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.

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.