Unvented Undersink Water Heaters. For D.I.Yers.

davezawadi (David Stone): 
 

The interesting point they don't tell one when they fit a water meter is the non-return valve! Perhaps a free expansion vessel should be fitted at the same time? This is beginning to sound like the smart meter saga….

The meters themselves don't have non-return valves, it is their housings, eg Water Meter Boxes - Johnson Valves the meters screw into them. I believe Thames water have a policy of replacing on-street stopcocks with these housings free of charge, with or without a meter. Presumably to monitor water leakage and prevent contamination of their supply with the non-return valve. This also has the effect of reducing the “earthyness” of main bonding to metal water pipes, as their underground length is shortened, becoming less useful after a broken PEN.

It would make sense to include a mini expansion vessel within the meter box, but they could be nicked for scrap quite easily i suppose. It does seem off that the water companies do not warn of the potential dangers of their installation of N-R valves. A bit like loft-insulation companies putting 300mm of insulation over shower and cooker cables.

 A bit like loft-insulation companies putting 300mm of insulation over shower and cooker cables.

 

So we are saved by the well oversized supply cable and the short use of the former, and the intermittent operation of cooker elements of the latter.

Z. 

So we are saved by the well oversized supply cable and the short use of the former, and the intermittent operation of cooker elements of the latter.

Z. 

Probably :) but there IS a potential for danger, however small. And these actions increase that risk, however marginally. You would think in these risk-averse times, with disclaimers, contracts and litigation, that these companies would mitigate the risks by making people aware of them beforehand allowing them the informed choice as to their course of action/inaction.

You would think in these risk-averse times, with disclaimers, contracts and litigation, that these companies would mitigate the risks by making people aware of them beforehand allowing them the informed choice as to their course of action/inaction.

Not at all - they just want a box ticked on a bit of paper that suggests that it wasn't their fault/responsibility.

   - Andy.

Not at all - they just want a box ticked on a bit of paper that suggests that it wasn't their fault/responsibility.

   - Andy.

I have emailed Thames Water, who are rolling out compulsory smart meters ATM, by law apparently. Will see what they say ;)

Sparkingchip: 
Compression fittings have a place, they are also something I would not use unless readily accessible. 

A plumber once told me that they are not permitted to be used where they are inaccessible. In other words, the situation is just like MF JBs.

Chris Pearson: 
 

Sparkingchip: 
Compression fittings have a place, they are also something I would not use unless readily accessible. 

A plumber once told me that they are not permitted to be used where they are inaccessible. In other words, the situation is just like MF JBs.

I have never found one that correctly installed has leaked. They are a fit and forget fitting. Also the maintenance free electrical connectors are a con just to boost profits. I have never found self loosening screws in junction boxes or wiring accessories. Fit correctly and forget.

Z.

Chris Pearson: 
 

Sparkingchip: 
Compression fittings have a place, they are also something I would not use unless readily accessible. 

A plumber once told me that they are not permitted to be used where they are inaccessible. In other words, the situation is just like MF JBs.

That is definitely true for gas pipework, but not water pipe work as far as I know.

I have never found one that correctly installed has leaked. They are a fit and forget fitting. …

Z.

depends on the composition of the brass and its age. Dezincification can occur which leaches out the zinc leaving just copper. I have stripped out old copper pipes and the brass fittings are the first things to snap on bending. You often see it on the brass waste outlets in basins which turn to cheese, or perhaps that has more to do with unblocking chemicals used. Also, they do tend to weep slightly over time and need nipping up occasionally.

Brass isn't as waterproof as you may think. There are articles on line which refer to verdigris attacking brass, but in fact I think that it is carbonic acid (IIRC) which turns the brass to verdigris. I had a nice pair of taps which were ruined in this way whilst in storage. Bronze is preferable where water is involved.

ETA: the water inside the pipe will not rot brass ‘cos it isn’t exposed to the atmosphere. There is not (should not be ? ) any water outside. Things like WC ball valves might scale up or the rubber seals perish, but they don't rot. I wonder why?