A system that is fed by the force of gravity starts with the water mains coming into the home through something called a main stop tap. As it leaves it goes straight upstairs and into the loft space. When it arrives up there, it runs through ball valve and begins to fill a small tank, called the feed and expansion tank. Woodford Plumbers can identify central heating systems. Now is the time that Gravity takes over and allows the water flow out of the tank away to the fitted boiler and on into the radiators. When the system is topped up a ball valve shuts and so the water within your boiler and radiators now circulates through the system for many years usually. The water will not leave. This means that you could leave the house for a week and still leave the heating on.How to identify your system:A quick and easy way is to climb up into the loft and look space and look for the feed and expansion tank. A Woodford Plumber can find the tank and identify the system. The tank will be around 500x300x300mm in size, and will be the smallest if two tanks are fitted. When you look inside the tank you will see that it is less than half full with the water inside looking dirty enough to stop you from drinking it. Try looking for the tank in the airing cupboard if you can’t find the tank up in the loft. The best clue for this system is that the tank really needs to be very high up in the home, being much higher than the radiators it will feed. So if you search and cant find it, then, you probably have a high-pressure central heating system.