Hot water Systems Heaters

Objectives You should be able to: Describe the various types of hot water heater Recognise the need for minimising the use of dead legs State the need for stratification in hot water cylinders. Identify Specific Pipework Installation Requirements for Showers Barry Spick

Storage Heaters Inlet controlled storage heaters also gas and electric, these appliances are controlled via an inlet tap either on the appliance or the appliance inlet pipe-work The outlet must not be obstructed or any connections made to it, as the open outlet allows for expansion of the water Under sink models require a special tap to allow for venting of the water heater Barry Spick

Multi-point Water Heater Heats water directly from the cold mains as it passes through the appliance. The amount and temperature of the water drawn off can be individually controlled at each tap unit. Outlet controlled As soon as any of the water points connected to the appliance are turned on Water pressure in the pressure differential valve drops. The burner ignites. This type of arrangement is best used where there are not excessively-long pipe runs to the various hot water outlets. In areas of hard water will require which device to be fitted? Water conditioner device e.g. scale reducer Barry Spick

Combi-boiler System Direct system 15mm hot water Hot water fed by combination boiler Combi also feeds Central Heating Sealed system of heating Service valve on Cold water inlet to combination boiler When hot water is being demanded then: Diverter valve changes priorities from heating to hot water Needs new drawing!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Barry Spick

Dead Legs and secondary circulation Hot Water Dead Legs and secondary circulation

Dead Legs Term used to describe long lengths of pipe from hot water storage vessel to appliance Water reg defenition is “a length of distribution pipe without secondary circulation Length of pipe measured from hwsv or heater to the outlet should be as short as possible Dead Legs Max lengths: 12mm 20m 12 to 22mm 12m 22 to 28mm 8m + 28mm 3m Bath Basin Sink Cloakroom Barry Spick

Secondary Circulation Is a method of overcoming the problem of dead legs Involves installing a flow and return loop Feeds all the appliances Kept circulating by gravity or a non corrosive pump ”Bronze” Return should be connected into top third of cylinder Timeclock Prevents cooler water lower down in the cylinder mixing with the hot water Bath Basin Sink Bronze Pump Barry Spick

Stratification Stratification must take place for the vessel to function correctly Manufacturers build stratification into the design Rules regarding stratification: The vessel should be cylindrical in shape The vessel should be installed vertically Cold should be in the horizontal position Cold feed connection 25mm lower than the primary return Hottest water 650C Strata based on water temperature Coldest water 400C Barry Spick

End of Dead Legs and Secondary Circulation Showers Barry Spick

Electric Showers Shower isolated by 45 amp double pole pull switch Position of switch to be ceiling mounted within the room. If not in room within easy access outside the room Cable to be 10mm2 If cold water connected to mains have to install check valve to shower outlet. WHY? Door Barry Spick

Showers Showers can be fed by: Storage Mains pressure Boosted supply Water regs require that: Backflow cannot occur Done by installing double check valve Shower with check valve installed Barry Spick

Showers Shower valve can be: Manual Thermostatic permits the user to adjust the quantity/mix of hot and cold water flowing to achieve a desired temperature . Mixer does not incorporate any safety features Possible to discharge hot water at the same temperature as the water in the cylinder Thermostatic permits the user to adjust the quantity/mix of hot and cold water flowing provided that the mixed water temperature does not exceed a pre-set level usually around 42ºC Incorporates a key safety feature in that the temperature of water leaving the shower rose is set at a pre determined maximum level so preventing the possibility of scalding. Barry Spick

Storage fed 1m Minimum Cold feed to DHW cylinder Above height of shower cold feed Alternative position for connection 1m Minimum Flange or specially produced cylinder Shower mixer Dedicated pipework for mixer Barry Spick

Gravity fed shower Min 1m head of water required to shower head from underside of cistern Separate cold distribution from cistern Size of cistern would then have to have a minimum capacity of: 230L Where possible direct connection to cylinder for the hot supply if no direct connection then other methods are available Essex Boss ‘S’ Flange Barry Spick

Connection to Cistern When connecting the cold distribution it must be installed : The cold feed must be installed above the cold distribution WHY? To prevent scalding Cistern Cold Feed Cold Distribution to shower Barry Spick

Boosted Single Impellor Pump 150 min Dedicated pipework for mixer Flange or specially produced cylinder Shower mixer Flexible connections Pump Barry Spick

Boosted Double Impellor Pump 150 min Dedicated pipework for mixer Shower mixer Flange or specially produced cylinder Pump Barry Spick

Shower Pumps Connected to pipework by flexible connections Base of pump are on anti vibration feet Inlet to pump normally has a strainer fitted Pumps operate by a flow switch When the shower is turned on Pressure falls, which activates the pump impellors If shower head is above level of water in cistern (Negative head) then the shower needs a pressure switch installed If not got a negative head then needs a minimum head of 150mm Barry Spick

End of presentation Barry Spick