Baxi Eco80 wont fire CH unless i turn on DHW tap

[rizz077]

I have an interesting problem with Baxi Eco80 boiler which i inherited when i moved into my flat a few month ago.

At first i thought it was the thermostat so i recently replaced it with a 3rd Gen Nest. However its evidently not the thermostat.

Problem occurs when the boiler has been idle for a long time i.e both CH and DHW have not been running.
When the thermostat kicks in, i can hear the pump running but no flame ignition. The problem seems to be resolved only by turning on a hot water tap after which the flame ignition sequence seems to work just fine and the CH system fires up.

Once the system is running it seems to be able turn off and on (as demanded by the thermostat) however if left off for too long the same problem occurs.

I have checked the system pressure is set correctly to 1.5 barg,

Ay idea what the problem could be?

 

[Dotty]

Yep.

One you need a gsr for. You need to prove your credentials to receive gas advice in a private forum on UKPlumbersforums.

No gas advice in open forum.

 

[Billy Bob Bob]

We wont give you advice on how to fix it but i will give you good advice as a experienced baxi engineer,its a easy boiler to work on,if its in good condition it will outlive most other brands,put a post up in find a engineer section,most good boiler repairers will know this machine backwards