Aquabrass Thermostatic Shower Adjustment HELP

I just installed an Aquabrass thermostatic shower and am having a problem in adjusting the water temperature. No matter what I do in using the shower, the outflow water is either too hot or too cold, no in-between. The worst part is that when I slowly move the handle through various temperature stops to cool the water, it finally gets too cold, and then when I move it back it continues to be very cold at the same settings where it was too hot, and finally reaching a setting where the cold stops and jumps back to very hot. Please, please somebody help before I am committed to a lunatic asylum. Thanks a million in advance.

No way to help you without being there to try to figure out why your adjustments are not working. BUT, the problem could be elsewhere and just showing up in the shower, which is why we would have to be there and do our own testing.

Thanks hj, but the same unit installed in the other washroom is working fine, so it doesn't seem the problem is elsewhere. What else do you think it could be.

Two things to check/verify: make sure the hot and cold lines aren't backwards; make sure that there's nothing partially blocking the inlets (may have filter screens, or it could be in the checkvalve or possibly a pressure balance spool but it may not have one of those). If the flow from both hot and cold into the valve aren't fairly even, it's hard for it to adjust. If there's anything caught inside, it may be restricting the thermostatic cartridge's ability to move freely. It could be a bad cartridge, it may just be gunked up and can be cleaned.

Message to canadatrue - were you able to fix the problem. I just installed one and have the same probem . It gets too hot or cold and nothing in between. Grateful for NY help. Thanks. Pls email me at nani.narayanan@rogers.com