Hi,
we have an old boiler (olympic 20/35b) and recently replaced old radiators and installed four more. Now and again the pilot on the boiler would go out and we would have cold water for one day then everything would be fine again. Recently however, the pump stopped working, and i changed the setting from 1 to 2 and it worked for about three days and stopped working again. i then changed the setting to three and it worked for about one week. Now the pump only works if manually push the top screw and the pump is extremely hot with lots of steam escaping . The pump will then work for about five minutes and stop. The baffling thing about this is black water. everytime i manually start the pump more black water comes out. I have bled this on numerous ocassions and the water become clear, however when it stops the black water comes back. if i need a new pump, could anyone replace the pump or should this be done by an expert? Thermostat on boiler has never worked, neither has the settings which are found in the hallway.
thank you in advance for your kind response.