Dantherm WA 45, Service Manual

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970006_SM_WA 45-300_4.3_EN-TY-FR_20100922.doc
1. FUNCTION
Dantherm Air Handling warm air heaters are direct-fired units for oil or gas burners. The heat
produced by the burner is transferred to the air, which by means of a fan is passed through the
combustion chamber and the heat exchanger.
The WA 45-300 units take in the cool air at the bottom of the unit and blow out the hot air at the top.
The operation of the unit is controlled as follows:
¾ When the room thermostat has signalled to the unit to start, the burner runs a pre-purge of the
combustion chamber. Shortly after the burner will ignite.
¾ In order not to have cold air blown into the room, the fan will start a couple of minutes later
than the burner. Sensor B2 is set to start the fan at a temperature of 50°C. Timer K2.1 (time
relay for enforced fan start, which is parallelly connected to sensor B2 ensures that the fan will
start after a fixed interval if sensor B2 does not reach a temperature of 50°C – please refer to
section 7 “Wiring diagrams”.
¾ When the room thermostat gives a signal to the heater to stop, the burner will stop, but the fan
will continue to run. After a couple of minutes, when the temperature has dropped to about
30°C, also the fan will stop. The purpose of letting the fan run for a few minutes longer than
the burner is to slowly cool down the combustion chamber and the heat exchanger to avoid
damage by rapid contraction of the metal. After the fan has stopped, it may happen that the
combustion chamber and the heat exchanger are still so hot that the fan will start cooling again
after a few minutes.
¾ If a fault occurs in the unit, the built-in safety thermostats will immediately stop it. The limit-
thermostat will switch off the burner when the air temperature has reached 80°C. When the
temperature has dropped, the burner will automatically start again. The fan is still running.
When the temperature inside the unit exceeds 100°C, the safety temperatur limiter (OT) will be
activated and switch off the unit as well as the fan. It will now only be possible to start the unit
after a manual resetting.
2. POSITIONING AND INSTALLATION
There must be free access to the unit from all sides, so that all components can be inspected.
The room in which the unit is placed must be sufficiently ventilated. Negative pressure caused by for
instance burner operation or exhaust must not occur, as this could result in oxygen deficiency in the
burner and lead to bad combustion or burner faults. In such cases a separate fresh air intake for the
burner will have to be installed.
Make sure that the unit is placed in such a way that it does not blow directly against pillars, shelves,
partition walls etc.
When positioning the unit all legal requirements such as
gas, electricity and building regulations must be observed.