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Expansion vEssEl and tEmpEraturE-prEssurE gaugE
11 expansiOn vessel and temperature-
pressure GauGe
11 .1 function
The Expansion vessel (I in Figure 10.1) function is to allow for the
volume expansion of the c.h. circuit water due to the temperature
rise.
11 .2 checks
figure 11 .1
J
Rear view of the boiler
1 Turn off the flow and return isolation valves and empty the
primary circuit of the boiler.
2 Remove the protective cap J (Figure 11.1) from the valve on
the top of the expansion vessel and connect a suitable air
pressure gauge.
3 Check the pre-load pressure and refer to the section Expan-
sion vessel in the User manual and installation instructions
for the correct value.
11 .3 removal of the expansion vessel
If there is at least 400 mm clearance above the boiler and the
rear exit flue can be easily removed, the expansion vessel can
be changed without removing the boiler.
warning: isolate the boiler from the mains electrici-
ty supply before removing any covering or compo-
nent .
1 Remove the front and left hand side panels of the case, turn
off the flow and return isolation valves and empty the primary
circuit.
2 Completely unscrew the connection K, the locknut L (Figure
11.2) and remove the expansion vessel from the top of the
boiler.
figure 11 .2
l
K
3 Re-assemble the parts in reverse order of removal.
11 .4 removal of the temperature-pressure gauge
1 Remove the front and right hand side panels of the case, turn
off the flow and return isolation valves and empty the primary
circuit.
2 Remove the fork M and the probe holder spring N (Figure
11.3).
3 Squeeze the tabs O to release the temperature-pressure
gauge P and remove it.
4 Re-assemble the parts in reverse order of removal.
figure 11 .3
p
O
n
m