Watts FRG3020-W Manuel De Montage Et D'utilisation page 12

9. TROUBLESHOOTING
X. FAULT
X.X
Possible cause
1. FBH heating circuits do not get warm; pump not running
1.1
Temperature limiter (TB) switches the control unit pump off.
Reason: TB set too low.
1.2 TB switches the control unit pump off.
Reason: The pump remains switched on despite closed FBH heating
circuit. The water inside the control unit can be warmed by waste
heat from the pump. The TB switches off when the maximum pump
temperature is reached.
1.3
The pump is connected to a room thermostat or electric control
manifold.
The pump switches off when all actuators are being shut. When it
has been standing for some time the FBH supply cools down. The
controller therefore causes the 3-way mixing valve to open. Hot
water is injected from the primary circuit. This causes the control unit
to heat up. When the maximum temperature of the TB is reached,
the contact opens. The pump does not switch on again.
2. FBH supply temperature will not set to the required value
or the supply temperature fluctuates heavily
2.1 Supply and return have been crossed, i.e. incorrectly connected.
2.2 The lift/pump level has been set too low.
2.3 The heat load is too great for the control unit i.e. the heat consump-
tion exceeds the nominal capacity of the control unit. This situation
may occur temporarily, for example, when heating up a "cold" floor.
MuB_10026618_FRG3020-W_(EN)_2010-08-16.docx
Remedy
Set TB about 10 K higher than the FBH supply temperature.
Pay attention to the permissible FBH maximum temperature!
The switch difference of the TB is about 5 K.
The control unit is ready for operation again more quickly if the
TB is set at the switch on temperature for a short while to cool down.
Take the TB off the control unit and install it on the heating circuit
manifold supply or on the return if necessary.
Use the electric control manifold with pump logic (relay). The pump
logic ensures that the pump only runs if at least one FBH heating
circuit is open.
Take the TB off the compact control unit and install on the heating
circuit manifold or on the return if necessary.
 1.1
Check all connections on the control unit to ensure they are correctly
connected.  Fig. 2 and 3
Increase speed or lift/pump stage of the pump.
Determine the maximum heat requirement and compare with the
nominal capacity. Possibly the heating circuits will have to be split with
a second control unit with an appropriate heating circuit manifold.
If the cause is the initial heating up of a floor, then after an initial
heating up period (2 to 3 days) operation may revert to normal. This
is particularly the case when operating at the upper end of the nomi-
nal capacity.
Subject to technical change without notice
EN
Page6