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LP gas furnace below grade ?


JPLomeo
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Hi all,

Last week I inspected an older home that was remodeled 5 years ago. In the crawl space were two Ruud, sealed combustion chamber, lp gas fired furnaces but no drain pans & drain lines under them (to daylight).

So I called it out as being unsafe, since any leak of LP could pool in the crawl space (below grade) and cause a serious explosion hazard.

The listing agent's HVAC contractor says they are ok.

Has there been any change in the code or has the technology gotten that good that a drain system is no longer required for an LP appliance located below grade?

Thank you for any info.

JP

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Hi,

Did you happen to notice if those furnaces were equipped with a pressure interlock that will cut power to the unit in the event of a pressure drop caused by a fuel leak? Sometimes all it takes is a call to the HVAC firm listed on the label attached to the unit to clear up things like that.

ONE TEAM - ONE FIGHT!!!

Mike

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Hi Mike

Thanks for the reply. Where would a pressure interlock be located on the unit? I could go back and look as the home is vacant and very near. If the gas pressure interlock were to fail however (as anything mechanical can) there is still nothing there to prevent the crawl space from filling up with LP gas (not a confortable feeling for me) [:-bigeyes

Thanks

JP

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I cant find my NFPA 58 but IRC FG 401.2 and UMC 304.6 (as listed in Code Check HVAC, 2002 edition, page 19) state that: propane appliance not to be located in pit or Basement. It also says that: the UPC prohibits propane appliances to be in a pit or basement that does not have a drain. LP gas is heavier than air and a concentrated pool of LP gas becomes an explosion hazard if allowed to accumulate in a pit or confined space.

You know, after re-reading , I think I'm going to stick to my guns on this and the agent and client what I think. No matter what safety devices are installed, they can still malfunction and I believe that a drain pan system (to the outside) is a very small price to pay for one's safety.

Thank you all!

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Originally posted by JPLomeo

Hi all,

Last week I inspected an older home that was remodeled 5 years ago. In the crawl space were two Ruud, sealed combustion chamber, lp gas fired furnaces but no drain pans & drain lines under them (to daylight).

So I called it out as being unsafe, since any leak of LP could pool in the crawl space (below grade) and cause a serious explosion hazard.

The listing agent's HVAC contractor says they are ok.

Has there been any change in the code or has the technology gotten that good that a drain system is no longer required for an LP appliance located below grade?

Thank you for any info.

JP

The IRC doesn't prohibit propane appliances in pits or basements.

Someone probably looked at the actual science that relates to the behavior of gases and realized that propane doesn't run out of a drain in the floor the way water would. They also probably realized that, despite popular myth, propane isn't heavy enough to be any more hazardous than natural gas. You can blow up your house just as easily with either one.

- Jim Katen, Oregon

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I've been under the impression that propane is about 1.5 times as dense as ambient atmosphere.

I realize that convection plays a role in the disbursement of propane, but in the absence of an air current, propane will settle in low areas displacing the air from the area. It isn't hard for me to imagine an eddy where propane congregations can settle and celebrate their density.

When the author used the word "drain", I didn't take that seriously to mean a conventional plumbing drain in the floor but rather a mechanism that would prevent a concentration of propane. I just now re-read the post and wish I'd addressed the terms used.

I've seen first hand an issue that was created by a gravity filled pit of gasoline vapor in an alignment pit that was sixty feet from the liquid fuel source. It was literally illuminating.

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Originally posted by Chad Fabry

I've been under the impression that propane is about 1.5 times as dense as ambient atmosphere.

I realize that convection plays a role in the disbursement of propane, but in the absence of an air current, propane will settle in low areas displacing the air from the area. It isn't hard for me to imagine an eddy where propane congregations can settle and celebrate their density.

The trick is to achieve an absence of air current. At 1.5 times the density of air, propane just isn't heavy enough to settle out to that degree in most instances. My point wasn't that propane was particularly safe in basements or in pits, but that it's as unsafe as natural gas. Natural gas is slightly lighter than air. Do we worry about it "pooling" on the ceiling and being ignited by light fixtures? In the real world, both gases disperse pretty well in air and both can make a house go boom if they disperse to an appropriate degree.

When the author used the word "drain", I didn't take that seriously to mean a conventional plumbing drain in the floor but rather a mechanism that would prevent a concentration of propane. I just now re-read the post and wish I'd addressed the terms used.

He was talking about some older code provisions (maybe current code provisions in some codes, not the IRC though) that required LP appliances in pits or basements to have drains intended to allow any leaking propane to flow to the outdoors. What really happens is that, most of the time, the air in the drains flows, in a most froward manner, in the wrong direction, preventing the propane from going anywhere.

I've seen first hand an issue that was created by a gravity filled pit of gasoline vapor in an alignment pit that was sixty feet from the liquid fuel source. It was literally illuminating.

Yes. My cousin turned himself into a human wick once. He was scrubbing his basement floor with gasoline (don't ask) when the water heater, about 30 feet away, ignited the gas fumes.

Gasoline vapors are significantly heavier than propane and tend to stratify much more readily.

- Jim Katen, Oregon

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I've seen first hand an issue that was created by a gravity filled pit of gasoline vapor in an alignment pit that was sixty feet from the liquid fuel source. It was literally illuminating.

Yes. My cousin turned himself into a human wick once. He was scrubbing his basement floor with gasoline (don't ask) when the water heater, about 30 feet away, ignited the gas fumes.

Gasoline vapors are significantly heavier than propane and tend to stratify much more readily.

- Jim Katen, Oregon

As do fumes from petroleum based contact adhesive[:-graduat

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Originally posted by charlieb

I've seen first hand an issue that was created by a gravity filled pit of gasoline vapor in an alignment pit that was sixty feet from the liquid fuel source. It was literally illuminating.
Yes. My cousin turned himself into a human wick once. He was scrubbing his basement floor with gasoline (don't ask) when the water heater, about 30 feet away, ignited the gas fumes.

Gasoline vapors are significantly heavier than propane and tend to stratify much more readily.

- Jim Katen, Oregon

As do fumes from petroleum based contact adhesive[:-graduat

Do I sense a story behind that statement?

Yes, toluene is even heavier than gasoline vapor. It would be a poor idea to put a contact adhesive manufacturing plant in a basement or a pit.

- Jim Katen, Oregon

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Of course you do. It was a kid proof kitchen remodel. The customer wanted everything clad in laminate. We did most of the work off site but took over the garage to glue up about 8 full sheets. Since the winter in MS is mild we had a Kerosene going. The sea of flames was a sight to behold. It simply did not last long. The adhesive on the glued up panels ignited but we quickly put them out.

A bit of fanning with the ruined sheets helped to dissipate the wisp of carbon. As we looked it all over and discussed how lucky (read stupid) we were the lady of the house drove up. She noticed the aroma in the air and asked about it. "We had a little problem with the glue" was the lead man's response. But hay, we did paint the garage at no cost. The owners new knew about "The Sea of Fire"

Just a short version. Gotta take my daughter out for lunch. My weekend has started.

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  • 2 weeks later...

OK, so what is answer? Are LP appliances permitted in basements? Some of the postings here seem to contradict each other. If they are permitted, then a fresh air vent (drain) in the basement floor is required. Never saw on LP appliance in a basement around here. Just curious what the final verdict is (and I know it also depends on what the AHJ says, too) .

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Originally posted by msteger

OK, so what is answer? Are LP appliances permitted in basements?

The IRC doesn't prohibit LP appliances in basements. If anyone has a citation from another code that prohibits them, bring it.

Some of the postings here seem to contradict each other. If they are permitted, then a fresh air vent (drain) in the basement floor is required.

Is it? By whom? Where's it written? How are you going to stop air from moving inward, in the wrong direction, through this drain?

Never saw on LP appliance in a basement around here. Just curious what the final verdict is (and I know it also depends on what the AHJ says, too) .

The AHJ can't just make things up. He's got to make his calls based on the code.

- Jim Katen, Oregon

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One post above says "IRC FG 401.2 and UMC 304.6 (as listed in Code Check HVAC, 2002 edition, page 19) state that: propane appliance not to be located in pit or Basement."

Another post says "The IRC doesn't prohibit propane appliances in pits or basements. "

Seems to be contradictory to me. I just want to be sure, so when I see my 1st LP appliance in a basement, I'll know what is permitted. I haven't seen one in over 6 years of inspecting.

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Originally posted by msteger

One post above says "IRC FG 401.2 and UMC 304.6 (as listed in Code Check HVAC, 2002 edition, page 19) state that: propane appliance not to be located in pit or Basement."

That reference is to the 2000 IRC. When I look at the section that he cites it says, "Liquified petroleum gas storage. The storage system for liquified petroleum gas shall be designed and installed in accordance with the International Fire Code and NFPA 58." It's got nothing to do with appliances, it relates to LP storage.

Another post says "The IRC doesn't prohibit propane appliances in pits or basements. "

So far, that seems to be correct. If anyone's got a reference to a place where the IRC prohibits them, please let me know.

Seems to be contradictory to me. I just want to be sure, so when I see my 1st LP appliance in a basement, I'll know what is permitted. I haven't seen one in over 6 years of inspecting.

If you want to know what is "permitted" in your inspection area, you need to buy the codes that apply in your region and read them. I can help with telling you what the IRC says, but that doesn't necessarily translate into what's permitted in your area.

- Jim Katen, Oregon

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Originally posted by msteger

PA uses 2006 IRC.

I can't find anything in the 2006 IRC that prohibits installing LP appliances in basements or pits.

That doesn't mean that PA doesn't have made an amendment that prohibits them and it doesn't mean that there isn't a prohibition in another code such as the fire code.

It also doesn't mean that it's a good idea to put an LP appliance in a pit.

- Jim Katen, Oregon

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