DOMINA 80 E
35
3.09 Connecting the central heating and domestic hot water circuits
Connect to the relevant connections as indicated in fig. 1.
Connect the pressure relief valve discharge pipe (15mm) to the outside of the building, where possible
over a drain. The discharge must be such that it will not be hazardous to occupants and passers-by or cause
damage to external electric components or wiring. The pipe should be directed towards to the wall.
To ensure long life, the heating circuit should be correctly sized and fitted with all the controls necessary
to ensure correct functioning and operation. The differential between the boiler flow and return pipes
should not be more than 20
°
C. You are advised not to use the boiler with return temperatures of less than
50
°
C in order to prevent patches of condensation forming and having a corrosive effect on boiler
components.
3.10 Boiler water characteristics
If the water is harder than 18 clarke degrees, the water used should be treated to avoid possible scale in
the boiler caused by hard water or corrosion by aggressive water. It should be remembered that as a result
of its low thermal conductivity, even scale of just a few millimetres thick can lead to considerable
overheating of the boiler walls, resulting in serious problems.
IT IS ABSOLUTELY VITAL THAT THE WATER USED IS TREATED IN THE FOLLOWING CASES:
a) Extensive systems (containing large quantities of water);
b) Frequent additions of water to top-up the system;
c) Domestic hot water circuits
If the system requires partial or total emptying, you are recommended to refill it with treated water.
3.11 Filling
When cold, system pressure should be about 1 bar. If while running venting off of air dissolved in the water
causes the pressure of the central heating system to drop below the minimum level described above, the
user must utilise a filling loop to bring it back to the original value. During operation, water pressure in
the boiler when hot should be about 1.5 - 2 bars. After filling, always close and disconnect the filling loop.
Note -
If there is a possibility of air pockets forming in certain points of the central heating system flow
and return pipes, you are recommended to fit an air vent valve at these points.
Note -
When the boiler is installed below the level of the central heating system, single check valve should
be fitted to prevent gravity circulation around the heating system.
3.12 Gas connection
Gas connection should be carried out using a rigid pipe.
The flow at the gas meter should be sufficient for the simultaneous use of all appliances connected to it.
Connect the gas supply to the boiler according to current regulations. The diameter of the gas tube leaving
the boiler is not the determining factor in choosing the diameter of the pipe between the appliance and
the meter. This must be selected in relation to length and pressure drop and in any instance should not
be less than 22mm.
The whole of the gas installation including the meter should be inspected and tested for soundness
and purged in accordance with BS6891-1988.
N.B. -
The filling loop will be fitted by the installer in accordance with water by laws at the time of installing
the system.
It is NOT a part of the boiler.
