Keston Thermomatic RSM20/FB, Installation & Servicing Instructions Manual, Page: 26 / 46

Page 26
Fig. 7.4. CONDITION 4.
The boiler is properly on. Is
the green operating light on?
Is the green lamp burnt
out?
Replace it.
Check the electrical
connections.
No Yes
No
Fig. 7.5. CONDITION 5.
1.Sw icth off electrical supply.
2. Remove vent plug
3. Apply screw qdriver to slot on shaft
end and rotate each w ay pushing in
and out until shaft turns freely.
4. Replace vent plug and sw itch on
electrical supply.
Is there 240V at the
circulation pump?
Does the room
thermostat (RT) call
for heat?
Does the
Anticondensing
thermostat call for heat?
When the w ater temperature
of the boiler exceeds 60º C
does the circulation pump
start (check w ithout draw ing
w ater).
See condition 6
Is the circulation
pump stuck?
Set SWS on
w inter
Set the room thermostat at a higher
temperature so that it can give consent.
Is the summer / w inter
s w itch (SWS) set on
w inter?
Faulty circulation pump,
replace it.
Check the summer / w inter
sw itch connections and if
necessary replace SWS.
Is the biometalic priority thermostat
(BPT) contact closed?
Set at 60º C.
Is the AT set too
high?
Check control box connections. If
necessary replace control box.
Check the mounting of and connections to the
BPT. If necessary replace BPT.
Yes Yes
Yes Yes
Yes
Yes
Yes
Yes
No No
No No
No
No
No