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Bosch Aquastar 125HX Gas Water Heater


Pros: Very economical, endless supply of hot water

I am very pleased with this water heater.  Waiting 30 seconds for water to warm is not a problem when you consider the waste of a conventional water heater reheating water constantly.  My old house was three stories with a conventional water heater in the basement and it took at least the same amount of time for the hot water to reach the third floor.


I now live in a one bedroom apartment loft and have the water heater installed in the bathroom above the toilet to avoid the cold in the garage below.  I believe local building codes for new construction should mandate the installation of tankless water heaters.


Cons: unreliable ignition/expensive to fix

I purchased and installed the aquastar 125HX NG heater in my home in December of 2006. It worked fine for about 2 weeks, then suddenly the ignition was unreliable. After several hours on the phone with their tech support and several diagnostic tests, I wound up having to "wiggle the pigtail" of the pilot burner around until the spark reliably ignited the gas to light the pilot.  Ok, so this worked fine for about 5 years, until last February (2012)...


The pilot stopped lighting. Again on the line with their tech support for several hours over many days, testing pretty much every component on the unit. They also told me the gas pressure was probably too low and that I needed to call out the gas company. I did so...the gas company said the pressure had not changed in at least 12 years. I purchased a new pilot burner and that did nothing. I purchased a new pilot electrovalve and that did nothing. I purchased a gas manometer and tested the gas pressure myself and that was also OK. Finally a friend explained that the spark was probably not getting the proper "burn time" and all this pointed to the electronic control unit. I purchased a new control unit for $ invested a total of over $300 in new parts and finally the unit started lighting again...for about 2 weeks.


Suddenly for a third time it stopped working. Assuming the electronic control valve was still good (seeing as how it was only 2 weeks old) I started "wiggling the pigtail" again.  Finally after an hour I got the pigtail in such a position so that the pilot would reliably light.


Their idea of a pilotless unit with the hydrogenerator is clever, but their technology is unreliable at best. I spent several hundred dollars getting the unit working again and I am now seriously considering replacing the entire unit with a good ole fashioned tank unit.


When the unit was working it was great.  However when you need hot water and can't rely on the water heater, efficiency and value become secondary priorities.


I would not recommend the Bosch Aquastar 125HX to anyone. Since they did not seem to do anything to help support my investment (such as offering to replace the unit), I can't say I'd recommend any Bosch product.


Bosch Aquastar 125HX Gas Water Heater

The Bosch AquaStar is designed to last. The quality of the AquaStar begins with this inside story: all water parts are solid copper or solid plastic. Unlike tank heaters, every part is replaceable or recyclable. Properly maintained, this may be the last water heater you ever buy. * all water parts are high quality copper and plastic * unit is constructed with stainless steel and aluminum * casing is finished with baked epoxy * heat exchanger is made of solid copper * burners are made of stainless steel * unit has a safety thermocouple and overheat shutoff protection * CSA design certified * compliant with ASHRAE 90.1 * longest warranty (12 years on the heat exchanger when professionally installed)

Additional Features
Volume Capacity
Power Source
Energy Factor.84
First Hour Rating2.5 Gallons
Minimum Flow to Activate
Fuel TypePropane
Input117 MBTUH
Water Flow Rate (GPM @ 75 deg. max)
Water Flow Rate (GPM @ 45 deg. max)
Release Date
Model Name/TypeMPNEAN/UPC
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