NG / LP Question...

[Peter B.]

Hello:

I'm thinking of buying a trailer home and had it inspected yesterday by an RV 'pro'.

The trailer isn't new, but it has never been used. It has been sitting idle for a few years and the inspection was intended to verify that everything still worked.

Everyone involved - the seller, the inspector, and I - had assumed the trailer's gas appliances were set up for LP. They weren't. Both furnace and range were natural gas, instead.

Before that discovery was made, an attempt was made to light both appliances off LP. Neither lit, and perhaps that's no surprise. But in the case of the stove, all four burners were opened wide for 30 seconds or more... and there wasn't even the odor of gas.

I'm thinking that even if the orifice was wrong, and the stove didn't light, there should have been a gas odor if the main gas line was clear.

Am I wrong?

Again, I'm in the end stages of my decision-making whether to buy. Paying for the NG to LP conversion is one thing... having a clogged gas supply line is something else.

I know this is pretty off topic, but I figured I could catch the attention of someone who'd know here.

Thanks Much.

Peter B.

-----

 

[Fsappo]

Gas would still flow to the burners even if they were converted wrong. Dont rely soley on odor. If you try to light the stove and it doesnt light via electronic ignition, you can have a bad ignitor. I would turn on one burner and hold a lighter there and see if that lights it. You may just have air in the line that has to be purged. Rare that a line is "bad" Could be a bad valve or regulator.

In summary, from what you described, I doubt its the conversion and I would have someone that works on appliances or someone from a local propane company do a service call to diagnose.

Hopefully someone smarter than I am will chime in here.

 

[Peter B.]

Franks:

Thank you for your reply.

I should clarify. No conversion was made to the range. Before realizing the range was NG, an attempt was made to light the burners on LP... but even after numerous tries and an extended period of time with the burners open full, there was NO GAS ODOR AT ALL.

Two different regulators were tried in the process.

What would explain no odor other than a clogged line?

Peter B.

-----

 

[Peter B.]

Adding more 'dimension' to the question...

I just spoke by phone with an appliance repairman who said in fact there should have been at least odor... and with LP feeding into an NG range, had it lit, the flames might have been a foot high due to the greater pressure of the LP.

He said there _might_ be a thumb valve at the lower rear of the stove that was closed... but - while there may be a valve - it seems unlikely it would be closed on a new unit intended to be put into service.

An attempt was also made (yesterday) to light the furnace, which is equipped with electronic ignition... and that didn't light off (or explode) either.

Again, two regulators were tried, with the same result. There was no main shut off valve in evidence.

Thanks to anyone who can shed more light on this.

Peter B.

-----

 

[Fsappo]

I hate to suggest this, but just like telling someone whos remote doesnt work to check the batteries...it sometimes solves a problem:

You say you tried 2 regulators. Are you talking about the mini regulators at the appliances or the main 1st and 2nd stage regulators at the tank and gas line entrance to the home?

Also, does the tank have propane in it? Are you judging by the gauge which could be faulty. Tank turned on?

 

[Peter B.]

Franks:

I don't mind being quizzed on the basics... I'd like to get to the bottom of this.

The seller brought a 20 pound (BBQ) LP tank and regulator for the inspection. Results were as described. The inspector had assured me this would be suitable for the test. When nothing lit, the inspector found another (BBQ) regulator in his work van, and that was tried. Same results.

No individual appliance regulator was 'identified' nor came into play.

I (personally) did not try to bleed off any gas from either the tank or the attached regulator to check. I kind of assumed the inspector had enough on the ball that... but...

Thanks for trying to help.

Peter B.

-----

 

[Fsappo]

Not so much bleeding the tank, but bleeding the line. You can take the appliances out of the equation by disconnecting them from the gas (you want a trained tech to do this) and use a combustible gas detector to tell when the gas hits the end of the line. A gas system is pretty simple, just gotta follow the stream.

Not sure if a bbq tank and bbq tank regulator will prove enough pressure to run those appliances. Should be good for a cook stove.

 

[Peter B.]

Franks:

More clarification, though much of this may have been obvious, I don't know.

The BBQ tank was only meant as a test. The inspector seemed to think it should work. Setting aside the fact that a BBQ tank won't last long supplying a 30K BTU appliance, what I've heard (no idea if it's true) is that the problem with a BBQ tank - for a furnace - is that the continuous flow rate is such that the line might freeze up. That wouldn't have been a problem in this instance.

(I'm currently running a BBQ tank on my kitchen stove... and have for over 20 years without problem.)

By 'bleeding' the tank, I simply meant checking to be sure there was actually gas in the tank... and getting past the regulator.

Anyway...

Peter B.

-----

 

[DAKSY]

Can you say "S-P-I-D-E-R?"
I'm thinkin you gotta check behind the burner orifices...

 

[Peter B.]

Given the fact that the trailer was left idle for a few years, I'm thinking the main gas line in might have been left without a cap for a season or more and...

Mud daubers, or other insect friends may have invested themselves... rare occurrence perhaps, but probly not without precedent.

Better answers welcome.

I can lean towards two bad regulators and coincidence... or insect minions.

I don't know what to think at this point.

Peter B.

-----

 

[DAKSY]

I'd see if there's a way to attach a Schrader Valve to the system
to see if you can dislodge the blockage with compressed air.
Are the lines copper, Corrugated Stainless Steel (CSS) or
Black Iron Pipe (BIP)?

 

[Peter B.]

To the best of my knowledge, the lines are black pipe... at least that's what could be seen underneath the trailer at the gas hookup. I assume they're BIP throughout.

I might be able to handle diagnosis and repair myself if the trailer were here, but it's about 100 miles away at the moment and it would be nice to know what a pro might charge. Given the nature of the problem, it looks like it would be a time and materials situation.

Thanks.

Peter B.

-----

 

[Fsappo]

Can you say "S-P-I-D-E-R?"
I'm thinkin you gotta check behind the burner orifices...

Was thinkin spider but would be too much of a co ink eee dink that it got the stove and the furnace? Guess not if they have been idle for a long time.

 

[Peter B.]

But all the way up into all four range burner orifices ???

Peter B.

-----

 

[Peter B.]

Franks & DAKSY:

You've both been very helpful, and I appreciate it.

If you have time, would you weigh in once more on this question, as simplified from the above?

Again, recall that the range is set up for NG, and LP was being used (in error) as a test.

Provided that LP was flowing from the regulator into the gas line, and the length of line to the range was no more than 15 feet, and all four burners were open for at least 3 minutes and none lit and there was no smell of gas, would you conclude that something was indeed WRONG?

And that regardless of the setup (NG/LP), gas should have been flowing as far as the burners?

Sorry to be so persistent, but it's important to me to be clear on this.

Thanks Again.

Peter B.

-----

 

[Highbeam]

I have had several RVs and I shut the gas tanks off each time I get home. Every time I repressurize the gas system, and especially if I remove a tank for filling, it takes a long time for the gas to reach the burners. I have a process for this. I open up all four range burners and hold a lighter to one of them. The non-flammable air blow on the lighter for quite a while before the mix is strong enough to combust. I then let all four burners run for awhile and I begin trying to start the fridge. The fridge has an autoignitor and the gas line to the fridge must also be purged before it will light. It might take three cycles. I have no significant leaks in my system, the RV place checks for that, no smells and the tanks don't run out on their own.

For some reason, shutting off the gas tanks and especially removing them, allows the lines to empty out on every RV I've had and on all of my friend's RVs. New or old. At the low regulated pressure it takes a long time to refill the lines.

Try again and be patient. You will be able to hear gas leaving the LPG tank and entering the lines. It is going somewhere and will eventually come to the burners.

I would worry about an RV converted to NG. Seems this was a live in RV. RVs aren't meant to be lived in full time and things will weat out and break quicker.

 

[Peter B.]

Highbeam:

Thanks... you've given me something fresh to chew on.

But you use the phrase 'long time' twice in your post and if you could put a (somewhat) more exacting value on it, it might help. My guess of 3 minutes was only a guess. Is 'long time' longer by a margin than 3 minutes?

The trailer home is a 'Park Model'... and intended for 3 seasons (plus ?). Though a 2006 model, it's actually unused. There <shouldn't> be significant problems with it, but it has sit idle for several years, with no attention. I thought an inspection would be best before I plunk cash on the counter.

Peter B.

-----

 

[yooperdave]

well, if you pressurize the gas lines without turning all the shutoff valves at the appliances off, you might just as well plan on replacing all the gas controls. you'll probably blow out the diaphram is each gas appliance's control. you will have to find the shut off for each appliance and turn it off...not the on/off switch of the gas control, rather-the shut off for the gas to each appliance.
why hasn't the seller taken care of this problem?? or the rv pro??? maybe you need to move on to something that you know is alright.
an earlier poster asked you, and i can't tell if you responded or not but, if the gas inlet to the rv was left uncapped or uncovered, (tape would be ok) this would leave access for bugs and weather to reach inside of the gas lines...possibly creating an obstruction. is this a trailer or a motor home? why was it set up for nat gas to begin with??? i thought all trailers and motor homes were lp due to the remoteness of their camp sites???? i realize that a trailer home would be set up for nat, but then you don't really move them around every camping season

 

[Peter B.]

yooper:

Actually, the LP pressure was regulated to 'normal' levels... not delivered full tank pressure... so I doubt damage was done in that respect.

The seller - quite frankly - 'has no clue'... and has done NO homework in advance of the sale... but has a reasonably nice, never used Park Model trailer up for grabs that I would (kind of) like to buy...

I hired the RV pro to do the inspection. From my standpoint, it was hurried, incomplete and inconclusive... and here I am.

I'm trying to determine whether the gas inlet / supply line is clogged... because setting aside the fact that the appliances have to be converted to LP, I don't know that there's not an additional problem with the main gas line. As you suggest, it <may> have been open to the elements... and I just don't know.

Being the even tempered guy I am, I'm trying to avoid stomping on the seller for being such a dumb ass... else I lose the deal.

It is a 'Park Model' home... considered an RV by most state laws, but (ironically) NOT designed for frequent highway travel. And evidently, the manufacturer thought the more likely 'destination' for the trailer would be a motor home park with NG than a remote site with LP.

Anyways...

Peter B.

-----

 

[btuser]

I don't know if this would help, but I know the regulator on my propane tank will shut down if there is no back pressure on it. At first, I was getting terrible heat out of the burners, but I found out later it was because I was opening the valve on the tank too quickly, which would cause the regulator to clamp down because it though it was a ruptured hose.

Maybe the regulator on your tank is interpeting 4 large burners with over-sized orafices as a ruptured line?

 

[Peter B.]

btuser:

Thanks for your reply.

I heard this suggestion from someone else yesterday as well. As it happens, I've got a small tank of LP and a brand new BBQ regulator on hand - pretty much duplicate items to those used in the test. I'll see what happens just screwing on the regulator and opening the tank valve... outdoors.

Peter B.

-----