I currently have a 300 gallon underground propane tank for the gas stove, clothes dryer and gas fireplaces in my home. Next to the house, a grey ¾â€ (ID) pipe comes up to a regulator then a copper line connects to the black iron ¾â€ (ID) pipe entering the house. I’ve placed a Kohler 12 KV generator about 75’ away and have some differing opinions on the gas supply. When the site work was done, I buried a 1-1/2†plastic water pipe between the existing regulator and the generator about 4’ underground.
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The data sheet specifies a ½â€ NPT inlet to supply 1.7-2.7 kPa (7 – 11 inches H20) gas pressure. The minimum recommended pipe size is ¾â€ NPT up to 25’ pipe length and 1†NPT from 50’ to 150’. Fuel consumption at 100% load is 2.5 cubic meters per hour (89 cubic feet per hour).
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One plumber recommends a ¾â€ or 1†plastic fuel line to the low pressure side of the existing regulator (actually, plastic stubbed to a metal pipe underground) connected directly to the generator. A second plumber recommends connecting a plastic or soft copper fuel line to the high pressure side and putting another regulator at the generator. He feels that a single regulator would not be capable of supplying the generator and house simultaneously and also feels that a ½ “high pressure fuel line would be more than sufficient for the generator supply.
I have no feel for these things nor can I do the math, but I have to make a decision. I’d appreciate any recommendations.
Replies
I would talk to the propane supplier. My supplier here has great tech guys who solve all problems like that, more readily than my plumbers, who are also very good but don't deal with issues like yours very often.
Unfortunately, I've had several fights with the propane supplier, who has promised to send a tech numerous times and never has. If I wasn't stuck with his underground tank (which I was originally told I would own, but lied to), I would use another propane supplier and service, but since I'm stuck with him, other propane suppliers won't touch it. Hence, my need to use a plumber.
Have another supplier come out and dig up the tank, transfer the gas to a new one, and bury it. Then stop paying the bill from the existing supplier and when they call tell them the tank is waiting for them to pick up. Those guys compete hard with each other and whoever you use should be giving you good service.
As I understand it, which I don't so don't believe anything that I say, the two limitations are the pressure drop in the line to the generator and the capacity of the regulator.
Clearly running high pressure to the generator takes that concern out of the mix.
I have no idea what the rating of the regulator is. But I would guess that you should be able to get a brand and model number and look it up.
Not knowing anything else and not really knowing anything about propane (and even replaced my propane torch with a MAP unit) my guess would be that a separate regulator by the generatore would be the best.
That's what I was thinking, but there is the added complication that all fuel must run thru the line to the first regulator where the tee is.
Yes, but the T would be on the high pressure side, before the regulator. There are some standard formulas that relate pressure and pipe diameter to fuel capacity, but my college math is just a haze.
Yeah, "meatball engineering" says that the best approach is to put a tee on the high-pressure side of the existing regulator and run a high-pressure line out to a new regulator near the generator. This allows you to run a smaller-diameter fuel line, and assures a more constant pressure at the generator, plus it overcomes any flow limitations of the first regulator.The one potential monkey wrench is weather -- I forgot to check where you live, but in extremely cold (-40) weather you may have trouble getting the propane to vaporize fast enough. In such situations you need an experienced guy to plan the setup, and you may need to put a heat exchanger in the line.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
Good thought. I'm in coastal southeastern Mass, winter temp rarely goes below 20 F.
I was never involved with propane before building this house. From what I'm told, most of the regional suppliers have been bought out, so now there's just a few large propane dealers that do not work very hard at competing with each other. Concensus is that they're all charging big $$$'s and not really going after each other's customers.
75 feet is a long way to run low presure LP. I would opt for the tee on the high pressure side and then install a second low pressure regulator near the genset. Make sure that you have about 10 feet of pipe between the generator and the low pressure regulator for some surge volume. If the pipe is too short the initial surge can swamp the regulator and cause engine starting/running difficulties. Roger
Hmm, never thought of that. I was going to come straight out of the ground to the regulator then to the generator (which did include a flex tube with 1/2" NPT fittings for vibration). I could fashion a coil of copper tube after the regulator, either above or below ground.
My 12KW Kohler next to the garage is piped HP to the unit with the regulator at the gen set. The HP side is about 35' from the 500 gal tank. In the future it will also feed two unit heaters
The house is about 85 feet from the tank. It too is fed HP to the regulator on the outside of the house that then feeds a manifold in the basement.
The household vac is louder than the genny. Other than looks there is no need to hide these gen sets.
I'm in Northern Maine and the work was done by the LP Co.
RobWes, can you tell me the size and material of the piping?
The matrial was a plastic sort of pipe about 5/8 ID. There are 3 dielectric isolators, one at the tank and one at each building. The regulators are mounted on the buildings. A short piece of 1/2 copper tubing connects from the reg to the gen set.
Thanks, RobWes. Could you please explain the dielectric isolators? How long is the copper tubing?
The copper tubing is only 2.5 feet max in length. It's a short run to the gen set.
The dielectric insulators I've been told protect the tank from rotting out. These are the 90 degree sweeps that come from underground to daylight. They are gray vinyl wrapped (dipped I guess is a better term) tubing with the compression fittings on each end.
It's been a long time, but I finally got a plumber to run a 3/4" high pressure line to the generator. Unfortunately, he did the job when I was away and when I examined it, I found that the pressurer regulator is rated at 3" to 6" and the fuel supply pressure spec on the generator is 7" to 11". Does this mean that this regulator will not supply enough gas pressure?
yessir..
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
Okay, assuming I don't want to endure the required two month wait to get him back, can anyone tell me where I can buy a propane regulator that will supply 7" to 11"? It looks like he used 3/4" NPT pipe.
ful scale plumbing supply house or propane tank dealer..
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
Here's how the story ends.
The plumber left the state to do a large commercial job. Sent him a couple voice messages and emaisl, but no response.
Traded a few emails with Rego Products, who helped me pick an appropriate propane secondary regulator with plenty of flow capacity (with must be a plumber to buy disclaimer). Found a supplier on the internet and bought it through one of my manufacturing companies. Replumbed the generator side to keep the regulator vertical (so the vent pointed down), tied the supply side into the medium pressure line and found a major leak with the connection to the line the plumber installed. @#%^*@ plumber was still screwing me from two state away.
Let a couple days go by to cool off, then peeled back enough of the line to indentify it as Tracpipe, a stainless steel gas line that looks like BX armour cable. Fortunately, the manufacturer Omegaflex has a nice web site that includes a technical document on installing and repairing, so had good insight into how to attack the leak with confidence. Really nice design, the only tool needed is a sharp tubing cutter. You slip a nut over the tube, insert a pair of half moon shims into the corrugation below the cut, then tighten the nut onto the fitting, which flares the tube end onto the fitting. Leaks are typically caused by a non-square tubing cut or contamination on the flair; I had both.
Hooked it back up, tested for leaks and fired up the generator for the first time. It was a beautiful sound. Now off to find my electrician.
Thanks, all.
excellent...
it's good to hear the final chapter...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
Agree with the other post, not enought pressure.
Sounds like you have a natural gas rated regulator. Have it changed out for a propane model. Roger