Better Heat Distribution from Dinette Vent

[chin_k]

I am confused by the math. So 2.8 is just for the fan motor? I assume the sticker will tell you the draw for the WHOLE unit, not just the motor. At any rate, we may need to put a ammeter at the DC fuse panel to figure it out.

It may not be a good idea to over rate the BTU if the rig is not going to be used in very cold places. The short cycling of the furnace will make it not very efficient if it is too powerful for the application.

[deppstein]

Thanks Chin for offering that thought about "over-rating" the BTUs...but since my 12,000 btu furnace was just to keep the Premier "cheap" and most of the Concourses came with the 16,000 btu units, I feel fine (warm actually) about the upgrade.
And, if you do dive deep and use an ammeter to figure out the actual draw be sure and let us all know the results.
David

[Blue~Go]

I am confused by the math. So 2.8 is just for the fan motor? I assume the sticker will tell you the draw for the WHOLE unit, not just the motor. At any rate, we may need to put a ammeter at the DC fuse panel to figure it out.

I agree, chin_k. Something sounds fishy. My guess is the RV place doesn't really know, they got with Suburban who told them 2.8 amps, and then they (RV place) added some stuff that they think most people might have.... and now it's all confused.

I wouldn't bet large sums on it at this point, but I have to say, rating the funace at 2.8 amps but "not counting" a bunch of other things that are part of the furnace itself just seems totally wrong. Technicians are going to go by that number to size wire runs, etc. While I'm sure Suburban would like to show a low amp draw, I doubt they would want a bunch of call-backs because someone sized the wire according to their specs but, Surprise! it draws twice as much. Now there is too much voltage drop and the motor is acting funny. That's a headache and they want it to work properly so that you just buy it, it works, and they can move on to the next sale.

So I bet it is 2.8 amps. The new one may have a quieter fan (which is a great thing in and of itself - certainly nothing to sneeze at), but apparently does not draw less than the old "non Q" one that came in my 1999.

Another clue: As I mentioned above, you can buy a new "Q" core pack to fit in the old "non-Q" furnace body. (Same core pack part number for replacement in a new Q or an older non Q body.) Well unless they sent you a new giant data plate (which I did not see anything about), the data plate would not match the furnace anymore (if the new one drew nearly twice as much), which again would be problematic. Also, since when do new better things draw more power? I mean, it's possible but certainly not the trend.

deppstein: Sorry about the weeds. I say it'll be great: You are going to have a new furnace, it's going to be larger than the 12,000 btu one which apparently was a bit small for your use, it'll drop in, and it should be quieter. Quieter! It may not draw any less, but it just sounds nuts to me that it would secretly draw nearly twice as much and I wouldn't believe that without more proof. So I think it's going to draw the same until testing proves otherwise.

[deppstein]

Amen to all of that! I am now officially extricating myself from the weeds to bask in the anticipated warmth that a new, bigger, quieter, and likely same amp draw furnace will provide. As promised, I'll report out on how it all works out. In the meantime, I trust that Blue, and Chin, and all you other deep sea divers will keep the rest of us apprised of any results further testing may yield.
David

[Blue~Go]

I don't have one to test or I would be happy to (I do still have my furnace but it is not installed). But I would be very pleased to hear your results.

[chin_k]

It has been in the 90's during the daytime in past few days, so I don't think I will be able to get anyone a measurement until the weekend when I have the time.

Edit:
It was too warm to sleep, so I went outside to cool off and decided to do the measurement.
When the electronic just came on, before the fan kicked in, it was drawing slightly less than 1.0 amp. Once the fan was on, and it was trying to ignite the propane, the amperage was slightly higher than 3.1 amp. So I guess the folks did not completely lied to you.

However, once the air got warm (propane is burning), it was drawing less than 2.5 or so amp. So the fan alone does not use 2.8 amp like it says on the label. I would like to stay longer, but it was getting too warm with the weather we have, and I decided to quit after 10 minutes. I do not think it ever got more than 2.7 amp in all that time after the propane was burning and the fan was blowing. The average was probably closer to 2.6 or less.

There is a lot of wasted heat venting outside, so I think it could be a lot more efficient with propane if they design it better, but it may end up using more DC power. I really think there is a lot of room for improvement, but I am not a thermo or HVAC fellow, but I want to see if the fan motor is induction or a cheap universal motor. My guess is that it is induction, since it is relatively quiet.

[deppstein]

Chin! You have made my morning...only hope it was not at the expense of your evening. I think I speak for more than myself here--Thank you indeed for taking the time to give us some real-time readings. I love you guys! I love this Forum!
David

[Blue~Go]

Thanks, chin_k! I love a good experiment. So 2.8 amps looks totally legit to me (obviously it can't be exactly 2.8 for the entire cycle but will have moments of higher and lower). Looks like we can trust the Suburban data plate on that one.

You are right about the efficiency. It's listed at 75% for both versions of the NT16,000 (Q and non-Q). Propex is around 92% by my calculations (they list btu input and output; I calculated). But the Propex cost more to buy and won't be as "drop in" as the Suburban (it is quite a bit smaller though, so would fit in the same space plus some extra storage), so they both have their place.

At under $500 for a 16Q "core pack," that's an especially low-priced option comparatively (if you have a Suburban 16 already). Interestingly, I looked on Suburban's core pack document (to see if there was one for the NT12, which there isn't) and it's the EXACT same core pack for the NT16 and the NT20. That suggests there is only some minor tweak in some area that makes a 16 a 20 or vice-versa.

[FatBuoy]

NIce! I'm adding this to my ever growing list of projects. Thanks for doing the thinking here.

[deppstein]

So, I just returned from having the NT 16SQ Suburban furnace installed in my 2004 Premier, as discussed earlier. I had the work done by Arlington RV SuperCenter in Rhode Island (an authorized Suburban dealer), and they seem to have done a fine job. I talked to the service manager and he confirmed that it was basically a plug-and-play removal of my Suburban 12,000 btu unit with this new, bigger, and supposedly quieter model. We leave next week for a month-long trip, mostly through the south-so not sure how much of a chance I'll get to see if I notice a difference in the amount of heat it puts out, how much quieter it sounds, or if it seems to draw the same/more/less on battery...but when I do get a chance to run it, I will report out my findings/opinions.
That said, I have to add one additional note to the discussion we have been having. To my surprise, the furnace plate on the NT16SQ says 3.1 amps...so actually slightly more than the 2.8 amps listed on my NT 12S, and the 2.8 amps that was relayed to me via Suburban when I inquired. I was a little bummed...but, frankly, not surprised given all the discussion we had about this AND Chin's real-time testing that yielded a 3.1 amp draw with fan on while trying to ignite (thanks again Chin for taking the time to do that). Oh well, at this point, it is what it is...I'll just have to see how I feel about it. And, yes, I did have them box up the old, still working NT 12S just in case!
David