David Lloyd Leisure Centre

The David Lloyd leisure estate comprises of over 70 large complexes across the UK that in addition to the normally available leisure facilities offer indoor tennis, indoor and outdoor swimming pools. The majority of the sites are very similar in lay-out and in the appliances installed.

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Heating and hot water is generally supplied from an Ener-g CHP which produces a steady 200kW of hot water running for 17 hours/day and 2, Hoval Euro SR 900kW boilers providing peak hot water requirements and pool make up during the night.

We were asked to install Dynamic Burner Management Units to the site in Gidea Park and to identify potential savings from upgrading the insulation using ValveWrap flexible insulation on the un-lagged valves and fittings.

Following a successful pilot at Gidea Park, the approach, given that the properties were very similar, was to survey a further 6 premises and use these results to determine a budget for the whole estate. A programme was then agreed and implemented during the following 4 months.

Savings Report

The Burner Management Unit has the facility to automatically take itself in and out of circuit on a continuous basis every 50 boiler cycles. During the Savings Test the DBMU measures the time that the gas burner is cooling and firing. It then compares the results and calculates the savings made.

As the test is short-term, no adjustments are made to the figures and the Savings Report holds three tests at any time which are constantly revised every 50 boiler cycles.

The Savings Report not only calculates the savings it also demonstrates the way the savings are achieved. This can be seen in the following download taken from one of the boilers.

The cooling phase of the boiler has been increased (shown in yellow) from 504 to 996 seconds, whereas the recovery of that heat loss in the burning phase has only taken an increase of 486 to 503 seconds (shown in red). Hence the additional 492s of additional cooling has only cost 17s of additional burn to recover the temperature lost. This delivers a 31% saving and 30 fewer firings of the boiler in a 24 hour period.

It must be emphasised that the Savings Report is a means of indicating savings over a short duration, hence there is no need for any adjustments, however, it will reflect the load on the boiler at that time and hence savings shown will be variable.

The Saving Report is designed to demonstrate that the DBMU is working in accordance with its independent certification (CFP 348) from the Building Research Establishment.

Payback and Integration

David Lloyd sites were not in general suitable for simple through the meter tests because of the complexity of the use of gas particularly with the CHPs. Tests were however carried out on several sites where there was no CHP and the results showed a 17% saving.

A further 2-3% saving was made through the ValveWrap insulation and the lagging of 50-60 large fittings on each site. Paybacks and CO2 savings were calculated for this work.

Payback and CO2 Savings

  • Project payback in under 12 months
  • £305,000 saved off utility bills
  • CO2 savings of over 537 tonnes

Integration with the BMS and existing controls

The existing BMS supplied the enabling signal to the Burner Management Unit which then interpreted the signal in accordance with its programme.