Girard Tankless Water Heater III - Error E7

[ScandentTrek]

Hey folks. TLDR: Getting an E7 error code on our tankless water heater, except sometimes it's an E1 code and sometimes it's an E2 code. What's the problem and how do we fix it?

We've been using our water heater with no problem as full-timers for almost 4 years. Finally, we moved out of the trailer and winterized it for the first time. We used an air compressor to blow it out as recommended and left for a few months. Now we're back in the trailer for a month and suddenly, for the first time, it's not working. We got the water hooked up and ran everything through the lines but when we switched on the water heater, it threw us E7.

We tried turning it off and back on again, cleared the propane lines by running the stove and the furnace, and everything else is working great. The water heater kept throwing E7, except a few times that it would start working and get hot, and then suddenly throw an E7 again. Sometimes it throws an E1 or E2 instead of an E7, but it seems random. We've been testing it periodically by turning on the hot water and getting these different codes every time.

Obviously, something is going on with the propane connection or flow that is preventing or stalling ignition, but since the error codes are vague, I don't know how to fix it, aside from ordering a new part (some kind of valve?) and taking it all apart, which I really don't want to do.

Has anyone else had a similar problem? Any troubleshooting or fix suggestions?

Thanks in advance.

[ScandentTrek]

Update on my repair attempts.

According to the Service Manual, the E7 code indicates a problem with the gas valve.

I purchased a new gas valve for $110 and used the service manual to replace the part. It wasn't complicated, but some rusted screws made it more difficult than it should have been. Once I had everything put together again, we ran the water heater and got the E7 code again. We turned it off and on again and fiddled with the wires and double-checked everything and still, it continued to throw E7 with the new part in it.

I went off and kicked a few things and swore and complained, and then I called Lippert Customer Service for technical assistance. The tech had me use a multimeter on the continuity setting to test the continuity of the wires leading from the part to the control board. My multimeter gave me a reading of 80ohms and the tech said that meant the control board was bad and needed to be replaced.

Now I'm kicking myself, thinking I should have tested that first and saved myself the money and trouble of replacing the wrong part. A new control board is $150, and if this doesn't work then the tech says the only thing to do is buy a new water heater for $450.

I will say that I was very pleasantly surprised by how knowledgeable and helpful the techs from Lippert Customer Service were. I should have called sooner.

[deltafired0g55s]

Try checking to sail switch for operation, make sure you have water pressure, and check for spider web in the burner orifice.  These are the most likely possibilities.  also the over temp limits switches.