Better Heat Distribution from Dinette Vent

[deppstein]

Ever since I heard that some of you have an additional heater vent in back somewhere below the frig, I have been jealous and trying to think of a good way to get some heat to that area--particularly when the dinette is collapsed to make a bed (which is how we sleep). I have never liked the way the heat gets trapped under the bed at night with nowhere to go but up into the bottom of the bed, which doesn't help much of anything. So, with Covid isolation time on my hands, I have come up with what I think is a decent solution. Using a "dryer hose quick connector"--essentially a two-piece plastic collar with bayonet connects...the fixed bayonet side of which screws into the dinette base (replacing the existing plastic vent) with the other piece attached to a 4' heater hose via a pvc connector (pictures of all this to follow). I purchased two of these connectors, so I could use one attached to the hose and another just as an open vent (with screen) for use when the dinette is in the upright position (hence hose not needed). This now means that I can direct air to either the area under the couch (think water lines under there) or out to the edge of the bed and into the back "hallway"...think easier for heat to rise, and a warmer bathroom (door open) for those night-time trips so necessary for us people of a certain age ! And, just to put icing on the cake, I have ordered and will install an upgraded propane heater (Suburban NT 16SQ model 2444A) that only draws 2.8 amps and ups my current 12,000 btu output to 16,000 btus. It fits into the current location and uses existing fittings.
I don't imagine that this will give me the capacity to do serious boondocking in sub-freezing locations...but it will address my particular concern of being able to have really adequate heat for those nights I am traveling in cold climates when no electrical hook-up is available--and not have to worry about waking up to drained House Batteries.
Anyway...in case anyone else is interested, here are some pics of what this set-up looks like.
David

[deppstein]

As follow-up to previous post, here are the final 3 pics of my new heater hose set-up
David

[Blue~Go]

What a great idea!

I have the club layout, so no problem with heat coming out from (the furnace I removed) under a bed, but dang, that bathroom is nippy! The thought of heat blowing out back there is glorious.

But yeah, there's not exactly a great path for a duct. Between the generator box and the fridge they kind of cut you off at the pass as far as getting all the way back by the door. I have had an idea to run a duct in very outboard side of my aft club base (above the wheelwell), then behind the oven area, and around the corner in aft end of the wheelwell on the floor in that cubby aft of the wheelwell, then out the face of the "toe kick area" at the aft end of the stove (this is just behind the wheelwell/just ahead of the generator box). Then aim the louvers aft. Basically you've already accomplished that, ten times more simply Plus you can heat the area under the couch. Bonus!

On the furnace: After I took the Suburban out and stored it away, I never did put in a Propex (I don't winter in a very cold area). And just the other week I was thinking huh, maybe I should just put my Suburban back in (granted, I do love that storage space). Then I got interested in the new version you are just ordering, and 2.8amps looked very enticing.

Then I got curious as to what the amp draw of my original furnace was (1999 original Suburban 16S). I had this idea it was 6 amps or more. Lo and behold it's also/only 2.8 amps. That said, mine is missing the "Q" part, and that quieter operation should be very nice on your new one.

Here is what I looked at to check. Mine is packed away, but I had taken this photo of the front plate when I was removing it. So now I'm curious: Did your original one draw more?

[deppstein]

Blue! Nice to hear from you.
I too cogitated a bit on some sort of permanent duct run...but the combination of routing and being close to cold wall deterred me. Then I happened upon this "quick connect dryer vent"...and the rest is history as they say.
Interesting about the amp draw of your old Suburban...I have just assumed my current (2004 model) draws 7 or so...I'll check it in daylight tomorrow and let you know.
David

[deppstein]

So, low and behold--my 2004 Suburban NT12s furnace also says 2.8 amps!
Must confess that I have a hard time believing that given all the info on amp draw of typical rv furnaces online, and the touting of low amp draw of the new model (why would they talk about that if its the same as it was in 2005)??? But, I have already ordered the new model, and it does produce 25% more BTUs AND it is supposed to be noticeably quieter...so, I'll stick with the plan. Must have saved at least that much by not going out to dinner over the past two years
David

[Blue~Go]

I know! I was almost disappointed to see that. I would still rather put in a Propex, but I thought huh, if I buy a new one of the Suburbans it will just drop right in, and 2.8 amps isn't all that bad. Then I looked at those old photos and saw the original 1999 one also only drew 2.8 amps. And it works just fine. Hmmph.

That said, quieter is nice! I think it was bfischer that put in a new one and did say it was quieter. I wonder how much quieter it is? Please let us know what you think when you put in the new one. And the high draw isn't a myth: My buddy's late model Airstream (2017-ish) had a stock furnace that drew around 7-9 amps. That sure adds up.

Warning: Tangent goes into the weeds. Proceed at your own risk

So now I guess I'm thinking either put the original furnace back if I want a furnace. Or go back to putting in a Propex and saving some space and power. I had been wondering if the Propex HS2800 would be big enough (of course that depends on how you winter). I see that the HS2800 has a 10,300 btu input and 9,550 btu output (92+% efficient, which is kind of nice compared to the Suburban's 75% efficiency (NT16S or NT16SQ).

What I couldn't find anywhere is whether the Suburban's 16,000 btu is input or output. If it's input, than they are closer together in terms of heat output (and in fact the Propex would be about the same as the Suburban 12,000btu). If that 16,000 btu is output (so around 20,000 btu input), then they are further apart. The Propex HS2800 draws 1.9 amps, which is really good but not THAT much better than 2.8 amps.

I did find something really interesting though that might benefit some of us here. Suburban also sells a "core" replacement. That's basically you keep the sheet metal, exhaust, and ducting of your current furnace, but drop in a new guts unit. Hmmm, could the new core drop into the old unit? Yep, the guts unit of the 16NTSQ (new quieter one) is the specified one you drop in to re-fit a 16NTS (the original one in many of our Chinooks, though I did see that at least in some years, the Premier got the 12,000 btu version). I didn't shop around, but it looks like it's around 2/3 the price of a new one (Dyer's RV: $436 for the core, $686 for a new furnace).

Here is the chart I found from Suburban that shows this:

Suburban_NT_Furnace_Core_Replacment.pdf

(86.21 KiB) Downloaded 69 times

So, while I might still go for the Propex HS2800, I also might consider putting my Suburban back in with a new "Q" core. After all, it's already out and could be plopped onto my workbench. Maybe that idea would interest someone else here too. For $250 difference over a new one, I'd have to look into how much work it is to swap cores. If relatively easy, it might be a good option.

And then of course you can implement deppsteins clever dinette heat distribution mod

[deppstein]

For those of us willing to wade into the weeds, the plunge is always worth it!
I am one of those Premier 12,000 BTU Furnace guys...go figure--skimp on the furnace but outfit my Rig in Cherry! Anyway, drop-in core therefore not an option for me. I think the PropexHS2800 would have been a sufficient BTU choice for my 12,000 BTU replacement. But since it still required some space and new piping (down and out), I opted for the Suburban upgrade to 16,000 BTU. I think Propex is a better unit, but simplicity of the install, a bit more heat, and not such a big difference in amps carried the day.
I have a couple of other things going--including a run to Indiana later this month to have DutchAire folks install their "new and improved" guts into my existing Frig (stay tuned for a separate report on how that Mod goes). So I won't get around to the heater install until end of March. But, once it is in, I will most certainly report back on how the bigger furnace feels relative to heat output and whether or not the "Q" for Quiet is noticeable.
David

[deppstein]

For those still mucking about in the weeds...the discussion about the amp draw of our propane furnaces got stuck in my craw, so I sent an email question directly to the Suburban Mfg via "RVupgrades.com" And here is their response:

"The Motor’s amp draw is 2.8 amps (at 12.0VDC). Module Board .5 - 1.0 amps the Gas Valve .5 – 1.0 amps, therefore the total is 3.8 – 4.8 amps. Keep in mind the higher the voltage, the lower the amperage and vice versa. ( Per Suburban) "

So, now I'm not at all sure that my battery drain will be any less with the install of my new NT 16SQ...bummer...but at least I'm going from 12,000 btu to 16,000 btu for the same draw--and supposedly quieter. I can live with that.
David

[Blue~Go]

"The Motor’s amp draw is 2.8 amps (at 12.0VDC). Module Board .5 - 1.0 amps the Gas Valve .5 – 1.0 amps, therefore the total is 3.8 – 4.8 amps. Keep in mind the higher the voltage, the lower the amperage and vice versa. ( Per Suburban) "

This makes not so much sense? So the furnace draws 2.8 amps (as noted on data plate on furnace). What module board? What gas valve (are they assuming we have a powered gas solenoid? I don't)? Whose total is 3.8-4.8 amps then, Suburban's or "RV Upgrades'"?

And sure, if your batteries are at 11 volts the "amp draw" will be a shade higher (3.05 amps) and at 13.8 volts a shade less (2.43 amps). But that's because it's all the exact same draw of ~33.6 watts. You don't gain or lose anything at higher or lower voltage (in the general 12-volt range). Of course you want to size wire and OCP for that slightly higher amp draw at 10-11 volts (but who would be cutting it that close anyway).

So it's not wrong that your new furnace will draw the same amperage as the old one. But I don't quite get what they are adding up to get 4.8 amps. Are they saying that "secret" parts of the furnace draw more? Or are they assuming added extras (that not all of us have) such as an electric propane solenoid? Whose module board are they referring to?

If they somehow have the inside skinny and the draw is 4.8 amps (nearly 58 watts), then suddenly the Propex looks a whole lot more differentiated at 1.9 amps.

[deppstein]

Now I'm beginning to feel pulled under by the weeds! I wrote my question to RVupgrades, but the "Per Suburban" made me think they had gone to Suburban for guidance. Regardless, I think Blue is right to point out that there are still assumptions being made by someone that serve to make it less than crystal clear what the total amp draw of our Suburban Stock furnaces are. And, if indeed the Propex is a solid 1.9 amp draw, I agree with Blue that it begins to look a whole lot better--especially for those people who need to watch their battery consumption on a regular basis or for extended periods of time. In my case, I still opt for the drop-in Suburban (upgrading from 12,000 to 16,000) rather than a new piped Propex. I really am just looking for something that will get me through those cold travel nights when I can't find a hook-up, or the occasional night in the 20's at some beautiful campground during the shoulder season--Unlike 68Camero, I'm not out there in the middle of winter fly-fishing!
David