The flow of water starts at a high rate then within 15 minutes it slows to nothing

If you have already descaled your Tempra 24 Tankless water heater and replaced the flow sensor, but the high limit switch is still tripping, there could be a few other possible causes of the issue: Malfunctioning thermostat: A malfunctioning thermostat may cause the heating modules to overheat, which can trip the high limit switch. You may need to replace the thermostat if this is the case. Insufficient water flow: The Tempra 24 Tankless water heater requires a minimum flow rate of 0.5 gallons per minute to operate properly. If the flow rate is too low, the heating modules may overheat and trip the high limit switch. Check the water flow rate to ensure it meets the minimum requirement. Electrical issues: If the wiring or electrical connections are faulty, it may cause the heating modules to overheat and trip the high limit switch. You may need to inspect the wiring and connections to ensure they are intact and properly connected. If none of the above solutions work, it may be best to contact a professional technician for further diagnosis and repair. It is unlikely that you would need to replace the entire unit if the issue is isolated to a single heating module.

well=== pure water flows at 5.1 gpm thru 1/4 pipe , now valves have a slight orifice to slow the flow down some as a 1/4 valve most likely has a 1/16 orifice value , but that's just an educated guess as I don't know what valve u have , also im assuming your using pure water with a specific gravity of 1.0000 (yes it effects the rate) say hydraulic oil has a value of .0898 this will also slow the flow thru the valve

This sounds like a low water flow situation. The heater is telling you that the high limit sensor is curring heater operation. The noises are the heat exchangers boiling the water either due to a blockage in the exchanger , a bad mixing vlve, or most likely poor water flow. This is tough to troubleshoot through a posting like this, but 1st thing is 1st. Check your water flow and make sure it is minimum 50 Gallons per minute.

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

There is probably a filter on the nozzel. This filter needs to be unscrewed, turning it to the left. Once removed the turn the fitting over in your hand and if needed, gently push the filter out. Once it is out you should be able to run it under the water flowing out and it small particles of crud should just wash out. Replace the cartridge, screw the fitting back onto the nozzel, turn on the water and see if the flow improves. Most modern faucets have some sort of screening filter arrangement in the nozzel ends. This is to restrict the flow of water somewhat as a water conservation effort. These screens can clog even if you think your water is clear, over time they are apt to slow the rate of water flow way down. BE SURE the water is turned off when you unscrew and replace the end of the nozzel otherwise you will get quite a bath! Good luck!

Hi .. first I would try and eliminate the filter as the problem. Remove the filter and try the water again. If the water flows strong, then the filter is the problem. If the water stills sputters and is low flow, then there is a partial blockage in the internal tubing , or a problem with the supply. If you roll the fridge out to get at the suppl. you could shut it off and disconnect the supply tube from the fridge, then turn the water on slowly to check the flow at the supply. If the flow is good there , then the blockage is internal.

Make sure you clean both screens at each end of hose. If they are clean,you got dirt caught in valve. Good luck.

Hi, In most cases the water is slowed by the water storage tank in the freshfood section is frozen. or if the water filter is dirty. You can try to turn the temperature up in the freshfood and see if the problem goes away, or you can replace the water filter. The water storage tank is behind the bottom drewers in the freshfood section. You can heat it up with a hair dryer to make sure it does not have any ice blocking the flow.. Good luck to you and I hope this will FixYa.
Michael Anderson
Anderson Appliance Repair
(865)945-3808

I don't understand why replies talk about the C2 and C3 errors... The problem is C1! I have the C1 error. I start a programme, it does the draining cycle to check empty then starts filling. MI can hear water entering but it sounds slow at a low flow rate. If I leave it going, eventually the programme stops and the error is displayed: C1 Opening and closing the door allows the programme to continue. I get the error after the various stages of the programme, when it is filling for the next wash or rinse. So it's 4 or 5 times I think during the programme. Now, if I help the filling... When the appliance is filling, I open the door, and poor in a kettle or two of water, then the error does not happen (the fill is within the time expected by the appliance?) So I am thinking one of two things is wrong: 1) I have a flow rate problem BEFORE the water connection to the appliance. E.g. It is blocked somehow. 2) There is something which opens/closes the "tap" within the machine which is causing the flow rate to be low and it does not fill quickly due to that. No idea which of these two, but I did disconnect the hose of the supply and check that water flows quickly from it into a bucket, so I am thinking there is something inside the machine which "opens the tap" and it's not doing a good job of it. Anyone got a clue?

its in your cold water line valve to the washer if it works good with hot water the valve are incoming line being blocked when you turn it on the pressure comes in fast then when pressure is gone water slows down so when its off the pressure builds back up it runs fast then slow