DIY Doctor UK DIY Forums

At the moment I am still suffering from air in the central heating. (open vented system). I know I have a faulty Actuator as the manual lever moves with no resistance. I am trying to find out why air is continually in the system. I have placed the end of the vent pipe in a small container of water. After a couple of days the level has go down, suggesting it is being sucked into the vent pipe. I can only assume this is how air is constantly coming into the system.

This has happened only over the last few months, system was working fine for years before that. Can anybody advise why this has suddently happened? Would it have something to do with the faulty actuator?

Thanks in advance.

Not knowing it the actuator is driving a 2 or 3 port valve, or how the system is piped, it would be difficult know if it is contributing directly to the air problem. Obviously the first thing to do would have the actuator replaced and see if it as an effect on the air problem. If the problem persists then there are other avenues that can addressed.

Check the pump setting. If its on the highest speed then turn it down to the mid setting. Does that stop it?

If not you may find that fitting a Myson aerjec or similar will fix the problem.

Cheers

Thanks for your replies. The actuator/valve is a 3 port mid-position model.

I looked again today and there is also hot water coming into the F&E tank, which I think suggests pumping over?

I tried to replace the actuator today, but it is impossible to reach to unscrew it, from the valve body, due to a poor installation position. I will have to go for the bigger job of replacing the whole valve.

I assume that the faulty actuator is causing the valve ball to be in the wrong position and therefore causing the over pumping - any thoughts?

Please be specific about which vent is pumping over and which is sucking air. From your first post I guesed you meant the vent to the F&E tank but it can't be pumping over and sucking air at one and the same time.

Did you check your pump speed and did altering it have any effect on the air being sucked in?

Cheers

It is the open vent pipe into the F&E tank.

With the pump setting on 2, the air in the system is much worse, with banging pipes and the occasional release of hot water into the F&E tank via the vent pipe. I have been into the loft and watched this happen,

There are odd times when air must have been drawn into the system via the same pipe. Turning the pump up to 3 does reduce this problem, but the pump was always previouswly set on 2.

The pump setting on 3 is a bit noisey.

The 3 port valve actuator is definitely faulty.

"It is the open vent pipe into the F&E tank."

Thanks.

"With the pump setting on 2, the air in the system is much worse, with banging pipes and the occasional release of hot water into the F&E tank via the vent pipe. I have been into the loft and watched this happen,"

Your system is "pumping over". Do not leave it as all you are doing is circulating oxygenated water which will cause corrosion in the system apart from filing the syetm with air. Pumping over is a symptom of a problem not the problem itself which could be:

1) An incorrectly placed pump,
2) Pump speed too high
3) Insufficient static head
4) Incorrectly configured system
5) System blockage

This topic has been covered many times before on this forum. Use the search functon and you will find the answers. Here are some threads for example:

https://www.diydoctor.org.uk/forums/viewtopic.php?t=7733

https://www.diydoctor.org.uk/forums/viewtopic.php?t=7738

https://www.diydoctor.org.uk/forums/viewtopic.php?t=7702


"There are odd times when air must have been drawn into the system via the same pipe."

You are guessing. If its pumping over you are circulating oxygenated water in the syetem. Thats where the air is coming from.


"Turning the pump up to 3 does reduce this problem, but the pump was always previouswly set on 2."

I suggested you turn the pump speed DOWN NOT UP. If its normally on 2 what happens on 1?


"The pump setting on 3 is a bit noisey."

Air in it most likely.


"The 3 port valve actuator is definitely faulty."

But thats nothing to do with your pumping over problem. Just because the manual control is a litle bit floppy it doesn't mean the thing is faulty. Its common and it still works. Ifyou have heating when you want it (nothwithstamding your pumping over issue) and hot water when you want it the valve is operating just fine.

Cheers