(A) Directly Fired:

Directly fired equipment uses as a fuel source, oil, coal gas, LPG or electricity or solar energy. Geyser is used in every room for heating water in houses. The fuel is burned and the resulting heat is transferred to the water.

Boiler are appliances which generate hot water or steam types of is boiler –

(A) Smoke Tube Boiler:

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The fuel is burnt in a furnace hot gas passes through smoke tubiesing a variety of panes which enable temperature of them to heat the water is the cylinder surroundings the furnace and the tube the spent gas are then led to the atmosphere by many.

(B) Water Tube Boilers:

Water is passed through a set of coils or tube bundles. The coil is exposed to heat in an enclosed furnace having an oil firing equipment. Water tube boiler have low warm up time & available to generate hot water quickly.

(C) Electric Boilers:

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Electrode boiler – in which the electrodes of carbon are directly, immigrates in water. Electrical resistance between the electrode & the water generate heat increasing the temperature of water. The rods are prop­erly insulated & protected electrically to prevent danger of electric stock to the user.

(D) Oil Fired Steel Boiler:

A refractory chamber re­ceives the hot flame of the oil fire. Combustion continues within the chamber and the fire tubes. Smoke leaves through the breaching at the rear wall. Outside the chamber receives the heat generated in the combustion chamber.

(E) Gas Fired C.I. Hot Water Boiler:

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C.I. section contains water that is heated by hot gases rising through these sections. Output is related to the number of sections. Additional heat is gained from electronic ignition instead of a pilot ignition 87% seasonal operating efficiency is attainable.

(F) Oil Fired C.I. Water Boiler:

Primary and secondary air for com­bustion may be regulated with burner unit. Flame enters the refractory chamber and continues around the outside of the water filled C I sections

(G) Baby or Simple Vertical Boiler:

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Is also used to generate hot water 300 Kg. / hr at 10 Kg/cm2 pressure.

Hot Water Heating Circuits –

1. Series loop system:

Usually run at the buildings perimeter. The water flows to through each base board or fire tube in turn.

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2. One pipe system:

Special fittings act to divert part of the flow into each base board.

3. Two pipe reverse return:

Water nearly at boiler temperature is supplied to each base board.

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Combustion Air-

The air should draw in from outdoor at a position close to the fuel burner or led to this location by a duct. For residence and other small buildings a louver about twice the cross-sectional area of the flue should prove satisfactory. It should be arranged to open at all times.

Primary and secondary air for combustion may be regulated with burner unit. Flame enters the refractory chamber and continues around the outside of the water filled C.I. sections.

Baby or simple vertical boiler is also used to generate hot water 300 Kg./ hr at 10 Kg/cm2 pressure.

For oil when more than 275 gallons is stored it is common practice to use outside tank buried in the ground.

Both direct and indirect methods can be utilized in a variety of equipment: Storage tank water heaters Circulating storage water heater Tank less heater central versus distributed equipment Distribution trees Thermo siphon Forced circulation.

(B) Indirectly Fired:

Indirectly fired equipment – A surface is between hot fluid (water, steam, gas) & cold water which needs heating. The surface may be in the form of tube.

Water may also be heated by blending which is direct injection of steam or hot water into the cold water which is to be heated.

Solar Water Heating:

Solar water heating systems are usually classified by the means of fluid circu­lation (passive or active).

The means by which heat from the collector piping is transferred to the DHW itself (direct or indirect or closed loop) & the means of protection against freezing.

  • Passive system
  • Active system
  • Direct system
  • Indirect system
  • DHW system Batch system
  • Thermo siphon system
  • Closed loop freeze resistant system
  • Drain back system
  • Drain down system
  • Air to liquid system
  • Phase change system

Solar Water Heaters May Be:

(i) Natural Circulation Solar water (Pressurized/Non Pressurized)

(ii) Forced circulation solar water heater –

The pump is operated by an off-on controller which senses the difference between the temperature of water at the exit of the collectors and a suitable loca­tion inside the storage tank.

System of this type is well suited for hotels.