44
45
SINGLE ROOM APPLICATIONS
All Polypipe under floor heating systems can be installed
in single rooms and connected to the existing wet heating
system. In rooms greater than 30m
2
it is recommended that
the connection to the under floor heating system is made via
a manifold and installed in the same way as a multiple room
installation with single area control.
Areas of up to 30m
2
should use the Polypipe Zonal Regulation
unit (ZRU) as this provides a simpler method of connecting
into the existing system, without the need for expensive
hydraulic or electrical alterations.
The ZRU simply connects to the existing heating system
providing:
• Water temperature control (30°C to 60°C)
for the under floor heating
• The correct flow rate the under floor heating
• Automatically switches On and Off via a built-in
pipe thermostat
• A wiring connection for a room thermostat
or wireless sensor
• Can be connected to operate the under floor heated
room independently with the existing system
Connections to the existing
wet heating system
The pipe work connections to the ZRU are for 15mm diameter
pipe and the ZRU should not be connected to the system from
any pipe smaller than 15mm.
A small number of boilers can be affected hydraulically by the
use of a second pump in the system.
NOTE:
Check with the boiler manufacturer to ensure
compatibility with the ZRU.
The preferred connection to the ZRU is to the main flow and
return pipe work of a 2 pipe system, i.e typically from 22mm
distribution pipe work. However it can also be connected to the
nearest existing radiator.
Pipe connection to operate under floor heating
at the same time as the boiler
The diagram above shows the ZRU connected to operate with the
boiler on/off firing. Due to the quick response of low mass systems
(Overlay™, Overlay™ Lite, MHP, etc) this is likely to be suitable.
Using this method for solid floor installations may require the
timings of the existing heating to be altered to allow the under
floor heating system to reach comfort temperature.
If the room is to be controlled independently of the existing
central heating system, a zone valve needs to be installed
between the boiler and the ZRU.
Pipe connection to operate ZRU / under floor
heating independently
Programmable room thermostat
Connection
from main
distribution
pipe work
Zone
valve to
under
floor
heating
Zone valve
to radiator, etc
Connection
from main
distribution
pipe work
Connection
from nearest
radiator
260mm
200mm
Pump
Pipe
thermostat
Heating
return
Heating
flow
Under floor
heating flow
Under floor
heating return
Thermostatic
blending valve
Pump speed
control
Tees and spigot
elbows for
second circuit
if required
Room stat (example) - not supplied
Pump
Remove
link if
using a
room
thermostat
Boiler feed thermostat
42°C close
31°C open
Mains
(Fused spur)
3amp
The pipe supplying the ZRU should be connected to the main boiler
distribution pipe prior to the connection of other zone valves.
A programmable room thermostat can be used to operate the
zone valve and, in turn, the end switch within the zone valve
can provide a signal to fire the boiler.
Installation of ZRU
The ZRU can be positioned either in the room where the under
floor heating is installed or in an adjacent area, 300mm from
the finished floor level to allow for pipe connections.
Fitting the ZRU
Step 1:
Screw unit to wall.
Connecting the ZRU
Step 2:
Connect heating pipe work via an isolation valve (as shown).
Step 3:
Connect under floor heating circuit(s) using an isolation valve.
Use tees and spigot elbows to form connections for 2 and 3
circuit systems.
Step 4:
Connect mains wiring (as diagram below) via a fused spur.
Wiring details
IMPORTANT NOTE:
If in any doubt you should contact
a qualified electrician.
The water temperature must be 45°C to operate the unit.
Wiring diagram
Filling the under floor
heating system
Use the heating system to fill the under floor heating circuits
and ZRU.
Blanking off the ZRU
Step 1:
Remove the under floor heating return pipe from ZRU and
blank off the ZRU under floor heating return port with a short
pipe with a blank end or a blanking plug.
Filling the ZRU
Step 2:
Allow open ended under floor heating return pipe to drain into
a bucket or hose.
Step 3:
Open the flow isolation valve to the ZRU.
Step 4:
When uninterrupted flow is seen from the under floor heating
return pipe, close the isolation valve and re-connect the under
floor heating return pipe to the ZRU.
Step 5:
Open all the valves.
Step 6:
Vent the ZRU through the air vent and pump vent.
Room packs
Open under
floor heating
flow isolation
valve
Blank off
under floor
heating
return to ZRU
Vent under floor
heating system from
under floor heating
return pipe
Type
Solid Floor
Overlay™
Overlay™ Lite
Area
12m
2
(
So12Z
)
12m
2
(
O12Z
)
12m
2
(
OL12Z
)
20m
2
(
So20Z
)
20m
2
(
O20Z
)
20m
2
(
OL20Z
)
30m
2
(
So30Z
)
30m
2
(
O30Z
)
30m
2
(
OL30Z
)
A 5m
2
Overlay™ Bathroom Pack (O5B) is controlled
with a temperature limiting valve rather than the ZRU
A range of room packs containing all flooring
and ZRU are available