Boilers and Plumbing

Competition saves you money.

Try to get three quotes, especially for larger jobs. Corporations give you slick sales material with compelling arguments but be aware that subcontracting is common. I do all the work myself and I get excellent feedback from my customers because I keep them informed. We've all experienced hanging around for a tradesman but with mobile phones it's unacceptable.

Condensing Boilers.

From 2005 all newly installed boilers must be “Condensing”. Condensing boilers have a second heat exchanger which extracts the latent heat released when steam in the exhaust gases condenses. But research suggests that these boilers rarely operate near full efficiency (more on this on Main Page). Spare parts are available for almost all old boilers so think carefully before scrapping yours. You could spend a lot of money only to find that your bills remain almost as high. Best case is 12% but this requires the temperature of the water returning from radiators to be below 55 degrees, which it isn't a lot of the time. 8% improvement is realistic. Having your boiler and central heating system set up correctly will save energy. Don't run the boiler too hot. And if you have a water cylinder make sure it is well insulated. Consider turning down the thermostat on the cylinder too.

Combi or System boiler – what's the difference?

Both boiler types heat water and push it through a central heating system with radiators. System boilers have a hot water cylinder too. Water flows through the boiler main heat exchanger where the gas is burnt and either circulates through the radiators or through a coiled pipe inside the hot water cylinder or both (when heating and hot water are on at the same time). These two circuits are opened and closed by zone valves according to the timer settings on the controller. Zone valves are a bit like a stop cock except they have a powerful servo motor to open and close them. They contain one or more micro switches to gauge whether the valve is open and to fire the boiler. This sophistication makes them prone to failure. Good ones have removable heads (with the motor and all electronics inside) which clip onto the brass valve, making replacement much easier.

Combi boilers do not require hot water storage. When you open a hot water tap, a diverter valve in the boiler senses the pressure change and closes the central heating circuit and opens the hot water heat exchanger. Very hot water comes direct from the burner area and on the other side of this heat exchanger is your mains water flowing to the tap. It rapidly absorbs the heat in real time. This needs a lot of power, typically 24 or 28 kilowatts for a two bedroom home. This is why you cannot have two showers running at the same time. With system boilers you can have several hot taps or showers running because you have a big cylinder of hot water on hand which has been heated up slowly. Heating up radiators is done slowly too, which is why system boilers are smaller for the same size home.

Combis have more parts to go wrong, but diagnosis is generally straightforward and you will save energy because you no longer have to heat a large volume of water in the cylinder every day, only the water you use, when you use it. You get high pressure showers and you are less likely to get rust inside your radiators (more on this on the Plumbing page).