The area footprint of this building is small, comprising of predominantly car parks in an underground level. This posed a problem for the location of services, especially domestic hot water as no room was available for metered central storage, nor was space allocated in the apartments for individual storage cylinders.
Electrical Consulting Services specified 27kW Stiebel Eltron DHB-E27 instantaneous water heaters, known for their German design and manufacture, and reliability.
Each apartment is ﬁtted with one “little white box” which supplies continuous hot water for the shower, hand basin, and kitchen sink. Russ Kern from ECS designed the electrical loading by allowing for the laws of diversification for each apartment to have a draw of 1.5kW.
After monitoring the electrical draw since residents have moved in, results show that the loading has averaged only 1.25kW per apartment. The difference of 0.25kW can easily be attributed to not having stored water and therefore costing valuable energy from heat loss which is ubiquitous with all hot water storage systems including solar. In comparison, a similar sized apartment block of 150 apartments resulted in a maximum demand of 1.64kW per dwelling. The only difference being this building has a3kW electric hot water cylinder in each apartment.
There are other benefits to instantaneous heaters too. Residents will never run out of hot water. Instantaneous hot water heaters heat the water as it ﬂows through the unit, providing the user with continuous hot water for as long as required.
The consumer is charged for exactly what they use, and once the tap is turned off the ﬂow of electricity stops, unlike
storage cylinders that require continuous electricity to keep the water up to temperature.
From a plumbing perspective, savings can be utilised as only a single cold water feed is required to the unit instead of hot and cold. This saves on both materials and labour.
In small apartments, storage space is often sacrificed for traditional electric hot water cylinders. The “little white box” simply attaches to a wall adjacent to the bathroom and leaves cupboard space for storage – a valuable commodity in smaller spaces.
Developer: Conrad Properties Ltd.
Electrical Engineers: Electrical Consulting Services Ltd. (ECS)
Builder: Hawkins Construction Ltd.
Plumber: DL Good Plumbers Ltd.
Product: Stiebel Eltron Instantaneous Hot Water Heaters
Apartment specification: 174 x 2 bedroom with electric cooker, heating, washer and dryer in each apartment
Water heater specification: 1 x DHB-E27 per apartment (3 phase, 27 kW, 40A per phase) Located in storage cupboard adjacent to bathroom
Maximum logged demand @ 55% occupancy: 1.25 kW per apartment (as per load diversity)