Vokera Excell 80SP -Intermittent hot water

[jack_s]

Could be a number of things but most likely and cheapest to try first is the DHW pressure differential diaphragm valve.

Flip down the flap (?!?!) and somewhere near the middle you'll see a brass disc-shaped object with 5 screws round the edge (there's two - it's the larger one you want). As you open the hot tap, the pin in the centre of this should come out and press against the grey fulcrum arm. This then pivots and makes the microswitch, telling the boiler to fire up. Chances are that the rubber diaphragm inside the brass disc is holed or torn slightly and the pin therefore isn't coming out enough due to the pressure dif being messed up. To test, run the hot tap and pull gently back towards you on the arm where the pin should hit it. If the boiler fires and your hot water is fine, there's your problem.

New diaphragm alone, assuming no greater problem with the valve, is 5 to 10 quid. Easy enough to change - turn off the boiler, turn off the cold to the boiler, drain out by opening hot taps, remove the fulcrum arm, remove the 5 screws around the edge, replace diaphragm, reassemble in reverse order. Job's a good 'un.

I'm looking to now change the DHW Diaphragm.

There is also a small weep around the pin which pushes the microswitch.

Reading other threads, I think I will have to change the seal around the pin which comes in the Vokera Excell T0019 Service Kit,
which I think is one of the brass sealing nuts (?)


Which other parts should I change while I'm at it in the DHW Diaphragm Valve, which come in the kit ??


Is it just those 2 parts, or are there others, rubber seal/s, white plastic thingy in picture ??

Any other advice appreciated.
Thanks

http://www.discountedspares.co.uk/vokera-t0019-service-kit-boiler

http://www.buyaparcel.com/pageview.php?page=show_product&ecommerce_stockcode=T0019

 

[DP]

How about ALL of them and one of the figure 8 O ring.

 

[jack_s]

How about ALL of them and one of the figure 8 O ring.

I'm just doing the DHW Valve for now.

Some parts in kit are for Flow Valve & Diverter Valve I believe, I'll do those another time.

Just want to know how many parts are for DHW Valve ??

 

[jack_s]

Few days ago I changed the Flow Microswitch as it was very badly corroded from the leak (weep) from the DHW Dipahragm Valve
immediately above it.

Decided to test, before changing anything else.

Hot water seems to flow better, but still getting times when hot water doesn't come on.

Went to check in this situation (no hot water flowing), can see that the DHW Microswitch & Flow Microswitch
are both CLOSED (operated), which I checked by gently pulling microswitch arm on both switches.

Any advice on this, why no hot water, both microswitches CLOSED (operated) ??
.

 

[DP]

Jack, why not change all the bits that came in the kit. How do you know the remaining bits are not defective? I do this work for a living and giving you advice free of charge. No skin off my nose if you chose to change domestic manifold dia and leave other bits for a fine day. The diverter section if gummed up will also cause your boiler to bellyache.

 

[jack_s]

Jack, why not change all the bits that came in the kit. How do you know the remaining bits are not defective? I do this work for a living and giving you advice free of charge. No skin off my nose if you chose to change domestic manifold dia and leave other bits for a fine day. The diverter section if gummed up will also cause your boiler to bellyache.

Fair enough.

I'm trying to avoid taking things apart & changing things might which cause other problems.

eg. when I switched off DHW cold water inlet valve, the valve started to leak/weep.

Just trying to work out what is going on, as I can see fulcrum arm has moved, both microswitches operated
& hot water does work reasonably frequently.

Trying to work out why boiler hasn't fired up.

 

[DP]

The dia right of your picture is intergral part of boiler operation.

If the stuffing box on the domestic manifold was shot, got chance remaining two will need to be replaced.

The spindles and bits that move will no doubt be scaled up and need to be cleaned and lubed for 'easy' operation instead of 'forced' operation (possible reason why the stuffing box was leaking) that is often the caase when boiler has not been serviced for many moons.

There are then parts that will need attention of a heating engineer to make this good boiler on its knees to stand up and start doing the good work again.

If you want to know the sequence of operation, get the boiler book out and read it- it is all there for you to see.

 

[jack_s]

The dia right of your picture is intergral part of boiler operation.

If the stuffing box on the domestic manifold was shot, got chance remaining two will need to be replaced.

If you want to know the sequence of operation, get the boiler book out and read it- it is all there for you to see.

I'm definitely going to do the diaphragms now (after changing corroded flow switch).

Checking further I see that when I still don't get hot water, the DHW microswitch just needs a tiny final push to start pump
& fire-up boiler.

Need to sort out the DHW diaphragm, so pin moves efficiently to maximum.
(although I have seen in some other threads here or elsewhere that the fulcrum arm diverter end can wear
& something about putting a 6pence in that end !!)

Question:
Servicing flow valve & diverter, manual says to turn off CH flow/return valves under boiler & relieve pressure using safety valve.

How do you correctly pressurise CH system afterwards, do I just turn on CH valves, then pressurise via link I have
to mains water supply ??
.

 

[kevplumb]

How do you correctly pressurise CH system afterwards, do I just turn on CH valves, pressurise via link I have to mains water supply ??

View media item 11214

 

[jack_s]

How do you correctly pressurise CH system afterwards, do I just turn on CH valves, pressurise via link I have to mains water supply ??

View media item 11214

I've got one of those connected already.

Just checking if there's anything else I need to do (eg. venting boiler or radiators).
.

 

[kevplumb]

make sure the aoto air vent on the boiler is open rads should be ok

but wont hurt to have a walk round and check

Servicing flow valve & diverter, manual says to turn off CH flow/return valves under boiler & relieve pressure using safety valve.

regardless of what the book says you shouldnt use the prv as a drain

check its not dripping when you repressurise the system

 

[jack_s]

make sure the aoto air vent on the boiler is open rads should be ok

but wont hurt to have a walk round and check

Servicing flow valve & diverter, manual says to turn off CH flow/return valves under boiler & relieve pressure using safety valve.

regardless of what the book says you shouldnt use the prv as a drain

check its not dripping when you repressurise the system

Is that spelt right "aoto" ?

Any idea where air vent is on this boiler (Vokera Excell 80SP) ??

How else do you relieve pressure (oher than prv), just undo parts or some other place ??

Thanks

 

[DP]

kevin do respect your views, but for me PRV being a safety component, I always drain from it. So, if it leaks, I carry spare so will replace if needed.

 

[kevplumb]

auto air vent just above the pump on the right

 

[kevplumb]

kevin do respect your views, but for me PRV being a safety component, I always drain from it. So, if it leaks, I carry spare so will replace if needed.

yeah danny but you repair for a living
a diyer won't have one handy