4
1. General
1.1 introduction
Construction of the heaters is in ac
-
cordance with the European standard for
gas heated water storage heaters for sa
-
nitary application (EN 89). The appliance
thus meets the European Directory for
Gas Appliances and is therefore entitled
to carry the CE-marking.
It is an open flue appliance without a fan
and with a flue gas down draught safe
-
guard (category B
11BS
). The water heater
is suitable for a maximum working pres
-
sure of 8 bar. The heater tank is manu
-
factured from low carbon sheet steel and
is glass-lined on the inside. In addition
the tank is fitted with a sacrificial anode
as an extra protection against corrosion.
A thick PU-insulation layer covered in a
steel jacket reduces unnecessary heat
loss. When the appliance is filled with
water it continuously is under water pres
-
sure. As hot water is drained from the
tank, cold water is added immediately.
A flue baffle has been placed in the flue
tube to improve heat transfer. The flue
gasses pass their heat on to the water by
means of radiation and convection. The
flue gasses are guided to the chimney
via the draught diverter. The exhaust
of the flue gasses is realized by natural
thermal draught (see Figure1).
Dead legs on a hot water installation
are undesireable. Where possible they
should be avoided. Where the inclusion
on the system of a dead leg is unavoida
-
ble the following restrictions should be
applied:
- for pipes not exceeding 19 mm. inside
diameter; maximum lengh of dead leg
permitted 12.0 metres;
- for pipes exceeding 19 mm. but not
exceeding 25 mm. inside diameter;
maximum length of dead leg 7.5
metres;
- for pipes with an inside diameter
exceeding 25 mm. maximum dead
leg 3.0 metres.
