Commercial 30 October 2020

Rinnai’s custom solution for commercial water heating

Almost 75% of the commercial systems supplied by Rinnai incorporate some customising, to a greater or lesser degree. But with manufacture occurring in New Zealand, this can be readily achieved with short lead times as was demonstrated by this recent project.

Rinnai provided a customised commercial water heater for an existing hotel/apartment complex in the Auckland CBD. The existing water heating solution was at the end of its economic life and there were questions as to whether it was fully compliant with current standards.

The plant room was in the basement below street level so finding a route for a flue was challenging. The solution was to incorporate 5 high efficiency condensing water heaters with a 280kW total output connected to a common polypropylene flue.

A number of options were considered for the flue route. In the final solution, the flue runs around two corners, turns vertically upwards to pass through the ground floor slab inside a decorative plant garden before exiting horizontally at street level.

The garden was boxed out inside to allow the flue to pass through. As this is adjacent to a public footpath, it was important to have the flue at a height where it would not cause an inconvenience. The flue gas exit temperature with the high efficiency condensing water heater is so low it wouldn’t even present a burn hazard to a small child riding on a parents shoulders.

Access to the installation location was poor and a truck couldn’t get within 200m of the site. So the system was supplied as a kitset and re-assembled in the plant room. This only took only two hours.

Custom aspects on this system included the common flue mounting and supporting brackets to accommodate the structural column midway down the back of the water heater.

The flue also needed to have a constant fall back to the water heaters to allow for the considerable volume of condensate to drain. To achieve this the system was made shorter than standard so the required fall could be achieved. The custom frame included water heater spacing and vertical support to span existing pipes in the plant room.

The compact installation location was also chosen so that the Rinnai system could be installed before decommissioning the old system. A new Rinnai dual active/primary pump set was also installed and piped in preparation for switching over to the new system.

As the existing system incorporated three thousand litres of storage, the old system was disconnected and the new system commissioned with an absolute minimum of disruption to the building hot water supply.

An added bonus was the re-purposing of the old boiler location into two new carparks in downtown Auckland.