Until recently, McCarthy & Stone fitted Pulsa Coil boilers in all their new developments. It was M&S policy to keep the boilers 'ON' at all times - even when the flat was unsold. In some instances this could be months or years. In consequence, lime scale and other detritus settled in the impeller and jammed the pump( in most cases the pump was a GRUNDFUS); as the pump only functions when the hot water suppy is actually turned on, via a tap. Thus, when the flat was occupied, and the hot water taps turned on, the pump impeller failed to rotate = no hot water! What too do!
Remove outer cover from pump, underneath is a slotted screw head, insert screwdriver and turn, HARD, clockwise. TURN ON ALLHOT taps first. That should do it. If not, the pump will have to be cleaned out. This is NOT a major task. A plumber will normally just fit a new pump and charge around £130 inc' vat. What too do!
Isolate boiler at main electricity box, undo three wires from pump connection to electrical supply (note wire colour code, and three connections screws for re-wire). You DO NOT have to drain the tank. The pump is connected by two unions, above and below. The unions each inccorporate a slotted screw head. Turn screw heads 90 degrees, this will turn off the water supply to the pump. Undo the two union nuts that hold the pump (WRENCH or STILSONS required), then remove. A small amount of water will issue from the top union - use a bucket. The pump is assembled with four screws, you will need ALLEN KEYS.
Remove pump cover, clean out pump, re-assemble, and replace. Set pump to max speed in hard water areas, slower if soft water area.
If there is air in the pump after refitting, remove pump cover, and turn screw (as described above). Allow water to squirt out from running pump, until all air is expelled, tighten screw head.* NOTE, YOU WILL NEED A BUCKET TO CATCH THE WATER AND THE WATER WILL BE *HOT* !!!!! I have carried out this procedure several times, it only takes about one hour.
Ivor Molegrip, January 2009
