What's this then? Where feed/expansion joins heating on open vented

[Ben Lumley]

Hey,

Could someone tell me what this chamber is for/what it is please?

Pipe out the top is the feed/expansion into the heating/dhw circuit (single pipe for both, splits in loft just before header).

Right bottom comes from boiler, left bottom goes to pump. Assume it's something to do with control of F/E, but interested as to what exactly it is!

Ta for reading

 

[Agile]

I cannot see your item.

But I expect its a proprietary device which is meant to help to separate air to send it to the vent pipe.

They are not really any advantage if the pipework is done correctly but many were installed during the 1970s.

Tony

 

[Ben Lumley]

Sorry, hadn't realised it didn't show - image was showing for me as logged in to where it's hosted. Should be working now.

Something along the lines of an air separator was my best guess; house built in late 80s, but I'm not a plumber.

 

[Agile]

I have not seen one before looking like that.

But I still think that is what it is meant to be for.

Its not very clear what the pipes are, but is the top to the vent and the two below the flow in and out?

Are there just three pipes or four???

 

[Ben Lumley]

Yes, three pipes. And pretty much as you say.

Bottom two are feed in/out - right hand bottom is flow from boiler, left hand bottom goes to the pump.

Top has a single pipe - combined vent/feed. It goes up to loft, where it splits just before the tank to separate vent/feed.

 

[Agile]

It therefore seems to be an air separator designed specifically for a combined feed and vent which are somewhat rare.

In fact normally only used as an after install as a cure for pumping over problems!

Tony

 

[Agile]

This is the usual one!

http://www.clickdiy.com/Aerjec-DE-Airator-p/ajec22.htm

 

[Ben Lumley]

Interesting; pumping over problems are my reason for trying to get a little bit more familiar with the system. There may well be more questions along that line once I've ruled a few other things out.

 

[Agile]

Yours cannot pump over!

At least not in the usual sense if that really is a combined feed and vent!

Tony

 

[Ben Lumley]

That's what logic tells me... no loop to pump round, so it can't...

Yet sometimes the overflow is dribbling outside when the heating is on - never seen it when the HW is on, but guess I can't 100% rule it out as it only happens sometimes with the heating on - maybe I've just never seen it when HW is running.

Ball valve is fine - so it's not that.
In process of flushing/cleaning at the moment, see if that sorts it.

Thanks for taking the time to reply.

 

[Agile]

The warning pipe is on the tank level.

Its probably adjusted too high. Should only be about 100 mm deep when CH is cold.

If it really increases then you have a faulty ball valve or a leak of mains water into the CH system. Sometimes a holed heating pipe in the HW cylinder!

Tony

 

[Ben Lumley]

Warning pipe - I presume that's what a novice like me calls the overflow? The white plastic one that takes the excess from the tank to outside?

If so - then yes, from memory the water level is only 15mm or so below that when system is cold. I shall endeavour to adjust the ball valve to keep the level down towards 100mm (and will no doubt end up breaking/snapping the arm on the float valve and needing to replace it...).

Assume it's 100mm from bottom of tank, and not 100mm from the outlet to the heating system? I guess it's not an exact science - just need more expansion room before it overflows through the warning pipe than it has now?

 

[ScottishGasMan]

Yea, the pros call it an overflow pipe aswell

Sounds very much as you have described that the water level is simply too high in the F+E tank, and when the system heats up the expansion is reaching the over flow point.

When your only heating the hot water, on the F+E/Primary side of the water system your only actually heating the coil in the cylinder, so a very small amount of water there for much less expansion than when all the rads are heating, that will likley be why its only happening when the heating is on.

As you say, get in there and try bend the ballcock arm a bit to lower the cold fill level. Sometimes its easyer to turn off the cold supply to the tank and drain a bit of water out so its not bouncing and splashing all over. Worst case get a new ballcock in, there relativly inexpensive, easy to fit, and most new ones are adjustable for the water level.