1. Hot water Systems
Heaters

2. 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

3. 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

4. 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

5. 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

6. Dead Legs and secondary circulation
Hot Water
Dead Legs and secondary circulation

7. 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

8. 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

9. 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

10. End of Dead Legs and Secondary Circulation
Showers
Barry Spick

11. 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

12. 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

13. 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

14. 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
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15. 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

16. 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

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

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

19. 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

20. End of presentation
Barry Spick