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 now 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, very old, standard hot water tank. Could this be part of the problem? If not, what else could be wrong?