Pressure Jumping

[doitall]

you are having a laff john

have a look at that cd i posted and see how the can works

 

[Big Lad]

The flow switch raises, operates the microswitch, then remains constant i.e it is not drifting up and down. also the temp of the water is constant.

I will ring Bosch Worcestor in the morning.

Thanks for all your help it is very much apreciated.

I will post the solution when I find out what it is

 

[kevplumb]

still dont have a shunt pump (as such) on a combi

 

[PEDANTICVINDICTIVEMAN]

What a bunch of useless shunts.

 

[doitall]

What a bunch of useless shunts.

Who ask you pvcman

 

[Big Lad]

I received an Email this morning off Bosch Worcester regarding this problem,

They say it can be caused by expansion pressure pressure being low, or air trapped on the water side of the diaphram in the ev.

As I have already checked the pressure in the ev and confirmed operation of the relief valve to vent the air, I decided to increase the system pressure slightly more than is recommended in the boiler manual i.e filled to 1.6 bar to see if that made any difference.
It now works fine, no jumping. I removed the pressure gauge and checked the calibration using a Druck pressure calibrator and it confirmed a range error of nearly .5 bar, so i recalibrated the gauge,refilled the system to 1.3 bar and it is now running as it should.

thanks once again to everybody for your help

 

[Big Lad]

I nearly forgot I have arranged for a Corgi man (friend of a friend) to call tonight to prove the integrity of the combustion chamber as recommended in an earlier posting.

 

[ChrisR]

You'd expect the pressure to read differently during CH operation - the pump's running, with half a bar pressure across it! Any air in the pump (did you VENT it???), or anywhere else as it goes round, would show a variable pressure on the guage.

Get your corgi to check the pressure vessel's pressure too. I wouldn't say you have to be corgi regd to do thet but he'll be a lot quicker!