Hi
I keep getting air in an open vented heating system

The header tank has water in it about 100mm or so about the 15mm feed pipe.
There is not a large amount of air a few seconds from 2 or 3 rads

I have run the pump on the lowest setting but still get air in there.

The layout is feed up from boiler then elbow in to a pipe with vent then cold feed then onto the pump
the vent and feed are about 1" apart and then about 6-8 " to the pump then from the pump about 8" to the three way valve

Any idea's?

Dave

A pic would help.

Hold a glass of water under the vent pipe, does it suck the water out if you turn the pump on and off a few times.

Does the air smell very strong, a bit like rotten eggs.

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Hi
No smell to the air coming out
I will try the glass under the vent pipe

Dave

Hi
This may help


Dave

Hi
Right just done the glass under the vent pipe and the level in the glass dropped about 1-1/2" after starting the pump three times
So its pulling air down the vent?
Whats the best way to stop this?

Dave

Need to see where the vent and feed join in the pic

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Hi
The vent is the pipe in the front with the white cable fixed to it
The feed is in the pipe going to the pump

Dave

The cold feed from the tank. ?

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Hi
Tank cold feed is back from the vent towards the pump in the middle of the pic
Will try to get a better photo up

Dave

Hi
1 is the cold feed
2 vent pipe
3 feed to pump



Dave

Run a magnet around those pipes and see whether it's sticks or any resistance.

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Hi
No a magnet dosen't stick and no resistance

Dave

Em, something is not quite right.

How high is the header tank and vent pipe, perhaps a pic showing them.

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Hi
The header tank is approx 6ft above the height of the hot water tank
The vent pipe is about 6-8" over the top of the tank

There is quite a bit of muck in the header tank could the 15mm pipe be restricted?
Would changing it to a 22mm feed help?

Dave

The signs say the cold feed is partially blocked, which is why you tried the magnet.

Would be worth cut a section out where it joins the system.

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