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Old 02-18-2021, 09:45 PM   #1
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General Cold Weather Heater Questions * Including Heat Pump Use * And Engine Start

I have very little freezing-cold weather experience so I need some coaching for diesel RV use:

* I know Air Conditioner system includes a Heat Pump.

* I know a heat pump has real problems heating below 40F.

* I know I prefer to use a 1500W floor heater when I have free shore power.

* I know fuel thickening occurs below 32F and it's wise to use a fuel winterizing agent in advance so your tank is saturated with this stuff.

QUESTIONS

* Do I pay for propane by the pound or by the gallon? ...And if it's by the gallon, does that mean propane costs more when I fill up at 100F vs. filling up at 40F? (Don't laugh. I'm curious how much temperature affects a gallon of propane at the pump?)

* If I can get the inside air in my RV above 40F, can I then supplement my Suburban heater with my Heat Pump? ...Specifically, will the heat pump work if the inside air temp is above 40F and the outside air temp is blow 32F?

* I typically use a 1500W electric floor heater when I have free shore power, but when I'm boondocking, and it's sub 25F outside, how many Amp-Hours is needed to get through the night running my Suburban SF-25 alone? ...I ask because know I will be running the Suburban heater and fans to circulate the air. The heater is really nice, but it sounds loud and the heat really blows out the air ducts. So I wonder how much battery power it takes to run a Suburban like mine on FULL for 10 hours?

* Will 420AH of battery storage get me through a freezing cold night if I turn off my residential refrigerator and don't open the door, and run my Suburban heater on full? (50% of 420AH is 210AH.) So is 210AH enough? And even that is not likely. In fact, I bet the average FLA bank of 420AH is only good for 180AH since FLA batteries rarely reach 100% SOC, except may on the first night (for reasons I will not go into here).

* If I run my Suburban SF-25 (25,000 BTU/Hr) on full... all night long for 10 hours, how much LP will this use?

* How full can I fill my propane tank if it's rated for 31 gallons / 38 gallons W.C.)?

* 38 gallons W.C. stands for Water Colum. So what? How many gallons can I put in at 68F?

* If I remember the most I can fill my tank is 3/4 full on the tank gauge, so how many gallons of propane is this assuming the above numbers?

* I am told when the temperature drops below 32F over night that it's a good idea to let the faucets drip. Is this true or just rumor?

* Will a 100W old style bulb help fight off cold in the basement?

* I would thing I would need 500W... and I would run a separate extension cord to the 20A-120V shore power plug if I have power.

* Do those RV fireplace inserts work very well or are they mostly for weather above 60F and for ambiance?

* Does the suburban heater loose efficiency as you go up in altitude? I'm guessing it is just like your stove burners... so every 3000 ft of altitude, how much should you de-rate the output of your Suburban heater? 10%/3000'? What do you think?

WHAT ABOUT DIESEL ENGINE PRE-START CONCERNS...

For example, when the weather is in the 30s the night before your departure and you know its going to be in the 20s the next day you want to drive off (this happened to me once in Banff)... I have these questions:

...You just need to run the battery charger to heat the batteries up, right?

...But if you are boondocking, can you cover the batteries with a space blanket or something that will make a difference and not cause a fire?

Note: I do not recommend taking weak engine start batteries into sub-freezing weather, because you may find your "Boost" switch will not be much help, because your frozen house batteries will be very strong at these temperatures.

* Does it make sense to run the engine the night before for 20 minutes... to run your dash heater for one thing... and to heat up the oil in the engine block for another? ...Will doing this make it easier to start the engine overnight or will freezing temperature affect the oil in less than 1-2 hour?

* How long do you need to run your engine block heater before you start your engine? ...Is there a rule of thumb for ever 5F below 38F? I.e., is 30 minutes for every 5F below 38F a good standard to go by?

* What have I left anything out?
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Old 02-18-2021, 11:14 PM   #2
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Suburban SF-25 (25,000 BTU/Hr) Heater Information

After I posted these questions I found some additional information that will help answer some of the questions above:

All numbers are based on my 2004 Itasca "Horizon" 40AD with a Suburban SF-25 (25,000 BTU/Hr) Heater: ...and I made a few assumptions so I misstated any facts, please let me know.

* 1 gallon of propane is 91,500 BTU

* Suburban Model #SF-25 furnace puts out 25,000 BTU at sea level.

If you have a 31 gallon tank (38 gallon Water Colomn, W.C.) and you can only fill it 80% at 68F, that’s about 24 gallons of propane you can squeeze into a propane tank, and your gauge will read ~80% or just over ¾ FULL.

So 24 gallons X 91,500 BTU/25,000 BTU/hr = 91.5 hours of use for a full tank on FULL HEAT.

Or you an look at it like this: A Suburban SF-25 heater will burn 1 gallon of propane every 3.8 hours. The equation is: 95,000 BTU / 24,000 BTU/Hr = 3.8 hours/gallon.

* So you need about 2.1 gallons of propane to get through a 8 hour night on FULL heat or 3.1 gallons of propane if you want to run your heater on FULL for 12 hours a day.

* So a full tank of 24 gallons will last ~11 days at this rate at 8 hour on FULL HEAT; and you will only get ~7.6 days on FULL HEAT if you run 12 hours per day.

Of course, having enough propane is one thing.

…And having enough battery Amp-Hours is another... if you are boondocking. And if your batteries go dead and you have no shore power, then your fans will not run to blow the heat out of the vent.
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Old 02-19-2021, 08:26 AM   #3
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Some thinking that is not backed by much actual Rv boondocking experience? I do not like cold weather as it is so much trouble so never plan cold weather RV use, only done it when caught with bad planning or emergency shelter use.
First thought is that the battery use is very much less when the batteries are cold and the need is very much higher. Cold battery effective time is cut way down and gets far less as the temp drops. Since lead acid batteries make fumes, it is very difficult to keep them warm and also vented well to avoid explosions. Anything that warms them causes fumes and anything that vents them will let them get cold, so little can be done except to keep the room warm. In the old days when telco service was regulated, we kept generators on hand for ice storms but now that is not required and service just stops when the batteries go dead in the repeater huts. consistent cell service is not required beyond just the normal "customer service" considerations.

Heat pumps stop when the area where the compressor is gets cold so it is the outside temp which changes the question and that adds to the problem.

Light bulbs do put off a fair amount of heat and it does work well to keep pipes from freezing if the space can be limited like in a wet bay. But they are not the most efficient as they are designed to produce more light and try to avoid heat. Not a good design to avoid it being heat but the idea is there. Other items like those designed for heat are more effective on energy use. Light might be considered a "waste product" when we heat with lightbulbs? I might consider heat tapes for pipes as a better use of the energy on hand?

We are now into the thawing of the ice on the roof and I wish I had heat tapes to deal with the ice dams we now have but it is too late for that and we will just have to suffer as there are few things to do to prevent the damage now.
For those not up on ice dams, they tend to form when the roof peak which is higher gets more heat and at the right temp that ice melts and runs down to the eave area which is cooler and refreezes into a thick ice layer forming a dam as the upper area ice begins to melt. This water coming down can pool against the ice dam and back up to go through the roof and you lose your sheet rock and insulation in the house!
If we had been in less crisis mode, we knew this might happen but there were higher priorities to deal with at the time, so now we have to pay the price for negligence! When you can't stay warm, flush the stool or get water to cook, you tend to deal with those questions first!!!
Which gets back to why I don't RV in cold weather. It's all just too much trouble and you do get into the mode where looking at the cost is not as important as simply FINDING the gas or propane needed without asking the price. In the past week, I have gone out daily to restock gas but I was only able to collect cans to hold about 8 gallons at a trip and it took 3-4 hours to find stations that were open and had gas so asking the price was not part of the deal!!! Just finding a line to get into and that line not using the supply before I got to the front was fun enough!
I should have had more stored or at least had far more cans on hand but I had to have the gas, so we do what we have to do. I found that I my new car is designed to NOT allow siphoning and we ran the RV genset until it ran out.
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Old 02-19-2021, 07:19 PM   #4
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Thinking Outside The Box + Getting your heat pump to work below 40F

Morich: I got a lot out of your post, but that's because I travel May-October or just during the summer.

Thanks for clarifying: The Heat Pump stops when the area where the compressor is gets cold so it is the outside temp (that counts) which changes the question and that adds to the problem.

You also talked about using heat strips as a better solution to many who talk about using old style light bulbs to product heat.

Along those lines, it's too bad we can't just wrap a heat strip to our Pex water lines to keep them from freezing like you can copper, but that's a different subject.

When it comes to keeping warm inside the RV, I'm surprised more owners are not running a separate Compartment Heater to warm-up the basement of the RV.

...I knew of some boat owners that use light bulbs, but I also know some caught on fire. When I was a boat owner I used a "Compartment Heater" which is safer to use vs. a common space heater like this one for $37:

https://www.amazon.com/Xtreme-Heater...3785941&sr=8-5

So if I was using my RV in cold weather, I would run a 12 gauge extension cord to the 20A shore power plug and heat my basement while I use the various forms of heat inside my RV.

QUESTIONS ABOUT HOW HEAT PUMPS WORK to provide supplemental heat:

* When using the Coleman Mach Heat Pump, does that mode turn off the outside blower so it does not suck any frigid air into compressor area?

* Can I change I increase the effectiveness of the heat pump by blocking off 80+% of the air flow through the Condenser?

* Additionally, I know my bedroom heater blows a lot of hot air into my bathroom and through just a couple of 3" ports. So I'm wondering, if I can divert some of that 110F+ hot air to the into the compressor side of the Heat Pump box... would the Heat Pump work?

* Has anyone tried to create a recirculating heat pump system with the inside cabin air?

Access is a challenge, but let's say I can figure that out. ...Would there be a benefit to an RV Recirculating Heat Pump System?

NOTE: All the follow diagrams focuses on maximum COLD AC efficiency. And if I remember right, the Heat Pump runs in the opposite direction; so when you read the diagram, you need to swap the HOT and COLD labels to understand how the air flow would look.

BASELINE: If the outside air is above 40F then the heat pump will work, right? So can't we just cutoff or drastically deduce the outside (freezing air) and replace it with a small percentage of cabin air... that gets expended to the ground thru the compressor exhaust? ...How to accomplish this would be the next step.

Fundamentally, I would like to ask others with more experience, would this work?
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Old 02-19-2021, 07:37 PM   #5
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You don't want to block air flow either inside or outside, the less air the less well it will work.

The outside blower still runs and moves air across the outside coil, as it needs to take the low pressure liquid refrigerant that is in the 0 to -20 F range and heat it by blowing outside air thru it, changing it to cold low pressure gas. Then the compressor makes the gas into warm/hot high pressure gas, that gives up heat thru the inside blower.

The colder the air blowing across the outside coil is the less effective the process is. As stated the point where it stops being worth doing is somewhere in the 40 to 45 F range.

. . . . .

Short answer is that trying to generate fuel heated air to blow into the outside coil would be less efficient than just using that source of fuel heated air directly in the RV.

You could build some kind of passive solar collector that captured the sun's heat to heat the air being drawn into the heat pump outside coil. But it would have to be huge to be effective, and the few systems I have seen have heat storage using tons of rock in large square footage size structures to capture the heat and hold it so that the benefit can continue even after the primary daylight hours are over with.
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Old 02-19-2021, 07:51 PM   #6
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Right...

I would like to note: My RV has a bedroom heater and a Suburban main heater and a Heat Pump in my Coleman Mach (2-Ton) System.

Now picture this: What if you build a 3/4 chamber that fits in front of the Condenser. This chamber is about 2'x 2'x 3/4" so you do NOT pass freezing cold air thru the condenser coils, and you DO pass warm air piped-in by porting heat to that chamber.

One side of this hot air box chamber is solid and faces the outside with rubber insulation to minimize heat exchange, and to prevent outside air from being sucked inside. And the other side of the chamber has lot of holes that let the hot air out... to be sucked into the air box.

So now you have the condenser side of the box that is much hotter than the other side of the box.. and then you let the heat pump take over and ratchet-up the relative heat inside the cabin... thru the ceiling vents in my case. And now where you normally would see cold air running the AC, you now get warm air in Heat Pump Mode.

...I'm guessing if this was possible it would already have been done, but I like to think out of the box.

...This may not be possible. Odds are not in our favor.

...But maybe some of you HVAC experts out there can noodle on the premise... and then we can figure out how to achieve a benefit by changing the circulation of air through that condenser.

Note: The evaporator side is not a factor since it's being supplied with relatively colder air though the air filter.
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Old 02-19-2021, 07:59 PM   #7
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Quote:
Originally Posted by imnprsd View Post
Right... So I'm wondering if there is way to mix a certain amount of cabin air (a total heat loss since all this air will go out the box exhaust to the ground)... to warm up the 20% of the outside air I let thru the condenser... to achieve a 40+F temperature to the coils in the condenser?

...I'm guessing if this was possible it would already have been done, but I like to think out of the box.

...This may not be possible. Odds are not in our favor.

...But maybe some of your HVAC experts can noodle on the premise and then we can figure out how to achieve a benefit by changing the circulation of air.
Possible? Yes. Cost effective. NO. The cost effective way is to use backup heat when your heat pump stops keeping you comfortable (electric if included in your site price, propane/diesel depending if your RV has propane or diesel heat, if not). Generally it will start being cheaper to use backup heat when it gets below about 40 F but the heat pump might not be able to keep up at that temperature with the heat loss from your RV. If you can cut your heat loss without spending a fortune, that's your most cost effective answer.

Note: depending on your RV's heat pump system, you might be able to use the heat pump when outside temps fall to as low as 35 F. Generally, this is what residental heat pump systems use for their switch over to emergency resistance electric heat mode switch over point.
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Old 02-19-2021, 08:25 PM   #8
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powercat_ras: You mean your can get more heat (for less $$$) out of a floor heater!

ha ha. The joke is on me!

So why is everyone trying to run their Heat Pump when the OAT is above 36F-40F? ...My guess is that the do not know this limitation.

...And you are saying there is no way to "trick" the heat pump system into working when you are in the OAT 30F-40F range?

Note: I bought my floor heaters at Best Buys and I also paid for their product insurance so I can replace the tall heater when they break. And after two exchanges, because these tall heaters kept falling over, I figured out the 12x12x12in cube heater was the way to go. And at less than 12" this cube does not fall over; and therefore you really don't need to pay or the insurance if you go for the cube!

... At least we know how our basement AC works in heat pump mode.

...Thanks for helping me learn more about How Heat Pumps Work by thinking out of the box!
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Old 02-19-2021, 09:31 PM   #9
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Below about 40F outdoor air temps, the RV heat pump does not increase the temperature of the indoor air enough for the air blowing out the ducts to feel comfortable, even though the air coming out the ducts is still warmer than what is being drawn in. Also as you can see from the curve below you have a lot more heat loss to make up for as the outside temp gets colder, while at the same time the heat output of the heat pump declines.

This "comfort" temp is higher in a RV than in a home because in an RV you lose a lot of heat between the air outlet of the heat pump and the air duct outlets, there is not as much insulation between the cold outside and the ducts. In a residence you have around R-38 insulation above the ducts in an RV you have maybe R-7 in a foam sandwich roof RV and slightly more (R-11) in one of the limited RVs that have fiberglass batts in the RV roof. The colder it is outside the more heat gets lost between the air outlet on the heat pump and the ducts blowing into the inside of the RV.

The warmer it is the more savings are gained by using a heat pump vs. electric heaters gets as the image below shows. The actual curves for an RV are going to be worse than this but it gives you the idea.

Note that COP is the ratio of how much more heat per dollar spent on electricity you get vs. a indoor electric heater.

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Old 02-19-2021, 10:21 PM   #10
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Got it.

* RV insulation "R-Factor" bad.

* RV heat pump unusable below 38-40F

* Battery output will be less. And if you use all your house battery storage to heat your RV though the cold night, you may not have any reserve power to "BOOST" your chassis batteries in the event you cannot start your engine.

==> But in the fortunate event you DO HAVE SHORE POWER....

...Let's turn this thread towards preparing for the cold as far at batteries and starting an engine are concerned.

I think people need a "game plan" to follow the night before a freeze.

I have faced this my self and I'm not sure I'm doing everything I possibly can do to ensure a normal departure.

For example, let's say the day and night before you want to depart your campsite... the OAT is going to drop from 50F to 40F to 28F by morning come. Sooooo... how should you prepare your diesel engine and battery bank the night before a freeze?
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Old 02-20-2021, 07:14 AM   #11
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Some answers in bold below by a retired engineer:

Quote:
Originally Posted by imnprsd View Post
I have very little freezing-cold weather experience so I need some coaching for diesel RV use:

* I know Air Conditioner system includes a Heat Pump.

* I know a heat pump has real problems heating below 40F.

* I know I prefer to use a 1500W floor heater when I have free shore power.

* I know fuel thickening occurs below 32F and it's wise to use a fuel winterizing agent in advance so your tank is saturated with this stuff.

I wouldn't worry about diesel thickening until below zero F.


QUESTIONS

* Do I pay for propane by the pound or by the gallon? ...And if it's by the gallon, does that mean propane costs more when I fill up at 100F vs. filling up at 40F? (Don't laugh. I'm curious how much temperature affects a gallon of propane at the pump?)

You pay by the gallon. Propane density doesn't change much between 40 and 100 F.

* If I can get the inside air in my RV above 40F, can I then supplement my Suburban heater with my Heat Pump? ...Specifically, will the heat pump work if the inside air temp is above 40F and the outside air temp is blow 32F?

The 40F restriction on using a heat pump is based on the outside temp, the temp of the air that is blowing across the outside coil. RV roof top heat pumps do not have a defrost cycle. Home heat pumps do and work down to about 20 F.

* I typically use a 1500W electric floor heater when I have free shore power, but when I'm boondocking, and it's sub 25F outside, how many Amp-Hours is needed to get through the night running my Suburban SF-25 alone? ...I ask because know I will be running the Suburban heater and fans to circulate the air. The heater is really nice, but it sounds loud and the heat really blows out the air ducts. So I wonder how much battery power it takes to run a Suburban like mine on FULL for 10 hours?

Your Suburban heater probably draws about 6 amps DC for fan and controls. For ten hours that will take 60 amp hours which your 420 Ah battery will supply just fine.

* Will 420AH of battery storage get me through a freezing cold night if I turn off my residential refrigerator and don't open the door, and run my Suburban heater on full? (50% of 420AH is 210AH.) So is 210AH enough? And even that is not likely. In fact, I bet the average FLA bank of 420AH is only good for 180AH since FLA batteries rarely reach 100% SOC, except may on the first night (for reasons I will not go into here).

* If I run my Suburban SF-25 (25,000 BTU/Hr) on full... all night long for 10 hours, how much LP will this use?

Propane has about 90,000 btu per gallon. So multiplying through gives about 3 gallons of propane for ten hours.

* How full can I fill my propane tank if it's rated for 31 gallons / 38 gallons W.C.)?

Not sure what the W.C. means in this context but I suspect that the gross capacity is 38 gallons and typically you can only fill to 80% or a bit over 30 gallons.

* 38 gallons W.C. stands for Water Colum. So what? How many gallons can I put in at 68F?

* If I remember the most I can fill my tank is 3/4 full on the tank gauge, so how many gallons of propane is this assuming the above numbers?

* I am told when the temperature drops below 32F over night that it's a good idea to let the faucets drip. Is this true or just rumor?


Might help to keep the fresh water pipes from freezing.


* Will a 100W old style bulb help fight off cold in the basement?

Not much unless the basement is completely enclosed.

* I would thing I would need 500W... and I would run a separate extension cord to the 20A-120V shore power plug if I have power.

* Do those RV fireplace inserts work very well or are they mostly for weather above 60F and for ambiance?

* Does the suburban heater loose efficiency as you go up in altitude? I'm guessing it is just like your stove burners... so every 3000 ft of altitude, how much should you de-rate the output of your Suburban heater? 10%/3000'? What do you think?

WHAT ABOUT DIESEL ENGINE PRE-START CONCERNS...

For example, when the weather is in the 30s the night before your departure and you know its going to be in the 20s the next day you want to drive off (this happened to me once in Banff)... I have these questions:

...You just need to run the battery charger to heat the batteries up, right?

The charger won't heat the batteries, but with good batteries a diesel should start down to zero F.

...But if you are boondocking, can you cover the batteries with a space blanket or something that will make a difference and not cause a fire?

Note: I do not recommend taking weak engine start batteries into sub-freezing weather, because you may find your "Boost" switch will not be much help, because your frozen house batteries will be very strong at these temperatures.

* Does it make sense to run the engine the night before for 20 minutes... to run your dash heater for one thing... and to heat up the oil in the engine block for another? ...Will doing this make it easier to start the engine overnight or will freezing temperature affect the oil in less than 1-2 hour?

Yes that probably is a good idea if it will be really cold the next morning, but down to 20 F I wouldn't worry about it.

* How long do you need to run your engine block heater before you start your engine? ...Is there a rule of thumb for ever 5F below 38F? I.e., is 30 minutes for every 5F below 38F a good standard to go by?

It will take a long time, probably several hours for a block heater to significantly warm up an engine as they are designed for continuous use. But like I said above, at the temps you are talking about I wouldn't worry about it.

* What have I left anything out?
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Old 02-21-2021, 02:40 AM   #12
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DavidM: Thanks for sharing.

I'm curious, have you ever owned a Diesel RV?

Do you have a residential refrigerator in your RV?

W.C. stands for "Water Column." So I'm not sure how that relates to PV=nRT. But somehow, 80% is all you can shove into a 31/38 gallon Propane tank.

So if you are sure that 100% full = 38 gallons of propane, I wonder why they spec 31 gallons?

My guess is that 31 gallons is 81.5% of 38, so they are "cheating" a bit. Surprise, surprise! ...But you would expect that. Other guess on my part is that OAT has a a little to do with the total mount of propane your 38WC tank will accept at full pressure. Does it? (PV=nRT??? if you remember that one?)

That said, I'm guessing if you hooked up a W.C... and filled the tank until it reads 38WC... then the fluid equivalent (at 68F???) maybe 31 gallons of Propane. (Again, I don't know.) Maybe someone can confirm or reject this theory?

Side note: If the time comes when you can't start your Suburban furnace with your gas stove top running, then maybe you need to do a WC check at the stove top while you adjust the tank regulator to spec.

Tip: If this happens, then turn off the gas stove top and start the Suburban furnace first... then try the stove top. Then get your propane regulator adjusted when you get home.
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Old 02-21-2021, 04:52 AM   #13
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Answers in bold below:

Quote:
Originally Posted by imnprsd View Post
DavidM: Thanks for sharing.

I'm curious, have you ever owned a Diesel RV?

No RV but I ran a bunch of diesel construction equipment that we had to start on cold Jersey mornings. If the batteries were in good shape and the engines had good compression, they started.

Do you have a residential refrigerator in your RV?

No but I have owned cruising boats for many years with DC fridges. These are the same as in RVs except for the really big ones on diesel pushers that have a true residential fridges.

W.C. stands for "Water Column." So I'm not sure how that relates to PV=nRT. But somehow, 80% is all you can shove into a 31/38 gallon Propane tank.

So if you are sure that 100% full = 38 gallons of propane, I wonder why they spec 31 gallons?

My guess is that 31 gallons is 81.5% of 38, so they are "cheating" a bit. Surprise, surprise! ...But you would expect that. Other guess on my part is that OAT has a a little to do with the total mount of propane your 38WC tank will accept at full pressure. Does it? (PV=nRT??? if you remember that one?)

That said, I'm guessing if you hooked up a W.C... and filled the tank until it reads 38WC... then the fluid equivalent (at 68F???) maybe 31 gallons of Propane. (Again, I don't know.) Maybe someone can confirm or reject this theory?

I do remember PV=NRT. I don't think WC has anything to do with propane tank filling. Your stove, furnace and water heater require a pressure of 10" WC for the propane supply.

Side note: If the time comes when you can't start your Suburban furnace with your gas stove top running, then maybe you need to do a WC check at the stove top while you adjust the tank regulator to spec. Yes, see above.

Tip: If this happens, then turn off the gas stove top and start the Suburban furnace first... then try the stove top. Then get your propane regulator adjusted when you get home.
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Old 02-21-2021, 07:31 AM   #14
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WC = Water Capacity
Or the 100% “full” capacity. So you have 31 gallons at 80% as you have noted.
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Old 02-21-2021, 08:40 AM   #15
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One thing that might help to point out is that a lot of the heat loss in RV is also from the floor, not just the ceiling and walls, etc., so that heat passes through the areas in the walls and compartments below to help heat the pipes!
You might want to check your specific Rv for having a heat duct run to the storage compartments below.
I have a small simple Rv that has very few of the features of the bigger RV but it does have a vent to pass air to the storage as we heat the interior.
We have somewhat limited height storage underneath and that area is almost totally open from side to side and front to back. Big enough to slide a six foot ladder in! this picture shows the vent for the storage.
That leaves a single tube dropped off the furnace heating the whole underneath where the wet bay and pipes may be. Other RV which have a far more restricted area like a totally enclosed compartment for the drains, we find a light did all we have needed.

The amount of heat needed is directly related to how much space, so when we lost power the past week, we kept most things from freezing by cutting the space around the lightbulbs way down. I protected the plumbing to a utility sink and the water softener with a 60 bulb at 9 degrees outside temp by throwing old moving pads over the whole thing. A 60 watt will not heat a room but it does do a lot for a space of 10-20 cubic feet!

The single pipe we lost was an outside faucet which we normally heat with a 9 volt Christmas tree light in a foam box. The problem came up when they told us we were having rolling blackouts but DID NOT tell us they were turning it off for several days, leaving me to sleep through the night while they turned the power off!

It's not the things you expect and prep for but the surprises that get you! I have learned that the state folks will constantly lie to us but they caught me this time!
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Old 02-21-2021, 07:14 PM   #16
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Morich: What sort of 3-D software are you using that produces these drawings you are so famous for?

In my 2004 Itasca "Horizon" 40AD my Surburban heater is under the sink. This means there are water pipes over the Suburban, which I have never been excited about, but that's the way Winnie laid out the system, and so far I have never had a water leak problem.

The Suburban heater will draw air in from... get this... under the shower pan... where you can find a register-grill faceplate attached to the 7" face of the fiberglass bottom of the shower pan that faces the bathroom; and the other way the Suburban draws air in is from under the sink; and then the heated air is exhausted to 3 or 4 floor registers.

=== 2nd Bedroom Heater ===

Next I have a separate bedroom heater that utilizes two 3" tubes to exhaust the heat.

One of these tube exhausts to the toilet closet area, and the other 3" tube exhausts to the hall in front of the bathroom sink.

This approach works quite well when I swing the toilet room door open and use it as a hall divider, but I also have a pocket door I would rather use. And I would prefer to keep the toilet closet door closed to keep outside cool temperatures out! ...But when I close the toilet door I'm locking all that heat inside.

Note: I don't normally worry about frigid nights, because I typically only RV from May-October (or parts thereof), but there are times when I encounter frigid temperatures nevertheless.

So I would like to UPGRADE my 2nd heater exhaust by routing that toilet heat either:

A) Into the bathroom hall, so it adds to the bedroom heat, and I keep the toilet door closed all the time; or... (See picture where I show #1 and #2 exhaust arrows to the bedroom, where I need to cut a 3" hole into the side wall, above the existing #1 exhaust port.)

or

B) I can route some of these extra toilet closet BTUs into my basement storage area... like Morich mentioned above.

Which do you (and others) think is more important?

CONSIDERATIONS

I accept I don't want to heat the whole coach; and saving propane is important too. So I think just cutting a hole in the wall between the toilet and the storage closet nest to the toilet area is the way to go. (Again see #2 in picture below.)

But I don't want to discount the value and benefits of heating the basement area.

I HAVE ONE CONCNERN ABOUT HEATING UP THE BASEMENT: Do you think there is any possibility this basement heat will attract mice? ...I really hate mice! ...Not because they are dirty vermin, but because they eat wires!

===

Morich: Can you easily produce a 3-D diagram of my Horizon "40AD" heating vents, so I can preplan for this grade while my RV is in storage? If this is a lot of work, please do not bother. I just think your 3-D drawing are cool. (MEMS like.)

BTW, how do you take those Winnebago B&W drawings and turn them into color 3-D renditions? It it magic or do you have a 3-D drawing source non of the rest of us have?
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Old 02-24-2021, 05:49 PM   #17
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imnprsd;

I ran a truck stop for 42 years before I retired. I filled lots of RV LP gas tanks in that time frame. I will answer a couple of questions you asked that I did not see that you got answers so I will chime in.

The stamp on your LP gas tank that says WC 38 means that the water capacity when 100% full would equal 38 gallons. Tanks are usually not filled fuller than 80% thus if you multiplied 38 X .80 =30.4 or around 31 Gallons. That allows about 20% for expansion when it gets hot and expands.

In our State of Wisconsin, LP is dispensed through temperature compensated meters using a mean temperature of 60º. When I purchased my LP the delivery truck used a temperature compensated meter and I resold the gas the same way. What that means to you is when you purchase LP and it is cold you get less gallons and when it gets hot you get more gallons. Cold gas has more BTUs than hot gas. I hope I have helped you to make sense of all this LP stuff.

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Old 02-24-2021, 06:23 PM   #18
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Lots of interesting info here. Let me just cover my actual cold weather experience. Normally I try to not be in cold weather, but sometimes it just catches you. In my 10 years, we have seen as low as single digits, mostly in the high teens and 20's occasionally, but mostly in the mid 30's for extended times.

1st, your RV heat pump is designed to pump heat out of the RV for cooling, and into the RV for heating. They usually comfortably work with a 30 degree differential, ie 37 outside, 67 inside, you can nurse more if you play with it. Although last week, when the cold snap hit Deep South Texas, I saw something I had never seen before, it was 22 degrees with 95 percent humidity. The heat pump was still working well down to about 34 degrees, lots of heat to pull out of that air!

The propane furnace not only provides lots of heat for the interior, it also sends hot air to the basement and the water compartment. No need to let water drip in your RV, but if hooked to shore water, you better insulate the hose and spigot pipe.

When starting the diesel engine when cold, I always turn on the engine heater for an hour prior to starting, it spins right up. During our most recent cold snap into the 20's, the generator had no problem running all day with the diesel I bought back in October, giving us power while the rest of Texas was dark. no additives.

We have had lots of occasional day or three at high altitude, or just a cold place, Winnebago builds them to work just fine. For longer stays, I used a couple of electric 1000w space heaters to take up lots of the heating work, but I also used a 100w light bulb in the water compartment if the propane furnace was going to only come on occasionally. (had a little thermostat connected, 36 degrees turn on, 42 turn off, worked like a charm.) (ran the extension cord to the outlet for the engine heater plug)

I calculated that our 31 gallons of propane will keep us comfortable for atleast 20 days of heavy use, longer if the heat pump shares the load. Never really needed to test it, as the cold never lasted that long.

Just my experience, others will be different.
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Old 02-25-2021, 08:52 PM   #19
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Winter

I run my diesel with additives all year round, improves the lubricity, adds a little to the cetane rating, controls algae and the winter formula helps prevent fuel gelling. A battery blanket plugged in with the block heater which could by the way be powered by the coach generator helps the batteries produce the most power. A dedicated battery charger for the chassis battery is also a good idea.
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Old 02-25-2021, 10:13 PM   #20
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Quote:
Originally Posted by imnprsd View Post
Morich: What sort of 3-D software are you using that produces these drawings you are so famous for?
That’s Winnebago’s 3D parts diagrams available at Winnebago.com under Owner’s Tools.
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