3 bar safety valve discharging water after new fan fitted?

[dazzawazza]

I've recently installed a new fan on my Glowworm Swift Flow 75E.
However the boiler is running at a higher pressure when the heating is engaged, about 2.5bar. Before the new fan was installed the pressure was just above 1bar. I have not made any adjustments after fitting the fan.
This higher pressure causes the 3bar safety valve to discharge water even though I've never seen the pressure gauge reach 3bar. Because of this I have to re-pressurise to 0.7 bar each time the system has cooled otherwise the boiler wont light.
The question I have is could the new fan be running more efficiently causing these higher pressures? If so what adjustments can I make to lower the pressure?
Also what pressure should this type of boiler run at? The manual recommends a cold fill minimum of 0.7bar, but doesn't mention a normal operating pressure when hot. If 2.5bar is normal then could the 3bar safety valve be faulty? Thanks

 

[LUNAT]

HI

replacing fan should not affect the boiler pressure.
most combi boilers run perfectly on 1 bar.
running boiler on high pressures eg 2.5 bar
will put unnecessary strain on the expansion vessel diaphgram.
if water is coming out when the boiler is running than most probable cause is faulty diaphgrm (expansion vessel)

 

[dazzawazza]

How do I lower the running pressure, remembering I have already set the cold pressure to 0.5-0.7bar??

 

[JPC]

have you checked ur exp. vessel is pressurised correctly

 

[doitall]

If you set the pressure at 0.7bar and it rises when cold then either the filler loop is letting by or the plate heat ex is leaking.

If it rises that high when getting hot then the expansion vessel is duff, lost it's pre-charge or undersized.

 

[dazzawazza]

I have read on the Internet that some expansion vessels can be recharged using a hand pump to 10 psi. Is this possible with the expansion vessel for a Glowworm Swift Flow 75E? Thanks

 

[dazzawazza]

When I press the valve on the expansion vessel air comes out, no water, does that mean the diaphragm is intact and therefore the expansion vessel is ok?

 

[Gasguru]

Read the FAQs exactly...the air pressure in the vessel can only be checked when the pressure on the boiler pressure gauge is at zero ie you have to drop the system pressure down to zero.