Valliant Eco Tech 28 boiler - Boiler pump issue

[curiosity2025]

Hi,

I'm seeking some advice regarding my Valliant Eco Tech 28 boiler. It recently started leaking. Upon investigation, I noticed water coming from the boiler pump. There's a grey knob on top of the pump with a small hole. When the heating is on, water pours out of this hole. I've adjusted the knob, which stopped the leak for a few days, but it has now returned. I've attached photos for reference.

I suspect this is an air release valve. Could anyone advise on the purpose of this knob? Is this a minor issue, or does it indicate the pump needs replacing?

 

[CountryFan]

Automatic air vent, which is replaceable, but get a professional in to check the expansion vessel and possibly the water quality.

 

[curiosity2025]

Automatic air vent, which is replaceable, but get a professional in to check the expansion vessel and possibly the water quality.

Thank you for your reply. Could you please clarify the function of this knob? Does turning it clockwise close it, and counter-clockwise open it? I'd also appreciate an estimate of the repair cost if you know. Since the boiler is out of warranty, I'm trying to determine whether it's worthwhile to repair.

 

[CountryFan]

Could you please clarify the function of this knob?

It automatically expels air

Does turning it clockwise close it, and counter-clockwise open it?

Yes

I'd also appreciate an estimate of the repair cost if you know. Since the boiler is out of warranty, I'm trying to determine whether it's worthwhile to repair.

Hard to say as I’m not self employed, and costs vary up and down the country, but definitely worth a repair. Part costs in the region of £25 so you have labour on top plus anything else, such as 26.9 checks as removing the cover requires checking for safety because it forms part of the combustion circuit.