Mini expansion device for portable water

Tim Watts · 2015-04-06T12:28:16+00:00

I've posted before about this - but I have new information. I have not chosen a boiler yet, although Viessmann looks like a good contender. Anyway, there are times in the winter where, if we say take a short holiday, my insurance says "turn the water off" - but I would like to leave the heating running. Is this a problem (rhetorical): Physically - if we've hydraulically locked both sets of our plumbing, a very small amount of expansion in the boiler's heat exchanger *could* result in a spike in pressure (copper pipes being not very elastic). Well - Viessmann say no as they say the Vitodens combi has a small expansion vessel built in on the potable side in addition to the main one on the heating side. But covering my bases in case I change my mind about the boiler, I looked at an old boiler manual of a boiler I had once: and on page 9 it says, on the right of the diagram, half way down: "Note: If the mains is fitted with water meter, check valves or loose jumper stop cock, then a DHW expansion device must be fitted." That clearly says to me that combi boilers should not have a hydraulic lock on the potable water circuit while they are running (unless the manufacturer has built in a safeguard like Viessmann). Anyway, I see no harm in adding a small external one - it might help with water hammer anyway. But which one? I see an american campany, Sioux Chief make the ones Toolstation sell: Does not say "WRAS" or "potable" but clearly its friend with the 3/4" threads on is designed to go on the cold mains near a washing machine. Checking further I think these things meet the equivalent USA version of WRAS. Neat, small and solid looking. The other option is something like: Bit lumpy, but more volume.

Apr 06, 2015 21 Replies

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Another John 11 years ago

You never heard of portable water? I was sold a large pack of it a few years ago, which I've kept in case of emergency: it's dehydrated, and when you need it all you do is add - um ...

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Johnny B Good 11 years ago

... water, preferably of the potable kind (like what you can draw off the public main supply in most parts of the UK, usually from a kitchen sink cold tap) if you wish to rehydrate yourself.

Plastic lemonade bottles with screw caps can be recycled as 'dehydrated water' readily hydrated from any kitchen cold tap or other potable supply you might find on your travels.

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