1. Lesson One

2. Direct Cold-Water System

3. Direct Cold-Water System
Advantages
Economical on pipework
Only needs a small storage cistren.
Disadvantages
If the supply is cut off even for a short period, there is no water available.
When the supply is cut off, back syphonage could occur which could contaminate the mains.

4. Direct Hot Water System
The water is heated in the boiler.
The boiler water is fed by the water in the cylinder
The cylinder is fed by the storage tank in the attic.

5. Boiler and cylinder placed close together to minise heat loss.

6. Direct hot water cylinder
Drain Cock
Incoming cold feed
Main tank immersion
Top up immersion
Expansion pipe
Hot pipe to fed taps
Cold feed out
Cold feed in

7. Storage tank

8. Hard water disadavntages
Hard water can cause water heaters to run up to 60 percent less efficiently than with softened water.
Clothes washed in hard water tend to wear out 15 percent faster than those washed in soft water.
The American Water Works Association has found that washing machines that use hard water can wear out up to 30 percent faster than those that use soft water.
Hard water can leave an unsightly film build-up on glasses and dishes.
Hard water requires much more soap, shampoo, or detergent than soft water,
Hard water leads to furring of pipe work therefore hot water travelling through these pipes does not effectively heat the house: more fuel is burned in heating the house

9. Pipes Carrying Hard Water, Clogged with Scale

10. Homework Assignment
Outline the main differences between direct and indirect (hot and cold) water systems, and the effectsthey have on both domestic costs and environment
words
Points to be dicussed:
Installation costs
Domestic costs.
Their use of fuel
Their effectiveness of tranmitting heat.
The effects of water properties on each system.

11. Lesson Two

12. Indirect Cold water System

13. Advantages of the indirect cold water system
provides a reserve of cold water.
Reduces the risk of contamination to the mains by back syphonage.
Since all sanitary appliances are fed from the cistren there is generally less pressure on taps and valves and therefore less wear.
This system also prevents pressure drop at peak demand periods

14. Indirect hot water system
The large storage tank supplies water to the cylinder.
The small storage tank supplies water to the boiler
This system is broking down in to two parts.
Primary System
Secondary system

15. Primary system
The water in the boiler mixes with the water in the cylinder.
The water in the boiler is onlt subject to fresh water after it is filled, when you need to replace any water loss due to evapouration.
This system requires a second expansion pipe due to its seperation from the secondary system.

16. Secondary system
Requires a larger tank due to it been the water which supplies the hot water to the taps.
The water is heatd in a closed loop circuit (coil).
Cold water exiting the coil returns to the boiler to be reheated, not the water in the cylinder.

17. Indirect Cylinder Drain cock Incoming cold feed Return to boiler
Flow to boiler
Heat exchanger
Immersion
Hot feed to tap
Expansion pipe

18. Primatic Cylinder
This cylinder was developed to elimanate the need for a primary cold water system and its feed and expansion pipes.
As the cylinder is filled so to is the primary system, creating an air seal in the primatic unit.
The expansion which takes place when the water is heated displaces some of the air in the upper seal. Any excess air is atumatically vented through the secondary system.

19. Lesson Three

20. One Pipe System. Advantage Ease od installation Low cost Diadvantage
The temperature of the water entering each successive radiator is gradually reduced therefore the last radiator would not be as warm as the first.

21. Two pipe System Advantages
The cold water exiting the radiators is returned to the boiler to be reheated therefore all radiators are receiving water at a high temperature.
Disadvantages
Costly due the the extra pipe work.

22. Standard Radiator

23. Vented and Unvented Heating Systems
The direct and indirect heating systems are called "vented" systems. Because they both contain a vent pipe (expansion pipe) to the atmosphere (tank in the attic) . They are open to atmospheric pressure and operate as "low pressure" systems. They both call for cold water from a cold tank stored, generally, in the roof space. Because they are low pressure, sometimes the flow from the taps etc is not as great as one might like and pumps can be introduced, both for the domestic hot water and the heating, to give greater flow.
An unvented system does not contain a vent pipe to the atmosphere due to the lack of storage tanks.

24. Safety devices of an unvented heating system.
Pressure reducing valve
Check valve
Expansion vessel
Expansion valve
Temperatire relief valvE
Tundish

25. Lesson four.

26. Pressure Reducing Valve
Reduces mains presure to a suitable level for supply directly to the storage cylinder
Overcomes the fluctuations in ressure from the mains
Supplys water to the cylinder at a constant pressure.

27. Check Valve Permits flow in one direction only.
Water running in the opposite direction to the flow will force the disc O ring down to close off the pipe.
Back syphonage therefore cannot occur.
The mains would be contanianted.
Parts.
Spider Unit
Spring
Disc and stem
Body “O” Rings
Clamp
Disc “O” Ring

28. Expansion Vessel
Acts the same as an expansion pipe in that it accommodates the thermal expansion of the water.
As the water expands the diaphragm gives way as the nitrogen is compressed in the chamber
Instaled in the cooler returen pipe which is the negative side of the pump to reduce wear.
Adjusted to provide min water pressure of 10 highest point.
Need to ensure that no water is contained in the vessels during instalation.

29. Expansion Valve
Used to releif pressure is the expansion vessel should fail.
Should be capable of withstanging 1.5 times the maximum pressure to which thay are exposed to.

30. Temperature Release Valve
These components are set to open at 95°C max and to discharge to waste. The sensing element is submerged in the water

31. Tundish
A funnel to catch overflow/expansion water from the safety valves.
The funnel is lead out through the cavity wall and into the gulley.

32. Advantages of an unvented heating system
Balanced hot and cold water pressures
Improved shower performance
Less pipework and no storage cistren
Reduced risk of frost damage to system
Saving n installation time and cost
High resistance to corrosion
Excellent heat transfer capability
Allows the use of a wider range of moderen tap fittings and showers
High efficiency insulation

33. Unvented System Pressure vessel Expansion relief valve
Cold water inlet
Temperature relief valve
Hot water outlet
Immersion heater
Visual overflow
Non-return valve
Cold to taps
Pressure limiter
Strainer
Stopcock
Mains
Discharge pipe.

34. Unvented heating system