I have 2 wh90 boilers connected onto a system, one of them is showing the code E164 low water pressure the pressure gauge is exactly the same on both 1.5, the other one is working perfect
its either a faulty hydraulic sensor or the gauge is blocked showing false pressure. try increasing the pressure if its sealed system and see if it rises. then u know the gauge is ok. if thats the case then its the hydraulic sensor
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