Vaillant 438

[royh]

We've just fitted one of these (conventional not combi) for a customer. Most of the time it fires up OK but once or twice a day it will shut down reading code S53 - "insufficient water flow". It will keep trying to fire up but often takes an hour (15 attempts!) to start working properly.

We've back-filled it and got a lot of air out so any ideas?

Also the hot water tank has a Flamvent fitted. Presumably this is a venting device but undoing the red cap on top doesn't release any air. How does it work?

 

[wnjswozo]

convert it to a sealed system,save a lot heartache

 

[oldplumber]

checkthe pump is running freely any resistance can cause modern boilers to register a poor flow and lockout, took me 2 months to resolve an issue like this as the customer assured me their pump was only 3 months old, (IT HAD BEEN IN 3 MONTHS, BUT IT WASNT NEW WHEN IT WENT IN!!!).