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?

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.

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.

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.

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!

Sorry to give you that news once you had already purchased it...

Do check out the Rheem units and some of the others.

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.

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.

I have had 2 systems over many years and they work very well. I like the hydro. I have had it about 5 years.