Worcester 28CDi combi boiler over pressurising

[Agile]

I am still waiting for Kevin to explain that to us!

Its just conceivable that if the rear mains water pin seal on the diverter is leaking AND the body does not leak too much AND the front manifold pin seal leaks then that could happen.

We see that on the Vokera 20-80 but they have a solid block of rubber to help the seal to prevent leaking water to get to the outside.

On the cdi that water usually leaks to the outside without forcing its way past the manifold seal.

I am still waiting for the OP to perform my second level test to confirm its the plate HE.

Tony

 

[nickso]

I am still waiting for Kevin to explain that to us!
Tony

ive been waiting weeks for you to explain to me how a faulty diverter can cause this fault..........!

come to think of it ive been waiting years for you to answer questions that i asked you.

no point in waiting for kevindgas to answer questios, he is even worse than you at it.

Its just conceivable that if the rear mains water pin seal on the diverter is leaking AND the body does not leak too much AND the front manifold pin seal leaks then that could happen.

wait, is that it? thats what ive been waiting weeks for?

what the hell does that waffle mean BTW?

We see that on the Vokera 20-80 but they have a solid block of rubber to help the seal to prevent leaking water to get to the outside.

ive told you before, thats not what its for.

On the cdi that water usually leaks to the outside without forcing its way past the manifold seal.

what?

!

! ?

 

[SteveZodiac]

With the water off I could see no noticeable increase in pressure (well for a few hours anyway). With Central Heating on pressure rises (as normal) but fails to drop down again fully when heating goes off. Day by day the pressure keeps going up and up.

I'm no expert here, but I've had a lot of trouble with my 28CDi (including pressure problems, thankfully fixed except for a slow loss of pressure over a few months) and am very interested in what's going on. If the mains water is turned off to the whole house at the stopcock (which I assume you've done), I don't understand how water can get into the heating system to make the boiler pressure rise, even after a few hours. Faulty stopcock together with a hole in the water to water heat exchanger perhaps?

 

[doitall]

I would go for the HX as well.

Does the gauge fluctuate if you open and close the hot tap quickly a few times.

 

[kevindgas]

no point in waiting for kevindgas to answer questions, he is even worse than you at it.

I don't sit here all F'in day and to say i don't answer is B*llx!

as for the original problem I have never had to change a H/E on a worcester but have done loads of diverter valves!

often the problem occurs when the heating is on and the mains pressure is greater the diaphragm then leaks as they are often perished!

 

[Agile]

often the problem occurs when the heating is on and the mains pressure is greater the diaphragm then leaks as they are often perished!

If the diaphragm is leaking then its only a leak across the water venturi and no water escapes,

If the rear seal on the diaphragm leaks then usually the water leaks out of the joint between diaphragm unit and manifold section.

For the heating pressure to become increased, that leak must be very small AND the front seal on the manifold pin seal must also be leaking.

I have never seen that happen on a cdi although several Voka 20-80 where the rubber bung helps to seal the flow to the outside.

Nikso does not seem able to follow that explanation.

Tony

 

[kevindgas]

Nikso does not seem able to follow that explanation.

Tony

that's because he's too busy being obnoxious

 

[nickso]

no point in waiting for kevindgas to answer questions, he is even worse than you at it.

I don't sit here all F'in day and to say i don't answer is B*llx!

as for the original problem I have never had to change a H/E on a worcester but have done loads of diverter valves!

often the problem occurs when the heating is on and the mains pressure is greater the diaphragm then leaks as they are often perished!

i dont sit here all day either. and you often dont answer questions asked.

the rest of your post just shows your ignorance of how a cdi works.

 

[nickso]

For the heating pressure to become increased, that leak must be very small AND the front seal on the manifold pin seal must also be leaking........I have never seen that happen on a cdi .

impossible. are you suggesting that mains water leaks out of the diaphragm housing, travels horizontally across the spindle instead of dropping vertically with the aid of gravity, then enters the diverter manifold through its spindle seal and thereby increases the heating pressure?

 

[nickso]

Nikso does not seem able to follow that explanation.

Tony

that's because he's too busy being obnoxious

obnoxious, maybe.

factually correct, certainly.

 

[nickso]

For the heating pressure to become increased, that leak must be very small AND the front seal on the manifold pin seal must also be leaking........I have never seen that happen on a cdi .

impossible. are you suggesting that mains water leaks out of the diaphragm housing, travels horizontally across the spindle instead of dropping vertically with the aid of gravity, then enters the diverter manifold through its spindle seal and thereby increases the heating pressure?

 

[djavery]

More 'tests' this weekend while I've been home.

It seems now that the cold water supply must be pressurising the system because I set the pressure at 1 bar last night and when I looked at noon today it had crept up to 2 bar. I did not have the heating on or run any water at all, as I was away for the night.

On Friday, I had the heating on in the evening. It was 1 bar early on and when I switched it off at 10, it was at 2.5 bar again and did not drop lower even after 2/3 hours of being switched off.

I am even more confused now. The key to top up the system is out and the grey topping up knob is turned off.

What can be wrong? Still the heat exchanger?

I'm leaving it today with the water to the house switched off, to see what happens.

 

[nickso]

change the domestic h/e.

 

[Agile]

As we have told you before you have to set it at 1 Bar ( or 1.5 Bar ).

Then close the stopcock.

AND open the lowest cold water tap and LEAVE it open!

Tony

 

[djavery]

OK, sorry Agile , I'm going to leave the water off and tap open until late tonight.

If the pressure stays the same (1 bar) we can assume the cold water is pressuring the system somehow when it's put back on?

And as Nickso says it's more likely to be the heat exchanger as the cold water supply is leaking across?

Sorry to be a pain, but you guys are the experts and I'm just trying to understand what's happening.