worcester heatslave 18/25 no pressure

[brucemcc11]

Hi,
I changed a radiator at the weekend and re-pressurized the system but it never goes above 0.2 bar.
When I run the hot water tap even though cold water comes out you can hear the boiler fire up and starts burning oil, but the water stays cold throughout.
I've bleed the values and hope all air is out of the boiler.

The burner is working fine and there is no lockout.

Any help would be most appreciated
Thanks
Bruce

 

[Burnerman]

There are three bleed points on the top of the boiler - have you checked these? There's also an automatic one which has a car tyre valve cap on it (which should be loose, but not leaking).
As for the low pressure, does water exit from the boiler through the vent pipe outside?
John

 

[brucemcc11]

Hi John,
Can you advise where the bleed points are from the picture below please.
The one with the car value cap is that on the expansion vessel?
I've checked the vent pipe and no sign of any water at all.

Untitled

• brucemcc11
• 9 Sep 2013
• 1

 

[oilhead]

When changing the radiator, did you drain down the system, or just close the valves?
If you drained down,then you may have air locks in the boiler. When you switch the boiler on, does it run to heat up the heatstore. Until this is up to temperature, you will not get hot water, it is not instant as on gas boilers.
There is an automatic vent in front of the domestic heat exchanger,(the stainless steel slab with 4 pipes on it to the left of your picture. This vents the heat store. When pressurising the boiler, put the diverter into the manual position using the lever on the valve actuator. On your model, I think you will find the vents on the pipework into and out of the boiler. Also bleed the pump through the screw in the middle of the head.

 

[Burnerman]

As Mr O says, the bleed points are square, just like radiator valves and can be undone using the same key.
It takes about 10 mins running from cold to heat up the heatslave tank - only after that will the heating (try) to work. The pump though runs all the time.
As for only being able to pressurise up to 0.2 psi, I'd actually suspect the gauge.....did it work before? You can hear water entering into the boiler through the filling loop, and the pressure release valve should automatically open at 3 bar and discharge to outside.
There is a car type valve on the red expansion vessel.....this is for topping up with air to 10 psi (system depressurised). If you press the valve tit and water shows, its goosed I'm afraid.
John

 

[brucemcc11]

When I changed the radiator I just drained down the system. I've checked all the bleed points and no air within the system. When the diverter is put to the manual position then hot water comes out of the taps. As for the 0.2 psi yes this did work before and was at around 2 psi all the time. I've open to allow more pressure but nothing still stays at 0.2psi.
Thanks for your help so far.

 

[slapper]

When I changed the radiator I just drained down the system. I've checked all the bleed points and no air within the system. When the diverter is put to the manual position then hot water comes out of the taps. As for the 0.2 psi yes this did work before and was at around 2 psi all the time. I've open to allow more pressure but nothing still stays at 0.2psi.
Thanks for your help so far.

Faulty pressure gauge ?

 

[Burnerman]

Still the need to expel air from the pipes on the top of the boiler, I guess....this won't be removed out by bleeding the radiators.
John