Heritage Exposed Valve Shower

The water temperature from the Heritage exposed valve shower started to fluctuate some weeks ago. At first I thought it was the boiler but that checked out fine. The only way I can get the thing to fluctuate between hot and warm rather than warm and cold is to decrease the water cold water pressure into the valve. I'm a little embarrassed that I can't sort this as there doesn't seem to be much to the valve......stumped! Any ideas or suggestions would be much appreciated.

Thanks
Pat

Not familiar with that brand, but it sounds like it may be a pressue balanced type, in which case replaceing the balancing module may fix the problem.

Thanks for the response. Its a fairly basic thermostatic mixer valve...I think. I have striped the thing down, cleaned the valve and enclosure, silicone greased anything that looked like it should move and re-assembled. It seems to be functioning fine now.

If in doubt....take it apart and put it back together. Works in IT so why not plumbing!