Viessmann Vitodens 333-F Service Instructions Manual page 93

Repairs
(cont.)
Checking the plate-type heat exchanger
Drain the boiler on its heating water
and DHW side.
During removal, small amounts of
water may trickle out and escape from
the removed plate-type heat exchan-
ger.
Checking 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, check the following:
1. Shut off and drain the boiler on its
heating water and DHW side.
2. Release side closures and pivot
control unit forward (see page 11).
3. Remove the siphon (see page 12).
4. Release compression fittings A,
screws B and pull out plate-type
heat exchanger C.
5. Check the connections on the heat-
ing water and DHW side for con-
tamination and scaling; if required,
replace the plate-type heat exchan-
ger.
6. Lubricate the new gaskets/seals.
Install in reverse order with new
gaskets.
Troubleshooting
93