Is the water so bad that their guts have been eroded away ? Try nipping them up by gripping the stems with a pair of Footprints. If they are slotted try just turning them until the slot is `across` the flow of water
If that fails, get a replacement pump and hire a freezer kit. Follow the instructions and `Hey Presto` a wonderful new pump.
To be honest if your valves have been eaten by the water, then a drain down and a good flush through using the correct chemical treatment and a refill with some decent inhibitor added to the water might well be the best idea. But be prepared for the fact that it might find some weakness somewhere else in the system.
Good luck.I need to change my hot water circulation pump!?Not yet, guess the isolating valve as mentioned is a non return valve (water will only flow one way) no back pressure can flow back, Suggest switch off the system, then drain the tank M.T till no pressure in the tank.
open both valves and check if the non return valves are frozen due to dirt or maybe lid broken, take a sample to any hard ware store and replace both valves, this will save your money. Good luck
