Old vented boiler blowing noise

[jido]

I moved into a house which is heated by an old floor standing unvented gas boiler.

When I light up the boiler, it makes a noise that is making me alarmed. It alternates between gas burning hum and a “blowing” sound, as if it was filling with gas.

Is that normal?

The control box is a Nova 820 https://www.sitgroup.it/wp-content/uploads/2017/09/820-Nova-GB.pdf

I wanted to share a video of the noise but the forum doesn’t seem to allow it.

 

[CountryFan]

I highly doubt it’s an unvented boiler, pretty sure they don’t exist. Post a photo of the boiler if you’re unsure of the make and model. As for video uploads, better using a 3rd party site such as YouTube.

 

[jido]

My apologies, the term I saw was “vented central heating system”. Here is a picture.

 

[fixitflav]

The control box is a Nova 820 https://www.sitgroup.it/wp-content/uploads/2017/09/820-Nova-GB.pdf

That's the gas valve. I doubt it's causing your symptoms

 

[CountryFan]

Could just be a delay on the solenoid and lighting. Any concerns you’re best getting a gas safe registered engineer out.

 

[jido]

My phone didn’t record the sound very well but here is a link.

2025-09-29 19-32-27.mov - Shared with pCloud

Store videos in pCloud. Share them with just the right people. Access them on any device. Create a free account now!

e.pcloud.link

Is it ok to have a delay on the solenoid and lighting? Will it settle down?

 

[jido]

I think there is a leak and escaping gas is lighting up. I am not starting that boiler again.

Is repair by a gas safe plumber possible?

 

[gas112]

I think there is a leak and escaping gas is lighting up. I am not starting that boiler again.

Is repair by a gas safe plumber possible?

not greatest recording but being open flued and you not knowing the history then you should be getting someone to check it out ASAP before using it again it may possibly be sooted up this can cause weird noises when on and is lethal .
Boiler is well over 20 years old solid boiler in its day .
.
.
.
.
Was the noise there on initial light up or after being on 20/30 mins ?

 

[jido]

Thank you for checking!

I think the noise was there initially, not very sure. I would say it started before 20 minutes of running.