New CH boiler Gurgle and air created at 3 port valvr

[75pete]

I have seen orifice plate ( washer ) fitted in the return pipe connection at the boiler. This can help reduce noise ( cavitation. )
Have a look at your instillation information and check if it say it can/should be fitted, given your problem it's worth checking.

 

[Christiane]

Thanks Pete, I will have a look. Although, the massive gurgle seems to originate around the 3 port valve travelling through the flow to the radiators...through them all ( incl downstairs ) ....can't hear it coming back to the return..plus any air that s left the autovent seems to let out...
Again, if HW is open all is well
I ll study literature and will mention it to plumber

 

[flameport]

Start the system.
When the noise has stopped, wait a few minutes more.
Close the auto air vent by screwing the black cap down.

Any difference now when HW is off / system is started?

 

[Christiane]

Thanks flameport,
We tried the screwing down the airvent before, even replaced it because we had suspicions it was sucking air in....no change.
I will try again though.Just not now, when I took photo earlier I noticed something....I have now got a slight leak where the system bypass was inserted Tuesday and water dripped onto the white connection box..so sharpish electricity supply to boiler and timer and else off, black plastic bag on the floor and sms to plumber....who isn't working until next week I fear.
That Sodd has got a lot to answer for with his law

 

[75pete]

When you do find and get it sorted, please do update your findings. What is the Boiler stat set at?

 

[Christiane]

...trust you me, I will !!!
When you say boiler stat, do you mean flow temperature ? It s now set at 60, so is the HW to avoid it switching off. REASON why it took so long to identify what it is was that boiler flow temp was set to 73 deg celcius and HW to 50. The HW was still heated by immersion heater on economy 7 at night
So, CH and HW on and then the gurgle randomly appeared after 1 HR..or 2 or 3 when HW reached temperature...
Massive gurgle to be heard downstairs travelleling through.
By putting both on nearly same temperature that doesn't happen anymore , apart from startup....and finish if on timer
If I switch of manually, I do CH first and then HW and all is well ....

Thanks again all, keep ideas coming please

 

[75pete]

Sorry wrong post, so removed

 

[MikeAustin]

Thanks again all, keep ideas coming please

I had a lot of gurgling in my system. One old radiator had blockages somewhere in the middle. When bleeding, a jet of water came out as if it were OK. I hit the radiator all over with a rubber mallet and was then able to release the air via the bleed valve. My Magnaclean picked up a load of magnetite from this!
I still have some rushing sounds and slight gurgles at start up and shut down, but most of the noise has gone. There is probably air trapped similarly in other radiators, compressing at start up and releasing pressure at shut down.

 

[jeff the gasman]

Bet there's magnetite in the old pipework where the old cold feed used to join the flow.

 

[Christiane]

Thanks Mike and Jeff. I collate all suggestions for next week.
Over Christmas I appear to be able to avoid if manually starting up HW first and then CH amd switch off CH first and then HW .
I am somehow convinced it is linked to the 3 port valve s position.
I clearly hear the motor moving and that either creates or eliminates the masses of gurgle .
As to the Magnatite, I understand system was cleaned possibly with Magnaclean and all radiatiors are boiling hot all over at all times.
But please keep on suggesting, there must be a solution out there

 

[flameport]

The only thing the valve is doing is adjusting the flow of water. Through the cylinder coil is a short path of low resistance. That through the radiators is far longer and has far more resistance to flow, probably due to partial blockage. The fact that the boiler overheats with the pump set to speed 1 further supports that. The blockage could be trapped air, or solid materials.
When the valve moves to radiators only, the pressure behind the pump falls significantly due to the increased flow resistance ahead of it, and is either pulling air in via the AAV / some other source (does this boiler have an air vent inside?), or causes cavitation.

Incidentally, on a properly working system, the radiators should not be 'boiling hot' all the time unless the TRVs and thermostat(s) have been set to maximum and left there.

 

[Christiane]

Thank you very much flameport,
sorry the radiators aren't all boiling hot just when all TVR s are open after system got refilled and they get checked to see if air is trapped.
Excuse my ignorance what does AAV stand for ? If it s the automatic air vent we have shut that to see if air comes in through there, it doesn't.
The air is also not just a little bit of a trickle , it is a massive gulp which travelles through the system
As to the pump, Mr Vaillant seems to think pump on 1 is too low and it s normal for boiler to decide it s too hot
However, again I will add you kind feedback to the list of things to run past the plumber who will hopefully turn up next week

 

[Christiane]

...just another question please how does one identify where the potential blockage is ?
Like I said CH with HW all is quiet, all radiators are as warm as they should be and all is happy ....so, where on earth do I start ? Process of elimination ? If yes, how ?
Thank you

 

[jeff the gasman]

Use a magnet on the pipes, they're copper so it shouldn't stick, if it's attracted you've found it.

 

[Christiane]

Oh, thanks, tried that, doesn't stick.
As to the radiator, one of them has got a patch pretty much randomly in the middle that is much colder than the rest of it
PHOTO attached .