Bosch AquaStar 125B NG Natural Gas Tankless Water Heater

Bosch AquaStar 125B NG Natural Gas Tankless Water Heater

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  • Excellent! If you understand what you are getting.

    May 12, 2010 by
    Rated a Very Helpful Review
    Pros: Small footprint, water heats quite quickly and never runs out, decent gas savings. 
    Cons: Proper installation is key, routine maintenance is required, you will spend more up front.

    Summary: I purchased a new Bosch 125B NG for about $300 on a great sale. It replaced my old 40gal tank heater from the early 1990's that was starting to leak. On the whole, I could not be happier with the unit. My wife and I are thrilled! But, as others have ... read more

  • Bosch AquaStar 125B Tankless Water Heaters... Meet High Demand North Americans

    Dec 18, 2007 by
    Rated a Very Helpful Review
    Pros: Good for the environment, save energy, no standby losses, compact.
    Cons: Often don't meet high water demands of North Americans, need maintenance plans factored in.

    Summary: Tankless, gas-fired, instantaneous water heaters have been trying to break into the North American markets since the late 1970's and early 1980's. It therefore isn't "new" technology, as countries like England, Germany, and Japan have all been ... read more

  • Bosch Aquastar 125 -- The modern solution to hot water

    May 13, 2007 by
    Rated a Very Helpful Review
    Pros: Energy savings, space savings, continuous hot water on demand, long life, earthquake safe.
    Cons: I had one service call during the last eight years.

    Summary: I have used a Bosch Aquastar 125 in my home serving a family of four for more than 8 years. This water heater works like a spa water heater by heating water as it senses water passing through a heating chamber. It is "on" only while the water is ... read more

  • When Size Really Matters: Tanks to Bosch, we're back in hot water

    Feb 18, 2005 by
    Rated a Very Helpful Review
    Pros: Takes up next to no space, endless hot water
    Cons: A bit difficult to install yourself

    Summary: Here’s the scenario: One Sunday morning, I took my usual shower and noticed the water was tepid, not hot like I prefer. As I got ready to leave the house, I mentioned to DH that either The Child had run us out of hot water (yet again) when he took ... read more

  • Endless hot showers... How could you not love this thing?!

    Jan 11, 2008 by
    Rated a Very Helpful Review
    Pros: It saves space. It's cheaper than any other tankless heaters I've seen. It's energy efficient.
    Cons: Difficult installation. Temperature varies. Faucet must be fully on to operate (no hot water trickle).

    Summary: The following review was my initial opinion of the Aquastar 125B. I have updated the title and pros/cons to better suit my current opinion but I'll leave the review alone because I think it helps illustrate how this heater can take some dialing in and ... read more

  • Just installed mine. I like it so far.

    Oct 8, 2006 by
    Rated a Very Helpful Review
    Pros: Inexpensive for a gas tankless. Works well. Saves space.
    Cons: Pilot light instead of electric start. A lot of work to install. Require maintenance.

    Summary: After 11 years, my 50gal gas water heater started leaking. I shopped around for alternatives, and decided that tankless was too expensive. I was at Lowe's to buy a new tank for $338, when I saw the Bosch 125B on clearance for $369. It's normally $499, ... read more

  • Bosch 125B

    Oct 27, 2008 by
    Rated a Very Helpful Review
    Pros: Lowest cost in it's class. Hmmm it's the only one in it's class...
    Cons: . If you like Russian autos, you'll love this.

    Summary: Having installed tankless for decades my experience says use this for one fixture at a time and do your homework before purchasing any tankless. If you do not feel you can service this, do not purchase it. In hard water after a few years of no service, ... read more

  • nice if you are looking for low price, but quality is not there

    Mar 22, 2008 by
    Rated a Very Helpful Review
    Pros: tankless
    Cons: 2 holes to the outside, quality is poor, size, breaks often.

    Summary: had it for quite some time and would not buy it again. Too little for more than 1 bedroom house, breaks often, repairs and replacement parts are not so easy to find and expensive. when installing have to make 2 holes to the outside because it needs to ... read more

  • Bosch AquaStar 125B NG Natural Gas Tankless Water Heater

    Mar 6, 2008 by
    Rated a Helpful Review
    Pros: you have Pro & has done 5 installs/give him your info-he'll know.
    Cons: No Pro you're taking chances. if it was your wifes suggestion, you might have chance.

    Summary: My experience was in my own home. I could hardly wait for my water heater to go out... my 40gal. track-house unit lasted 18yrs. I purchased mine from home-depot, and bought the highest output rated unit they had. My problem was wife and Daughter.. It ... read more

  • WARNING - things you should know about a tankless heater

    Mar 1, 2008 by
    Rated a Very Helpful Review
    Pros: Pros: Endless (but limited volume of) hot water, smaller than tank.
    Cons: Cons: Temperature surges, expensive, maintenance

    Summary: Note: I donít own this hot water heater, but I own a similar one. The comments I make here apply to all tankless heaters, regardless of brand. These are things you should consider before making a purchase. They are also things you wonít hear from the ... read more

  • I like it but I had to fix it

    Aug 17, 2005 by
    Rated a Very Helpful Review
    Pros: Smallest hot water heater, unlimited hot water, runs two showers at once.
    Cons: Cost, Maintenance and Installation

    Summary: I like this thing. Sure it's expensive, requires maintenance and was a real challenge to install, but it saved a ton of space. I now have a hot water heater, microwave, dishwasher, a little counter space and 3 shelves in the same space that used to ... read more

  • Don't waste your money .

    Jun 22, 2011 by
    Rated a Helpful Review
    Pros: Endless supply of hot water. Space saving design.
    Cons: No one seems to know how to service them. Endless repairs.

    Summary: We bought our Bosch Tankless water heater five years ago after building our first new home. We had two teenage daughters, and were excited about the endless supply of hot water and were impressed with the Energystar ratings. Well, it didn't take long ... read more

  • Bosch Support is a Nightmare

    Jan 22, 2010 by
    Rated a Very Helpful Review
    Pros: A very long hot shower is always available.
    Cons: Lack of qualified companies that install or fix a unit that has quit.

    Summary: Warning – Technical Support at Bosch is an absolute nightmare!  Before you buy this product, do yourself a huge favor and call their customer support line to see how long it takes to get the help you need.  I averaged sixteen minutes to ... read more

  • Ok Unit, If you're handy

    Dec 18, 2009 by
    Rated a Very Helpful Review
    Pros: Constant hot water.  Nice for taking really long showers or when company is over.
    Cons: Just read the main review.

    Summary: I've owned this model for about 5 years now, after buying it to replace a worn out 40 gallon tank.  Buyer beware...the $500 purchase price does not reflect the full price to get this unit up and running.  You can offset many of the costs if ... read more

  • Good, if you donít take bathís/donít ever have guests /like adjusting things

    Dec 30, 2006 by
    Rated a Very Helpful Review
    Pros: good for cottages, one person house holds, for spatially challenged areas.
    Cons: Horrible: Output GPM, COST of Unit, installation, maintenance.

    Summary: I've installed one in my home also. At first I was satisfied, but now I have grown annoyed with the heater. No one else in the household can use the hot water while you’re in the shower, or else you will get doused with cold water. Also, it takes ... read more

  • Maintenance

    Mar 4, 2005 by
    Rated a Helpful Review
    Pros: All fixtures are low flow we can run two showers simultaneously with no problem.
    Cons: WARNING: Check CEC web site required maintenance every 2-5 years. High maintenance cost!!!!

    Summary: Had this product installed in a new house when built. Cost was a little higher than conventional hot water heater, but I believed that they would be outweighed by the long term benefits. Having been stationed in Germany for seven years, I had a lot of ... read more

  • Don't Buy Bosch Water Heater

    Dec 30, 2009 by
    Rated a Very Helpful Review
    Pros: Endless hot water when it works!
    Cons: Unreliable, inconvenient, over-engineered.

    Summary: I built my dream house and immediately planned for a tank-less water heater. Designed the plumbing system for it, had a special place built in the house for it, and decided on Bosch because of their good reputation in the automotive industry. One morning ... read more

  • Aquastar 125 hx dont buy

    Sep 15, 2009 by
    Rated a Helpful Review
    Pros: hot water all the time
    no tank so you have extra storage space
    hangs on the wall
    Cons:  maintennance is high-quality of plastic parts and glues are questionable-expensive parts

    Summary: this unit is less than 4 years old - every year for 4 years  the carbon builds up so it has to be regularly cleaned in order so that it can  ignite -On a second visit the plumber decided to give me his steel cleaner and he showed me ... read more

  • Nothing but Trouble

    May 13, 2008 by
    Rated a Helpful Review
    Pros: Available at Lowes for a good price
    Cons: Bosch said I should PAY a plumber to repair new heater!

    Summary: My first Bosh water heater I bought from Lowes. I paid $150 to have it installed and we were not able to get it lit. After it would not light I called Bosch they wanted me to pay for a plumber to come out and repair it.I asked the operator if they would ... read more

  • Expensive to own and use

    Apr 22, 2008 by
    Rated a Very Helpful Review
    Pros: Endless hot water.
    Cons: Hard to control temperature + other high costs.

    Summary: I have had this unit for about 6 years. I was happy once I go over the installation and it was all said and done. We did enjoy not running out of ho water but there are some huge trade offs. You will immediately notice that you cannot control the amount ... read more

  • NEVER PURCHASE A BOSCH -Faulty products, Zero customer service

    Nov 5, 2007 by
    Rated a Helpful Review
    Pros: none
    Cons: EVERYTHING! wastes water, won't stay lit, unethical tech support behavior

    Summary: Since the purchase of this faulty water heater, it has never worked right and has been a persistent problem. It can shut off 3 times during a single shower, or the pilot light may extinguish when not even in use. For years I have been on the phone ... read more

  • If you enjoy wasting time and money and WATER- BUY A BOSCH TANKLESS

    Dec 10, 2006 by
    Rated a Very Helpful Review
    Pros: Absolutely NONE
    Cons: Expensive, wastes water, no tech support, EXPENSIVE to call plumbers who know NOTHING

    Summary: I just built my "dream home of a lifetime" - Chattahoochee Riverfront in the North Georgia Mountains. We wanted our home to be top quality, state-of-the-art. We did research (Not as much as we SHOULD have, turned out) and bought the Bosch Tankless ... read more

  • Aqua Star Bosch tankless water heater

    Nov 28, 2006 by
    Rated a Helpful Review
    Pros: space saver, illusion of continuous hot water
    Cons: cost, high maint., poor performance, horrible service, low water pressure.

    Summary: The 125 has a plastic water valve, replacement part is $150 for another piece of plastic. Mine exploded less than 3 years after installation, but after the 2 yr warranty on parts had expired. The box gloats of a 15 yr. warranty if professionally ... read more

  • No Support for Two Year Old Water Heater

    Nov 12, 2006 by
    Rated a Helpful Review
    Pros: small size, no pilot light
    Cons: water not HOT, no service, and too expensive for a boat anchor, probably floats.

    Summary: I have a Bosch AuqaStar and installed it to save money and "do the right thing energy-wise". What a mistake. I could have bought at least conventional water heater for what I paid for the tankless. I could live with that if it was a money saver. It ... read more

  • Aquastar 125 BNG

    Aug 11, 2005 by
    Rated a Very Helpful Review
    Pros: Constant hot water if you like to be scalded.
    Cons: Demands consistent cold supply water

    Summary: At first we thought "what a great idea... saving money and energy", but the cons out weight the pros of this unit. We bought the Bosch Aquastar 125BNG tankless water heater from Home Depot to replace our still running 21 year old 40 gallon water heater. ... read more

  • Express Customer Reviews

  • Great service in BC

    Nov 6, 2012 by
    Rated Show
    Pros: Our 25 year old Paloma was serviced and is good for another 25 years!
    Cons: Our reconditioned Bosch is in a laundry shed supplying washer and shower.

    Summary: Astravan Ltd. in North Vancouver BC, Canada offers excellent support and does amazing service on tankless hot water heaters.  You do have to take the machine to them, which is not a big deal.  We took ours in off season from the ... read more

  • 10 years good hot water

    Jul 2, 2009 by
    Rated Show
    Pros: endless hot water.
    Cons: less flow and one shower a time.

    Summary: I had this water heater for 10 years. The reason I got this water heater is that I am not strong enough to handle 50 gallon water tank. My son helped me remove the old tank and still dented on the garage floor.  Took me couple hours to install ... read more

  • Best water heater I have ever owned.

    Apr 26, 2009 by
    Rated Show
    Pros: No wait between showers/baths.
    Trouble-free operation
    Less expensive to operate.
    Cons: Can be more expensive start taking REALLY LONG showers.

    Summary: This unit was a bit of a pain to install because of the larger vent requirement, but wasn't a major issue.I have owned this water heater for 9 years, and have never had any trouble with it. I do have to adjust the temperature twice a year, once ... read more

  • Really great for my small house!

    Jan 30, 2008 by
    Rated Show
    Pros: Space saving and saves energy. No electricity required.
    Cons: Costs more than a tank water heater.

    Summary: Endless hot water in the shower / bath and I was surprised how much money it saves me. I switched from an electric hot water heater with a tank and I am saving about 30% on the energy. This is a reliable unit. I have it installed in a pumphouse with ... read more

  • We love it!

    Dec 28, 2007 by
    Rated Show
    Pros: Endless hot water. Energy savings. Takes up almost no space.
    Cons: Somewhat more complicated than your ordinary tank heater.

    Summary: After replacing an old conventional water heater, we have depended on the Bosch 125B for over one year. Like with all technical products it is important to understand how they work. It is fair to say that a tankless heater is more complicated than one ... read more

  • Love this unit!

    May 21, 2006 by
    Rated Show
    Pros: Endless hot water; space saving; reliable.
    Cons: Must not flush toilet/fill washer while someone is showering - reduces cold water pressure.

    Summary: I had this water heater (then made by e.l.m.) installed early in 1995. I had it professionally installed as I did not even have a gas outlet or flue in the room. It has been worth it's weight in gold; we have showered by candlelight when the power was ... read more

  • so far so good

    Sep 29, 2005 by
    Rated Show
    Pros: limitless hot water, silent, saves energy, compact
    Cons: handheld showers can go cold if the pressure isn't constant

    Summary: We got our tankless hot water heater about two years ago primarily to do our bit to help the environment by cutting down on energy use. We have been happy with it so far with no problems. It does indeed give limitless hot water although sometimes the ... read more

  • A Bit of HEAVEN!!

    Apr 22, 2005 by
    Rated Show
    Pros: size (NO bulky tank), endless hot water even with power outage, low bills, low maintenance
    Cons: short duration of decreased water flow if another appliance/person uses at same time

    Summary: Have had the unit for 6 plus years in our vacation house we use every other weekend. I LOVE IT! PROS: --No more fear of using up all the hot water when someone is taking a bath behind you. --Hot water even if the electric power goes out! --The first ... read more

  • Bought it 3 years ago and love it!

    May 5, 2006 by
    Rated Show
    Pros: Energy efficient. Never run out of hot water!
    Cons: Sensitive to water pressure--turning on too much cold water and the heater shuts off.

    Summary: I have had my AquaStar 125B for 3 years. I bought it mainly to save space as my 30 gallon was blocking part of the door into my utility room. I had it professionally installed but even this was a difficult and lengthy process. The installer had to ... read more

  • Endless hot water fits my needs

    Apr 12, 2005 by
    Rated Show
    Pros: Provides all the hot water I need,energy efficient and space saving.
    Cons: Installation is time consuming.

    Summary: I purchased a 110 gallon therapy tub and my 40 gallon heater just didn't cut it. The recovery time took almost 2 hours to fill at a 108 deg temp. After installing the 125B I filled the tub with 110 deg water in 40 min. The installation was harder and ... read more

  • aquastar 125b return line on heat exchanger bursts

    Feb 10, 2009 by
    Rated Show
    Pros: Never a problem other than that.
    Cons: Heat exchanger replacement costs $250.00 or silver solder repair $60.00.

    Summary: Owned for 10 years--only bursts in winter.  Used double wall vent pipe,  six foot horizontal run before exterior wall penetration and vertical run six foot outside.  Return line burst three times in past in same location.  Is it cold ... read more

  • Don't buy it

    Aug 22, 2007 by
    Rated Show
    Pros: Takes up little space, can't shower and run water in other areas at same time.
    Cons: Terrible customer service, hardly any licensed repairmen, expensive.

    Summary: We've had our Bosch for just under 3 years and it worked fine until the last six months. Suddenly the hot water is only intermittent. My husband, who is a licensed plumber, installed the unit and called customer service to get advice on what might be ... read more


    Oct 20, 2011 by
    Rated Show
    Pros: small
    Cons: TERRIBLE customer service, faulty product not once but twice!

    Summary: We have not even been in our newly built home for 3 years and we have already had to replace the unit not once but twice!! Last summer we went 1 month with constant problems and little to no hot water before finally diagnosing the problem-- the whole ... read more

  • Bosch tankless water heater - think again!

    Mar 7, 2011 by
    Rated Show
    Pros: Plenty of hot water, once it gets there.
    Cons: Tremendous waste of water.  High repair costs.  Forget customer service.

    Summary: We have had our tankless water heater from Bosch for a little over three years.  In that time we have noticed very little decrease in our natural gas usage, but a hugh increase in our water and sewage bills.  While the company portends that ... read more

  • Tankless water heater, big price, big mistake

    Oct 17, 2010 by
    Rated Show
    Pros: Storage size
    Cons: Hot water not consistent.

    Summary: We bought a Bosch 250 about 3 years ago. Unit was costly and installation was expensive.  As with many of the complaints you've probably read, I cannot run hot water anywhere else in the house if I plan to use the shower.  Since the ... read more

  • Scalding or ice cold are the only settings

    Jul 29, 2008 by
    Rated Show
    Pros: saves lots of energy when you can only take a 3 minute warm shower
    Cons: Sometimes I need more than 3 minutes of warm water, replace old gas lines

    Summary: I have seen similar reviews from people who have had the same experience as me. The water starts cold, warms up, then becomes scalding hot (without me changing from the "warm" setting), and when I try to put it back to warm, it shuts off all hot water. ... read more

  • Do not Buy a Bosch tankless

    Feb 26, 2008 by
    Rated Show
    Pros: Lots of HOT WATER
    Cons: Non-returnable new parts, no money savings and could fail in a short time.

    Summary: I purchase a Bosch Aquastar system hoping to save money. So far the system Cost has outweighed any benefits. The system cost with taxes nearly US Dollars $2000.00 The installation for Pipes (certain size and stainless still exhaust installation by ... read more


    Jul 12, 2007 by
    Rated Show
    Pros: none..does take less space
    Cons: read above

    Summary: Customer service is horrible for one..Takes forever to get tech support...They battery on the phone runs down or the lunch hr is used up.. The product is lousy for another..the housing around the control panel cracked and water was seeping out causing ... read more

  • Bosch 240sx

    Jan 14, 2007 by
    Rated Show
    Pros: Nice idea when it works
    Cons: bad company {both Bosch and Solarbiz}, many error codes have to reset often

    Summary: Nice idea bad company: I bought two of these units {Bosch 240sx} from an online dealer {Solarbiz} (Big mistake: I would suggest buying from the same people who are to install the unit) He didn't want to know me when I had a problem after the sale. He ... read more

  • aquastar 250x

    Dec 24, 2006 by
    Rated Show
    Pros: space saver
    Cons: tempermental, doesnt work holidays or weekends. tech support sucks

    Summary: what a mistake, a $1,000.0 plus mistake. i installed this 7 months ago. the first week is made a loud whislting noise through the vent the whole neighborhood could hear. I called the tech line, waited on the phone for 1 hour. he told me to make an ... read more

  • These things suck

    Oct 24, 2006 by
    Rated Show
    Pros: None
    Cons: Too many to mention here.

    Summary: Tankless water heaters should be avoided like the plague. Any gas savings will be offset by enormously increased water bills. In addition, you get to stand around at the sink or shower waiting for the water to heat up -- what used to take seconds in our ... read more

  • Avoid like the plague! Very high maintenance

    Dec 16, 2005 by
    Rated Show
    Pros: it is tankless
    Cons: very high maintenance and expensive to maintain

    Summary: It is nice when it works, but it breaks down a lot. Most plumbers don't know how to fix it, and even if they are willing to learn they charge you the hourly rate for their education. Service from the manufacturer's representative is quite poor. Parts are ... read more

  • High maintainence water heater-not recommended

    Jun 26, 2005 by
    Rated Show
    Pros: Compact size, delivers continous flow of hot water when working.
    Cons: High maintainence, energy factor of the 125b is the same as well-insulated tank.

    Summary: Installed a 125b 3.5 years ago. I choose tankless due to the need to install a unit in a small space and the potential energy savings. The unit generally works well but the pilot light goes out about 3 times a year with the need to clean the pilot ... read more

  • Thumbs Down to the Aquastar 240fx

    Jun 5, 2005 by
    Rated Show
    Pros: Tankless concept looks great on paper
    Cons: 1.Water temperature fluctuates,cost too high

    Summary: Talk about planned obsolescence-We purchased an Aquastar 240fx just 2 years and 4 months ago. The only ting that's under warrenty after that is the heat exchanger.The unit came up with a flashing light and cold water yesterday. I was on hold almost an ... read more

  • Aqua Star 125 expensive to buy, install and maintain.

    Mar 4, 2005 by
    Rated Show
    Pros: Small space required for installation
    Cons: Expensive to buy, install and maintain. Very limited service support for the product.

    Summary: I have owned an Aqua Star 125 for 8 years. Just recently converted back to a high efficiency water tank. During my period of ownership, I experienced high maintenance costs, poor service, and a lack of support from the manufacturer with problems. ... read more

  • To Potential customers of a Bosch Tankless Water Heater

    Jan 18, 2010 by
    Rated Show
    Pros: Lower cost of energy when they work
    Cons: They are absolutely unreliable and the company provides unacceptable support.

    Summary: From a current owner of a Bosch Tankless Water Heater. Do not buy one.  The first unit we installed failed often with EA errors (No flame ionization detected with water flow) and had to be replaced. The second unit worked for a year ... read more

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