Boiler Temperature Not Settling

[SE82]

Hi,
I have a Baxi Duo-Tec Combi 40HE.

The last few days I have noticed a lot of condensation/air coming from the flue. I checked the boiler with the intention of reducing the maximum temperature going to the rads to reduce the condensation but found that the thermostat on the boiler is cycling between 49-53 degrees. Usually it's set at 65 when heating the rads and drops to around 53 on the return phase. When I try to adjust the boiler temperature its changing so rapidly its impossible to see what the temperature is.

The boiler is currently still coming on when heat is called for by our Cosy thermostat. Is it as simple as replacing the boiler thermostat or do I need to so something else?

I'm competent at performing most easy tasks on the boiler - new pumps, chemical flush, fixed a seized return value.

 

[martygturner]

Is the condensate drain blocked.

 

[SE82]

Is the condensate drain blocked.

Thanks for the quick reply.

Good suggestion. I haven't checked.

Its not frozen outside and the boiler isn't making any noises.
I'll go and detach the pipe at the boiler end now and see if theres an issue that side. Is there any other part of the condensor pipe I should check?

 

[martygturner]

the ball valve sometimes gets gunked up

 

[SE82]

Is the condensate drain blocked.

So I removed the condensate pipe at the boiler. No blockage there.

I'm expecting this isn't the part you mean though?

 

[martygturner]

its part 12 on the following link..... https://www.sparesbase.co.uk/baxi-duo-tec-40he-a-10000671-3548975/explodedviews

 

[SE82]

its part 12 on the following link..... https://www.sparesbase.co.uk/baxi-duo-tec-40he-a-10000671-3548975/explodedviews

Thanks. I thought it might be.

I've had a look in the Baxi book and it looks like it should be cleaned as part of the annual service (which is due shortly). I may wash and refit it tomorrow (looks straightforward). If not will it do any damage to wait until the service?

 

[martygturner]

If they get blocked up then water is retained in the heat chamber and cue white smoke, banging if its bad and temp all over the place.

I had a tenants that was half full of water, after having a regular service every year by a fully qualified gas safe engineer.....insulation panels shot, sparker gone and a replacement spark detector, the boiler still ran half full of water and only stopped when the spark detector became submerged.....cost £490 + vat....so I would advise getting it cleaned out....