Preesure drop

[meditek]

I have a Worcester greenstar CDI 42 combi boiler.

It was just been serviced 2 weeks ago and is one year old.

I am getting a .75 bar drop in pressure between hot (88C) and cool (48C). Is this normal (acceptable) because I do not remember this happening prior to the service?

Thanks

 

[Dan Robinson]

As long as it settles at the same point then it should be OK... Your expansion vessel charge may need checking though as a .75 pressure rise is a little excessive...

 

[meditek]

Thanks. I had my suspicions about the expansion chamber. I got the same guy (Worcester-Bosch) back again after the service because it wasn't happening before and he claimed the boiler was A1. What, apart from the boiler can cause this discrepency?

Thanks

 

[kevplumb]

Thanks. I had my suspicions about the expansion chamber.

so why didnt you air them when the guy came to do the service

or after when you got him back

 

[jamestaylor]

As long as it settles at the same point then it should be OK... Your expansion vessel charge may need checking though as a .75 pressure rise is a little excessive...[

It`s a pressure drop, not a pressure rise as the system cools it will drop.

 

[Dan Robinson]

Depends whether your starting point is hot or cold.


A drop from hot is contraction/cooling and is perfectly normal - as is a slight rise from cold.. A drop from cold would be a leak and not what the OP reported.

 

[jamestaylor]

I am getting a .75 bar drop in pressure between hot (88C) and cool ]

 

[Dan Robinson]

and...

OP is saying the pressure goes down as the boiler cools.

So, for example.

When cold the boiler is sitting at 1 bar. It heats up to 88 degrees and the pressure goes to 1.75.

As the boiler cools again the pressure returns to 1 bar.

 

[kevplumb]

 

[Dan Robinson]

Is it me or is it a wind-up...?

 

[jamestaylor]

a .75 pressure rise is a little excessive...

Err... he isn`t getting a .75 rise is he ? he`s getting a .75 drop which isn`t spectacular.

 

[kevplumb]

ex vessel and prv then cliver

 

[jamestaylor]

ex vessel and prv then cliver

if it was ex vessel then the boiler would show it to be over pressurised probably around 3 bar immediately , if it was the prv then it would indeed be losing pressure via the blow off, easy to check innit....Basically what I am saying is: his boiler is performing exactly the way it should be and there is no problem..

 

[Dan Robinson]

if it was ex vessel then the boiler would show it to be over pressurised probably around 3 bar immediately

Not if it was only marginally under pressured.

Let me know what hospitals you work in, so I can avoid being ill in those areas...

 

[swidders]

Let me know what hospitals you work in, so I can avoid being ill in those areas...

Broadmoor???