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Guildford Spectrum changes chiller plant for ice rink

06 February 2015

Replacing a chilling plant at an ice rink isn't as straightforward as you’d imagine. Here’s how Guildford Spectrum did it.

Of the many gravity-defying techniques you could witness at the Guildford Spectrum’s Olympic-sized ice rink, perhaps none is as dazzling as the one performed by Alan Hankin, the centre’s ice and bowl manager. One of Hankin’s jobs is ensuring the rink is operating efficiently and safely at all times. It’s open all year round, hosts ice hockey matches, figure and leisure skaters and junior ice hockey players and a Christmas Pantomime on ice

The rink – which hosts the Guildford Flames Ice Hockey team, and which brings in annual revenue of £2m – is only one part of the leisure centre, which includes a 10-pin bowling, swimming pools with wave machines, slides, diving facilities, running track and several squash courts. In fact, the Guildford Spectrum is the largest leisure complex of its type in the UK.

When Freedom Leisure, which manages the facility on behalf of Guildford Borough Council, started planning a replacement for an aged chilling plant that was incurring substantial maintenance bills, legislative compliance, sustainability, energy efficiency and longevity were key drivers. Indeed, UK councils were in a race against time at the end of last year to ensure their rinks were refrigerant compliant when the ban on recycled and virgin HCFC came into force.

But Hankin was one step ahead: he’d begun his own migration away from R22 plant by replacing the rink’s aged refrigeration plant with an ammonia chiller from J&E Hall.

“We were well aware of the R22 ban and had been devising a strategy for quite some time in preparation for the refrigerant ban,” says Hankin. “Freedom Leisure was keen to address its own as well as the council’s environmental objectives while taking advantage of the energy saving and environmental properties a modern refrigerant system could offer.”

Replacing a chilling plant may sound fairly straightforward, but it’s not: as Hankin points out, the rink is extraordinarily busy. It sees 400,000 people annually, while the centre has just under 1,8m visitors, Hankin says. “We’re open from 5am to 1am, so it’s a 21-hour a day operation.”

During this time, the rink is put through its paces. “It really gets hammered between December and March. There are times when we have up to 800 people on the ice. After an hour turnover time, we’ll put another 700 or 800 back on, followed by another hour turnover before a further 700 or so are allowed back on. It’s very demanding, so my pulse starts racing if the plant starts to wobble or we get any indication of a breakdown.”

J&E Hall entered the equation when Martin Storey, south-east area manager, received a call from Mike Davey, a consultant with Clarkson Alliance, in spring 2013. Storey had previously worked with Davey on helping Oxford Ice Rink with its compliance issues. “Mike said ‘There's an opportunity at Guildford. It’s a bit 11th hour, but are you interested?’”

Storey was interested. He discovered another solution provider was quoting Guildford for standard HFC refrigerant chillers. “Mike asked if we wanted to quote like-for-like, but once we’d investigated, we discovered ammonia would be better for Guildford, just as it was in Oxford. We just needed to persuade Freedom Leisure.”

J&E Hall delivered a presentation expounding on the benefits of ammonia and the glycol chiller as opposed to the HFC option. “Mike got back to us about a week later saying the centre wanted to go ahead with ammonia,” Storey recalls. “It was to our benefit that the council saw the environmental and cost-effective energy advantages of our solution and decided to go down that route.”

A dual circuit 350kW Ethylene glycol/ammonia chiller designed and manufactured by J&E Hall was specified and fitted with permanent magnet variable frequency drive motors (VFD) for capacity control to enhance the performance of the chiller at part load. The VFD option can help reduce running costs by as much as 25% with an 18-month payback.

“Ammonia is one of the most efficient refrigerants,” says Hankin. “We’ve seen other rinks benefiting from the energy savings and the zero GWP (global warming potential) and ODP (ozone depletion potential) satisfies any environmental concerns.”

The first phase took place over a two-week period in June 2013 when J&E Hall’s team of engineers carried out the pipework including glycol pipes, heat recovery and heater mat pipework. Additional connections were also provided to enable the use of temporary chillers which also serve to ensure that in the event of breakdown, hire chillers can easily be used on site if necessary. As the ammonia chiller was being sited external in a purpose-built compound, pipework had to be run from underneath the rink through a tunnel under the road to the compound.

Once the process to replace the plant began, Hankin had to ensure the rink stayed open with minimum fuss. “We had a two-week window to do a lot of pre-work and pipework. The challenge was staying open, particularly as our existing plant failed when we went to restart so we had to delay the reopening of the rink. Then we had to bring in a temporary chiller in September - a lot sooner than we’d planned.”

A temporary chiller ensured the quality of ice remained in peak condition so the rink could remain open, while installation of the new refrigeration plant took place. The main refrigeration equipment was supplied on a skid which was sited outside by the existing air cooled condensers. Electrical panels were fitted in an existing plant room and the new condenser was sited externally on steel supports above the two compressor packs and flooded evaporator which were manufactured and supplied as a stand-alone package.

“Even on the day of the delivery of the plant we had cranes and lorries coming in. There were complications you wouldn’t usually imagine such as trying to get the 40-foot lorry to turn round at the far end of the leisure centre car park, while trying to maintain an access route for deliveries.”

In order to ensure matters went smoothly, Mark Prince, south east area project manager for J&E Hall had to indulge in some intricate industrial jiggery-pokery. “While we had the hire chiller outside and running, we had to isolate the existing chiller, and remove it out the plant-room. When the new ammonia chiller arrived, it was connected to the rest of the chiller and the hire chiller was decommissioned.”

The objectives included not losing ice, keeping the ammonia charge light (it worked out to about 45kg per system), and ensuring ammonia was expelled outside the building, which was made possible by its conversion to glycol. Glycol is preferred over ammonia as a secondary refrigerant. “You don’t want ammonia running through a building – if you’ve got a leak, it’s dangerous. We keep ammonia outside and run glycol through the system. By using glycol percentage charts, we can apply the appropriate percentage of glycol to the system to provide the chilled glycol as low as -12 degrees C.”

The interplay between hot and cold is particularly interesting at an ice rink. In the case of Hankin’s facility, the heat from the chiller is used to heat the ice pit, where the excess ice is placed after the rink is skimmed to maintain its quality after each skating session. The ice melts in the pit, then just runs as clean water to drain. A heating mat under the ice ensures the concrete doesn't freeze.

Prince also had to oversee different set points for the ice, which allows the centre the option of running normal skate sessions, ice dancing, figure skating and ice hockey. “The hockey players like the ice colder so they can cut it and change direction quickly,” says Prince. “Dancers like it softer so when they land it’s not so brittle and doesn't easily break.

“There were a few strategic issues as we went along but the relationship we had with Mark and his team was the key to the success of the whole project. If I needed anything, Mark would stop everything, and sort it out.”

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