Vessel

[fishnchips]

Just wondering, I have a spare 18l potable vessel, can I use this for heating??

i wouldn't do it the other way but surely I don't see why you can't. Just seeing what your thoughts are??

cheers

 

[Best]

Yes, probably okay. The air precharge needs to match the lower charge needed for a heating system, - usually 1 bar perhaps instead of 3bar in many potable vessels for unvented cylinders! Check with manufacturer or agent if you can to see if vessel suitable.
The potable tend to be a balloon inside them (not a diaphragm) for the water to expand inside against the outer air in vessel. That means potable water won't rust the vessel.
Others are stainless steel.
Your potable vessel would be a lot more expensive than an ordinary heating one! You maybe should sell it on to someone.

 

[Meady]

You can use a potable one for the heating but not be other way round.

 

[fishnchips]

Cheers for your replies, just needed expert confirmation

 

[Gray0689]

I thought a potable one was stainless steal to

 

[Best]

I thought a potable one was stainless steal to

No, I also used to assume that. The vessels supplied with all the unvented cylinders that I see (usually white or blue in colour) have a stainless steel bolt on flange on them, but instead of a diaphragm in the middle of the vessel, they have a balloon linked to the flange (water) end.
Scary bit is if the balloon membrane holes, the mains water gets at the light steel of the vessel and soon rots it through! Mains pressure water running through your house. That's why it is recommended to replace the vessel as little as 5 years.

 

[happyflyer]

Isn't they epoxy coat inside, surely not just MS

 

[Best]

Although I have opened a potable vessel that had a burst 'balloon' membrane, I can't be sure what it was like inside. It was just mild steel though. No need of it to be stainless steel while the 'balloon' stays intact, but I think for when it bursts that vessels should be stainless steel.
Certainly a weak point with unvented units!
I know that stainless steel vessels exist, but I don't think the vessels we see are that. Colour of vessel is irrelevant, - they can be any colour, although most potable are white or blue, they can be red.
I did see a Telford Copper unvented unit with vessel built in to the top of it, which had 2 vessels fail & flood a very nice house within a few years, before I worked for the owner. I replaced it with a stainless steel unit with vessel separate. I suspect heat gets at the vessels built into the top.