Bosch 1600H NG AquaStar 4.3 GPM Indoor Tankless Natural Gas Water Heater

by Bosch

Product Description

From the Manufacturer

Who said water can't light a fire? The Bosch AquaStar Model 1600H incorporates a revolutionary hydro-generated ignition system, allowing the heater to operate without a standing pilot, electricity, or a battery. This innovative technology uses the energy from the flowing water to ignite the spark. The Bosch AquaStar Model 1600H is the first tankless water heater of this kind.

Product Description

Bosch, 1 Major Appliance Or Shower At A Time, Hydro Ignition, Natural Gas Tankless Water Heater, Hydro Ignition Means No Standing Pilot Or Electricity Needed, Water Flow Spins The Hyrdro Igniter Which Generates The Millivolts Needed To Ignite The Gas To The Burners, 117,000 BTU Input Delivers 3.3 Gallons Per Minute At A 55 Degree Fahrenheit Rise, Standing Pilot, 1/2 Gallon Flow To Activate Burners, Vertical Venting Only, Must Use 5" Double Wall B Vent Pipe, Modulating Gas Valve From 28,000 To 117,000 BTU's For Optimal Performance, 1/2" Male Nominal Pipe Thread Gas & Water Connections, Natural Gas Pressure, Minimum 7" Water Column To Maximum 14" Water Column, Water Pressure Minimum 18 PSI To Maximum 150 PSI, 69% Energy Factor, 80% Thermal Efficiency, T & P Valve Included, Warranty 12 Years On Heat Exchanger & 2 Years On Parts, Qualifies For The Energy Policy Act Credit, CSA Certified.

Product Details

Energy Guide Manual [PDF]

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Water Heater Manual [PDF]

• Product Dimensions: 8.5 x 16.8 x 25.8 inches ; 33 pounds
• Shipping Weight: 37.4 pounds (View shipping rates and policies)
• 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: B000KXWZ4G
• Item model number: 1600H NG
• Average Customer Review: 2.1 out of 5 stars  See all reviews (25 customer reviews)
• Amazon Best Sellers Rank: #27,573 in Home Improvement (See Top 100 in Home Improvement)
  • #53 in Home Improvement > Rough Plumbing > Water Heaters & Parts > Water Heaters

Customer Reviews

Most Helpful Customer Reviews

52 of 53 people found the following review helpful:

4.0 out of 5 stars My experience with the Aquastar 1600H, December 13, 2007

By 

DoItYourSelfer (Ohio) - See all my reviews

This review is from: Bosch 1600H NG AquaStar 4.3 GPM Indoor Tankless Natural Gas Water Heater (Tools & Home Improvement)

EDIT - 1/11/08 -------------------------------------------------
I've been having trouble with the Aquastar lately. It still works but doesn't like to work when the furnance is running. I assumed the furnance was drawing down the gas pressure in the line but after having the gas company out and an HVAC technician they both concluded the pressure is steady and sufficient. Contacting Bosch technical support has proven to be an exercize in patience to say the least. Each phone call (there have been 3) has taken a minimum of 50 minutes on hold. I've spoken to three different techs and have been given three different solutions. First call, very nice lady, apolgized for the wait, I told her the problems and she sent me a new control box (didn't work). The second time I called, the tech told me it was my problem and not the Aquastar. He said I had insufficient gas pressure (I didn't), said I had a vent back draft (tested, I didn't) basically he blew me off. He gave me the phone number of a local tech (wasn't local-40 miles away) that I'd have to pay for (because it was my problem) to come and diagnose my Aquastar. I decided to call back because I was very unhappy with the technical support I had just received. My intent was to make a complaint, but on my third call I talked to yet another tech who diagnosed yet another possibility. He sent me another part to replace, which still hasn't solved the problem. Which is where I'm at at the moment.

I've done some more research on the internet and it seems that Bosch Hotwater tech support is reknown for poor service. Unfortunately that's something you only find out when the unit isn't working.

I'll have to change my recommendation from a buy to a don't buy at this point based solely on customer service. Hot water is not something you can readily do without for any period of time and if you do have a problem with the Aquastar, waiting days to have it fixed is not a solution.
Another curious observation, why is there such a wait for tech support? Must be a lot of broken Aquastars out there.

END EDIT ------------------------------------------------


I installed the Aquastar 1600H myself in about 3 hours. I bought it at Lowes and like the other reviewer, had to go to HomeDepot to buy the 5" class B ducting. I gave the Lowes sales ppl an ear full about that but it just went in one ear and out the other.

If you're comfortable with sweeting copper and plumbing your own gas lines its really not that difficult. My biggest problem was positioning the unit so I could vent the exhaust gases. If you don't have a straight vent stack and have to feed the exhaust into the chimney like I did, it required placing the unit really low on the wall. You are required to vent straight up for the first 12" before you can elbow the vent. Along with the minimum run vs. rise of the vent pipe, it forced me to place the unit just barely a foot off the ground. Your situation may be different but keep it in mind. Also, it requires a minimum of 3/4" inside diameter black iron gas pipe. In some cases if you're tapping into the same gas line as your furnance, you may have to install 1" gas line. This unit requires a lot of BTU's and if you choke down below 3/4" it will not run properly. So that means no yellow flexible line to make the last connection. You'll have to hard plumb the iron pipe all the way to the unit.

There are both benifits and negatives to this unit. First the benifits. Long, long, long showers. Literally, you can take a shower all day. Then the next person in line doesn't have to wait for the water to heat back up. It's ready to go. Great for a family getting ready in the morning. Second, big savings on the gas bill. My bill dropped $20 the month after I installed this unit. I figure it will pay for itself in less than two years after the tax credit.

Now for the negatives. Low hot water pressure. That takes some getting used to. The unit has a maximum 4.3 gpm, but that's really unreasonable.(Take into consideration that I'm in the Northern USA and the water in coming into the house is at 50 degrees.) At that flow rate the water doesn't heat up above 90 degrees. That makes it warm not hot. You have to turn down the flow rate to 2.3 gpm to heat the water to 120 degrees. At that flow rate / pressure, if you open two hot water spigots anywhere in the house at the same time it becomes a trickle. There is no way you could run the shower or any other appliance like the dishwasher or washing machine at the same time. If you turn the Aquastar back up to 4.3 gpm you could, but you'll be taking a warm shower not hot (in my case).
Also, at 2.3 gpm, it takes a long time for the hot water to actually get to the faucet. It probably takes 4 to 5 times longer than it used to for hot water to flow from the tap than it did with the old tank system. For example, if I'm washing my hands, by the time I'm done lathering up and rinsing, the water is just now starting to get hot. I've come to realize its not even worth turning the hot water on for short burst of hot water like that.
It takes adaptation to get use to this, like this trick I use in the morning. I turn the hot water on and brush my teeth while the water is slowly making it's way to the tap. Once it's hot, then I turn on the shower. Otherwise I have to let the shower flow for what seems like a very long time before it starts getting up to temperature.

Would I recommend this unit. It depends. If you really need the ability to run two showers or two appliances at the same time, then no way. You'll have to go with the next unit up that has a faster flow rate. There's no way this unit can handle that.

But if you think you can adapt to the low flow rate and really enjoy taking all day hot showers while saving money on your gas bill then this is the unit for you. I really enjoy the savings and long showers.

One more thing. The manual says you have to clean the unit once a year to maintain its efficiency. That means disassembling some parts in the unit. Clean them and put it back together. I haven't had to do this yet, but its just one more thing to consider before you switch to tankless hot water.

31 of 33 people found the following review helpful:

2.0 out of 5 stars Remember to add a grit filter, January 7, 2009

By 

Macs R We (Arizona) - See all my reviews

This review is from: Bosch 1600H NG AquaStar 4.3 GPM Indoor Tankless Natural Gas Water Heater (Tools & Home Improvement)

I installed a Bosch 1600H-NG in a small (900 SF) home a little over a year ago. Installation wasn't tough, and hot water flow was adequate for a small home in our warm climate.

I bought this unit because its piezo ignition feature would guarantee us hot water even if power to the home went out. There were battery-driven units, but I figured if you had a choice between having to change batteries regularly or not, why sign up? Trouble is, the turbine in the ignitor is insanely sensitive to small particles of grit and rust, which jam it and shut down the heater. I have had to disassemble and clean this turbine three times in the past year (twice in the past three weeks) which is a messy job (the plumbing attachments on the bottom of the unit ensure that all spilled water is generously dispersed over the floor). This is despite my having put a whole-house grit filter on the water feed after the first instance. Right now, changing batteries looks a lot more attractive. I wouldn't buy this unit again.

Update, 9/09: After the first problem with grit and the installation of the whole-house grit filter, it appears that the subsequent problems were caused by the improper reinstallation of the turbine rotor. The instructions are completely unclear on this step, and it's possible to install the rotor reversed and have it work, at least for a little while. Once I installed the rotor in the proper direction, I have had no more issues with this heater. I'd like to upgrade my review to four stars, but it appears that it's no longer editable. The basic point stands: don't install this heater without a grit filter on your water system.

35 of 39 people found the following review helpful:

4.0 out of 5 stars Fresh Hot Water, December 12, 2007

By 

Thomas "Tommy" (Austin Texas) - See all my reviews

Amazon Verified Purchase

This review is from: Bosch 1600H NG AquaStar 4.3 GPM Indoor Tankless Natural Gas Water Heater (Tools & Home Improvement)

There is a lot to learn and get use to when you make the transition from a tank type water heater to tank less. I installed it myself. We have a Home Depot which handled the 5 inch double vent pipe. Lowes had all the plumbing fittings missing from Home Depot but no double wall 5 in. vent pipe yet they handle the Bosch line of tank less heaters. It took both stores to find all the parts plus a roofing supply company for the roof penetration collar. It took about 200 $ of parts to install it. I installed it in the same location as my old tank type heater. I knew all of the plumbing would have to be changed which can be done at different times prior to the removal of the old tank heater. You don't want to be left without hot water over night. The general contractor around here can really make your life hell (my wife). The roof vent was a bit of a pain. The main problem is trying to use the existing vent pipe path through the roof (to avoid having a extra hole in the roof) .Enlarging the holes (since old vent system was a smaller diameter) is a pain and clearly point out to me why years ago I should have paid better attention in geometry class. I lived in an 80 year old bungalow I replaced my plumbing with copper pipes a few years ago but mineral build up could be a problem for some people in install.
Unforeseen problems: Low flow plumbing fixtures. All newer fixtures have flow restrictors. If there is any mineral build up it might reduce the flow rate so as it will not trigger the ignition of the heater. Wear in any mixing devices in the fixtures might stop ignition. High temperature supply water. Here in Texas the summer supply water was 90 + you use very little hot water taking a shower causing the heater to cycle on and off. This is where one of the most undesirable issues with a tank less water heater shows up. You are getting hot you adjust the water temperature down and the heater goes off but you don't notice since all the pipes are hot and the temp continues to slowly fall then you notice so you increase the hot flow but all the hot water is gone there are yards of cold water flowing in the pipes toward you . I think there might be a term for this called the cold slug. Cold slug of water. I think the best way is to say the performance of the tank less heater is like a diesel car rather sluggish as compared to a tank type heater which is more the performance turbocharged gas car's brisk acceleration. Another problem I have is my new Kitchen Aid dishwasher will not ignite the heater (to low of a flow rate) but not really a major issue. I live in a old part of town the houses size 80 years ago was around 1000 sq feet now they go to 3k foot easy and a lot more units put in as multiple residents on single family lots . We are using the same gas pipe my forefathers used. So when it gets cold we have low gas pressure. It is getting a lot like a third world county around here nowadays. So lower performance output on those days.
The Plus side of this new contraption. I never will have to use that stale old hot water again only fresh hot water for me. There are only 2 of us living here. I never realized how little hot water we used. We kept 50 gallons ready to go at all times. There was a 300$ tax credit. Fuel prices went nuts this thing will pay for itself probably within 2 years. Actually it cost about the same as the old tank type which I had to replace anyway. When you take in account the tax credit it was basically a no cost upgrade . That general contractor likes to take baths (my wife). It took two tanks with the old heater to get the tub just right. Filling took a long time. One uninterrupted filling now. No more of her camping in the bathroom filling the tub.
Things you might want to consider. They make a larger unit it cost more but it might be worth it for most people. It has a simpler smaller diameter vent which would simplify the install.