How much propane is supposed to be used when running the furnace full-time?

[Alaska1932]

Sent: 12/2/2003 6:58 AM

My husband and I are full-timing in our Indian-- I wanted to ask how much propane are you suppose to go through when using the furnace every night and keeping it low during the day? We only have one 20lb. tank hooked up right now and we have been emptying it every 2 days, is that about normal? I ask this because I was just checking, I don't think we have any leaks. We don't even use our stove either, and have been using that much.--- Amy

[DaveVA78Chieftain]

Sent: 12/2/2003 11:18 AM

Amy,
Propane usage in your situation will depend on a few factors.  The walls are only around 3/4" to 1" thick foam board.  That only gives you a insulation factor of around R-3 or so.  The floors tend to get cold easily (waist up warm, feet cold).  The single pane windows allow a lot of cold air to get in.  Overall, these rigs are not that well insulated.  Most here put their rig to bed during the winter and do not have to worry about winter cold.  Given you have a different situation though...

1.  Windows
   A.  Install shrink film windows.  They seal out drafts and act like a double pane windows.  I used the channels with press-in retainer strips instead of the double faced tape.  This way they are reusable from year to year and you do not have to hassel with removing the double sided tape.  I mounted them on the portion of the window frame that extends out over the inner wall.  They are basically hidden by my mini-blinds.  Cut small sections to fit the corners if you have rounded windows instead of having the strip run out to the paneling.  I still have to make that adjustment.
  B.  You will most likely have to replace the window felt at some point.  It comes apart with age.  It is still avaialable from Winnebago.  There is a thread on this (has the part number) somewhere on this board.   The shrink windows will also help solve that in the interium.

2.  Add insulation
  A.  I plan on installing 2" foam core insulation under the floors of my rig.  The yellow colored stuff that has aluminum on one side and black plastic on the other has a R value of R-13.  You use Liquid nails to put it on.  It's very light weight, costs about $20-25 for a 4 x 8 sheet, and is easy to cut into shape.   You may need to use some roof flashing to make heat shields around exhaust/engine areas though.
  B.  Install either foam board or fiberglass insulation over the walls in closed in areas like closets, behind drawers, bench seats, under the dash, etc.  Might loose a little storage space in the back of a cabinet but it should help the cold and fuel usage a lot.  Use Aluminium tape to seal the seams and edges.  The insulation rolls sold at RV stores is also available at Lowes/Home Depot in bulk rolls.  Cheaper that way.  Should be able to use it in places like the engine cover.  Ensure the steering wheel, brake pedal and gas pedal rubber boots are sealed.  Ensure the holes the wiring goes through the floor just forward of the pedals are sealed.  If you place your hand under the dash the cold air there will surprise you. 
  C.  Install a skirt around the bottom of the rig to prevent drafts under the rig.  Most fulltimers use either a vinyl tarp or hay bails.  The grey/black tank area is of primary concern.  Need to create a sort of enclousure there and then use a 40 watt 110VAC bulb to help keep the temps above freezing.  Frozen poop is not pleasant to deal with.
  D.  Install some sort of a foam plug in the vents to prevent heat loss.  For the bathroom area, make sure you can crack it open a bit to use a vent fan to remove moisture from showers.
  C.  Make some sort of a thermal blanket to cover the door area at night.  The doors are real bad for drafts.  I have noticed the foot well is real bad for drafts.  I place a pillow in there to stop drafts at night.  The warm air of the room can cause a lot of condisation to form on the metal around the door (like droplets on a glass of tea).  Use the stove vent when cooking to help extract moisture.  Yes, the things are noisy. 

3.  If you have tile floors, use area rugs to help hold the heat.  They also feel much better on the toes too!

4.  Make yourself some sort of front window area heat shields.  I glued 1/2" blanket batting from Wal-mart (a couple of layers thick) glued to the back of windshield aluminium sun reflectors cut to fit.  Hold it all in place with felcro tabs.  I will put some sort of a backing on them at some point (sheesh, only just so much time!) but works great for now.  Acts as both a thermal blanket for heat retention and will reflect the sun in summer.  They work well but are a bit bulky rolled up.  I chose that approach vs shrink film because I wanted to maintain winter driveability and summer insulation.

5.  Get yourself a 12VDC hair dryer.  You might need to thaw a lock free some morning in order to get out of the rig LOL

6.  SEAL all holes/openings with either expanding foam or weather stripping chaulk.  Careful with expansion foam though, it actually can expand to the point of seperating joints and walls.

7.  Get a double propane tank valve so you can hook up 2 20lb tanks.  Use one, switch to the other and then you can have heat while getting the other one filled.  You can also get larger tanks.  I saw a new 100lb tank for $80 here locally.  If you do go larger, find a local propane dealer who will fill it from thier truck.  I am at odds with the tank refill part.  Local RV dealer wants $2/gal to refill my permant 65 gal tank.  I can buy a 20lb gas grill refill tank for $16.99 exchange.  Thats less than $1/gal.  Profit can be an evil thing at times.  Shop around.  I get the best 20lb exchange price at a Food Lion grocery store rather than a hardware or gas station.
8.  In very cold climates, you may need a 40 watt 110VAC bulb in the reffer access area.  Apparently the chemicals in the coils can freeze at very low outside air temps.

9.  An electric blanket can be a godsend.

10.  A small electric heater in the bathroom area helps to knock the chill off for showers and such.  That way you do not have to run it all the time.

11.  Make sure the thermal blanket around the water heater tank is in good shape.

12.  Open the oven door after cooking to reuse the heat for creature comfort.

13.  Ensure the window caulking is in good shape all the way around the windows outside.  Even if it's water tight, air tight it might not be.

14.  If you have one, don't forget to insulate/seal the inner wall in the electrical access/storage area at the back of the rig.  Lots of dead air space and potential for air leaks there.

15.  The generator compartment is a big metal box.  It can easily transfer cold air into the rig.  Insulate it too.

All comes down to, you have to think differently when using these rigs for winter fulltiming.  For occasional winter camping, most can live with a few drafts and such.   For winter storage, not even a  concern.  A bit different when year-round fultiming though.  So, you have to adapt a rig designed for summer fun to winter creature comfort.  Besides, almost all of this will have the added benifit that it will also help the A/C perform better in the summer. 

Good luck and stay warm
Dave

[mightybooboo]

Sent: 12/2/2003 12:27 PM

" wanted to ask how much propane are you suppose to go through when using the furnace every night and keeping it low during the day"

Amy,heres what we did... In a 23 foot class C we put a blanket between cab and house area and kept rear bath closed.Used the heat shrink plastic on the house windows.Using the heater about 10 hours a day in mid 40s night temps and 60s in daytime used about 12-15 gallons every 3 weeks.

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Summary: It's OK but didn't work at first
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Rating: 5
Summary: Every floor of your house should have one!
Comment: One reviewer questioned if these really work... YES they do! I had a new furnace installed recently, and the installers made a mistake. Without detectors in the house I might never have known, and my family could have suffered greatly (ie somebody could have become ill or even died!).
We had had them for years and they ALWAYS read 0. When we started seeing it detect CO we knew we had a problem. Occasional low readings (such as near your kitchen on Thanksgiving if you have a gas stove) are ok, but any consistant reading is cause for real concern particularly if it is away from any known source of CO (stove, fireplace, etc).

I strongly reccomend folks place a detector on each occupied level of your home. If something happens you may very well get different readings on different levels (I did).

When selecting a CO detector be sure to pick an electornic one with a digital readout. They cost more, but are well worth it. The only maintenance with a unit like this one is replacing the backup battery. (BTW, a backup battery is a really good idea. Each year many folks die because they used various types of gas heating devices during power outages with inadequate ventalation.) Also, the digital readout will help track down problems envolving lower levels of CO and may give you earlier warning of a malfunctioning heating system.

Finally, this particular unit has an advantage in that it can be placed directly over an outlet, or the included power cord can be used to allow higher wall mounting or placement on a table/shelf/etc.

You could consider a catalytic heater,but it should have a low oxygen shutoff and you really need a carbon monoxide detector.You need the detector even for the regular furnace,1 member here almost died from fumes,our home heater vent failed and the detector warned us it was happening.35 dollars at any walmart,get one for christmas and save a life.I have a NIGHTHAWK digital readout plugged in next to the wall heater,it never goes off the zero reading.If i hold a lit cigarette below it it alarms in 15 seconds.It was about 55 bucks or so
The cat heater works well,I used one for years,6000 BTU and 5 gallons lasted over a month in my old bus conversion.Kept the bedroom toasty at night.And I didnt die either,(for the naysayers who are convinced you will.)

BooBoo 

[griffs]

Sent: 12/2/2003 5:41 PM

THANK-YOU Dave;
  I like going to the mountain  to camp and gold proseting . Were it can get cold . Now have a new todo list. # 1. on the list (thank -for the info).

                                                                   GRIFF

[DaveVA78Chieftain]

Sent: 12/3/2003 5:45 AM

Your welcome Griff. - Dave

Amy,

A little more info about propane useage.  A gallon of propane is rated around 93,000 btu.  Now a 20lb propane tank is only filled to 80% capacity which is 16 lbs.  Allows for gas expansion when outside temps are higher like they are in summer.  Thats controlled by the Overfill Protection Device (OPD) in the fill valve for tanks 40lbs and smaller.  Larger tanks are also limited to 80% but is manually controlled.  Anyway, 16lbs gives you a potential of 1,488,000 btu's/tank  A properly setup furnance is rated around 25,000 btu.  So, if it ran continiously, you would use up a tank in 59 hours.

If your furnance is rated at 30,000 btu's, then you would use a tank up in 49 hours if ran continiously.  Ideally, it would not run continiously.  It would have lets say a 40% duty cycle (only on 40% of 1 hour).  For a 25,000 btu unit, that means you would only use 10,000 btu's/hour of the potential 25,000btu's/hour.  So, that means you would get 148 hours of usage from one tank.  This is why I concentrated on the insulation stuff on my previous post. 

Now, you also said you are fulltiming.  I take that to mean you are also using your water heater.  It's btu usage also has to factored in.  I believe 12,000btu (not sure right now) is the value if it ran continiously.  Then there is the duty cycle factor to roll in.  They run far less than a furnance.  If properly insulated, even better.   Pilot model appliances use a littlebit more becasue the pilot is always on.   So, the amount you use overall/day is dependent on how often all of your propane appliances have to run. 

The better insulated the rig, the less they run because they hold the heat inside.
These rigs were designed primarily for summer fun so the insulation has to be beefed up to more adequately support winter fulltiming.  The bigger the rig, the more area to keep heated ergo more btu's consumed.  Still, propane is the least cost approach for heating from a btu perspective.   

Dave

[LJ-TJ]

Sent: 12/6/2003 4:02 PM

Dave...You have to much time on your hands. Awww just kidding. 
Nice piece! I was wondering the same thing. T.J.

[mightybooboo]

Sent: 12/6/2003 7:56 PM

Dave,do you sell "Propane and Propane Accessories"?
Had to ask.
Boomhower

[DaveVA78Chieftain]

Sent: 12/6/2003 10:28 PM

LOL - nah.  Been going through getting my systems online.  Done a lot of research in the process. Like effects of condensation in the regulator when you have freezing temperatures outside.  Had a problem just the other day with that.  Still, it's hard to find info on things like the Coleman Presidential DSI model furnance.  I have mine working but not entirely sure it is just right.

Burner chamber heats up to the point that it shuts down for a bit (thermal cutoff) but the ignitor board will restart it automatically once the temp goes down.  Funny thing is, power to the DSI board remains on and there are on.  Appears there is a time delay retry feature built into the board.  This may be the correct way for it to run.  Would make sense but without reference info I am not positive.  Added some monitor lights to mine.  One to see thermostat status, one to monitor power to the DSI board and one to observe gas valve open signal from DSI board.  Helps me to monitor what it's doing.  Lots of power in them ole furnances.   

I will upgrade to a dinisour fan shut off type DSI board in the future.  This old one is on it's last legs.  Just have to many little details to do at the moment.  Happy that all systems are now either working as designed or I have an alternative worked out (like the small dorm style reefer).

Dave
78 26' Chieftain

[RJgonfshin]

Sent: 12/11/2003 8:35 AM

Your propane consumption is normal when you are heating w/ the very inefficient system that is standard in your Coach

I use 100% Catalytic heaters for mot of my heat, and use the furnace just to keep the heat regulated to a constant temperature. They use 1/4 the propane as a furnace does.

If you do not believe in using Catalytic heaters, then I can't help. But no matter what you do, that furnace will still be the most inefficient propane sucker in your Coach.

I also use propane lights during our awake hrs. They are really effecient, providing light and heat at the same time. But I do nothing but dry camping, so I take all the effeciency that I can get in this cold weather

Rich

[Lefty]

"Local RV dealer wants $2/gal to refill my permant 65 gal tank.  I can buy a 20lb gas grill refill tank for $16.99 exchange.  Thats less than $1/gal."

Wrong...

A 20lb cylinder holds about 4 gallons of propane. If you are exchanging them for $16.99 each, you are being charged around $4.25/gal. for the propane. Considerably higher than the other place you mentioned that wants only $2./gal.  And WAY higher than the $1./gal price you thought you were paying.

[SoakedKarma]

My 20 lb tank holds 4.76 gallons of propane and I squeeze in 5 often, and why they are called 20 lb tanks..

Air space is factored into size of tank and can be figured out by WC# stamped on tank divided by 8.34 
WC: Water Capacity 47.6 lbs ÷ 8.34 lbs = 5.57 total gallon capacity for my 20 lb tank...
20 lbs ÷ 4.2 lbs = 4.76 gallons propane..

Exchange bottles are always Under Filled by +3 lbs.. Read all the little signs posted on the cage and you will see this to be true.. will take a photo next time I pass by the two local exchange cages and post.. You are always getting short changed when you use them..

Their are some fill stations I have run into that use a scale to this day and they set tank on scale and add 20 lbs of fuel plus TARE weight.. Always make sure sellers filler neck/hose is factored into weight or you will be over charged for product if they charge by pound..  Same trick butchers used to use by putting finger on scale..

WC=Water capacity in pounds..  ÷ 8.34 lbs = total tank gallon size including air space
TW=Tare Weight empty tank weight.. my 20 lb tank is 18 older tanks were made of thicker metal.. I have one 30 lb tank from my 1972 Weyerhaeuser built coach which has  TW of 28.5 WC 66 while 05-06 tanks TW is 23.5 WC 71.5
DT=Dip Tube length.. tube connected to bleeder valve my 09/07 Manchester 20# is 4" but 3.6" is also common..  my 30# tanks Worthington 11/05 = 7.5", Manchester 12/06=116mm, of course 07/72 Manchester tank has no DT stamp as it was manufactured long before 1998 OPD valve requirement.. 

AmeriGas service personnel say to hang onto old tanks as they were made with thicker steel as evidenced by higher TW weight.. My tank has been stamped so much there isn't a place to stamp anymore.. Good thing they use adhesive stickers now..

Getting back on track my main Dometic forced air furnace 16,000 btu output uses 20,000 btu gas input according to spec plate..  20% btu loss just in burning the fuel.. In the winter I keep front of coach around 45ºF and rear bedroom 65ºF using 9,000 btu output Suburban forced air heater.. Plate states furnace has a 75% efficiency.. Half the fun is seeing breath while cooking breakfast..  between down comforter and electric blanket when the temps drop into the single digits all is good at night.. 

30 lb 7 gallon cylinder lasts me 7-10 days with nights in the low 20's and days seldom reaching 42ºF.. It's all about how low you set the thermostat..