Yeoman DEVON 50 manual Central Heating System

INSTALLATION INSTRUCTIONS

CENTRAL HEATING SYSTEM

1. General

This appliance gives out heat in two ways:

—Directly into the room in which it is fitted through convection and radiation.

—Hot water to heat radiators and domestic hot water.

The installation must comply with building regulations and use best practice advice.

2.Boiler Sizing

2.1It is very important to determine the correct size of appliance for the house:

—Too big a boiler will run too hot and will not be efficient.

—Too small a boiler will not maintain the desired temperature.

2.2Size the boiler correctly by calculating the following heat loads:

RADIATORS - the amount of heat required to run the radiators efficiently. The correct size of radiator depends on the required temperature for the room, the room heat losses and the radiator manufacturer’s guides.

HOT WATER - the amount of heat required to provide the desired amount of domestic hot water.

LOSSES – the amount of heat lost in pipe work - typically 10% of the combined radiators and hot water loads. There are national guidelines for calculating these figures*.

2.3Careful consideration must be given to where the appliance is fitted. It must be sized correctly for the heat load required and the size of the room. These requirements can be found in the Technical Specifications.

2.4All Yeoman appliances are thermostatically controlled. The burning rate is adjusted to the demands of the connected heat load. If the radiators do not require heat then the thermostat will act to shut down the appliance and the direct heat output to the room where it is fitted will reduce (see heat output graph on page 15 to show the ratio between direct heat output and water heat output). To prevent the room becoming too cold, fit a thermostatically controlled radiator as well as the appliance.

3.Hot Water Cylinder

3.1The domestic hot water cylinder must be an indirect vented double feed type to meet national standards** and should have a minimum capacity of 117 litres. Houses with more than one bathroom or a separate shower will need a bigger tank.

Fully insulate the tank.

The water draw off pipes to the taps should be in a dead leg connection from the vent pipe.

4.Open Vent And Cold Feed System

4.1This system must be fitted with a minimum of 22mm diameter open vent discharging into a heat resisting feed and expansion tank. There must be at least 25mm air gap between the end of the pipe and the water level. The cistern tank should have an overflow with a minimum diameter of 22mm

The cold feed must be a minimum 22mm and enter the system as the last connection on the common boiler return.

The open vent and cold feed must not be fitted with any valves, manual or automatic.

Do not use plastic pipe in any part of the flow and return.

5.Heat Leak Radiator

5.1A heat leak radiator must be fitted in the gravity circuit to dissipate any excess heat produced from the boiler when connected demand is low. The domestic hot water cylinder may not be able to disperse heat at all times due to modern insulation. This radiator is commonly fitted in the bathroom and should be rated at 2kW (6500 btu) or 10% of the total boiler output.

This radiator ensures that the appliance is not shut down completely for long periods resulting in the fire going out.

Fit the heat leak radiator in the gravity circuit using 22mm pipe reducing to 15mm for no more than 300mm before the radiator.

Fit the radiator with two ‘lock-shield’ valves that are set in the fully open position and cannot be shut down. Use diagonal connections. Do not fit thermostatic valves or manually adjustable valves to the heat leak radiator.

In the UK:

*See BS 5449:1

**See BS1566 Part 1 grade 3 minimum

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