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On-demand Bosch Confort 13 water only works intermittently

We bought a new on-demand Bosch Confort 13 water heater (in Mexico) for our cottage. It seems to only work intermittently, with the burner not turning on immediately, or turning off when still in use. The unit is new, with fresh new batteries for the ingniter. We have tried adjusting the temperature control, as well as the flame intensity control on the front of the unit with no improvement. There is adequate water pressure and volume, and the 5'' exhaust meets specs. My Spanish is OK for traveling, but not good enough to thoroughly understand the manual. Thanks

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Will still be under warrent call supplier

Posted on Oct 25, 2009

  • fox8337 Jan 07, 2011

    I had the same problem. I think I found the solution. Your water pressure is too low and the heater is shutting off from overheating. Turn the heater way down so you can run only the hot without scalding. This is working for me. I will be installing a pressure booster pump on the water intake line for the heater.



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Upvote the help.
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I have a Bosch confort 13 tankless water heater in my Mexico home. I have had problems with consistent water temperature. My contractor told me they have problems with them down there...not sure if it...

Your contractor understand the market there, but problems are mirrored in US also.
As evidenced by fixya.

1) Tankless cannot be exposed to more than 11 grains hard water, and require minimum water flow and water pressure or sensors will shut down burner or element.

2) For example, tankless might turn on with 2/3 gallon-per-minute water flow, but then another faucet is turned on so pressure and water flow drop, and tankless turns off. Or neighbor's water usage causes decrease in line flow, so tankless turns off. This is called 'cold water sandwich.'

3) If problem is water pressure, you can add in-line pressure tank, but root causes vary widely with more than one factor as suspect.

4) Also incoming water temperature can be a factor, along with temperature setting of unit. Most tankless are preset to 120 degrees F, which is modest temperature and certainly not very high. If tankless cannot raise temperature of incoming water fast enough, then tankless turns off. Of course water flow continues, so you get dose of cold water.
You can add simple120Volt 30 gallon tank-type electric heater as a tempering tank that pre-heats water either passively or actively:

5) Both internal and external factors affect tankless, with bottom line that these high-tech devices are not do-it-yourself repair for most people.

6) Install DIY tank-type gas water heater and avoid the whole headache

7) In my opinion, the genius of tankless is not that they save money or energy. Because they don't.
The genius is marketing that targets a certain affluent who believe tankless save money and energy.

Add a comment for more free help.
Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

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