What Is A Fill And Spill System?
Posted on 22nd March, 2023 by Dura Pump 
A fill and spill system does the same job as a pressurisation unit but is typically found on larger systems or in older buildings.
It is designed to maintain pressure within a heating system and usually consists of a large tank or vessel, pumps, spill valve and a control system.
How Does It Work?
The fill and spill system works by monitoring the pressure in the system, using a pressure switch or a pressure transducer.
If the pressure in the system is too low the pumps are automatically turned on to draw water from the tanks and add it to the system, thereby increasing the pressure. The pumps are turned off automatically when the desired pressure is reached.
If the pressure is too high, the spill valve – which can either be a mechanically operated valve or an electric solenoid valve – opens, allowing water to pass into the tank, thereby reducing pressure within the system.
The expansion happens when the system is heating up which causes the water to expand. Then as the system cools down, the water condenses, dropping the system pressure.
Other Features Of A Fill and Spill System
A fill and spill system also has safety interlocks with the boiler so if the system’s pressure is too high or too low it will send a signal to the boiler, cutting it off.
However, while this is a good safety feature, if the boiler is cut off, it will cause loss of heating and hot water to your building.
The risk of losing heating and hot water to a premises means that maintaining a fill and spill system correctly is critical. Fill and spill systems should be serviced regularly, typically every 6-12 months.
These days, fill and spill systems are less widely used and many of them are now becoming obsolete because standard pressurisation sets and large pressure vessels can be used in their place.
More widespread use of standard pressurisation sets also means standard components can be used, so a pressurisation set is often a more cost effective solution than a fill and spill system for many people. However, some fill and spill systems are manufactured by companies such as Flamco, and available through Dura Pump.
Dura Pump can also create custom built fill and spill systems. Please contact us for further information.
