Bosch Aquastar Tankless Review

Discussion in 'Tankless Water Heater Forum' started by debbethune, Jan 31, 2013.

  1. debbethune

    debbethune New Member

    May 11, 2011
    I just wanted to give a review of the Bosch Aquastar 125vp tankless heater, which is a propane model. I installed this unit in my home in 1987 and it is still working flawlessly today, in 2013. Yep, that's 26 years. Try doing that with any tank heater. And maintenance? Even though they recommend flushing the coil every year or so and replacing some parts periodically, I did a flush one time in 26 years and even then, it didn't really look like it needed it. I had a the diaphragm and a few other parts replaced in a one-time preventative maintenance at a cost of about $400 (and that's parts and labor). That was probably 10 years ago. This is even more amazing since I am on well water, although I do have a water softener installed. Other than the one preventative maintenance, we have had no issues with the heater. Needless to say, I have been very pleased with the Bosch Aquastar name. I would highly recommend tankess, but it's not for everyone and you need to understand its limitations and be willing to work within those. The model I have will only heat one shower at a time. You can get bigger models, but since we only have a 2-person household, this worked for us. If you have a large family, however, with several people typically showering at the same time, I doubt you would be happy with a tankless. The only other quirk is you need to understand how the unit senses when it needs to turn the burner on or off. First, you need to make sure you have a certain minimum water flow. So if you have a lower-flow shower head, for instance, you may need to boost the flow so the unit doesn't turn itself off leaving you in cold water. We accommodate this by turning on the vanity faucet to a 1/4" stream when using the low-flow shower. Problem solved. Next, you don't want to quickly adjust the hot water flow downward or, again, you risk an unexpected cold blast. Small, slow adjustments work best, keeping in mind that there must always be sufficient hot water demand through the unit to keep it from turning off. This may even mean turning DOWN the temperature at which you set your unit so that you have to increase ow much you open the hot water valves at your faucets. You just need to be patient and learn what works for your unit.
  2. Brian D

    Brian D New Member

    Aug 20, 2013
    I had purchased my Aquastar (not Bosch) about that same time. It is a 125?? model, it is one that measured out going water temp and adjusted gas flow accordingly. That feature only lasted less than ten years, after it quit, I bypassed the sensor and the performance really wasn't any different. A few years after I got it we had a cold winter and the air backflowed freezing and cracking the heat exchanger. After replacing the heat exchanger was just cleaning the pilot orifice and a couple minor things like that.

    Overall 25+ years with 5 in the family(2 bathrooms), we always had enough water. The freezing heat exchanger was my fault for not installing the flue properly. But now its time to replace it, I'm shopping for a new one now. Right now it has a pinhole leak in the heat exchanger, drip....drip, and two days ago a crack developed in the control unit putting it out of service for good. Absolutely no idea how the crack got there, but gas leaks through it when it starts, not good, it wasn't there a couple weeks ago when I was looking at it.

    Well these things aren't meant to last forever.
    Last edited: Aug 20, 2013
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  4. Brian D

    Brian D New Member

    Aug 20, 2013
    One thing I did was make sure my shower heads were not too low flow and I had no problem with heater not starting.(hey I'm in Michigan we have lots of water) One thing I did was add a thermostatic tempering valve to the water line that went upstairs to the kids bathroom, when they were little I did not want them to get a blast of too hot water in the shower, it worked great.
  5. ElenaXena

    ElenaXena New Member

    Oct 9, 2013
    Austin TX
    "Even though they recommend flushing the coil every year or so and replacing some parts periodically, I did a flush one time in 26 years..."

    Shortly after returning to the US after living in Switzerland where tankless heaters have been in use for many years, I had a new natural gas 125K AquaStar tankless installed in 1987. A couple months after installation the burners would not ignite and I had to "flush it". After that experience I promised myself that I would throw the dang thing out if I ever had to do it again. Most people probably would have rushed to install a water softener...a high maintenance appliance if there ever was one!

    Fortunately, with a little online research, I learned about installing a pair of magnets with cable ties onto the main supply line house side of the water meter and another pair of magnets on the heater's hot water OUTPUT to keep the lines clean of ALL deposits. Once the magnets are installed it's a set it and forget it moving parts involved. YouTube has a video.

    As explained to me back in 1987, this is why the magnets work: The first pair of magnets sends positively-charged molecules of water to the heater but, as the water passes through the heat exchanger, the molecules become all jumbled up and lose their positive "alignment". It takes the second smaller pair of magnets that fit the smaller outlet pipe to re-align the water molecules and that positive re-charge keeps the pipes clean of deposits. Too simple - it must be voodoo.

    Why did I have to remove the aerators from all the faucets in the house? Because, I was told, in 2- 3 weeks time ALL the old deposit accumulation will be removed in the water lines of my home built in the 1960's. If I didn't see a difference, I was guaranteed my money would be refunded. Needless to say, I didn't ask for a refund and $300 was a big expense for me back when.

    Luby's, a restaurant chain down on I-35, had these magnets installed after replacing their copper pipes when the water lines clogged the supply to their commercial dishwashers. The high BTU tankless heater supply to their dishwashers caused the mineral buildup in the pipes. I was shown a cutaway of the original copper pipe that was removed when the water lines were replaced and the buildup was so excessive only a pinhole was visible. The magnets have kept the new lines clean and they are still in place.

    There was one time I called for service for a different matter that required turning off the water main. Imagine my surprise when I just happened to see the tech put the pair of magnets he had removed from the main into his truck! Gotta' be watchful.
    Would a retailer/repair company even talk about magnets if a tankless heater functions longer with minimal maintenance? "Planned Obsolescence" is built in to most, if not all appliances or it costs an arm and a leg for parts and labor to repair.

    I have read all the reviews about magnets and what a scam they are thought to be. But my experience proves to me the reason my Aqua Star has functioned all these years with minimal maintenance (just a diaphragm in the water valve and a small washer on the push valve replaced). We have very hard water in Austin and high intensity burners compound the problem but I have maintained this unit all these years by following the instructions in the owners manual. I didn't find this forum until today or I would have posted my experience using the magnets sooner.

    There are a few companies out there selling magnets of different colors, but all share the same basic principles of physics. I found mine down the road in Schertz (Texas, that is). In my opinion, manufacturers don't do a good job of explaining to homeowners how and why the magnets work in solving these water treatment issues. People everywhere could save a lot of money and also help the environment by switching to tankless heaters. It's especially difficult to accept that many homeowners return to the tank-type heaters for lack of information and a lot of false information about maintaining a tankless water heater. My take on this FWIW
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