Piping hot scheme for hospital hot water

Spirax Sarco has helped Morriston Hospital save thousands of pounds a year in maintenance costs by replacing the old calorifiers that were providing domestic hot water.

Spirax Sarco has helped Morriston Hospital, Swansea, save thousands of pounds a year in maintenance costs by replacing the old calorifiers that were providing domestic hot water with a Spirax Sarco plate heat exchange engineered system.

"The calorifiers were massively oversized and were a real maintenance liability", says Hardy Rodde the hospital's estates energy manager.

Rodde estimates that it would have cost several thousand pounds just to get the calorifiers through their next annual insurance inspection.

They originally provided hot water to over 15 Nightingale-type wards and surrounding buildings in an old part of the hospital.

Only two of the original wards and an outpatients department are still in use, so the calorifiers' capacity far exceeded current demands.

Hot water is circulated around the remaining wards and several surrounding buildings by a 200m long 150mm diameter pipe.

Rather than heating the water and storing it in a separate vessel, Spirax Sarco in conjunction with the hospital engineers came up with the innovative solution of using the pipe circuit itself to store the water.

Steam from the boiler feeds a Spirax Sarco plate heat exchange engineered system that in turn supplies hot water to the pipe as required.

The water enters the pipe from the heat exchanger at 60C and returns at well over 50C.

The demand for domestic hot water required fluctuates dramatically.

For example, one of the buildings still served by the system is a nurses' home, which has a large surge in demand after each shift as staff return from work and bathe.

The water temperature must be maintained at all times and, in the absence of a separate hot water storage 'buffer', rapid response from the heat exchanger is critical.

Electrically actuated valves can take up to a minute to change from fully open to fully closed, which would have provided to slow a response rate.

Instead, Spirax Sarco opted for pneumatically controlled valves, which take just one second to respond.

"It's an elegant solution to the problem", says Rodde.

"Only the pneumatic controls can act fast enough to maintain the required water temperature".

Rodde adds that the domestic hot water temperature control is excellent and whilst the new system will also save energy, the expected long-term savings in maintenance will be much greater.

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