Air in system after new boiler

[Kev123456]

I have a conventional boiler with gravity feed hot water.
Had a new boiler put in before xmas and now I'm getting air biuld up in a few of the radiators where I never had this problem before the install.
My old boiler was a glowworm ultimate 40ff (12kw I'm told) and my new boiler is a Valient 18kw. Apart from the install at the Boiler point none of the systems pipe work was changed.

I have a Wilo pump and I did notice that for some reason it was turned up to max of 31W after the new boiler was installed. I have turned it down to 15W and this has helped a bit with air, it takes longer to get the Air in about 4 Rads, but only one really bad (about 10 days)
I have no Air seperater installed on the system but I never had an Air problem before the new boiler was installed.
Was thinking of using Alladdin autobleeding valves on the rads that get air and installing an Air seperator myself, do you think this is athe way forward?
The new boiler was installed by a Gas safe engineer and I was pleased with the neat job he made but do you think it's possible that incorrect installation is in some way responsible for Air?
Thanks for taking the time to read.
Kevin

 

[Agile]

I would first check that the pump is pumping in the correct direction. Was it changed?

Then that the flow at the boiler is in the correct direction.

Last that the feed and vent are correctly configured.

Do you have TRVs on all the rads? [ Recommended to fit them with a new boiler now ]

Tony

 

[Kev123456]

Hi Tony,

Thanks for your reply.
Pump was not changed.
New boiler was only installed on a like for like basis but I will double check the flow at the boiler tonight when I get home.
I do have TRVs on rads already but I have them fully open and have taken a few of the heads off because they were sticking (would that make a differance?).
As far as I know feed and vent are correct, like I say never had problem before new boiler.
I have attached a photo of Pump and pipework

 

[jeff the gasman]

There could be some magnetite in that pipework.

 

[Kev123456]

Thanks for reply,
I had a chemical magnetic flush when boiler was fitted and plumber agreed that water was clean, no sludge, there was biuld up on the flush magnets but couldn't see that in water so system was reasonably clean

 

[jeff the gasman]

Thanks for reply,
I had a chemical magnetic flush when boiler was fitted and plumber agreed that water was clean, no sludge, there was biuld up on the flush magnets but couldn't see that in water so system was reasonably clean

I'd still check for magnetite powerflush won't remove it.

 

[Kev123456]

Silly question but how would I check for that?

 

[jeff the gasman]

Silly question but how would I check for that?

Use a magnet around cold feed and vent area, where they join the flow pipe.

 

[Kev123456]

Thanks, I will try that tonight and let you know

 

[Kev123456]

I have quickly checked with a magnet and the magnet sticks strongly to the TEE Joint just above the pump and also sticks lightly to the Tee and elbow at the base of the Vent pipe and the Elbow on the right above the pump, which I'm presuming is the cold feed (It is 22mm).

What does it mean, that I have to insert new pipework at the joints to get rid of it, should I repumb with an Air seperator?

I have to go out now but with double check feed direction of pump and Boiler later

 

[jeff the gasman]

Cut out and replace mate. You can combine the vent and feed to stop it happening again. Air separators are not required.

 

[Kev123456]

Can that be what causeing the Air now I have a new boiler?
When you say combine feed and vent do you mean use a TEE from feed going directly up to vent?
Is it worth putting in an Air seperator while I'm doing it?
Would you replumb the cold feed the same as it is?
Thanks

 

[jeff the gasman]

I'd just tee the cold feed into the vent, everything else the same. Minus cold feed obviously.
Air separator not needed, you won't get any.
Magnetite causes this symptom.

 

[Kev123456]

I

have attached a sketch of what I think you are telling me how to reconnect the pipework. Have I understood you right?

 

[jeff the gasman]

Yes.x