high water pressure on vokera 20/80 flomatic

[tonymac233]

Before you embark on replacement HE, I would be looking to service the three port valve. The tail end/ domestic manifold can let by secondary to primary.

Replacement of HWHE is quite tricky.

Our water has pH of 7. Cannot remember replacing one of these HEs

I agree with DP on that one.

I have seen lots of these passing via the 3 way valve and pressurising the system.

Thats always my first port of call.

Hi Scatmanjohn could you please have a look at my wedsite http://www.zen65048.zen.co.uk and see if i am on the right road. thanks tonymac

try http://www.zen65048.zen.co.uk/heating[/QUOTE]
this one is right http://www.zen65048.zen.co.uk/heating.html

 

[scatmanjohn]

The O ring that can allow mains pressure water to pass to the heating is located on this one.

Near the little x is a small threaded plug with a hole through it. That plug holds in a tiny o ring.

If you drain the boiler and remove the 3 way valve you will be able to see if the o ring is passing by turning on a hot tap.

Oh and by the way also remove the donut washer from the tail peice of the 3 way valve as this plays a part in it as well.
Its the one on the top left of this one

You will probably find that the tail piece needs replacing and the 3 way valve needs refurbing. (requires a special tool to remove the guts of the valve.)

 

[Robbie1980]

The O ring that can allow mains pressure water to pass to the heating is located on this one.

Near the little x is a small threaded plug with a hole through it. That plug holds in a tiny o ring.

If you drain the boiler and remove the 3 way valve you will be able to see if the o ring is passing by turning on a hot tap.

Oh and by the way also remove the donut washer from the tail peice of the 3 way valve as this plays a part in it as well.
Its the one on the top left of this one

You will probably find that the tail piece needs replacing and the 3 way valve needs refurbing. (requires a special tool to remove the guts of the valve.)

Any chance of seeing these photos again? It might help me.
Thanks
Rob

 

[Robbie1980]

The O ring that can allow mains pressure water to pass to the heating is located on this one.

Near the little x is a small threaded plug with a hole through it. That plug holds in a tiny o ring.

If you drain the boiler and remove the 3 way valve you will be able to see if the o ring is passing by turning on a hot tap.

Oh and by the way also remove the donut washer from the tail peice of the 3 way valve as this plays a part in it as well.
Its the one on the top left of this one

You will probably find that the tail piece needs replacing and the 3 way valve needs refurbing. (requires a special tool to remove the guts of the valve.)

Any chance of seeing these photos again? It might help me.
Thanks
Rob

Please....

 

[Robbie1980]

Untitled

• Robbie1980
• 6 May 2008
• 1

Gents,

Is it just 0341 in this diagram (the fibre washer for the 3 port valve) that is the common source of leaking and pressurising the system?

This is near the tail piece, so i presume it's the one being talked about.


Thanks
Rob

 

[Robbie1980]

Hi All,

My current understanding is that the primary system pressure (displayed on front of boiler) could not be influenced by using hot water only, so the fact that my system pressure rises without using the central heating could not be down to a leak in the expansion vessel.

I've been speaking to a boiler man at my cricket club tonight and he tells me that the primary water heats the mains water drawn into the secondary heat exchanger to give hot water when a tap is opened, so a rise in system pressure could still be explained by a damaged expansion vessel(big one behind combustion chamber), even though the central heating has not been switched on.

Please could someone confirm this?
Thanks as usual,
Rob

 

[Robbie1980]

The O ring that can allow mains pressure water to pass to the heating is located on this one.

Near the little x is a small threaded plug with a hole through it. That plug holds in a tiny o ring.

If you drain the boiler and remove the 3 way valve you will be able to see if the o ring is passing by turning on a hot tap.

Oh and by the way also remove the donut washer from the tail peice of the 3 way valve as this plays a part in it as well.
Its the one on the top left of this one

You will probably find that the tail piece needs replacing and the 3 way valve needs refurbing. (requires a special tool to remove the guts of the valve.)

Any chance of seeing these photos again? It might help me.
Thanks
Rob

Please....

Scatmanjohn,

You say to remove the donut washer in the tail plate as this plays a part in it. Do you mean remove and replace or just remove.

Daft question i'm sure, but that part (the donut washer) is now obselete. Do you know why? Does a replacement come with a new tail plate or is the new tail plate a different design and the donut washer not required?
Cheers
Rob

 

[DP]

Take the doughnut washer out of the old tail piece and fit this into new tail piece. Also replace the small O ring around the spindle sticking out of the six screw unit front plate (domestic manifold). Stick to following advice given by regulars and your boiler will be working again

WRT your cricket mates, tell them to concentrate on cricket as they know nothing about boilers. Wxpansion vessel at the back of the main heat exchanger goes no where near the water that flows from hot tap, so cannot play any part in transfer from secondary to primary circuit.

 

[scatmanjohn]

Is it just 0341 in this diagram (the fibre washer for the 3 port valve) that is the common source of leaking and pressurising the system?

This is near the tail piece, so i presume it's the one being talked about.

No its not that one.

This is what i do.

Drain boiler, leave cold mains on for now.

Remove 3 way valve.

Behind the 3 way valve is the DHW flow valve.

Now turn on hot tap, you will see the pin pop out.

If water is coming out of where the pin comes from then that is the source of the problem. New o ring will sort it.

I usually bin the donut washer because without it the boiler can't overpressurise (the water just drips from the bottom of the tail piece instead)

I always refurb the 3 way valve at the same time.

 

[Robbie1980]

Is it just 0341 in this diagram (the fibre washer for the 3 port valve) that is the common source of leaking and pressurising the system?

This is near the tail piece, so i presume it's the one being talked about.

No its not that one.

This is what i do.

Drain boiler, leave cold mains on for now.

Remove 3 way valve.

Behind the 3 way valve is the DHW flow valve.

Now turn on hot tap, you will see the pin pop out.

If water is coming out of where the pin comes from then that is the source of the problem. New o ring will sort it.

I usually bin the donut washer because without it the boiler can't overpressurise (the water just drips from the bottom of the tail piece instead)

I always refurb the 3 way valve at the same time.

DP & Scatmanjohn,

Thanks again for your patience and advice.

I removed the 3 way valve earlier and did as SMJ said and water (when hot tap opened) did pass a little past the tiny o ring secured in by the plug. Only a small amount, but i can imagine how washing up and a shower a day could equate to having to drain off a pint a week.

I replaced this also the large diagraphm (as it was badly marked and looked pitted in one area) in the manifold and cleaned it all. The small o ring didn't look damaged but there was gunk around the spindle and where the o ring was seated. I guess with mains pressure on, water only needs a tiny gap to leak and pressurise.

Cleaned out bit of gunk in the back of the tail plate infront of the large donut washer but left this in (didn't see this post till after!). Oh, i opened the hot tap again for a while when changed and seemed OK.

So, if it isn't passing the small washer, there should be no place the system could pressurise, except the secondary heat exchanger (if pinholed)

The pressure of the leaking water was shuttling the 3 port way internals which fed the water into the primary (heating) system?

I've enjoyed learning a bit about my boiler and yes, i'll ignore by cricket boiler mates!
Cheers guys,
Rob

 

[scatmanjohn]

Thats correct.

The ones that i have seen overpressurising have been:

DHW o ring = 99%

Passing fill loop = 1 %

DHW heat exchanger = 0%