2 port valve and combi

  • Thread starter undertrained
  • Start date



The scenario: Potterton promax HE combi, zoned off up and down.
Issue: heating staying on when stats are off, boiler stat up to about 62 degrees

I think I have diagnosed correctly. So one of the 2 port valves wasn’t spring returning when turned off at room stats. When I pushed the lever to make micro switch contact, the heating led came on. When released it went off. Replaced actuator head. Seems to be working fine.
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If the zone valve didn't return to closed and/or didn't disconnect the switched live to the stat/boiler once the demand is met, then yes the boiler would stay on.

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