Polypipe Under Floor Heating Systems, Technical Installation Manual

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51

FAULT FINDING CHARTS

Before using this flow chart please ensure that both the primary and under floor 

heating systems are full and that all isolating valves are fully open. Please also 

ensure that the room thermostats are calling for heat.

Hydraulic fault finding chart

YES

YES

YES

YES

YES

YES

YES

YES

NO

NO

NO

NO

NO

NO

NO

NO

Is the fused spur 

switched on?

Is there 230V at 

‘L’ terminal on PCB?

Is Green Power 

LED illuminated?

Is 230V present on 

all T2 terminals?

Is 230V present on 

all T1 terminals?

Are the zone valve 

and under floor heating pump 

operating?

Is there 230V to NC Boiler 

switch live connection?

(Check operation 

of Volt free relay 

connections if using 24V)

Is the boiler firing?

Check boiler connection

Turn the fused spur on

Replace 3A fuse in spur

Replace fuse on PCB 

(2.5A 230 Vac Type 5x20)

Faulty PCB - 

replace unit

Faulty room thermostat - 

replace unit

Relay 1 faulty replace PCB

Relay 2 faulty replace PCB

System operating correctly

Electrical fault finding chart (master connecting box)

This testing procedure should only be carried out by fully qualified persons. 

Testing should be done with all switches on and room thermostats calling.

Fault finding 

complete

Adjust pump speed  

and set flow rates 

in accordance with 

the system design 

data as provided

NO

NO

Is the boiler firing 

and the primary 

pump operating?

Check for 230V signal 

to boiler from master 

wiring centre

YES

NO

Is there hot water 

present prior to 

under floor heating 

mixing valve?

Check if the under 

floor heating zone 

valve is open

Electrical fault 

(see electrical fault 

finding guide)

Boiler fault 

Primary flow and 

return crossed or 

debris in mixing valve

YES

Check 230V signal 

to zone valve from 

master wiring centre

NO

NO

Under floor 

heating pump 

operating

Check 230V signal to 

pump from master 

wiring centre

NO

Is the system 

performing 

correctly?

Ensure that manifold 

lockshield valves are 

fully open

YES

START

YES

YES

YES

YES

YES

YES

NO

NO

NO

Is hot water passing 

through under floor 

heating manifold?

Check temperature 

adjustment on 

under floor heating 

mixing valve

YES

YES

NO

NO

Is there a visible flow 

present through 

all under floor 

heating circuits?

Check if the 

actuators are open 

Electrical fault 

(see electrical 

fault finding 

Pump fault 

Zone valve fault 

Electrical fault 

(see electrical fault 

finding guide)

Actuator fault

Check 230V 

signal to actuator  

from slave unit 

YES

START