Older school boilers can be inefficient with waste heat being emitted into the atmosphere through the boiler flues and into the boiler room. However, replacing a school boiler, unless it is really inefficient, cannot often be justified on the grounds of energy saving alone, but is more likely to be driven by reliability. Instead of replacing your boiler it is often better to improve the heating controls that control the boiler.
Condensing gas boilers are more efficient
If you are replacing the boiler, try to ensure that its replacement is a ‘condensing’ boiler which is 10% more efficient than the non-condensing type. Also, ask to have a ‘cascade’ of smaller boilers installed. Cascades are more efficient in milder weather when one smaller boiler can supply all the heat to the building with the other boilers being automatically turned off. It also provides the school with some leeway if one boiler breaks down.
What to ask when replacing your boiler
If you are purchasing a new boiler ask the installer the following questions:
Is it a condensing boiler?
Will there be a cascade of boilers?
Does the boiler support 'weather compensation'? (less heat is wasted in milder weather)
Does the boiler support ‘optimum start control’ (heating start time varies depending on how cold it is) and will the thermostat be located somewhere representative? (e.g. a classroom as opposed to a corridor or hall)
Can the heating be zoned? This is useful for community/out of hours usage and means that you can avoid heating the whole building.
Is the boiler's frost protection system efficient?
How user friendly are the heating controls? Can they be operated remotely? (e.g. to turn the heating off for a holiday and turn frost protection on)
Gas boilers use fossil fuels
If we are to meet our climate commitments, we will need to replace our gas boilers in the next 15 years. Switching to a heat pump should reduce your carbon emissions by 80%, however adapting them to work in older schools can be problematic because the radiators and piping may not have the capacity to distribute the lower temperature heat output by heat pumps. So if you need to replace your gas boiler, you should consider the alternatives like electrically powered heat pumps. Ask a specialist heat pump company for advice (and not your gas boiler engineer as they have a vested interest in saying they will not work.)