Bosch 1600H tankless water heater (NG)

15 years ago

We installed a Bosch 1600H (natural gas) yesterday. When we first tried to start it we would get a spark but it would not light (the green light would not come on). After about 10-15 minutes of trying different faucets we no longer get a spark.

We know it is getting gas. We reduced the gas flow into the unit from 3/4" to 1/2" because of existing pipes from the previous standard hot water tank. Could this be part of the problem? If not, what else could be wrong?

Thanks!

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Comments (9)

mungo
15 years ago
It has hydro generated ignition with a min flow rate of .6 gpm. NG: 30,735-117,000 Btu.

Have you tried generating a larger flow than a faucet? Like a tub spout?
zl700
15 years ago
As Mungo said, it requires .6 GPM or more to activate the burner, more than most units out there, get what you pay for.

What you thought you would save in gas may be somewhat wasted in excess waetr usage.

I doubt the gas is a issue if the 1/2 isnt over 10', but water pressure, flowrate and piping sizes usually are the killer on the lower priced, DIY units.
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Not being rude alice, calling it like I see it. Would you care to direct us to any manufacturer's warranty language that specifically states you must "prove" you used a plumber on a company "list" to do your flushing? I don't see language in rinnais warranty outlining this scenario. You should have threatened small claims court in your county with a letter from your attorney if necessary and you would have gotten a new heater. Your receipt for the pump and hoses and a grocery bill would have sufficed too, especially in court. Sorry you had problems and rimmai was a gorilla about it. Warranties are contracts and often times courts are needed to enforce these, as companies aren't particularly interested in giving a warranty or new product to people with used units even when their own products are faculty. That's why we see the Feds force auto makers into recalls, and other forced mass buy backs. Seems to me you'd have named Rinnai front and center for treating you so poorly so other people round here could make an informed decision. Who's to say Takagi or Norritz wouldn't have just shipped you a new unit, or that Navien would have sent a new unit with a rep to install it. That'd have been more helpful than saying "better pay a plumber or you'll be sorry" without any context whatsoever. I think it's week known especially to GWers that companies try to wiggle out of warranties, it's a fact of the marketplace, so who's to say you wouldn't have been caught in section number three after you provided the plumbers invoices for de scaling?
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@Karen Williams This is the control panel on my tankless water heater. Water Set Point ... the output temperature the unit feeds into the hot faucets ... can be set in 1°F increments between 50°F and 140°F. Temp Up and Temp Down buttons adjust the Water Set Point temperature. Then press Temp Set to make it the normal at-all-times temperature if desired ... otherwise the adjustment is temporary and will revert back after a number of minutes. I have 103°F as the "normal" temperature and raise it when needed for washing dishes or clothes, without pressing Temp Set, and it reverts back to 103°F after 30 minutes so I don't have to remember to do that. That's just how my unit works, they're not all the same. Setting the temperature "at the faucet" means I set the water heater to the temperature of heated water I want/need "at the faucet" ... such as 103°F for a shower, instead of 120°F or 135°F which is much hotter than needed for a shower ... and I turn on only the hot faucet (or set a single-lever faucet to full-hot with no cold mixed-in). Thus, the tankless unit has a high-enough flow rate passing through it for the duration of the shower to insure it doesn't shut off due to too-low flow. 120°F, 135°F, 140°F output temperature requires mixing in cold water and turning down the hot flow at the faucet to get a comfortable shower, which reduces the flow through tankless possibly below the required rate which can cause it to shut off completely and the shower goes cold. Remote control panel means exactly that ... some tankless water heaters can have an optional extra temperature control panel installed at a convenient location such as bathroom or kitchen so the homeowner doesn't have to go down to a basement or out to a garage or wherever the heater is located to adjust the temperature. My heater doesn't have a remote control but it's located in a broom closet in my laundry room behind the kitchen near the center of the house so is easy to access any time I want to change the setting.
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aidan_m
15 years ago
I think a 3/4" gas line is minimum required for that model. You report getting a spark but no ignition. For a spark the flow switch must be activated by the required 0.6 gpm. Did the water warm even slightly? No temperature change at all? It is not getting gas. It stopped sparking completely after 10-15 minutes of trying different faucets because the computer went into error mode. You have to reset the computer. Get out the installation and troubleshooting guide. Don't bother calling Bosch Tech support, so many DIY people install these units and have problems the wait is hours on the phone. Check the gas pressure at the port inside the unit.

If there is sufficient gas pressure, what about fresh air? Is the fresh air intake coming from outside? Did you even remove the blank cover for the required fresh air intake? The unit requires an air intake and exhaust. That will be 2 separate 3" stainless steel vent pipes. You can have your air intake from the ambient room if it is a garage or other large room. But the air needs to be clean. Dust can clog up the burners. Outside air is best.

I have the Bosch Aquastar 250NG. The 1600 is the equivalent model being made today. I had to re-install the thing correctly after two years of intermittent problems mainly caused by my dusty garage workshop. I also added a 5 gallon electric tank heater in line directly after the tankless and keep it turned to its lowest setting. This extra 5 gallon reserve of hot water helps with the low-flow issues associated with washing dishes and hands.
jake2007
15 years ago
I have just heard so many bad stories about Bosch units, particularly with the water powered igniter, that I wouldn't ever recommend a Bosch tankless. They are giving all tankless a bad name.

Don't get creative with sizing the gas line. Install what is called for. You will remove one more variable from a system that's probably not going to be as reliable as you wanted.

That said, there are many other gas tankless units that work well and reliably. My Rheem has been great.
soonergirl99
Original Author
15 years ago
Many thanks to all who have taken the time to read our question and post responses. We thought we had done our homework regarding this unit but we obviously didn't do enough research. After spending a couple more frustrating hours last night working on the issues with this tank and 2 trips to the hardware store we have decided to scrap this unit and get a different tankless unit or go back to a conventional tank unit.

Thanks again ~ Garden Web members are great!
jake2007
15 years ago
Sorry to give you that news once you had already purchased it...

Do check out the Rheem units and some of the others.
bstarz
15 years ago
Most problems with units have to do with installation. The unit must have the correct water pressure and gas supply, next the power must have the right polarity. If not, it will not work. Reread directions step by step, also the venting must be correct. No short cuts with this type of unit.
jakethewonderdog
15 years ago
bstarz

Dude, I agree with you up to a point. I absolutely agree that you need to install according to directions. Don't skimp on the gas line (for example, going down to 1/2") and don't get creative with the venting.

The thing is that these Bosch units use "hydro generated ignition" to avoid needing AC. It is a hugely problematic design and requires significant initial flow to get it to fire in the first place. If you look through the board, you will see a lot of people complaining about them.

Even if they needed power, I don't know about "polarity" on the power being a big issue since these are AC units anyway. Of course you want to wire it correctly, but let's not make an issue where there isn't one.
eye144144
13 years ago
I have had 2 systems over many years and they work very well. I like the hydro. I have had it about 5 years.

Bosch 1600H tankless water heater (NG)

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Bosch 1600H tankless water heater (NG)

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