Thermal Store Installation

The below is a recommended guide of actions and checks that should be undertaken during the commissioning of an Open Vented Thermal Store :-


  • Fit an Overflow to the thermal store system.
  • Check the incoming mains water pressure, if it exceeds 3.0 bar, fit a Pressure Reducing valve set at a lower pressure where the cold supply enters the property.
  • Ensure that connections are fitted in accordance with the sketch supplied.
  • Fill the Feed & Expansion Tank manually or adjust ball valve so water is at lowest level.
  • Restrict the ball valve fill to allow for the overflow to cope in event of failure.
  • Ensure sufficient clearance above the Feed & Expansion Tank to allow for access.
  • Ensure that 500mm height difference is in place between the highest point of the radiator circuit and the bottom of the Feed & Expansion Tank.
  • Ensure that all exposed pipework is insulated to minimalise any heat losses.
  • Check the boiler pump setting is set as high as possible without emitting excessive noise to prevent a boiler temperature differential of greater than 11°C.
  • Leave on the power after the thermal store has been filled to prevent the central heating and boiler pump from sticking.


  • Use a combined feed and vent.
  • Use tube smaller than 28mm between boiler and THERMflow if the boiler exceeds an output of 60,000 Btu (17kW) output.
  • Place any clothing or other combustible materials against or on the THERMflow.

Click here to find out more about our THERMflow thermal store or contact our technical sales team now on 01592 611123.