Cold Water Revision Notes PDF

# Cold Water Revision Notes ## Water Regulations Advisory Scheme (WRAS) - WRAS approved fittings are: Legal Requirement, Corrosion Resistant, Avoidance of Contamination - BS EN 806 - Design, Installation and Maintenance. ## Rainwater Cycle - Evaporation, Condensation, Precipitation ## Water Sou...

# Cold Water Revision Notes ## Water Regulations Advisory Scheme (WRAS) - WRAS approved fittings are: Legal Requirement, Corrosion Resistant, Avoidance of Contamination - BS EN 806 - Design, Installation and Maintenance. ## Rainwater Cycle - Evaporation, Condensation, Precipitation ## Water Sources - **Above ground:** Lakes, Rivers, Reservoirs and Streams. - **Below ground:** Wells, Bore Holes and Natural springs ## Water Mains - Water Treatment plant -> Trunk Main -> Principle Main -> Local Main-> Communication Pipe -> Service Pipe - Mains Water Pipe known as MDPE (Medium Density Polyethylene) is Blue. ## Installing a Cold Water System When Installing a cold water system, you must consider the Pressure and Flow rates at peak times. - **Pressure:** measured using a pressure gauge - **Flow rate:** measured using a Flow/Weir Cup Lts/s or Lts/m ## System Types - **Direct System:** all cold outlets will be fed from the mains, all points will be drinkable! - **Indirect System:** all outlets (except Kitchen Tap) will be fed from the CWSC (Cold Water Storage System) in the loft. ## Fluid Categories | Fluid Category | Description | |---|---| | 1 | Wholesome water supplied by the water Undertaker | | 2 | Wholesome but some of its qualities are slightly aesthetically impaired | | 3 | Slight Health Risk and should not be drunk | | 4 | Significant Health Risk and could be toxic | | 5 | Severe Health Risk and most likely fatal | ## Isolation & Valves - **Sure Stop:** A diaphragm valve closing under water pressure - **Fullway Gate Valve:** used on Low Pressure (Gravity), cannot repair if it becomes defective you must replace complete valve. - **Stop Valve:** used on mains pressure (high Pressure), can be maintained and parts can be replaced if it becomes defective. - **Isolation/Service Valve:** quarter turn valve which should be installed before any appliance. E.g. Toilets, basin taps, boilers, CWSC. - **Drain Off valve:** fitted at all low points throughout the system to enable emptying the system fully. - **Float operated valves** - **Part 1:** Portsmouth Valve, Brass, Bottom Outlet, Piston type, no longer used due to risk of back flow. - **Part 2:** Brass, Diaphragm washer, Top outlet, CWSC and Toilet Cistern. - **Part 3:** Plastic, Diaphragm, can be Side or Bottom entry, top outlet, used in toilets not suitable in CWSC as it could become brittle. - **Part 4:** Plastic, Equilibrium valve, Diaphragm, bag attached to top outlet to help fill quieter and will also prevent back flow. (Can get in brass just for CWSC only) - **Pillar Tap:** has a rubber washer that closes against the seat. - **Ceramic Disc Tap:** is a quarter turn on and off tap. When the 2 discs align then the tap opens when its closed the disc's are out of alignment. ## Cold Water Storage Cisterns - **Byelaw 30 Kit:** (Screened vent, Tank Lid, Tank Insulating Jacket, Overflow/warning pipe, Dip Pipe, Screen for overflow, FOV Part 2, Tank connector) - CWSC should be situated on Plywood (Not on chipboard as it is not sufficient when it gets wet) and the boarded should be 150mm all the way round the base of the tank. It should have 350mm minimum above for maintenance access. ## Taps - **Pillar Taps:** Rising spindle and Non rising spindle have a washer and Jumper plate. Used for Bath, Basin and Bidet - **High Neck Pillar Tap:** Same as a normal Pillar Tap just a taller tap used on Kitchen Sinks - **Quarter turn Ceramic Disc Tap:** contains to discs with holes in which when turned a quarter the holes align it will allow the water through and when turned a quarter back will shut of the water. - **Mixer Taps:** the hot and cold water mixes within the body, must have backflow prevention - single check valve - **Bi flow mixer:** The water does not mix in the tap. - **Bib Tap:** is a wall mounted tap mainly used for outside taps or for butler sink. ## Backflow Prevention - **Backflow:** When water travels in the opposite direction to which it was designed to travel - **Back Siphonage:** When water is drawn backwards via negative pressure (suction) ## Check Valves - **Single Check Valve:** Used to protect Fluid Cat. 1 From Fluid Cat. 2 (Mixer taps H&C mix in the body of the tap) - **Double Check Valve:** Used to Protect Fluid Cat. 1 From Fluid Cat. 3 (Outside tap or Filling loop on a heating system, ascending spray bidet) - **RPZ Valve Reduced Pressure Zone Valve:** Used to Protect Fluid Cat. 1 from Fluid Cat. 4 (Swimming Pools) ## Air Gaps (For protection of Fluid Cat. 1 from Fluid Cat. 2) - **AG:** Height between FOV and Overflow/Warning Pipe (25mm) - **AUK 1:** Height between the WC pan spill over and WC cistern spill over (300mm) - **AUK 2:** Bath, Basin or over the rim Bidet outlet of tap to the spill over of each appliance - **AUK 3:** Kitchen Sink (Food prep so more risk of contamination so Gap needs to be higher) ## Decommissioning - **Temporary decommissioning:** a system is isolated for a period of time while work is carried out, after which the system is put back into normal operation. - **Permanent decommissioning:** a system or appliance is taken out of use. The system will be isolated at the incoming mains stop valve and then drained. The pipework can be removed and the pipework capped either above the stop valve, if the whole system is decommissioned, or at the end of a branch pipe to stop stagnation of water. ## Dead Legs Passive dead leg: a section of pipework through which water cannot be drawn off or flow. Pipe not being cut back to a branch end or a drop with no DOV - these can give rise to bacterial growth. ## Testing - **Rigid pipework (Copper or LCS):** fill the system with water, allow 30 mins for temperature stabilisation and at this point make sure there are no leaks. Then raise pressure 1½ times the working pressure and leave for 1 hour. E.g. working pressure 3 bar will raise to 4.5 bar. - **Plastic pipework:** slowly fill the system and raise to 1 bar for 45mins, then raise pressure 1½ times the working pressure and leave for 15mins. Then reduce pressure to 1/3 and test for a further 45mins.