54
No.
Fault symptom
Possible cause
Explanation - Solution
14
In 2-zone tempera-
ture control, only
Zone2 does not
reach the set tem-
perature.
1.
When Zone1 and Zone2 are both in heating
mode, the hot water temperature in Zone2
does not exceed that in Zone1.
1.
Normal action no action necessary.
2.
Faulty wiring of motorized mixing valve
2.
Refer to "5.3 Wiring for 2-zone temperature control".
3.
Faulty installation of motorized mixing valve
3.
Check for correct installation. (Refer to the manual included with each motorized
mixing valve.)
4.
Incorrect setting of Running time
4.
Check for correct setting of Running time.
5.
Motorized mixing valve failure
5.
Inspect the mixing valve. (Refer to the manual included with each motorized mix-
ing valve.)
15
When a PUHZ-
FRP outdoor unit is
connected, DHW or
Heating operation
cannot run.
The outdoor unit is set to have operation of the
indoor unit of air conditioner take precedence
over that of the hydrobox, and in the main control-
ler settings "Electric heater (Heating)" or "Electric
heater (DHW)" is turned off.
Turn ON Electric heater (Heating) or Electric heater (DHW) using the main controller.
16
When a PUHZ-FRP
outdoor unit is con-
nected and is in heat
recovery operation,
the set temperature
is not reached.
When the outdoor unit is set to have cooling
operation of the indoor unit of air conditioner take
precedence over that of the hydrobox, the outdoor
unit controls the frequency of the compressor
according to the load of air conditioner. The DHW
and heating run according to that frequency.
Normal operation no action necessary.
If Air-to-Water system is given priority in operation, comp Hz can be regulated de-
pending on the load of DHW or Heating. For more details, refer to the PUHZ-FRP
installation manual.
17
After DHW operation
room temperature
rises slightly.
At the end of the DHW mode operation the 3-way
valve diverts hot water away from the DHW circuit
into space heating circuit.
This is done to prevent the hydrobox components
from overheating.
The amount of hot water directed into the space
heating circuit varies according to the type of the
system and of the pipe run between the plate heat
exchanger and the hydrobox.
Normal operation no action necessary.
18
The room tempera-
ture rises during DHW
operation.
3-way valve failure
Check the 3-way valve.
19
Water discharges
from pressure relief
valve.
(Primary circuit)
1.
If continual – pressure relief valve may be
damaged.
1. Turn the handle on the pressure relief valve to check for foreign objects in it. If the
problem is not still solved, replace the pressure relief valve with a new one.
2.
If intermittent – expansion vessel charge may
have reduced/bladder perished.
2. Check pressure in expansion vessel.
Recharge to 1 bar if necessary.
If bladder perished replace expansion vessel with a new one.
20
Water discharges
from pressure relief
valve (field supplied
item).
(Sanitary circuit)
1.
If continual – field supplied pressure reducing
valve not working.
1. Check function of pressure reducing valve and replace if necessary.
2.
If continual – pressure relief valve seat may
be damaged.
2. Turn the handle on the pressure relief valve to check for foreign objects inside. If
the problem is not still solved, replace the pressure relief valve.
3.
If intermittent – expansion vessel charge may
have reduced/bladder perished.
3. Check gas-side pressure in expansion vessel.
Recharge to correct precharge pressure if necessary.
If bladder perished replace expansion vessel with a new one with appropriate pre-
charge.
4.
DHW tank may have subjected to backflow.
4. Check gas-side pressure in DHW tank. If pressure in DHW tank is similar to that in
incoming mains, cold water supply that merges with incoming mains water supply
could flow back to DHW tank. Investigate source of back-feed and rectify error in
pipework/fitting configuration. Adjust pressure in cold supply.
21
Noisy water circula-
tion pump
Air in water circulation pump .
Use manual and automatic air vents to remove air from system.
Top up water if necessary to achieve 1 bar on primary circuit.
22
Noise during hot
water draw off
typically worse in the
morning.
1.
Loose airing cupboard pipework.
1. Install extra pipe fastening clips.
2.
Heaters switching on/off.
2. Normal operation no action necessary.
23
Mechanical noise
heard coming from
the hydrobox.
1.
Heaters switching on/off.
Normal operation no action necessary.
2.
3-way valve changing position between DHW and
heating mode.
24
Water circulation
pump runs for a
short time unexpect-
edly .
Water circulation pump jam prevention mechanism
(routine) to inhibit the build-up of scale.
Normal operation no action necessary.
25
Milky/Cloudy water
(Sanitary circuit)
Oxygenated water
Water from any pressurised system will release oxygen bubbles when water is run-
ning. The bubbles will settle out.
26 Heating mode has
been on standby for
a long time (does
not start operation
smoothly.)
The time of “Delay” set in “Economy settings
for pump” is too short. (Go to “Service menu”
→ “Auxiliary settings” → “Economy settings for
pump”).
Increase the time of “Delay” in “Economy settings for pump” .
. Troubleshooting
