Smelling propane inside RV but Pressure Test shows no leaks

[salty14]

Has anyone else run into this issue?  Tuesday evening returned home after work; windows had been closed all day, propane was on, furnace set to on and 68deg.  Was not actually running at the time I arrived.  Opened the door and smelled what I thought was probably propane.  Opened windows, ran the fan and left door open until smell dissipated.  Turned furnace on, sounded 'off', not normal, so shut it back down again.  Left furnace in off position overnight, but propane on.  Next day called the Gas Company that provided and services my large onsite tank to check for possible leaks.  They found nothing.  Got home that night and turned furnace to on position.  Within an hour I started smelling propane again - seemed to be coming from the furnace.  Turned propane off at the big tank.  Next day I got a Certified RV Technician out there; he did the Pressure Test for 6 minutes.  Absolutely no drop in pressure so he said he was positive I had no leak.  Neither of us could smell anything while he was there.  Within 15 minutes of him leaving - again about 45 minutes of furnace being in on position though not running - I smelled it again.  Is it possible a critter got inside the furnace and partially blocked the exhaust causing it to backflow and then seep out through the vents?  The smell is similar to what I've smelled outside at the exhaust vent.  Propane sensor has not gone off and neither has the CO2 sensor.  I know for sure the propane sensor works as I set it off accidentally spraying Lysol in the area.

 

[Gizmo]

Several years ago in a sticks and bricks home I owned, I came home to a smell of gas in the kitchen.  Did as you did, turned off the gas, opened windows and turned on a fan, then I called a service guy who came out who did a pressure test and said there was no leak.  After he left I kept smelling gas and since it was definitely in the kitchen I surmised the smell was coming from the stove.  I pulled it out and put some soapy water on the joint and at first nothing, but upon further and very close inspection I began to see very small and fine bubbles.  I turned off the gas again, disconnected the joint put some plumbers dope on the threads and tightened the joint, no more smell.  Perhaps you might try this as well.

 

[salty14]

Worth a try; I am not comfortable doing this myself but I have another appointment scheduled for next week.  I intend to have him take a real close look at the furnace.  Thanks for the suggestion.

 

[PJ Stough]

First of all I dont believe it to be a good idea to start a fan if you suspect there is propane in the air.  I would think that the motor could produce a spark that could ignite any propane in the air.

As far as the smell of propane, but not finding any leaks, sometime when a bad battery is being charged the gasses produced can smell like propane, so I would check your batteries.

 

[mel s]

Has anyone else run into this issue?  Tuesday evening returned home after work; windows had been closed all day, propane was on, furnace set to on and 68deg.  Was not actually running at the time I arrived.  Opened the door and smelled what I thought was probably propane.  Opened windows, ran the fan and left door open until smell dissipated.  Turned furnace on, sounded 'off', not normal, so shut it back down again.  Left furnace in off position overnight, but propane on.  Next day called the Gas Company that provided and services my large onsite tank to check for possible leaks.  They found nothing.  Got home that night and turned furnace to on position.  Within an hour I started smelling propane again - seemed to be coming from the furnace.  Turned propane off at the big tank.  Next day I got a Certified RV Technician out there; he did the Pressure Test for 6 minutes.  Absolutely no drop in pressure so he said he was positive I had no leak.  Neither of us could smell anything while he was there.  Within 15 minutes of him leaving - again about 45 minutes of furnace being in on position though not running - I smelled it again.  Is it possible a critter got inside the furnace and partially blocked the exhaust causing it to backflow and then seep out through the vents?  The smell is similar to what I've smelled outside at the exhaust vent.  Propane sensor has not gone off and neither has the CO2 sensor.  I know for sure the propane sensor works as I set it off accidentally spraying Lysol in the area.

salty14
When batteries are overcharging they can release, (out gas), an odor similar to, (and often mistaken for), the smell of propane.

 

[salty14]

P J - You're probably correct about the fan, but it was the fan in a/c unit on roof - I thought with windows open and propane usually hanging out low to the ground, and the fact that the sensor still showed green, I would be ok.  Maybe just lucky

P J and Mel - RV is parked and plugged into electrical so no battery usage or charging should be happening.  Thank you for the information though, I would not have thought of that being a similar smell.

 

[PJ Stough]

If you are plugged into shore power, and unless you have your charger shut off, the batteries will continue to be charged, and with a lot of OEM chargers that are not three stage chargers, the charger can and will over charge the batteries causing a smell similar to that of propane.

 

[salty14]

Well, I had no idea.  I will check to see if the charger is shut off when I get home tonight.  Still don't think that's it though with the odor being around the furnace and not smelling it at all when it's turned off.  Only in 'on' whether running or not

 

[Rene T]

Is it possible a critter got inside the furnace and partially blocked the exhaust causing it to backflow and then seep out through the vents? 

Hi Charlene. Welcome back.  What did you buy for a RV?

The combustion chamber and the rest of the furnace are completely isolated from each other. You'd have to have a hole in the combustion chamber in order for that to happen. How old is the furnace. Make and model may help.

It may also help later on if you go into your profile and create a signature of yourself telling us a little bit about you and your RV. 

 

[salty14]

Thanks, I'll do that.  It's a 2016 Keystone Cougar travel trailer, rear kitchen.  Well, okay it seems unlikely to have been a critter then.  I asked because the smell from the outside exhaust is very similar to the smell I'm smelling inside.  Plus the bedroom is completely away from all appliances and I smelled it in there when the furnace was running so I thought maybe exhaust got into the vents and travelled back there that way.  I'm completely baffled then.  I guess I'll need to have the Technician take the furnace housing apart and really check for any leaks or loose fittings.

 

[Lou Schneider]

Like Rene said, you may have a crack in the furnace firebox.  The firebox should be sealed with the inlet and outlet going to the outside of the rig.  A crack would let the propane exhaust fumes mix with the interior air flowing around it.

What you're smelling when you smell propane is the mercaptin oil added to it to provide an odor so you can smell a leak.  Propane by itself is odorless, as is it's exhaust after it burns.

If the exhaust is leaking out of the firebox, it can carry unburnt mercaptin oil with it, letting it settle on the metal parts of the furnace and giving you the propane smell when you turn the furnace off.

 

[grashley]

You do need 12V power for everything to work.  This includes power to circuit boards for the fridge and water heater plus almost all lighting.  The furnace is 12V and propane.  No 120V required.

Most modern systems have a converter (battery charger) and battery connected directly to the 12V power / fuse panel.  If you turn off the converter, the battery will supply 12V power - and be drained.  With the converter on, the converter / battery provide 12V power to the camper and the battery remains charged.

 

[salty14]

Thank you all for the good information - I learned several things I didn't know before.  The issue is resolved, no more smell in the RV.  I believe that some exhaust fumes wandered inside when I was cooking the weekend before - I had the kitchen window open and the furnace was running.  I haven't smelled propane at all for four days now and the furnace is running fine.

 

[Rene T]

That's awesome. Thanks for getting back to us.