38kw starting issues due to propane pressure?

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devon
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I have a new 38 KW Generac generator that has unfortunately had issues starting reliably since it was installed. It seems to be too much pressure building up over time after the 2nd stage regulator and before the generator valve solenoid. After the generator has sat for a few days, it often will not start. It turns over great, but won't fire. If I bleed off the pressure from the 2nd stage regulator, it will then fire up and run well.

The generator folks, and the propane folks, have seen slow pressure creep from 11" upwards. However after replacing the 2nd stage reg several times, the latest theory from the propane folks is that the sun is heating the metal pipe which runs about 7 feet from the 2nd stage reg to the generator and this is causing the pressure increase. I've wrapped the pipe today in reflective insulation to try to minimize solar gain on the pipe, etc.. but also tried starting it this morning before I wrapped it in 60 degree weather with the pipe shaded by plywood, and it wouldn't start until I released the pressure by removing the manometer port plug.

Long story short the generator guy says the propane is building too much pressure for the solenoid valve to open against. The propane guy says this is the 5th regulator and it seems steady at 11" as long as he keeps plywood over the pipe. If this reflective insulation doesn't solve the problem, I'd like to know if anyone has seen anything like this and has any ideas or suggestions?

My next thought is to replace the first and second stage regs myself with better quality units. I've also bought a manometer so I can take my own readings and watch pressure over time better.

I'd welcome any wisdom or suggestions.... Thanks!
Chris
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Let's see some pics of the gas setup! You ideally want 10' or more of large diameter (1-1/4") pipe between the gen and the reg.
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Birken Vogt
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We just went through this with a 30-something kw Generac. It was definitely proven that the sun heating the pipe was increasing the pressure beyond the opening point. The customer buried the second stage piping and the creep-up stopped.

This is one of the reasons we prefer to run low pressure from the tank or wherever rather than placing the regulator close to the generator. The other is that code requires some regulators to be at a distance.

After all this, the customer also had us install the taller electric solenoid. We tested its ability to open against overpressure and we were able to get it to open well beyond 20" pressure on the inlet. Chris can set you up with one of those if you need it.
Birken Vogt
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Also I wanted to add that standard max pressure for propane is 14" static, and the customer found his OE solenoid valve would lock shut at somewhere around 16" propane pressure, it did not take much.
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