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Forum Index : Other Stuff : Off grid Bosch HWS repair

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Joined: 03/11/2015
Location: Australia
Posts: 28
Posted: 09:30am 20 Aug 2019
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I have a Bosch 10H HWS operating on LPG that is gradually losing its ability to provide really hot water. The degradation is slow over the past year or so but the water is now only very warm rather than hot. I have adjusted the two controls that are available to normal consumers although they work (able to modify the gas output and water volume) the water is still not hot enough. I have also replaced the main diaphragm which stopped a small leak but that also has no effect on the hot water temperature. Lastly, also replaced the regulator between the LPG gas cylinders and the HWS but that also made no difference. Everything else looks fine and clean.
Any suggestions from handy people here who may be off gridders ?

Joined: 25/07/2019
Location: Australia
Posts: 3
Posted: 10:29am 20 Aug 2019
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sounds like an instant hws to me and they work on reduced water flow to give the heat from the gas burner time to heat the water going through the core and heat from the gas burner so one of those functions has changed.id check the gas jet/burner and see if its blocked.does the flow coming out of the unit seem greater then before?

Joined: 09/08/2007
Location: Australia
Posts: 3324
Posted: 10:33pm 20 Aug 2019
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This short video will probably not tell you anything you don't already know.


But it really all comes down to water flow and gas flow.

My own unit is Rinnai not Bosch, but there will always be a burner gas pressure test port.  The correct burner pressure is often listed on the rating plate, or it will be in the service manual for certain. If that is o/k and the burner jet is not obviously blocked or damaged, then it has to be an excess water flow problem.
Cheers, Tony.
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