Horstmann HRT4-ZW User Guide

HRT4-ZW and ASR-ZW

User and Installation Instructions

Wireless Z–Wave Battery Operated Electronic Room Thermostat with

TPI temperature control software and ASR-ZW receiver unit

The HRT4-ZW is a wireless electronic battery powered room thermostat that uses
interoperable two-way RF mesh networking technology to provide optimum
comfort with close control of the energy used to heat the home without the need
for additional wiring or unsightly cable runs.

The HRT4-ZW will only operate when 2 x AAA batteries have been fitted and the
thermostat is installed and communicating with the ASR-ZW receiver unit.

INSTALLATION AND CONNECTION OF THE HRT4-ZW SHOULD ONLY BE CARRIED OUT
BY A SUITABLY QUALIFIED PERSON.

1

For the user

What is a room thermostat? ... an explanation for householders

A room thermostat simply switches the heating system on and off as necessary. It works by sensing
the air temperature, switching on the heating when the air temperature falls below the thermostat
setting, and switching it off once this set temperature has been reached.

Turning a room thermostat to a higher setting will not make the room heat up any faster. How
quickly the room heats up depends on the design of the heating system, for example, the size of
boiler and radiators.

Neither does the setting affect how quickly the room cools down. Turning a room thermostat to a
lower setting will result in the room being controlled at a lower temperature, and saves energy.
The heating system will not work if a time switch or programmer has switched it off.

The way to set and use your room thermostat is to find the lowest temperature setting that you are
comfortable with, and then leave it alone to do its job. The best way to do this is to set the room
thermostat to a low temperature - say 18°C - and then turn it up by one degree each day until
you are comfortable with the temperature. You won’t have to adjust the thermostat further. Any
adjustment above this setting will waste energy and cost you more money.

If your heating system is a boiler with radiators, there will usually be only one room thermostat to
control the whole house. But you can have different temperatures in individual rooms by installing
thermostatic radiator valves (TRVs) on individual radiators. If you don’t have TRVs, you should
choose a temperature that is reasonable for the whole house. If you do have TRVs, you can choose
a slightly higher setting to make sure that even the coldest room is comfortable, then prevent any
overheating in other rooms by adjusting the TRVs.

Room thermostats need a free flow of air to sense the temperature, so they must not be covered
by curtains or blocked by furniture. Nearby electric fires, televisions, wall or table lamps may
prevent the thermostat from working properly.

2

User Instructions

The Horstmann HRT4-ZW thermostat uses the latest control technology to provide extremely
accurate temperature control which will help to keep your energy usage as low as possible without
affecting your comfort levels. In fact comfort levels may well be improved as the control accuracy
should ensure that the room does not ‘overheat’ before switching off.

The display will show the
required temperature setting
and can be adjusted in
increments of 1°C.

To adjust the required
temperature setting turn the
dial anti clockwise to decrease
it and clockwise to increase it.

When the
thermostat is in
the ‘call for heat’
condition a flame symbol
will appear in the display.

The aerial symbol complete with radio wave symbols in the display of the HRT4–ZW
thermostat indicates that it is communicating satisfactorily with the ASR-ZW receiver.

A flashing radio wave indicates a loss of communication. This may be temporary and
can often be restored by turning the thermostat dial and increasing or decreasing the
temperature to make the thermostat switch. If this has no effect please see Z-Wave
pairing instructions on page 10.

Pressing the temperature
setting dial will allow the
user to check the current
actual measured room
temperature which will be
displayed for approx 7 seconds
before returning to the set
temperature.

A radio mast symbol with no radio waves indicates that the HRT4-ZW has not been
signed on to enable it to communicate with the ASR-ZW receiver. In this case you
may wish to contact the Installer as the indication is that the product has not been
commissioned when the installation took place. Alternatively see the Z-Wave pairing
instructions on page 10.

Further information on how the thermostat operates is contained in the ‘Explanation
for householders’ that precedes this section.

3

Battery replacement

The HRT4-ZW runs on 2 x type AAA (Alkaline) non rechargeable batteries and is designed to give
a battery life of approximately two years.

When the batteries are nearing the end of their life a low

Batteries should be
changed immediately

battery symbol will appear in the display and the batteries
should be changed within a few days. If the batteries are
not changed at this point eventually a ‘LO’ battery message

Low battery symbol
appears rst when the
batteries are nearing
the end of their life

flashes intermittently in the display and if this happens the
batteries should be changed immediately.

To change the batteries it is necessary to remove the
thermostat from the wall. To do this first undo the two
captive screws at the base of the thermostat and swing the
thermostat up and away from the wall plate.

Remove the old batteries and replace them with two new AAA size
alkaline batteries ensuring that they are fitted correctly as indicated by
the terminal markings in the battery compartments.

Once the batteries are fitted, re-fit the thermostat to the wall plate
by engaging with the lugs at the top of the wall plate and push the
thermostat into position. Locate it over the captive screws at the base
of the wall plate and tighten so that the thermostat is locked into
position.

Check the temperature setting is correct and adjust if necessary.

Please dispose of the batteries responsibly.

ASR–ZW receiver unit

4

The ASR–ZW receiver unit receives the Z-Wave radio
signals from the HRT4–ZW room thermostat.
In the unlikely event of a communication failure it is
possible to override the system and switch On and Off
using the On/Off buttons on the ASR-ZW receiver as a
local override.

If the override is used to override the HRT4-ZW
thermostat when it is functioning correctly then the
override will be cancelled by the next switching operation
of the thermostat and normal operation will be resumed.
In any case, with no further intervention, normal
operation will be restored within one hour of the override
being operated.