Plate heat exchangers supply hot water ‘on demand’

Stokvis Energy Systems’ plate heat exchangers instantaneously generate hot water at the required temperature, with flow rates measured in hundreds of litres per minute.

In the past few years, modern commercial gas boilers have been transformed in terms of not only efficiency, but in scale, reliability and safety implications.

In addition to mechanical improvements in components such as burners, gas valves, pumps, flues and heat exchangers, technology has evolved in terms of the control systems, sensors and electronics which optimise their performance.

Modern high efficiency boilers are fully-modulating and include an automated premix that matches output with demand. As well as extracting the maximum energy from the gas burnt, it also results in very low NOx and carbon dioxide generation. Newer boilers also feature a much lower water content than conventional boilers, with a far greater heat exchanger surface area.

These contemporary condensing boilers are often installed in a cascade arrangement, where the duty is shared between units to meet demand. When no hot water or heating is required, the boilers will modulate right down and turn off.

A modern day plant room – especially those with custom-built, modularised plant rooms – is a clean compact and contemporary building services solution. However, one of the greatest changes is the size and form in which hot water is delivered.

Econoplate plate heat exchangers

Stokvis Energy Systems specialises in replacing hot water storage vessels with its Econoplate plate heat exchangers. The heat exchangers offer an ‘on demand’ alternative for maintaining the temperature of large volumes of stored water. 

The Econoplate units feature low water content and comprise a series of corrugated, corrosion-resistant stainless steel plates. These are able to optimise the transfer of heat between the boiler’s primary circuit and the domestic hot water feed, or secondary circuit.

Plate heat exchangers therefore instantaneously generate hot water at the required temperature, with flow rates measured in hundreds of litres per minute. This allows for a sufficient supply of hot water in areas of high usage, such as large hotels and conference centres.

Stokvis Econoplate plate heat exchangers feature factory-fitted primary pumps and fast-responding three or four-port valves on the primary circuit. The units include a bespoke PID controller which can be used to monitor the secondary water temperature and regulate the motorised valves. The exchangers can be readily linked into the main Building Management System.

Safe storage

Despite a wealth of knowledge available regarding the Legionella virus in water, there still remains a considerable risk to health when storing hot water.

By generating instantaneous hot water, plate heat exchangers negate the dangers associated with storage vessels that have a temperature gradient from the bottom to the top of the vessel. It is not required to raise the temperature above 60C with a plate heat exchanger as often as it is with storage vessels.

Solar thermal installation

In addition, the focus on alternative energy sources and the Renewable Heat Incentive has seen the popularity of solar thermal installation rise dramatically in recent years.

On a domestic scale, solar gain is usually delivered to a twin coil cylinder. For commercial applications however, Stokvis recommends employing the output from the collectors as a solar pre-heat arrangement, preheating the water in a vessel from where the water is fed through a plate heat exchanger, in order to ‘top up’ the temperature to the required level for delivery.

In essence, modern modulating low water content gas boilers combined with compact modulating low water content plate heat exchangers can meet hot water demand reliably, safely and economically.