New member, DIY renovation 1898 home Gas WH flue question

**jonathan dickinson** · 03-11-2014, 07:02 PM

Hi, I'm retired veteran of several old houses but definitely not a pro.
In latest old one, propane WH 3" flue now meanders around heating ducts and is rotted out near chimney. I plan to move ducts to get two straight runs of about 6' each with a bend in the middle to get around the basement stairs. Current 16" initial rise allows for about 10" over the 12' but would pass only about 4" below the floor beam by the stairs. Should I reduce initial rise to 12" to get more clearance? Is single wall flue OK. Also, propane supply is through simple copper tubing (~3/8 OD). Is that a problem? My experience is with black pipe and natural gas.

**Brian Hannigan** · 03-11-2014, 07:03 PM

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**Scott Patterson** · 03-12-2014, 05:47 AM

Originally Posted by jonathan dickinson

Hi, I'm retired veteran of several old houses but definitely not a pro.
In latest old one, propane WH 3" flue now meanders around heating ducts and is rotted out near chimney. I plan to move ducts to get two straight runs of about 6' each with a bend in the middle to get around the basement stairs. Current 16" initial rise allows for about 10" over the 12' but would pass only about 4" below the floor beam by the stairs. Should I reduce initial rise to 12" to get more clearance? Is single wall flue OK. Also, propane supply is through simple copper tubing (~3/8 OD). Is that a problem? My experience is with black pipe and natural gas.

I would not want LPG in the basement. As for the type of vent pipe, you need to stay with what the appliance manufacturer is recommending. Most likely that will be a double wall "B" vent pipe. Depending the age and condition of the copper line, I would most likely update to modern CSST.

**John Arnold** · 03-12-2014, 09:54 AM

Originally Posted by Scott Patterson

I would not want LPG in the basement....

Because it's heavier than air, so leaks accumulate rather than dissipate up through the house?

**Scott Patterson** · 03-12-2014, 01:27 PM

Originally Posted by John Arnold

Because it's heavier than air, so leaks accumulate rather than dissipate up through the house?

Pretty much the reason. If you have a leak it becomes a deadly pool of LPG that will kill you either when you turn the light on, the furnace turns on and blows up the house or you don't realize what is happening and it suffocates you if you are in the basement.

Several years back I opened a crawlspace hatch and I saw what looked like a heat wave wafting across the crawlspace floor. I could not smell anything because the wind was blowing the LPG away from the entrance after I opened the hatch. If I had not realized it and gone in, I would most likely not be here today.

**John Arnold** · 03-12-2014, 03:13 PM

Originally Posted by Scott Patterson

...Several years back I opened a crawlspace hatch and I saw what looked like a heat wave wafting across the crawlspace floor. I could not smell anything because the wind was blowing the LPG away from the entrance after I opened the hatch. If I had not realized it and gone in, I would most likely not be here today.

Wow. Good to know. I rarely inspect places with propane.

**Raymond Wand** · 03-12-2014, 03:32 PM

The stats don't back up the claim LPG is unsafe as compared to propane.
I bet their are more explosions from natural gas than there are with propane in homes.
Just today the explosion in NY was due to natural gas.

Propane Statistics

https://www.nfpa.org/research/report...cs/fire-causes

**Jerry Peck** · 03-12-2014, 05:37 PM

Originally Posted by Raymond Wand

The stats don't back up the claim LPG is unsafe as compared to propane.

LPG is propane.

I suspect you meant to compare LPG (is heavier than air) with natural gas (is lighter than air).

**Mark Reinmiller** · 03-12-2014, 05:41 PM

Originally Posted by John Arnold

Wow. Good to know. I rarely inspect places with propane.

I always recommend a combustible gas detector placed near the basement floor when the house has propane. It is not foolproof, but better than nothing.

A few years ago an employee or contractor working for a builder was badly burner when he tried to light a water heater. Propane had accumulated near the floor. You may see a note on gas company approvals on new construction stating that they did not approve the equipment because propane tanks were in the house. They want the tanks used for portable heaters out of the house before the equipment is used because of this potential.

**Raymond Wand** · 03-12-2014, 05:47 PM

Good evening Jerry,

Thanks for picking up on that, yes I meant to say there are far more natural gas explosions then LPG related.

Cheers,

**John Kogel** · 03-12-2014, 08:35 PM

To the OP, the water heater I saw today, on NG, has a long flue like what you describe, from garage to attic,two elbows, a long horizontal, then a roof stack.There is a lot of condensation collecting in the pipe, which is dripping rusty water all ove rthe top of the water heater. This pipe is mostly double-wall (B-vent). I am recommending they look into installing a direct vent unit with a shorter vent.
So, try to keep the pipe as short and straight up as possible.

1/2" copper line is adequate for propane. Propane is denser than NG.

Last year, a construction crew here had a 20 lb propane cylinder stored in a steel strorage container. The valve must have been open a crack. When a worker opened the door, maybe he had a cigarette going, the explosion blew the doors off and sent him flying. Lucky it was early and most people were still in bed at the time. A witness said he saw one of the doors sail 100 feet into the air.

Man near blast at Saanich building site escapes with minor injuries - Local - Times Colonist

**Jerry Peck** · 03-13-2014, 04:37 AM

Originally Posted by Raymond Wand

... there are far more natural gas explosions then LPG related.

Raymond,

I suspect there are several reasons for there being more natural gas explosions than LPG, including:
- LPG gas systems are smaller and each system is an independent system
- natural gas distribution lines are run through many major cities and across the country with many of the old gas lines failing and leaking
- natural gas piping is in many old buildings, and like the the natural gas distribution lines are also old and leaking
- more LPG systems are smaller systems for smaller buildings while more natural gas systems are larger systems in large buildings (such as the buildings which exploded yesterday in New York City)

**Chris Weekly** · 06-16-2014, 06:21 PM

Raymond. I looked at the NFPA site and found this chart (for years 2007 - 2011) on page 4 of a 187 page document with information about all types of fires. The chart does delineate between natural gas and LPG. The stats show that 54% of the fires were caused by natural gas; and 28% by LPG gas causing a fire. A few more deaths with LPG and about equal with injuries and property damage. I didn't read all 187 pages. But wouldn't you agree that there is enough info to warrant that we inspectors defend a property and its' occupants by warning of potential hazards we see? Propane may be just as safe as natural gas....but it also is equally hazardous when leaks occur or improper installations are found.
DSC08234 (Small).JPG

**Raymond Wand** · 06-17-2014, 04:36 AM

There may be mitigating circumstances which lead to more deaths with LP the particulars as to why there were more are not provided in the stats. I don't raise red flags where they are not needed. And of course I do raise concerns where and when warranted.

**Galen L. Beasley** · 06-17-2014, 09:28 AM

Google LPG odorant fade. The odorant that is added to LPG can under certain circumstances fade and not be detectable if a leak occurs. I remember reading about an explosion at a property that had been vacant for several years. There was an LPG tank on the property with some product in it which had also sat for a long period of time and the odorant in it had become undetectable. When the tank valve was reopened to the appliances there was a leak that was undetected and an explosion occurred that killed several people.