t.
01923 232335
www.hrshevac.co.uk
39 of 48
HRS Hevac Ltd AquaModule AMB
Installation, Operating & Instruction Manual
13
Trouble shooting
FINDINGS
PROBABLE CAUSES
REMEDIES
Pump not operating
Locked rotor or damaged
Force to rotate. Replace if required
Corresponding led is not lit
Replace Power Board
Pump relay damaged
Replace Power Board
Pump protection fuse blown
Check then replace if necessary
High Alarm condition detected
Clear alarm then reset system
No voltage to control board
terminals
Check power supply cable and fuses
No voltage to pump motor terminals
Check protection fuse on main
board, cable condition and
connections
Controller improperly set
Contact After Sales Service
Low temp alarm condition
Primary pump stopped
See “Pump not operating”
Too low primary temperature
Check for a closed valve in the
primary
Too high tap water flow rate (SI)
Reduce buffer vessel charging flow
rate
Set point too high
3 way valve remains closed
See “Modulating valve does not
operate”
Modulating valve does not
operate
Damaged or broken actuator
Test and replace if necessary
Broken or improperly tightened
coupling
Check and replace if necessary
Valve blocked
Replace
No signal from the controller
Check then replace if necessary
Supply wires improperly tightened
Check wires, re-tighten connections
Actuator stroke restricted
Dismount then clean the valve
High alarm condition detected
Charging pump stopped (SI
versions)
Refer to ‘’Pump not operating’’
above
Low recirculation flow rate (I
versions)
Check and fix problem
Alarm differential too low
Check and set the controller
Modulating valve not closing
Refer to previous box above
Too much differential of pressure
across the modulating valve
Check the way the TWM is piped-
up. Mixing arrangement should be
used
Correct temperatures across
the exchanger not obtained.
Valve and pumps operating
satisfactorily
Excessive exchanger scaling at the
primary or secondary side
Open and clean the exchanger
according to cleaning instructions
Primary pipe work obstructed or
strainer upstream clogged
Inspect primary pipe work.
Clean strainer on the primary side
Isolation valve closed
Open isolation valves
Air presence in the primary
Purge. Check no high parts where
air could be trapped exist
Excessive pressure drops
Check pipe size is suitable for
nominal flow rate
Temperature does not
increase in the buffer vessel
and the tap water value is
correct.
Recirculation flow rate exceeds
charging flow rate.
Check and measure charging and
recirculation flow rates. Adjust when
necessary
Recirculation FR < 0.6 x Charging
FR