Servicing Mixergy Cylinders

A Mixergy service and maintenance guideline for installers.

Performing visual checks 

• Look for any obvious defects or damage in the cylinder shape, connections, pipework, Mixergy controller box, and any Mixergy additional components (for example, the PV Switch, Solar Diverter or Heat Pump Kit).
• Check all of the wiring on the cylinder, including the Mixergy controller. Ensure any loosely hanging cables are tidied with suitable clips and not left hanging against anything warm or hot.

Safety valve operation

• Manually operate the temperature/pressure relief valve for a few seconds.
• Check that water is discharged and that it flows freely through the tundish and discharge pipework.
• Check that the valve reseats correctly when released.
• Repeat the above procedure for the expansion relief valve.

Expansion vessel charge pressure

• Turn off the isolating valve before the Pressure Reducing Valve or the mains stop cock to the system.
• Open the lowest hot tap in the system to relieve the system pressure.
• Unscrew the black plastic cap on the expansion vessel to reveal the Schrader valve; with the aid of a pressure gauge, ensure the pressure reads 3.0 bar.
• If there is insufficient pressure within the vessel, top up the vessel using an appropriate pump and recharge to 3.0 bar.

Strainer

With the mains supply turned off and the lowest hot tap open:

• Using a spanner, unscrew the pressure-reducing cartridge and remove the moulded housing. The strainer will be removed with the cartridge.
• Wash any particulate matter from the strainer under clean running water.
• Replace the strainer and screw the pressure-reducing valve cartridge into the moulded housing.
• Close the hot tap, turn on isolating valve or main stop cock to the system. Check for leaks.

Descaling immersion heater (if necessary)

With the mains supply turned off and the lowest hot tap open:

• Isolate the electrical supply and turn off the boiler or heat pump.
• Attach a hosepipe to the drain cock having sufficient length to take water to a suitable discharge point below the level of the unit.
• Open the cover(s) to the immersion heater housing(s) and disconnect the wiring from the immersion heater(s).
• Unscrew the immersion heater and withdraw it from the cylinder.

• Carefully remove any scale from the surface of the element(s).
• Ensure sealing surfaces are clean and the gasket is undamaged; if in doubt, fit a new gasket.
• Refit the immersion heater(s), ensuring not to trap the gasket.
• Rewire, check, close, and secure immersion heater housing cover(s).

Re-commissioning

• Check that all electrical and plumbing connections are secure. Close the drain cock.
• With a hot tap open, turn on the cold water supply and allow the unit to refill.

• When water flows from the hot tap, allow it to flow for a short while to purge air and flush through any disturbed particles.
• Close the hot tap and then open successive hot taps to purge any air.
• When completely full and purged, check the system for leaks.
• The heating source (immersion heater, boiler or heat pump) can then be switched on.
• Check the outlet temperature at the outlet closest to the cylinder to determine whether the immersion thermostat is operating correctly.