Boiler Replacement

Boiler Replacement


Incentive Carbon Management were commissioned by Renaissance Care to undertake ESOS assessments and submission for several residential care homes in Scotland and identify areas for efficiency improvements.

One of the properties, Persley Castle in Aberdeen, had an ageing boiler and water heater which were of advanced age, inefficient and single points of failure which would have severe impact on service delivery should they fail.

The ESOS report identified this as an area of efficiency improvements and this was developed into a scheme to deliver replacement with minimal disruption to operations – as a residential care home, turning off the heating for a prolonged period was not an option.

The Identified Condition

Heating was provided to the whole building via radiators fed from a floor standing gas fired boiler rated at 120kW output / 150kw input.  (80% burner efficiency).  There are four heating circuits each with its own pump set but no control valves for either compensating or zone control.  The heating is required to operate for significant periods of the year.  Hot water was via a single direct fired water heater.

The Proposal


The specified boilers (Ideal Evomax 60P) were wall mounted with a total output rating selected to at least match the existing output and due to their compact size it was possible to install and set operating one of the boilers prior to removal of the existing boiler.  This required re-routing of one heating circuit in the boiler room so rooms fed from this were temporarily provided with electric heaters.  After removal of the existing boiler, the second boiler could be installed and commissioned.

The additional free floor space then made it easier to install the two new water heaters in lieu of the existing single heater, again with minimal disruption.

The Performance

The above graph indicates the relationship between gas consumption (kWh – blue line) and degree days (to a base temperature of 15.5°C – red line – this is basically a record of cold weather for heating).  The green vertical line indicates when the boilers and hot water heaters were changed.  Clearly shows the peaks in gas consumption after renewal is considerable lower than before.

The peaks in winter are associated with the heating operation whereas the baseline gas consumption throughout the year is associated with hot water, cooking and laundry appliances.

Our estimate of gas reductions associated with changing the boilers and water heaters was for a reduction of 84,750kWh, reducing expenditure by £2.5k (plus further reductions associated with maintenance call outs).  The achieved reductions in the first two years has averaged at 93,600 kWh equating to a reduction of £2.7k.


Successful replacement of heating and hot water plant with minimal disruption, within agreed budget and exceeding identified reduction targets.  Providing improved performance, reliability, resilience and reduced operating costs.

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