Viessmann Vitodens 333 Service Instructions Manual page 84

Troubleshooting
Repairs
(cont.)
3. Replace the sensor in case of
severe deviation.
Checking the plate type heat exchanger
Drain the primary and secondary side
of the boiler.
During removal, small amounts of
water may trickle out and escape from
the removed plate type heat exchan-
ger.
Checking the temperature limiter
Check the temperature limiter, if the burner control unit cannot be reset after a
fault shutdown, although the boiler water temperature is below approx. 75 °C.
84
1. Shut off and drain the boiler on the
primary and the secondary side.
2. Release the side closures and
pivot the control unit forward.
3. Remove the siphon.
4. Release compression fittings A,
screws B and pull out plate type
heat exchanger C.
5. Check the primary and secondary
connections for contamination and
scaling; if required, replace the
plate type heat exchanger.
6. Lubricate the new gaskets/seals.
Install in reverse order with new
gaskets.