Pump power

[bushmins]

In another thread i have been trying to fault find my heating system, im now looking at the pump.

Ive taken my pump out of the heating circuit. The motor is going around and i can feel suction and blowing. I just went out an bought another motor (same as the old one) when i let it run dry for a few seconds it seems to suck/blow the same as the old one.

I dont want to risk fitting it if there is no problem with my old motor as i wont be able to take it back for a refund.

An ideas on what the pump should be like when run dry?

 

[grahamderek]

Never run a dry pump!
If the impellor is slipping on the shaft, it will not show up in air

 

[bushmins]

Never run a dry pump!
If the impellor is slipping on the shaft, it will not show up in air

When i took the old motor off i jammed the impellor (gentley) and tried turning the back of the spindle under the rear inspection screw, it seemed pretty solid.

Im thinking my problem lies with the boiler. When i put the old pump back on i could hear the system starting back up where the boiler is (water going through the pipes).

On the boiler Im fairly sure i hear the fan start, then the pilot light but i dont think the main heater turns on, the boiler doesnt seem to get hot at all.