Anyone know what this tank is?

Interesting!

It's obviously been retro-fitted ( looking at the painted /non-painted DHW pipework over by the lovely purple wall ).

I notice that the primary circuit only has 1 pipe into it, and what looks like an air vent or something hanging off the side.

So this device is on a dead-end, as far as the primary circuit is concerned!

A heat exchanger of some sort? Can't see how, given the dead-end installation on the primary.

Some fancy method of getting air out of the primary by methods unknown involving the DHW?

Primatic bubble thingy.... hmm.... thinking.... possibly...

One reason why I suggested this is that I can't find any evidence of an F&E tank, with its associated connections. So maybe filling from the DHW system and expansion are catered for in some way by this weird and wonderful device?

It surely can't be a one-off - *someone* must have seen one somewhere and must know what it is?!

What a weird object. I don't know what it is either, but it has one secondary inlet and two secondary outlets, so its job is maybe to split the secondary supply somehow? The pipe leading out of the bottom of it - is what I can see at the bottom of the picture a pump? It's not a Heath-Robinson secondary loop by any chance?

Peter

I don't think so. Yes, the pump is just out of shot at the bottom. But the pump is definitely in the *primary* circuit - with its input coming from the boiler, and with its output going to two zone valves (CH + HW) and a by-pass valve.

I thought of that too ( secondary circulation ), but then why not just a tee? What's the volume of the cylinder for? And the air venty thingy ?

Also, on secondary circulation, the pump is nomally on the far end of the DHW pipework, after the last draw-off, pumping back to the cylinder. Not on the supply side. ( well, on the systems I have seen. )

But with the 'Heath Robinson' qualifier, who knows.

However, the device looks well-made and not heath-robinson ( well, it was well-made for *some* application... )

To me, it looks like some kind of air removal device. No reason for that, just gut feeling.

My best guess would be an air seperator that has been fitted upside down. The bottom pipe should be at the top and vent the cylinder to the tank, but then why the need for a auto vent. Don't know. Legin

Isn't it a bit big for an air separator? Is it usual to fit them in the DHW flow pipe from HW cylinder to taps? Why would it be connected *both* to the primary *and* secondary circuits?

You can see things I can't. Perhaps a better photo or two would help... Peter

There were references to additional photos supplied by 'Bawser' in the "baxi Bermuda boiler problems and leaks" thread - but I only cited the one which was most relevant to the question about the mystery cylinder. If it will help, the others are:

I'm sure I saw something like that on 'Torchwood'. You don't have a cellar do you?.. ;-)