Bosch 125B-NG AquaStar Natural Gas Tankless Water Heater

by Bosch

Product Description

From the Manufacturer

Cut water-heating costs by up to 50 percent with the Bosch AquaStar 125B-NG tankless water heater. The 125B-NG is fueled by natural gas and heats water on demand, supplying hot water at a rate of 4.3 gallons per minute--enough to meet the needs of one major application (shower, dishwasher, etc.) at a time. The 125B-NG uses a standing pilot for ignition. Stainless steel burners and a copper heat exchanger help ensure long life, and a modulating gas valve provides temperature control. A boon for basement-finishing plans, the 125B-NG takes up much less space than a tank heater and can be mounted in a closet or on a wall on included hooks. The unit is designed to vent vertically, but the optional AQ1 kit allows you to vent it horizontally through a wall. The purchase is covered by a manufacturer’s 12-year limited warranty on the heat exchanger and a two-year limited warranty on parts. Check with your gas provider for energy rebates on this purchase.

Product Details

Choose the Right Water Heater [1.16mb PDF]

• Product Dimensions: 8.8 x 18.2 x 29.8 inches
• Shipping Weight: 43 pounds
• Shipping: This item is also available for shipping to select countries outside the U.S.
• Shipping Advisory: This item must be shipped separately from other items in your order. Additional shipping charges will not apply.
• ASIN: B0006GVNZ4
• Item model number: AQ125B_NG
• Average Customer Review: 3.6 out of 5 stars  See all reviews (23 customer reviews)
• Amazon Best Sellers Rank: #324,450 in Home Improvement (See Top 100 in Home Improvement)
• Discontinued by manufacturer: Yes

Customer Reviews

Most Helpful Customer Reviews

37 of 37 people found the following review helpful:

5.0 out of 5 stars This is an excellent unit, April 22, 2006

By 

bob sacamano (USA) - See all my reviews

This review is from: Bosch 125B-NG AquaStar Natural Gas Tankless Water Heater (Tools & Home Improvement)

Well, looks like my prior review on 4/22 has been deleted. I highly suspect that the complainers here, or one of them, "reported" me because I referred to their reviews and that probably violated policy, yada yada yada.

Ain't it the way of the world? Wonder how long this one will last.

In any event, if you are at all interested in the AquaStar, just listen to the positive reviewers, hook it up properly, and you'll be very happy with it I'm sure.

I suspect that the most common problems folks have are twofold:

1) They probably don't use the required 3/4" gas supply pipe and try to get by with the old 1/2" pipe that supplied their old tank-type hot water heater. Most 30-40 gallon tank types have a BTU input specification of 40,000 BTU's. The 1/2" supply line is adequate for that number of BTU's, but the AquaStar requires 117,000 BTU's and that's three (3) times as much. Thus you DO need to use the 3/4" supply line or you're just not feeding the thing enough fuel.

Don't give it enough gas to burn and what do you think is going to happen?

2) A lot of folks might try to get by with the old 3" vent pipe their old heater used. Again, that's not going to work. You NEED to vent the AquaStar with the proper-sized vent pipe or it's not going to breathe properly and thus not going to work properly.

Other than that, there's not much to worry about with the installation of this unit.

Install it properly and it will perform well for you and meet your expectations fully for many, many years to come.

Also, as I noted in my amended review previously -- now deleted of course -- this model here has changed from when I bought mine a few years ago. This new 125B has a standing pilot. If you want one like my old 125B, you now need to get the Model 125HX, which has the electronic ignition, as does mine. The difference between mine and that one is that mine uses 2 D-cell batteries, whereas the 125HX uses a water-powered turbine to supply the necessary electical power to fire the unit. Neato.

Also note (as I mentioned previously) that the former manufacturer, CONTROLLED ENERGY CORP., has been acquired and thus is no longer the current manufacturer. Try going to their former website and see for yourself.

I doubt this has compromised the quality or service, but it's something you should know.

19 of 19 people found the following review helpful:

5.0 out of 5 stars big wood construction, December 20, 2005

By 

David A. Wood "Big Wood Construction" (Los Angeles Suberb, CA) - See all my reviews
(REAL NAME)   

This review is from: Bosch 125B-NG AquaStar Natural Gas Tankless Water Heater (Tools & Home Improvement)

After reading several reviews on the Aquastar, I was coinvinced to write a review after reading W. Youngs' review. From personal use of the water heater in my own home and installing seveal higher priced competitors models in customers homes, I am happy that I installed the Aquastar for myself. First of all, the Aquastar cost at least half of most other models. Second, it does not require any electrical supply saving one less thing to do during installation. Third, Mr. or Mrs. Young must not have done a correct installation because these water heaters definitly work. They may have accidently crossed a cold water line with the hot line allowing cold water to enter through the hot water side of the faucet. Or, maybe they didnt have the right size gas supply to the unit. Overall, this unit performes with the best. I recently moved and already have installed one in my guest house and plan to install one in the main house during upcoming construction. There's nothing like a hot shower after a long, dirty day on the job site.

21 of 22 people found the following review helpful:

5.0 out of 5 stars This unit is a real jewel., July 19, 2005

By 

James A. Collard (Pacific Palisades, California USA) - See all my reviews
(REAL NAME)   

Amazon Verified Purchase

This review is from: Bosch 125B-NG AquaStar Natural Gas Tankless Water Heater (Tools & Home Improvement)

I have installed two of these units and have found them to be excellent water heaters. They are easy to set up, the pilot (if you have one that uses a pilot) lights easily, and they instantly deliver water so hot you will need to adjust it with the cold water tap to not scald yourself. Also, they never run out of hot water and you will save money on your utility bill because, unlike a typical (boiler) water heater the water does not need to be maintained at a constant high temperature whether or not you are currently using it. The water is only heated at the time of demand.