
THERMAL INNOVATIONS (UK) LTD | THERMAFLOW® ELECTRIC COMBINATION BOILER |
Tel: 0870 850 5207
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WARNING: FOR YOUR OWN SAFETY
SERVICING AND MAINTENANCE SHOULD BE CARRIED OUT BY A PERSON WHO IS
COMPETENT TO DO SO.
3.2 ISOLATION
•
Before commencing, refer to section 1. Installation
Checking the pressure in the expansion vessel
The primary expansion vessel (volume 25 litres) is the red or vessel connected to the central
heating return pipe or to the branch of the tee where the auto air vent is connected to on top of the
boiler. Its purpose is to take up expansion in the boiler and central heating system.
The pressure can be accurately checked with the pressure relieved on the other side of the
diaphragm. To do this drain some water from the central heating system until the pressure gauge
registers zero. Connect a pressure gauge to the car tyre type valve on the vessel. The pressure
should register 150 KPA (1.5 Bar). Refill heating system as described in section
2.7.2
The secondary expansion vessel (volume 1 or 2 litres) is the white or silver vessel connected to the
hot outlet of the pre-heat coil at the top of the boiler.
Its function is to take up expansion in the hot water pipe work and so protect the blender from
damage.
The pressure can be accurately checked with the pressure relieved on the other side of the
diaphragm. To do this, isolate the water supply to the Thermaflow and open a hot tap. Water will run
for a few seconds then stop.
Connect a pressure gauge to the car tyre type valve on the vessel. The pressure should register
100KPA (1.0 Bar) on the 1 litre vessel or 350 KPA (3.5 Bar) on the 2 litre vessel. Close the hot taps
and turn the water supply back on.
Checking the inline strainer
Whilst the water is off, remove and clean the gauze in the brass strainer assembly. To remove the
gauze for cleaning un-screw the brass plug.
Checking the hot water blending valve
With the store temperature fully recovered, run a hot tap and check the flow rate and temperature.
If the hot water has deteriorated suddenly (over less than a month) then this points to a problem
with the blender.
A broken blender is usually linked to a loss of pressure in the secondary expansion vessel. The
expansion vessel protects the blender from damage when the water in the secondary system
expands as the water re-heats after water is drawn off.
Check the pressure in the secondary expansion vessel as detailed previously in section 2. If it does
not hold pressure it will need to be changed along with the blender.
Strip off the blender and check hot and cold mesh filters for blockage. (Clean if necessary).