Stokvis Energy Systems has responded to the increasing popularity of communal and district heating systems by launching its new H-Series Econoplate interface units.

There is a choice of single and twin plate units to provide heating and hot water services within dwellings such as apartments, student flats or around sheltered housing schemes. These in turn might be fed from a central plantroom – incorporating perhaps Stokvis Econoflame Boilers, a Stokvis Solar Thermal System, combined heat and power (CHP) unit, biomass boilers, heat pumps or some wider district heating source such as the waste heat from a power station/incinerator.
From the point of view of safety and simplicity, the concept of district heating does away with individual flues as well as gas supplies, and therefore also annual gas inspections. The Stokvis H Series units are compact enough to fit within a kitchen or utility cupboard and incorporate all necessary valves, controllers and energy metering.
Econoplate H2 (Twin Plate) units separate the district or communal heating system from the dwelling and provide heating and hot water separation via two plate heat exchangers.

Econoplate H1(Single Plate) units have direct heating where the district water circulates around the dwelling and hot water is via a plate heat exchanger

H1 (Single Plate) units can also be provided for heating only with separation of district mains from the dwelling, again with a single plate heat exchanger. This option would be used when either there is no hot water or hot water is to be provided by an indirect cylinder or other means.

The range extends to cover underfloor heating applications through the Teleheat models which operate down to temperatures below 450 C, as is characteristic of many heat pumps; whilst also providing for a separate hot water supply via a separate plate heat exchanger.
Addressing maintenance issues there is an anti-lock feature which runs the pump for five seconds once a day during periods of non-use, and also pump run on after hot water provision to prevent calcification.
Operational description
Heating mode
When there is a heating demand, the solenoid valve opens and allows full flow of the district supply which then goes through a modulating control valve. The diverter valve will send the district supply to the heating plate heat exchanger on H2 units or direct to the heating circuit on H1 units.

A temperature sensor is fitted at the outlet to the dwelling, which measures the heating flow temperature. The electronics will ramp up the flow temperature over a period of 3 minutes and will then aim to keep the flow temperature at the desired setting whilst there is a heating demand. When the heating cycle finishes, the solenoid valve will close, and the pump will stop.

Hot water mode
Hot water has priority and when the DHWS sensor detects water flow above 2.6l/m, the unit switches into hot water mode. The solenoid valve opens and allows full flow of the district supply which then goes through the modulating control valve. The diverter valve will send the district supply to the hot water heat exchanger.

On the secondary side of the heat exchanger a temperature sensor is fillted to measure the hot water flow temperature. The electronics will control the flow of district supply in order to provide hot water at the set temperature. There is an addition preheat function available to speed up hot water production.

When the hot water flow falls below 2.4l/m, the unit will switch out of hot water mode. The solenoid valve will close and the unit will then return to heating mode if required.

Stokvis Energy Systems has produced detailed technical literature on the H-Series to accompany the launch, while the company also offers comprehensive technical support to specifiers and installers.