UPDATE: plumber working on the generator project stopped back by.
He replaced the regulator on the line to the heater with a different version that he explained has a 1/2 inch rather than a 3/8 inch orifice. He says the new regulator is rated to deliver up to 700k+ BTUs and the old one was rated at a little over 400k.
After the replacement, we retried the Hayward heater and it fired up (it missed one time probably due to clearing air in the lines but then started the next two times and has been running ever since).
ALSO: the plumber was able to find some notation on my gas lines that shows the buried pipe is 1.25" rather than 1". He said it's just the risers that are 1" and he said that is how he would have done it as well. So, it looks like perhaps the gas pipe was correctly sized after all.
ALSO: the plumber told me that the gas meter I have is rated for up to 1.1M BTUs. That seems odd because when I look up the model, it says 250k BTUs. But, I did a little calculation by timing the meter as the heater is running and I can see it is delivering about 470k-480k ft3/hour to the heater (nothing else in the house is running). So, it must be able to deliver more than 250k. So, it seems that perhaps the gas meter is sized correctly as well (though he said the gas company might replace it when they come out on Friday -- he submitted all the documentation on everything our house has to the gas company and they will run the calculations and decide if it needs a bigger meter or just increased pressure in order to add the generator).
FINALLY: I asked him about putting the regulator next to the heater. He said he likes to leave at least five feet of straight pipe between the regulator and the appliance so it has gas in the pipe to draw from as it starts up. My pipes come out of the ground so close to the heater there would not be a way to leave this much between the regulator and the heater. But, since he discovered it appears the pipe in the ground is the correct size, perhaps this is not an issue. If I ultimately need to make a change, I could just have new pipe run but we shall see.
Hopefully all goes well with the gas company upgrade but things are looking up so far. I appreciate all of the help I received here as it gave me exactly what I needed which was knowing the right questions to ask and how to point everyone in the right direction.
He replaced the regulator on the line to the heater with a different version that he explained has a 1/2 inch rather than a 3/8 inch orifice. He says the new regulator is rated to deliver up to 700k+ BTUs and the old one was rated at a little over 400k.
After the replacement, we retried the Hayward heater and it fired up (it missed one time probably due to clearing air in the lines but then started the next two times and has been running ever since).
ALSO: the plumber was able to find some notation on my gas lines that shows the buried pipe is 1.25" rather than 1". He said it's just the risers that are 1" and he said that is how he would have done it as well. So, it looks like perhaps the gas pipe was correctly sized after all.
ALSO: the plumber told me that the gas meter I have is rated for up to 1.1M BTUs. That seems odd because when I look up the model, it says 250k BTUs. But, I did a little calculation by timing the meter as the heater is running and I can see it is delivering about 470k-480k ft3/hour to the heater (nothing else in the house is running). So, it must be able to deliver more than 250k. So, it seems that perhaps the gas meter is sized correctly as well (though he said the gas company might replace it when they come out on Friday -- he submitted all the documentation on everything our house has to the gas company and they will run the calculations and decide if it needs a bigger meter or just increased pressure in order to add the generator).
FINALLY: I asked him about putting the regulator next to the heater. He said he likes to leave at least five feet of straight pipe between the regulator and the appliance so it has gas in the pipe to draw from as it starts up. My pipes come out of the ground so close to the heater there would not be a way to leave this much between the regulator and the heater. But, since he discovered it appears the pipe in the ground is the correct size, perhaps this is not an issue. If I ultimately need to make a change, I could just have new pipe run but we shall see.
Hopefully all goes well with the gas company upgrade but things are looking up so far. I appreciate all of the help I received here as it gave me exactly what I needed which was knowing the right questions to ask and how to point everyone in the right direction.