DORCHESTER DR-RS 105, Installation, Commissioning And Servicing Instructions

Page: 45 / 64

Draining the water heater
Instruction manual DR-RS 45
gis
3. Open the nearest hot water draw-off point
m
.
4. Open the supply valve
i
on the cold water side
a
so that cold water flows
into the water heater.
5. Completely fill the water heater (when cold water flows at normal pressure
from the nearest hot water draw-off point, the water heater is full).
6. Vent the entire installation of air, for example by opening all hot water draw-
off points.
7. The water heater is now under water supply pressure. There should be no
water coming out of the expansion valve
o
nor the T&P valve
c
. If this does
happen, the cause might be:
-
The water supply pressure is greater than the specified 3.5bar.
Rectify this by fitting a pressure-reducing valve
a
.
- The expansion valve in the protected cold supply setup is defective or
incorrectly fitted.
4.2.2 Filling vented installations
To fill the water heater, proceed as follows.
1. Open the stop valve
i
in the hot water pipe and, if present, the stop valves
d
for the circulation pump.
2. Shut drain valve
g
.
3. Open the nearest hot water draw-off point
m
.
4. Open the supply valve
i
on the cold water side
a
so that cold water flows
into the water heater.
5. Completely fill the water heater (when cold water flows at normal pressure
from the nearest hot water draw-off point, the water heater is full).
6. Vent the entire installation of air, for example by opening all hot water draw-
off points.
7. The water heater is now under water supply pressure. There should be no
water coming out of the T&P valve
c
. If this does happen, the T&P valve
might be defective or incorrectly fitted.
4.3 Draining the water
heater
4.3.1 Draining unvented installations
Some service activities require the water heater to be drained. The procedure
is as follows:
1. Shut the water heater down by putting the On/Off switch to
position 0 .
2. Disconnect the water heater by putting switching the mains isolator off.
3. Shut off the gas supply
h
.
4. Close the stop valve
i
in the hot water pipe.
5. Close the supply valve in the cold water supply
a
.
6. Open the drain valve
g
.
7. Vent the water heater (or installation) so that it drains completely.
4.3.2 Draining vented installations
Some service activities require the water heater to be drained. The procedure
is as follows:
1. Shut the water heater down by putting the On/Off switch to
position 0 .
2. Switch the mains isolation off.
3. Shut off the gas supply
h
.