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Central Heating Consultants

Gledhill Thermal Stores

Welcome to our page dealing with Gledhill Thermal Stores. A thermal store unit is designed to supply mains pressure hot water on demand without involving pressure relief valves and annual maintenance. They also have the added advantage of requiring a smaller boiler than a conventional system.

Systemate Flow Pattern Gledhill Thermal Stores in Basingstoke.
As many owners of these units have found out, Gledhill Thermal Stores do not like hard water, neither do their manufacturers. As Basingstoke is a very hard water area, these units are very susceptible to lime scale unless an adequate scale prevention device is fitted.

Manufacturers Recommendations:
Gledhill recommend that if their Thermal Store units are installed in an area that has more than 280 ppm hardness, that as a minimum, some form of phosphate feed be fitted. As we have recorded water hardness levels approaching 400 ppm in Basingstoke and have only ever seen small electronic scale inhibitors fitted, it is hardly supprising that owners of these units suffer problems caused by excessive lime scale build up.

Common Problems:
As these Thermal Store Units deliver mains pressure hot water that is heated either through an internal coil within the unit, or on later models, via a plate heat exchanger, both of which are receiving either untreated or inadequately treated cold water, the main problem we have encountered to date is poor hot water delivery. This is normally wholly attributable to a lime scale build up within the internal coil or plate heat exchanger, but occasionally may be caused by a sensor error.

Whilst models with an internal coil can be flushed with an acid solution to remove the lime scale, models with a plate heat exchanger will need a replacement heat exchanger. The frequency that this remedial work would be required is totally dependant upon the hardness of the supply water and the amount of hot water used.

Further problems we have encountered on these units include heavily fouled feed & expansion tanks and heating circuits that are starting to show signs of excessive corrosion. These conditions are normally due to the system having not been cleaned properly after installation, inadequate or no corrosion inhibitor added, or, the inhibitor has been weakened either through draining down or age and requires replacing. As it is rather time consuming to Powerflush these units, we recommend that if your system is showing any of these symptoms, remedial action is taken before corrosion levels start causing component failure.

What we can do to help:
If you are having problems with your thermal store unit, wish to tackle your water hardness before you encounter problems or want to check that your system has sufficient corrosion inhibitor installed, contact us on 01256 844344.

01256 844344
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