INDIRECT MAINSFLOW CONTRACTOR has two coils and is heated indirectly by the boiler. The stored water in the Mainsflow is static and separate from the primary water by virtue of the Superduty Multicoil heat exchanger mounted in the base of the Mainsflow Indirect store.

Compatible with both 'Y' plan and 'S' plan control systems Mainsflow Indirect Contractors may be used with boilers with or without pump over-run in traditional open vented or sealed primary systems. The static store remains open vented. The space heating is powered directly from the boiler.

Indirect Mainsflow thermal store systems may be sited anywhere in the property - it is not necessary to be at the highest point of the system.

Indirect Mainsflow thermal store systems are designated Hot Water Stores.

DIRECT MAINSFLOW CONTRACTOR has one coil and is heated directly by the boiler. The stored water within the Mainsflow is primary water flowing throughout the boiler and radiator circuits.

The store thermostat controls pump one and the boiler to heat the store. The boiler operates on maximum setting (choose a boiler with a flow minimum 80°C) and heats the store to 75°C. In turn the room thermostat will operate pump two and circulate hot water around the radiator circuit providing instant heat - a very useful benefit on cold winter mornings.

Mainsflow Direct units function in open vented primary systems. The feed and vent must be at the highest level in the system. They are not compatible with sealed primary systems.

Direct Mainsflow thermal store systems are designated Integrated Thermal Store.