Thermal stores for buildings and small plants
Store heat.
Shift the peak.
Ostra Keel is a 40 kWh phase-change heat store for offices, schools and small plants. It charges when power is cheap or clean, then delivers hot water when the building needs it.
Where it fits
Three kinds of site we have sized so far. Each has a heat load that lines up with cheap or surplus power.
Offices
Charged overnight, the Keel covers morning hot water and the winter radiator run that normally drives the gas boiler at peak hour.
Schools
Sized for a kitchen and a sports hall. Most of the charge happens in the holidays, when nobody needs heat and the grid is quiet.
Small plants
Process hot water at 60 to 90 °C from surplus power, with Modbus or BACnet controls that talk to the building system you already run.
How it works
Charge
The Keel draws up to 22 kW from the grid or an on-site array when power is cheap or in surplus. The control board sets the timing, not a fixed tariff clock.
Hold
The salt hydrate medium melts and keeps the heat for up to 48 hours. Loss is under 3% a day, measured on our test rig.
Deliver
Hot water leaves the unit at up to 90 °C on demand through a plate exchanger, so building water never enters the store.
Running in real buildings
Three pilots are live. Each runs for six to nine months, and we publish the monitoring data alongside the site name.
Peak-hour gas use dropped by about a fifth through the winter.
Hot water arrives when the kitchen asks for it, not when the tariff says.
Book a site survey
A surveyor visits, measures the plant room and returns a sizing note within ten working days. The survey is free. Installation is quoted only once you decide to go ahead.
Call 01632 960 802 to book a survey, or email us.