Installing a furnace in a T@G

WilliamA

Now that I am finished with the vista window screen project, it's time to get on to the next biggest item on the "To-Do" list.

Here's another one I've been wanting to do for a long time. A bit of history is perhaps in order here. Before I got my T@G XL, I had an LG 5W that I dragged around for a couple of years. I dearly loved it and would still be towing it were it not for a couple of problems....My boys.... It was just too small for what I was doing with them so I stepped up to the T@G. While I had it, I also installed a furnace in that one. Here's the link to that build thread over on the LG forum:
https://golittleguy.com/forum/#/discussion/5249/lg-5-wide-electric-furnace-installation
It worked famously and I used many of the ideas from that to install the electric furnace I currently have in my T@G. To be sure, the one I have in the T@G now is working flawlessly and has been running quietly and efficiently since I put it in there. I've pretty much let it run all winter out in the yard and it keeps whatever temperature I set the thermostat to without my oversight. For the winter, I had it set to about 45 or 50 degrees just to keep the mildew out and also to keep me warm when I was out there putzing away. I've no problem with this one at all with a couple of exceptions:
1. It's a bit ugly. I'll get to the that, but basically, because of the design of this one, I had to mount it with the air out and cold air return in were on opposite sides of the television. That's fine, but it makes for uneven heat on one side of the room and also required me to move the tv out a few inches to clear the grates.
2. There are "forced-air" heaters and then there are "coaxed-air" heaters. The one in the Little Guy was pretty much a forced-air heater. The one in the T@G is a coaxed-air job. This has more to do with the design of the fan. the fan in the LG heater was a squirrel-cage affair (highly efficient) and the one in the T@G now is more of a plastic dinner plate with some fins glued on. I think the principle is that if you just paddle the air into foam, some of it will eventually get where you want it to go by accident. That's fine and has worked for a century in bathroom vents everywhere, but it's far from efficient.
3. The last item is safety. Now don't get me wrong, when I set to work on a thing, the first and last things on the list are safety and safety. I haul my kids around in this thing. I feel that both are very safe. Perhaps as safe as is possible with any form of heat system. It would be difficult to make one more safe than the two I put together. But the system I put in the LG was a bit nicer. It had two features that this one in the T@G does not. It had a time delay in the heating circuit so when the thermostat called for heat, it would wait for 30 seconds or so before running the blower. It also ran the blower for a minute or so after the heating element shut off to help avoid any potential heat-sink inside the furnace. That was a nice feature. The LG furnace also had overheat protection in the form of a thermal breaker inside the unit wired through the heating element. This one does not. It has overheat protection, but in the form of a thermal strip on the heating element itself. It this one trips, I'd need a new element.

As I collect the bits necessary to do the work and start building, I'll be picking each system apart in more detail. For now, all I really need is to pick up the unit. I don't need to install any other bits as the thermostat and hi/lo switch are already in use with the current furnace.

This is the unit I used in the LG and is the same unit I want to put in the T@G:
https://www.homedepot.com/p/Fahrenheat-1-500-Watt-Toe-Space-Electric-Heater-with-Built-In-Thermostat-FTS1500T/206126188

I need to set to work doing some detail drawings of the mounting system and plenum for the new one, but I still have all the drawings I used to install it in the LG so most of the information will be the same.

I know there has been a lot of discussion about this topic in the past so I will try to be diligent and detailed.

Also, in the audience participation section of the discussion, I'll be trying to design something that can be put in either a 5 wide or 6 wide. If anyone with a 5 wide would care to throw a tape measure across the panel that the television mounts to, I'd love to know the width and height of that framed opening for comparison.
Gotta get to work....

WilliamA

LuckyJ

Ok, so

I still have the original television configuration, if that change anything.

The frame is 17" wide (that is inside mesurement)
The cabinet is 21" wide.

I do beleive that the difference between the 5' and the 6' is the side cabinet. The space on each side for the 5' is 18 1/4".

Now, a question.

I do not know how far you are digging for this, but I am thinking of relocating the lower AC vent from under the trailer to two side low cowbells. I am just not sure I like the possibility of water and dust coming from under, and do think that it would not be as bad higher on the side, or that it would be eaiser to close if needed. Are you digging deep enough for this, or do you have any tought on it.

And I will be following or course!

WilliamA

Lucky,
I had been assuming that for the difference between the 5W and 6W was the side cabinets, not the center console where the TV and A/C are. Makes sense to me. I am planning to at the very least fully explore the possible use of the A/C vents on the sides of the cabinet for either hot air out or cold air return. There are many turns and twists to get around in there so I'm not sure I would be comfortable with all of the restrictions, but as you say, it's certainly worth a full massage to see if they could be used. I can do the heater/furnace install without using them but won't leave any stone unturned. Right now, though I've gotten rid of my A/C, I still use the cowbell vents for ventilation (reversed) to flow air in. I'd like to keep that for the time being. We'll see how the numbers work out. Thanks for the measurements. I'll see what I come up with.

WilliamA

LuckyJ

Happy to help. It is not often that I am exactly where the TD is when such question arise!

WilliamA

I got done with my outside chores today so I spent a bit of time starting to work over the furnace installation. When I originally put the furnace in and built this wad, I was in a bit of a hurry as my oldest and I were on our way out the door for a fishing weekend down in Spring Green, Wi. I stuffed in the grills you see there and blasted off, intending to put in something more permanent. That was a year or so ago. First order of business was to address this mess in a more appropriate decor:

The grill closest to the camera is the cold air return and the other side is the warm air out.

Here's a more proper grill assembly I put together today from aspen 1X4" boards and birch veneer plywood in 1/4" thickness. I needed a beefy subframe as this thing holds up the television.

This whole affair fits inside the O.E. face frame behind the television. I had put a larger and longer tele mount in but am reducing that as well. I needed some stand-off between the tv and the hot air outlet, but now I've come up with something a bit different and more compact. I picked up a set of ball-bearing drawer slides and will mount the tv to that, then the grill mount. When I need to use the furnace, I can just slide the tv over to the right (drivers side). I need to do a minor modification of the bottom drawer slide so it has a lock mechanism both in and out. I'll come up with something. I have a couple of ideas for that but need to get the grill frame mounted and run the wiring for the tv up and through it to see where it all comes out first.

I am happy.

WilliamA

WilliamA

More work today getting things in order with the new grill assembly.

Here's the new grill installed with the TV hanging off of it. I put a couple of L-brackets inside the grill shell that transfer the weight of the TV from the front face of the grill (1/4" birch plywood) to the 1X4" Aspen subframe. Seems beefy, or at least beefy enough.

I also put the new drawer slides on the TV mount so I can slide the TV out of the way for heater usage. As it turns out, the slides already have a lock on them so I don't think I'll need to make one up. Nice. Works well and has plenty of travel. Maybe too much. I might pin it down a bit so it only travels about 6 inches or so. I'll use it first and see how I like it.

Here's the TV in the stowed or travel position. I don't think I'd need to move it for heater use as it's got plenty of standoff, but I don't want the TV to overheat. Just a precaution...

While I had the center cabinet insert out, I got around to pulling up the center board. The stocker was badly warped which didn't make any difference for the A/C unit, but it held the center of my cabinet insert up at a weird angle. I had a bit of Aspen left over so I just cut a piece and replaced the O.E. compound bow. It all sits nice and flat now.

I'm really happy with the way it all worked out. I need to source a few stick-on cord stays so the HDMI cable doesn't stick up wildly in the back but I'll grab a couple on my way through town. I still have to decide if I want to use both television mounts or remove one or the other and just have one. I'm heading out next week for a couple of days down on the Mississippi River to try things out and I'll see how it works then. I might take the drawer sliders off and repurpose them for another project I have in mind....

Now I can get down to a proper write-up of the furnace installation. I took a bunch of photos today while I had the cabinet insert out and will be doing a write-up either tonight or tomorrow.
WilliamA

WilliamA

I've got a bunch of photos ready to do the write-up, but my Mac has crashed again. No bluetooth mouse or keyboard...again. I'll need to haul it down to the geniuses again so they can throw more parts at it and vacuum out my billfold....again..... Until then, I will be back to (short) posting from my $140 Android tablet. On the bright side, the tablet has been bulletproof, if slow to type on. The screensaver on the Mac is better though. It just keeps going......and going.......and going.....

WilliamA

WilliamA

Okay....I was able, with the help of the internet, to hack into my Mac OS and get my mouse working again. So far, so good.

I'm going to start posting photos and then do the write-up second, in case my Mac quits or goes on strike.

This is my furnace installation in my T@G. It's a very simple affair. I purchased the heater off the shelf from a local big-box and stuck it in there. I did not use the grill that it came with and elected to make a different ducting system in order to better separate the hot air out and cold air return. I've been running this thing for more than a year pretty much constantly and it works flawlessly and quietly. What I mean by "running this thing for more than a year pretty much constantly" is exactly that. I keep my trailer plugged into shore power and just set the thermostat for about 50 degrees. Whenever I go out to work on my trailer, the interior is nice and toasty. It's also dry and moisture free.
As you can see, there are 2 110V wires for this unit. One is power supplied to the unit from the A/C plug box. To grab power from there, I replaced the outlet for that plug with a better 20 amp outlet and put that in a better mounting box on the wall. for that, I enlarged the hole in the wall and installed what is commonly referred to as a "Remodel box. It's a standard size wall box for outlets, but has ears on it so you can surface-mount the box in a wall that isn't against a stud. They can be had at any home-store such as Lowes, Home Depot etc. They cost about $3 bucks. The outlet cost about $3 dollars as well. Once I replaced the RV style, all in one wall outlet with a more conventional house outlet and box, I simply tapped into that outlet and ran my power wire from there over to my furnace. It stands to reason that even if you have retained your A/C unit, you'd never be using both the A/C and the furnace at the same time.

You'll notice in the above photo that I have a plenum screwed to the plywood and the heater mounts to that plenum. This is to both provide a bit of "standoff" from the wood to keep it cooler and also to better separate the hot-air out and cold air in. In the standard wall unit heater, the hot air simply blows out through the same grill that the cold air goes into. Quite inefficient and also subjects the unit to overheating as it recirculates its own heated air.

A discussion of heater types is in order here:
The term "Furnace" is loosely defined (mostly by me) as a permanent-mount, hardwired heater that has a forced-air blower. Whether gas or electric, the "permanent-mount" thing is the key.
Electric furnaces have many advantages over portable heaters. They are more safe, quiet, take up less room in the room and don't have cords running around the cabin. I think they are more efficient than any other heat source. Propane furnaces are a good source of heat for long-term off the grid heat, but there are problems associated with them too. First, propane heaters don't like to heat things up "just a little bit". They prefer to run at a temperature that keeps moisture out of the air. I'd say that 60 degrees is a minimum for heating with propane. You can't set them to 45-50 degrees because they don't work very well unless the heater "balance" (temperature difference between cold air return and hot air out) is not sufficient to keep moisture from building up. Propane combustion also increases the moisture content in the heater exhaust and in very cold temperatures, can freeze. Then there's carbon monoxide too. Last but not least is the cost. My "furnace" cost me about a hundred bucks. The only propane heater I would use in a T@G is the Propex unit and it's on the order of $800 or so, plus installation.

Don't get me wrong, I'd still seriously consider putting in a Propex furnace if I had the money as they take less energy (electrical) for off-grid use. This is offset by the need to carry more propane, but it's a viable alternative to electric if you can clear the price hurdle. Tonopah has installed a Propex furnace in his trailer and it's an impressive little unit. It's just out of my league, financially speaking.

The heater I purchased (see link below) came with a dual-element for heat. Some do, some don't. If it has a dual element like mine, you can elect to run only one of them for half the heat output. I've run extensive testing to see how much heat it takes to efficiently heat a T@G and that works out to about 600-750 watts. That number depends of course upon the outside temperature, but I can say I've used mine in temperatures down to about 10 degrees for a week at a time and it keeps up just fine on 750 watts.
When I installed my heater, I wired in both heating elements and put in this switch to control the second element. That's to say, it runs automatically on a single element or 750 watts but this switch controls the second element in the event I want double the heat output. It works fine but neeedless to say, is WAAAAAYYYYY too much heat for the T@G. If I had it to do again, I'd get a unit that has dual-elements and simply use one of them. There's no need to have more than about 750 watts of heat. Besides, the lower 750 watts means it will run just fine on any standard 15 amp outlet. If you're camping at Aunt Jessie's, you can just plug into the garage outlet and run the furnace on that. No need for any special (high) amperage plugs or outlets. Standard 15A outlets work fine. The heater I have draws about 6 amps on low so there's plenty of power in a standard outlet to run the heat and everything else too. I'd eliminate this switch, but I'd have to fill the hole so it'll stay. I just don't use it.

The two white wires (romex...size 12/2) that you see here are the power and thermostat lines. One runs from the A/C plug, the thermostat wire runs out to the thermostat by the door to turn the unit on and off.

Which leads us to the brains of the whole operation. This is a simple, "line-voltage" thermostat. It means exactly that. The thermostat is simply a switch that runs all of the voltage the furnace requires through it and turns the unit off and on. They are common and come in many varieties. You most often see them running electric baseboard heaters. This one is rated at 15 amps. It has the adjustable heat range plus a dedicated "off" position. When it's set to off, the furnace won't run regardless of the temperature. I elected to mount it by the door as it gives a better reading of the actual temperature inside the trailer and also, it's easier to reach there.

Here's a variation on a theme of the heater I used. This one has only a single element in 1,000 watt. That's a bit high, but within the range of what's needed. I'd look for one that has a 600-750 watt heat output on a single element.
https://www.fleetfarm.com/detail/cadet-com-pak-1-000w-120v-white-fan-forced-air-wall-heater/0000000313031?bc=11434|11695|11700|11702

WilliamA

WilliamA

I'm doing a hit and miss on winter prep maintenance and just doing a walkaround to see what's in need of a bit of tlc. I'm not planning any overnighters for the next 6-8 weeks but there are things that are actually better done in the cold. One of those things I've had on the list is to recalibrate the thermostat for my electric furnace. I never really messed with it when I put it in a year and a half ago, coupled with the fact that many of my interior goo-gaws have taken a recent beating at the paws of my grandson and his crumb-snatching friends who think it's the bridge of the Enterprise and that said, it's time to do a tune-up.

As I mentioned, I'd not calibrated it when I put it in and just let-fly with whatever the factory setting was. There are no numbers on the thing anyway (Line voltage thermostats are notoriously innacurate due to many variables like humidity and drafts, so most manufacturers have taken to not even putting temperature numbers on them at all. Saves many angry customer calls) so it didn't matter to me much where the sweet spot was. Following the close encounter by the kids, I noticed it was waaaaaaayyyyy off to the tune of being 70 degrees or more with just a quarter turn on the control. I decided to test/calibrate it when the weather was appropriate. It's a balmy 37 degrees out today so I set to work on a re-cal.

It's easy-peasy. There are two allen screw adjusters on the thermostat. The left one is just to set the "off" threshold. That one was fine as it was. The right one sets the comfort threshold temperature. I just turned the furnace on, let it run until it hit 60 degrees, then adjusted the set screw until the furnace went off with the dial pointer at straight up.

That's all there is to that. I used the thermometer stuck on the wall so 60 degrees is actually more like 65 in the center of the cabin. I usually like to have the indicated temp in the trailer at 60 in cold weather so the overall cabin temp is between 64-66.

WilliamA