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Is there a trick to?

Printed From: R-pod Owners Forum
Category: R-pod Discussion Forums
Forum Name: Podmods, Maintenance, Tips and Tricks
Forum Discription: Ask maintenance questions, share your podmods (modifications) and helpful tips
URL: http://www.rpod-owners.com/forum_posts.asp?TID=3195
Printed Date: 16 May 2024 at 11:09pm
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Topic: Is there a trick to?
Posted By: secretbard
Subject: Is there a trick to?
Date Posted: 21 Jan 2013 at 1:21pm
Hey everybody.  Is there a trick to using an entire bottle of propane?  I've been hanging out in the Pod from time to time in the coldest of weather and have been using my furnace.  Well, when I get to about half a propane bottle, my furnace won't light on a cold start.  It seems to me that the furnace needs a bit more propane flowing to the furnace for the furnace to light on the start.  I've had this happen to me while camping as well where I have no problem lighting the stove and the hot water heater, but the furnace has a problem lighting.  Is there a trick to this.  Maybe opening the propane valve slowly on the start?  Everything else is great with the pod, but I just had to ask the rest of you if you too have had similar issues with the furnace and what you did to overcome it.

Gary


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2010 Rpod 172   :)
2004 Chevy Trailblazer



Replies:
Posted By: Our-pod
Date Posted: 21 Jan 2013 at 3:49pm


Posted By: Our-pod
Date Posted: 21 Jan 2013 at 3:58pm
I haven't yet experienced this, but I'm guessing that it's due to the cold temperature effect on the gas pressure.  It goes back to the ideal gas law: P*V=n*R*T, where P is pressure, V is volume, n is the amount of gas in moles, R is the gas constant and T is temperature.

For this situation, V, n and R are all constant - they don't change with temperature (alright, V changes slightly, but let's ignore that for now).

So then you see that P is proportional to T - i.e. lower the Temperature and the Pressure will fall.  It's possible that the furnace requires a little more pressure or flow than the other appliances, and this could be the problem.

Filling the tank to 20lbs on a cold day would reduce the effect of temperature drop on the pressure.

My two cents.


Posted By: Camper Bob
Date Posted: 21 Jan 2013 at 7:54pm
Who's on first?  Safe Travels.

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Camper Bob and Camper Sue
Gracie the Wonder Dog (12 LB. Mini Dachshund)
2013 Rpod 171HRE(ORPod)
2016 Lance 1685
2015 Nissan Pathfinder


Posted By: techntrek
Date Posted: 21 Jan 2013 at 8:31pm
Unless you are out in your pod in -20 F temps (or below), it sounds like you have a problem with your furnace.  Possibly a partially clogged orifice.  Propane evaporates from liquid to gas in the top of the tank down to -40 F, which is why they are never filled above 80% (and why pressure gauges won't tell you the level of fuel in the tank - another discussion) because it needs that empty area.  However, at -40 F it will only support a very light load, like the fridge or stove.  Once it gets fairly cold out propane will not evaporate as quickly to support heavier loads like the furnace.  Without looking up technical details to figure out how low you can go and run the furnace, but I would guess you shouldn't have a problem down into the negative teens which is why I asked if you were out there at -20 F.  If you are having problems and it is 25 F (above zero) then the propane supply isn't the problem.

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Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ http://www.rpod-owners.com/forum_posts.asp?TID=1723 - Pod instruction manual


Posted By: secretbard
Date Posted: 21 Jan 2013 at 8:51pm
Do you know how I could unclog the partially clogged orifice?  The furnace works and works well and is relatively new, so I really don't see there being an issue with the furnace itself.  It does click to come on, at least I think it does.  It could be the ignitor, but I really doubt it as with a full tank of propane, it clicks and comes on almost immediately.  I'm thinking it might be a pressure problem where not enough gas is getting to the ignitor which very well could be a clog.  I've already had the front panel off of the furnace.  Any idea of how to clean out the lines?  Thanks for the help.  I always prefer doing any maintenance myself as this will help me learn how to care for my Pod.  Maybe I'll look in the manual and see if I can figure it out.  There really should be no reason why the furnace can't run until the propane tank is nearly empty.

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2010 Rpod 172   :)
2004 Chevy Trailblazer


Posted By: secretbard
Date Posted: 21 Jan 2013 at 10:27pm
I think I may have found the answer in an older thread:

http://www.rpod-owners.com/forum_posts.asp?TID=2604&PID=24690&title=furnace-wont-ignite#24690

It seems to me that the lines need to be purged and this might be accomplished through lighting the burners until the flames are good and blue.  This still doesn't explain why my furnace would run and heat the pod, but when the tank got to the halfway point, the furnace would fail to light.  Ah, I will have to figure this one out through trying what I've learned in the above thread.


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2010 Rpod 172   :)
2004 Chevy Trailblazer


Posted By: Our-pod
Date Posted: 22 Jan 2013 at 2:50am
The only time I've had a similar issue was when I had a partially clogged burner orifice in a furnace. The burner orifices in these furnaces are tiny. In my case, a little flake of dirt had traveled down the line. The furnace would light some of the time, but it seemed to have more trouble in the cold.

Sorry if my discussion of pressure and temperature wasn't clear. Unless you are really cold it should be fine, but temperature and pressure are directly related for gasses.


Posted By: Keith-N-Dar
Date Posted: 22 Jan 2013 at 8:24am
have you made sure that the tank was fully purged prior to its first fill?

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Keith-N-Dar
Boris & Betty (Boston Terriers)
2011 R-Pod 177
2010 Ford F-150


Posted By: secretbard
Date Posted: 22 Jan 2013 at 3:28pm
Originally posted by Keith-N-Dar

have you made sure that the tank was fully purged prior to its first fill?

I actually buy my propane refills from Walmart or Lowes, so I'm not sure exactly what I'm getting.  Do you think it would help if I just refilled my propane bottles at the local gas station?  When you do a propane exchange, you never really know what you are getting.  


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2010 Rpod 172   :)
2004 Chevy Trailblazer


Posted By: Keith-N-Dar
Date Posted: 22 Jan 2013 at 8:03pm
I hope that the places that fill them all day long are more likely to get it right.  New tanks are shipped filled with air and have to be bled out when filling for the first time.  If you are using refilled tanks my bet is that they are fine.

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Keith-N-Dar
Boris & Betty (Boston Terriers)
2011 R-Pod 177
2010 Ford F-150



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