What kind of check valve, if any, is required on the feed to WC cistern? Or are they usually built into the cistern these days?
R.
- posted
14 years ago
Check Valves
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- posted
14 years ago
There is no requirement for a check valve in a wc cistern as there can be no back siphonage due to the air gap between the outlet and the water.
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- posted
14 years ago
Air gap or collapsible tube.
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- posted
14 years ago
But you do need to make sure the filling (ball-float) valve is a suitable type. One occasionally sees a "Part 1" valve, which has its discharge below the centre line of the valve, fitted to a cistern on which the overflow outlet is on the same centre line as the fill valve. This means that under overflow conditions the fill valve is discharging under the water level of the cistern rather than over it, so there's no air gap, contra the regs. The correct type of valve discharges above the water level at overlfow.