Thermals store

[Lee Johnson]

Is there any reason why I couldn't convert a non vented thermal store to a vented version by replacing the AAV on the top of the cylinder with a header tank?

I don't trust the aged back boiler to be pressured on my new second hand log burner and also don't want a pressured vessel

 

[oldbutnotdead]

Running woodburners on a pressurised setup is risky....post some pics of your unvented, your plan will probably work but you might be better with a new cylinder if existing doesn't have loads of bosses for the extra pipework)

 

[Lee Johnson]

I'm yet to install anything, just have the log burner but can't find a cheap second hand un vented thermal store but have found a non vented one so was thinking of using that by converting it. Just checking I wasn't missing anything before I buy it!

 

[oldbutnotdead]

Main thing you need is enough connection bosses so you can connect woodburner, boiler, radiators, dhw heat exchanger etc to the cylinder proper (rather than all the sources sharing a single pair of connections, which will give you problems.
These lot https://www.heatweb.co.uk/hot-water-storage/heatbank-thermal-stores/ aren't too bad on pricing....

 

[Lee Johnson]

I've found this one cheap second hand (attached file) and I thought I would replace the automatic air vent on the top with a header tank to make it a vented tanks, I can't see a problem with that, was just checking that I wasn't missing anything

 

[oldbutnotdead]

That's a non pressurised cylinder anyway, the vent at the top is just so you don't get an air bubble at the top- your vent & feed setup need to be vertically up from the boiler (or other heat source).
As expected there's only 1 set of inputs to the cylinder (which you'd use for the woodburner), you really need another set of inputs for the boiler otherwise you will get bizarre back circulation problems.
EDIT If your woodburner will be the sole heat source for the cylinder then it'll work- but that's a very labour-intensive way of heating the place