Baxi 105e hot water

12 Nov 2010
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United Kingdom
I have an ongoing saga with a Baxi 105e.

New diverter valve fitted after having a lack of hot water unless the heating was running. Putting on a hot tap would result in the rads getting warm and luke warm DHW.

New PCB fitted, pt no. 5112380, after diagnosing a problem where the boiler woudnt fire up. The fan would do 1/2 a rotation then switch off and the fan fault LED would light.

Boiler has been working fine for a week (albeit the hotwater temp cycling slightly when something like the shower was running), but now wont run with a hot water demand. The CH runs OK, stable pressure and temp, but with a DHW demand the pressure gauge starts rising to the 2.5? bar limit and the PRV dumps. Pressure then drops to the pre DHW demand level of around 1.5bar.

Any suggestions would be much appreciated.
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Thanks for the response.

The other thing i should note is that the Expansion Vessel failed 8 months ago and a 12L external vessel has been fitted on the return.

I will check the pressure on the vessel but with the boiler off and the system cold the pressure gauge holds steady at around 1bar.
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