1 A flow restrictor is factory fitted to all models except the
Combi Max and Condensing Combi 36, to limit the flow
rate to approximately 15 litres/min. The flow restrictor is
located in the outlet side of the cold water inlet isolating
valve.
The boiler may still operate down to a pressure of 1.0 bar but
with a reduced flow rate. The minimum flow rate needed
for the flow switch to operate is 3 litres/min.
3 To ensure economic use, the pipe runs between the boiler
and hot taps should be as short as possible and in 15 min
copper pipe or 22 mm for the Combi Max and Condensing
Combi 36 only. Where possible the pipework should be
insulated to reduce heat loss.
4 All taps and mixing valves used in the domestic hot water
system must be suitable for operating at a mains pressure of
up to 8 bar.
5 If required, a shower may be fitted in the domestic hot water
system. It is recommended that thermostatically controlled
shower valves are used to protect against a flow of water at
too high a temperature. If a fixed head type shower is used,
no anti-syphonage devices are required. If a loose or flexible
head type shower is used, it must be arranged so that the
head cannot fall closer than 25 mm above the top of the
bath, thereby preventing immersion in the bath water. If this
is not practicable, an anti-syphonage device must be fitted
at the point of the flexible hose connection.
6 The supply of hot and cold mains water direct to a bidet is
allowed (subject to local Water Undertaking requirements)
provided that the bidet is of the over-rim flushing type. The
outlets should be shrouded and unable to have a temporary
hand held spray attached. Arrangements for anti-syphonage
are not necessary.
8 The mains water connection to the boiler must be the first
connection from the mains supply.
A water hardness kit is supplied with the boiler. This should be
used to determine the water hardness as follows:
Fill a clean container with a sample of water from the mains
cold water supply to the boiler.
Immerse the test strip in the water for approximately one
second, ensuring that all the test zones on the strip are fully
wetted.
Shake off the surplus water and wait for one minute.
Assess the hardness of the water by the colouration of the test
zones on the strip using the following chart.
Note: (1 mg/l = 1 ppm (part per million)
Should the total hardness of the water exceed 125 ppm it is
essential that an in-line scale inhibitor or, preferably, a water
softener is fitted in the cold water supply to the boiler to reduce
scale formation within the boiler. Failure to do so may
invalidate both the manufacturers warranty and any extended
warranty covering the appliance. Consult the local water
undertaking if in any doubt about the hardness of the water or
the use of a water softener.
The water conditioner or softener should be fitted to the cold
water supply serving the appliance and in accordance with the
manufacturers instructions. Grant Engineering (IRL) Limited
cannot be held responsible for any damage or misuse caused by
the fitting of any water conditioning device.
2 The incoming mains water pressure should be between 1
and 8 bar to ensure efficient operation. If the pressure is
above 8 bar a pressure reducing valve must be fitted.
IMPORTANT:
Do not immerse the test strip in running
water and avoid contact.
Please protect the domestic hot water system from
harmful effects of scale.
Problems caused by the build-up of limescale are not
covered under the terms of the warranty.
7 Before the mains water supply pipe is connected to the
boiler, it should be thoroughly flushed out to avoid the
danger of dirt or foreign matter entering the boiler.
5.9
\
Domestic hot water system
5.10
\
To use the water hardness kit
Green areas Violet areas Hardness
Total hardness mg/l (ppm)
4
0
very soft
<50 mg/l calcium carbonate
3
1
soft
>70 mg/l calcium carbonate
2
2
medium
>125 mg/l calcium carbonate
1
3
hard
>250 mg/l calcium carbonate
0
4
very hard >370 mg/l calcium carbonate
Outdoor Combi 90 V3, Combi Max and Condensing Combi
21
5 - GENERAL BOILER INFORMATION
