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Heat pump portal > Heat pumps in detail > Frequently Asked Questions > How well does my old boiler work?

A number of reference values can tell you how well a heating system transforms the energy stored in the fuel into heat: The first is the so-called exhaust gas loss.

When carrying out the annual emission measurements, this value is measured by your local chimney sweep and recorded in the measurement report. A 12-percent exhaust gas loss indicates that approximately one eighth of the energy consumed disappears through the chimney without being utilised. This value is also significant for the replacement periods (see below).

Especially in the case of very old boilers – change-over boilers modified for gas or oil operation, for example – the so-called surface losses are even greater than the exhaust gas losses. Surface losses indicate the heat which is lost through poor insulation of boilers and hot water cylinders. On average, this amounts to 18 percent of the energy invested. Additionally, 5 percent of the fuel is wasted through unnecessary cooling of the boiler. Thus, together with the exhaust gas losses, thirty-two to thirty-five percent of the valuable and paid-for energy is lost. This means that instead of heating rooms, this energy is responsible for polluting the earth’s atmosphere (e.g. the greenhouse effect).

The simplest way of determining the efficiency of your boiler is to consult the measurement report of your chimney sweep, which can normally be found on a label fixed to the boiler. There you can also find the date indicating when the appliance should be replaced. And it won't be long before this date arrives, since old boilers have to be replaced depending on the output of the system (measured in kilowatt/kW) and their quality (measured by the exhaust gas loss in %).

In any case, every day of procrastination means one more day of burning money up the chimney.

Due to high fuel prices, common sense dictates that operators decide in favour of upgrading older heating systems as soon as possible to considerably reduce operating costs. Heat pump manufacturers like Glen Dimplex now offer systems in which the heat pump, DHW preparation and control are designed as a comprehensive system, right from the start.