13 ! but can get them today.
One final question.
I know i have to isolate the mains feed to the boiler ( at the boiler) and switch the lowest hot tap on. with the exception of the bathroom sink all taps are mixer, so switch them to full hot should i expect them to run dry or will there be an element of cold running through? Just preparing myself as to what to expect.
Thanks in advance

no switch the tap to Hot and just leave it open, you will get a short spurt of water then it should completely stop, take note if you are still getting water out with the boiler inlet isolated, do not proceed, that means you have a fauly mixer which would give you the same symptoms as a blocked plate heat exchanger

 

[Stringman_uk]

Ian many thanks
I have had a look at the boiler and it seems relatively easy to get the plate out.
My one concern is that when i looked at the pipework below it was not obvious(to me) which pipe I should isolate as the isolation taps have lost their coloured handles. Also I am presuming I dont actually have to drain the boiler as such just the hot tap? As an aside I am sure you skilled chaps will notice the filling loop seems to be disconnected. There was some issue with so that has been moved to the side of the boiler alond with the magnetic filter thing. So I would presume ( well guess) that the valve I need to switch off is the one to the right of the Gas pipe? Off to buy the c rings now !

 

[ianmcd]

the valve I need to switch off is the one to the right of the Gas pipe?

Yes that is correct

Also I am presuming I dont actually have to drain the boiler as such just the hot tap?

No you need to competely drain the boiler, the plate has both primary and secondary water in it that is how it works

 

[Stringman_uk]

No you need to competely drain the boiler, the plate has both primary and secondary water in it that is how it works[/QUOTE]

Ah bugger where would i find the drain valve? I thought it was the red valve but thats the PRV?

 

[Daveydub]

Drain offs just to the right of ch isolation valves

 

[Stringman_uk]

Drain offs just to the right of ch isolation valves

Do you mean the little pipe coming out of the bottom of the far right pipe that looks like its operated by a square type screw ?(the photo isnt brilliant) if so do I also need to isolate the ch valve to be safe?

 

[ianmcd]

Do you mean the little pipe coming out of the bottom of the far right pipe that looks like its operated by a square type screw ?(the photo isnt brilliant) if so do I also need to isolate the ch valve to be safe?

there is a drain off on each of the CH pipes you need to open both, dont touch the isolation valves or they will leak

 

[Stringman_uk]

there is a drain off on each of the CH pipes you need to open both, dont touch the isolation valves or they will leak

Do I presume that on the picture this is pipe 1 and pipe 5 with the ridged pipe outlet?

 

[ianmcd]

Do I presume that on the picture this is pipe 1 and pipe 5 with the ridged pipe outlet?

yes

 

[Stringman_uk]

Thank you so much.
I have a day off tomorrow so will give it a go then!