Just changed my bathtub/shower valves water flow changes

Most on demand or tank-less units require a minimum flow rate before the unit will fire up, they designed them that way so small water leaks (drips etc.,) keeps the unit from going on needless;y. Try opening the shower hot water fully and see if it comes on, If it does, try closing it slowly to see where it shuts off. Make sure your shower head is clean and not blocked with calcium, which will restrict the water flow. You could also try changing the shower head to one that allows more gallons per hour flow rate. Also make sure the cold inlet and hot outlet valves on the unit are fully open and the diverter on the shower is fully open as well.

One rule I live by: more parts, more problems. Sounds to me that the plumbing/valves were not insalled properly. If you hired a profesional plumber, have them fix it. I am a licensed profesional plumber and I offer a 1 year warranty on all my work. If the contractor did the work and does not hold a plumbing license, that person is still responsible and may have to suffer legal consequenses.

1. COLD MIX, HEATER DEACTIVATES
   If inlet water temperature is over 70°F due to geographic location, water maybe very hot out of the tap. This requires a lot of cold water to be added with it in order to attain a useable hot water temperature. The addition of too much cold water will overpower hot water demand from the tankless water heater. This slows the flow within the tankless water heater, decreasing it below activation point, which shuts off the heater. The end result is nothing but cold water coming out of the outlet. See: TWH E2-04 Overcoming fluctuating temperatures [PDF].
2. FLUCTUATING WATER PRESSURE
   If the water pressure in the home is erratic and the water flow is not consistent while a tap is opened, then the temperature of hot water will fluctuate. The minimum water pressure for the home should be 30psi or greater. For people on well systems the minimum pressure range is 30-50psi. The use of a pressure reducing/regulating valve is an effective way to maintain constant water pressure to the water heater. Watts brand 25AUB- ¾" or N35B-¾" pressure reducing/regulating valves or equivalent is suggested.
3. CHANGING FLOW RATE
   Major changes in flow rate can adversely affect the output water temperature of the heater. Increases from one major fixture running to multiple fixtures running at one time can cause the temperature to fluctuate. Stay within the heater's specifications. See: TWH E2-03 Outlet temperature vs. flow rate [PDF].

From the Bosch website.

Good Luck,
Gary

it sounds like the tub filler itself. When you pull the knob up it's supposed to divert the water to the shower, if it's coming out both, I'd look at that piece, inexpensive and easy to replace

You don't indicate what kind of valve(s) you have in your shower/bathtub.

It is sometimes the case, when you have separate hot and cold valves that use the traditional flat washer, the rubber/viton washer wears over time and actually becomes cut, such that a part of the washer protrudes from the valve face.

Hot water will cause the distorted washer to expand. Consequently, as more and hotter water flows through the valve, the washer expands to the point where it constricts the flow of hot water.

Replace the washer, at least on the hot water valve.

I have a triton opal shower.

I turn shower on low pressure and cold water. then no low pressure and piping hot water for a very short time then low pressure and cold water.

I've changed the solenoid and the little black plastic ball.

Help !

If you are having trouble only at the one fixture (shower), and no where else, the problem is most likely in the shower valve...which either needs new cartridges, or a complete replacement.
hope this helps

Usualy when this happens you need to change out the cartrage that controls the water. try to find your faucet at the link below. If you find it click on it scrol down and you can view the manual. It will terr you how to change it out.

http://www.deltafaucet.com/bath/index.html#tubshower_

Good Luck

If you put on the cold and Nothing at all comes out, check the water supply valve to the tub. If it comes out alittle ...the washer probiblly came off and is stuck you will have to remove the valve ,but 1st check that the handle is not stripped ,and that is actually moving the valve to the open position Turn the handle and see if the handle backs out ,like its trying to open.
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