20 Most Recent Bosch AquaStar Indoor Natural Gas Tankless Water Heater with Vent Hood #125 - Page 5 Questions & Answers

Some tankless heaters have filters built into the machine. You might want to consult your owner's manual regarding the filter.
The minimum flow rate is hard programmed into a tankless heater; it won't be changing over time. You might want to check the aerators of your fixtures for buildup of sediment and scale.
The temperature control of Bosch units is always going to be crumby because they are cheap products. The only thing you can do to improve temperature stability is to increase water flow (de-scale fixtures and possibly remote flow restrictors)

if the leak is behind the handle take the handle off and tightn the packing nut, do not over tighten, as far as luke warm water is this with just one facucet on, they way these tankless water heaters work they are by gpm, gallons per min, if you have more gallons of water going thru the unit then it is designed for then it won't get hot, if your water pressure is to high going thru it will push it to fast thru the unit and won't get hot, your house pressure should be no higher then 75lbs no lower then 65lbs

the piliot light can not be adjusted, it is what it is,, the only ones that can be adjusted are from back in the 60's where they had a seperate gas line off the primary gas line,, you might have to much gas pressure and might have to have a regulator installed

if it is leaking behind the handle take the nut off remove the handle and tighten the packing replace the knob and your done,, good luck

it sounds like the flue pipe out side may have something blocking it , it has a fresh air return on it and when the unit is blowing out it also pulls in the outside air, make sure ther is nothing in the way making the air circulate back in,

it is a loose washer in a valve,,, when the water hits it just right it makes the sound,, either check the valve by turning it on and off while water is running that will let you know wich one it is

the only time it's the valve is when you loose pressure on the hot side of any faucet, depending on the age of it you could just call the company bosch and they will tell you how far away a real tech is from you and contact them for you, you do have a 1 year labor 5 year parts warranty with the tankless unit, for you I hope you are within your warranty,,,, if not change it to a rinnai system the will send people to you if you have a problem

It's inside a removable inspection plate on the side of the heater - ususallly real close to the heating element.

Bosch has had problems with these heaters for sure. They are the best known thing out there in the market.They are mostly responsible for the bad rap being given to all tankless heaters, but a big part of the problem is installation. They are being sold to homeowners at box stores as DIY kits. These are not units to be homeowner installed, venting and fuel requirements are different from regular heaters and they will not function correctly if improperly installed. I have installed several of the Rannai units over the past few years without any issue whatsoever.

the diaphram is the pushing force for the gas valve to open, if you have a split or worn diaphram it will ned to be replaced.

Hi Welcome to fixit.com
Make sure the gas/propane is on and or working elsewhere in the house. If the piolet wont light ....and its a standing flame piolet ....its the thermocouple gone bad. Please rember to leave me some positive feedback ! Thanks !

sounds like your mixing valve or tempering valve not unit.Somewhere there is a unit that prevents scalding temperatures- I expect this is your issue find and adjust this first- there are directions on it when you find it.

First thing I would do is clean and rebuild the watervalve. The watervalve on this heater mandates everything. This watervalve has a maintenance schedule in the manual. She be rebuilt every 3 years. Also sounds like the diaphram in the watervalve may be damaged.

Sounds like you're dealing with a pesky issue. It could be a technical glitch or just a setting hiccup. Have you tried resetting the timer or checking the settings? If that doesn't do the trick, it might be worth getting a professional to take a look.U can also check some info about alphamechanicals. They got my air conditioning installation in Orangevale, CA https://alphamechanicals.com/service-area/orangevale-hvac-service/ and as I know they has to know something about bosch devices

Losing pendant displays on cool to cold mornings with your Bosch Highflow 25 EC hot water heater could be caused by temperature-related issues affecting the display module. Cold temperatures can affect electronic components, causing them to malfunction. It's possible that there could be a loose connection, moisture buildup, or a fault in the display module itself. I'd recommend contacting Bosch customer support or a qualified technician to diagnose and fix the issue.

If your Bosch Highflow 21e hot water system is experiencing fluctuations in water temperature while showering, it could be caused by a few different factors. Here are some possible reasons for this issue:

1. Flow rate too high: The hot water system may not be able to keep up with the demand if the showerhead or tap is allowing too much water to flow through. This can cause the water temperature to drop suddenly. Try reducing the flow rate by turning down the tap or using a low-flow showerhead.
2. Water pressure fluctuations: If the water pressure in your home fluctuates, it can cause the hot water temperature to vary. This can be caused by various factors, such as other appliances using water at the same time, or changes in municipal water supply pressure. Installing a pressure regulator or a flow restrictor may help to stabilize water pressure.
3. Blocked or dirty water filter: A clogged or dirty water filter in the hot water system can restrict water flow, causing the water temperature to fluctuate. Check the filter and clean or replace it if necessary.
4. Malfunctioning thermostatic mixing valve: The thermostatic mixing valve (TMV) regulates the water temperature in the hot water system. If it's faulty or dirty, it can cause temperature fluctuations. A licensed plumber or technician can inspect the valve and replace it if necessary.
5. Faulty temperature sensor or control board: If the temperature sensor or control board in the hot water system is faulty, it may not be able to maintain a consistent water temperature. A technician can diagnose the issue and repair or replace the faulty component.

If you're unsure about how to diagnose or fix the issue with your hot water system, it's best to contact a licensed plumber or technician for assistance.

The Bosch JSRZ 5-T PG tankless gas water heater may not start automatically because of problems with the magnetic sensor valve, power supply, or control unit/thermostat. Possible troubleshooting steps are:

• inspect the water inlet valve and replace if faulty
• confirm that power to the unit is functioning
• if the problem continues, seek professional repair service.

Do you live in a climate where the hot water line could have frozen? If your heater did freeze up, that could be very bad. This is because water actually expands when it freezes and can do a lot of damage to pipes and to the water heater itself. My other thought is possibly a clogged in line water filter. But typically a clogged water filter would make it run with reduced pressure rather than a complete shutdown all water flow.

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