Maintenance; General; Routine Inspection & Maintenance Operations Domestic Hot Water System - Heatrae Sadia HI-MAX INSTANT ID 5-60 Installation, Operation And Maintenance Manual

9. Maintenance

9.1 General

9.1.1 Maintenance requirements
HIUs have an annual maintenance requirement in order
to ensure safe working and optimum performance. This
is of particular importance in hard water areas or where
the water supply contains particulate matter.
It is essential that the safety relief valve(s) are periodically
inspected and manually opened to ensure no blockage
has occurred in the valves or discharge pipework.
Similarly cleaning of the district heating fl ow strainer
fi lter mesh and the cold water inlet fi lter will help to
prevent possible operational faults.
Other areas to check are the gas charge in the
expansion vessel and the pressure gauge within the
heating system.
The maintenance checks described below should be
performed by a competent person on a regular basis,
e.g. annually to coincide with other maintenance work.
After any maintenance, please complete the relevant
Service Interval Record section of the Benchmark
Checklist on page 55 of this booklet.
WARNING
Any valves and exposed pipes may be hot!

Before commencing
maintenance on the HIU ensure that the electrical
power supply, the district heating connections, the
apartment heating connections and the domestic
hot water connections are all isolated.
9.2 Routine inspection & maintenance
operations - Domestic Hot Water System
9.2.1 Expansion relief valve operation (where
fi tted)
WARNING
Water discharged may be very hot!

If fi tted, manually operate the expansion relief
valve for a few seconds by turning the knob or
lifting the lever.

Check water is discharged and that it fl ows freely
through the tundish and discharge pipework.

Check valve reseats correctly when released.
Figure 54: PRV strainer example
any servicing or
9.2.2 PRV Strainer (where fi tted)

Turn off the power supply to the HIU.

Turn off the cold water supply into the property,
space heating system and district heating systems.

The lowest hot water tap should then be opened
to de-pressurise the system.

Remove the pressure reducing cartridge to access
the strainer mesh.

Wash any particulate matter from the strainer
under clean water.

Re-assemble ensuring the seal is correctly fi tted.
DO NOT use any other type of sealant.
9.2.3 Potable water expansion vessel (where fi tted)

Turn off the in coming cold water supply.

Drain down the expansion vessel.

Check the gas charge in the expansion vessel and
recharge as necessary. This should be set at the same
pressure as the incoming cold water supply. If in
doubt check the setting of the PRV.

Turn on the cold water supply.
DANGER
If the Stv is showing signs of scale build up and
is affecting its operation it is important that this
is replaced.
9.2.4 Descaling

Where scale has been allowed to build up and is
affecting the operation of the unit, remove and
replace the component(s).

In hard water areas where scale build up is
an issue it is recommended that a suitable scale
prevention device is fi tted.
CAUTION
Do not use a sharp implement to remove
scale from a component as damage may
occur.
PRV cartridge
Strainer Mesh
37