Which Central Heating System - Which Gas Boiler – is Right for Me?

 

There are three types of central heating system and many variations of these systems. However it is all to do with the hot water and the amount of hot water you require for comfortable living conditions. It is about the additional space that can be gained from removing the cold water tanks and the hot water cylinder.

 

The regular gas boiler is part of a stored hot water system. If you are not looking to gain space and you have a stored hot water system with fully pumped hot water and central heating system, then think twice before converting to a combination system. The regular gas central heating boiler and system offers a good flow of water to every tap in the house simultaneously. It will supply a flow rate of 35 litres/minute at bath tap. Regular gas boilers are Gas Sedbuk rating ‘A’ 90% efficient. Therefore the regular boiler offers a good flow of water; it has the back up of stored water and the back up of an electric immersion heater for hot water. The regular gas boiler has a longer life with less maintenance. The stored hot water system will normally have an airing cupboard.

 

The system gas boiler combines with a stored hot water system much the same as the regular gas boiler. The system gas boiler however operates without a small tank in the roof space known as the ‘feed and expansion tank’. This means that the heating system pipe work is fed directly from the mains cold water then turned off when the desired pressure is reached and sealed against further water entering and is known as a ‘sealed system’ or ‘pressurised system’. The term ‘sealed system’ best explains the system gas boiler because ‘pressurised system’ gives the impression that the heating and hot water pipe work may be under very high pressure whereas in practice it operates at only 1.5 bar. In effect water is sealed in the pipe work and air is sealed from gaining entry in to the pipe work. With very little air in the system, corrosion is kept to a minimum. Thus the system gas boiler, controls and pipe work will be at a maximum efficiency for longer periods, and throughout their life expectancy will be operating more quietly and generally requiring less maintenance.

 

The system gas boiler will allow radiators to be installed in the roof space, will overcome air ingress from pumps and is generally thought to be the best system. However one thing to bear in mind is that the smallest water leak within the system will drain the system of the pressure required to run it and it will shut down. These leaks could be from radiators or pipe work and which evaporate before they become noticeable, making it very difficult to trace them.

 

 

Filling the System with Water to a pressure of 1.5bar

 

The opening of an air release valve will reduce the boiler pressure and may reduce it to a low enough level to prevent the boiler from functioning – for instance disconnection of radiators for decorating.

 

Before Boilers came with their own key

 

Locate the filling hose; remove the caps which seal the open ends. Screw the hose into position tightly. Open the adjacent valve slowly until the pressure gauge reaches 1.5 bars, turn off the flow valve and check all radiators return and if the system requires topping up, carry out to 1.5 bars. Remove the flex/hose and seal ends with caps.

 

If your boiler is within the last couple of years the boiler comes with its own filling system – the key must be kept safe at all times. Remove the white plastic base plate from the base of the appliance. Insert the key much the same as an ordinary light bulb and turn 90 o; once turned there is a small plastic knob adjacent to the key, open the valve by turning the knob gently. Watch the needle in the pressure gauge rise to 1.5 bars, turn off and check for air, much the same as for the hose system. Remove the key and replace the white base plate. Be gentle with the key and knob, they are made of plastic and only require the smallest amount of pressure to operate them. If you overfill a system, don’t worry just drain it out via a radiator bleed or a drain cock which would normally be located in the lowest point of the system.

 

Finally when filling the system initially or when the pressure has dropped, air can become trapped in the system. This may take 2 – 3 weeks to remove and will only be done by checking each day initially, then alternate days and finally weekly.