Unfortunately my poor plumber had a bad day - he called me because there was 'funny noise' upstairs. He then realized the pump was running as he'd forgotten to turn the boiler off. The system finished filling up after he'd left - he will return if I have a problem. However, before I open the drain cock a little to see if system has filled up, can anyone let me know what might happen if the pump has been damaged by running on empty? :?
Firstly, the water is used to lubricate and cool the pump's bearings. If the pump runs quietly when refilled, maybe it will be fine, but the accident is sure to have reduced the pump's life span. It's just a question of how much.
Secondly, the circulating water cools the motor windings. If allowed to run for a long period, the motor will burn out. Again if it works, you may be fine, but the windings may have been damaged and could fail in the future.
Unfortunately, if the pump works now, apart from any bearing noise, there is no way of confirming the pump has been damaged in any way.