Boiler noise - jet fly-past or trumpet (audio attached)

[ClockPie]

Hi
Vaillant turbomax 828. Ignore the rattles and fan noise - its been like that since we moved in 6+ years ago

Recently changed the HW heat exchanger, and all good. Boiler working well for hot water and heating.

However, it is making a strange noise which is sounding like a jet fly past, or elephant, or trumpet. Only briefly, and only at the start of cycle. It happens on CH so its not the changed parts. The wife says it was doing it for a while before hand, just not as bad.

Researching suggests its either (a) debris or flow constriction in the primary (flame-water) heat exchanger; or (b) CO2 mixture on the gas valve needing adjusting; or (c) its debris in the pump. (The pump was removed during the HE swap). Nothing visible appears to be resonating.

Seems strange its just come on but its possible some new (or moved) debris is now at the primary HE/pump as the boiler was pressurised/emptied a couple of times. And its possible the gas valve may've been accidentally touched/knocked during HE replacement.

I've attached a short sound clip - and the noise is from 10-21s and would never be heard from again. (attachment is a ZIP file containing a short audio file).

Is anyone able to point at what element this might be?
If its debris, then I'll give it a flush and clean.
If its gas valve needing adjustment, then I'll get someone in, but what "skill" am I specifically looking for? Any gas-safe engineer? Or one with tool XXXX? Vaillant specific?

Many thanks

 

[ClockPie]

Hi

Just a quick "bump" - Any thoughts on heat exchanger blockage or if its gas-valve tuning required?


(I am planning to put in some chemical cleaner and flush the system and reverse-flush the gas/water HE just in case - but would be good to know if I need to locate a gas safe man - and know what skills I'm looking for if it needs gas valve adjustment)

 

[Razor900]

I think the only advice you will get on here is to get a decent gas safe person in.....

 

[ClockPie]

I think the only advice you will get on here is to get a decent gas safe person in.....

Right - the point being, if its a noise from the HE then flushing out and cleaning the system is DIYable
If its a noise from the gas valve, then yes, I don't/won't touch that, and will get someone in. The question being - what skills am I seeking? Will any gas-safe guy have the right flue/diagnostic equipment? Will it need to be boiler (Vaillant) specific engineer? I have no idea so don't know what to ask for.
If the sound clip isn't enough to diagnose then so be it - I'll try flush/clean first, but just want to know direction to go.

your links don't work
MOD

 

[ClockPie]

@ MOD - lol - you are correct. Violating google terms of service? Not sure why maybe it sounds like a band. Thanks for making me aware

 

[ClockPie]

Just an update on this in case it helps anyone.

I flushed the system with clean water, and then added Fernox F3 cleaner. The jet noise has decreased significantly (95%+), and sometimes there is no noise at all running heating or hot water. And if there is noise its much much quieter/shorter. Will be flushing the cleaner out on Tuesday and will stick some more F3 in for a second clean. Not sure its a permanent fix, but deffo points towards the main HE having a restriction rather than anything more serious.

So seems cleaning is worth a try! I'm rather surprised to be honest.