My plumber is stuck, and don't have much clue, so I am after any ideas that I could pass his way!
We have a hot water loop, with a Grundfos UPS 15-50 pump circulating the hot water, fitted on the return just above the hot water tank (which is downstairs). We know it is working because the hot water comes out hot in the kitchen almost immediately (this is the end of the loop), and the return pipe is hot.
The problem is that when the pump is on, we get almost nothing out from the upstairs hot taps. When the pump is switched off however, and we just have gravity on our side, we get a reasonable flow from these upstairs taps.
Has anyone seen anything like this before, or got any clues as to what may cause these symptoms?
We have a hot water loop, with a Grundfos UPS 15-50 pump circulating the hot water, fitted on the return just above the hot water tank (which is downstairs). We know it is working because the hot water comes out hot in the kitchen almost immediately (this is the end of the loop), and the return pipe is hot.
The problem is that when the pump is on, we get almost nothing out from the upstairs hot taps. When the pump is switched off however, and we just have gravity on our side, we get a reasonable flow from these upstairs taps.
Has anyone seen anything like this before, or got any clues as to what may cause these symptoms?