I solved my air flow problems

univmd wrote:
On the 2015 Newmar King Aire, is it possible to open the air dump vents on the kitchen AC, so that the air dumps out directly underneath, instead of going through ducting?

Newmar Roof units are bolted from the top and there is NO Dometic inside plenum assbly that can have the air dump. All you have on a Newmar inside roof is the round vents intake and exhaust. Doug

On the 2015 Newmar King Aire, is it possible to open the air dump vents on the kitchen AC, so that the air dumps out directly underneath, instead of going through ducting?

Arctic Fox tts have the right size conduits and we love the way ours works. Only thing ever happened was in Louisiana at 100 and 100% the AC dripped around the vents. No biggie, at least it worked.

So the effect of the plenum collapse was a venturi effect that reversed air flow to what should have been the kitchen discharge? Any place else in the plenum and you probably would have never known.

A bit interested to read what Newmar replies with so please post when they do.

I think if you always have 50 amp or run the generator, having divided systems is fine. I think in the case of "holstein13" and many others, including me, there will be few occasions that I will need A/C to work on 30 amps. With that said, I think many others need to be aware of dividing the units if they are frequently using 30 amp power.

holstein13 wrote:

dougrainer wrote:
As the other poster stated, you have made your unit a true 3 zone separate system. As he pointed out, you HAVE to have each AC running for your blocked off Zone for that zone to supply cool/heat.

I've been thinking about this a little bit and can't see any situation where you would want one A/C to split air between the living room and the bathroom.

Between the load shedding feature and the thermostats, you can direct a zoned A/C to any area of the coach you would like. If you are limited to one A/C, that means you can direct the air to the part of the coach you are using, i.e, kitchen / living room during the day and bedroom during the night.

Have you actually lived in one of these coaches with the single ductwork? Having a freezing bathroom during the middle of the night and having the kitchen A/C running constantly is not very practical. I realize that you said this is not normal, but you didn't say how effective the "normal" operation is for cooling the zones.

I base my comments on extensive work on Newmar ducting and roof AC/HP for over 20 years. In HOT climates(North Texas), I have never had a complaint on the common duct system Newmar uses(almost all motorhome ducts ARE common and not separate, I have never seen one with separate ducted zones but there may be some out there), other than customers that are NOT on 50 amp service or have the Intellitec EMS and want to use 1 roof AC to cool the entire RV (38 to 45 foot) and complain it will not do that when Newmar did NOT design 1 or 2 AC units to cool the entire RV unless you had the 2 or optional 3rd AC on. The 40 foot and smaller Newmar's will cool the complete RV with 2-15k AC un its. You need the 3rd for units longer than 40 foot. The nice thing about the common duct is, For quiet, you can run the front or middle on COOL/hi fan and then have the bedroom on lo fan and this will pull cold air to the bedroom without the noise of the bedroom compressor. What I am telling you is, your system should NOT need those block offs in the duct. If you are happy with it ,OK, but it is NOT correct. Doug

dougrainer wrote:
As the other poster stated, you have made your unit a true 3 zone separate system. As he pointed out, you HAVE to have each AC running for your blocked off Zone for that zone to supply cool/heat.

I've been thinking about this a little bit and can't see any situation where you would want one A/C to split air between the living room and the bathroom.

Between the load shedding feature and the thermostats, you can direct a zoned A/C to any area of the coach you would like. If you are limited to one A/C, that means you can direct the air to the part of the coach you are using, i.e, kitchen / living room during the day and bedroom during the night.

Have you actually lived in one of these coaches with the single ductwork? Having a freezing bathroom during the middle of the night and having the kitchen A/C running constantly is not very practical. I realize that you said this is not normal, but you didn't say how effective the "normal" operation is for cooling the zones.

holstein13 wrote:

DSDP Don wrote:
Good fix, but one thought. I think a lot of RV's use this ducting system that runs the length of the coach so that when on 30 amp and only one A/C is available, you can get some A/C to all portions of the coach.

In your situation, 3 A/C's, if you were stuck somewhere on 30 amp, you will have blocked off the ability to provide air to the rest of the coach when running the center A/C unit.

I'm guessing in your coach and how you use it, 30 amp camping is not a common thing....same with us, but others may run into an issue by blocking the ducting to the center unit.

A neat solution by Newmar would be some powered baffles that could be turned on and off if there is limited amperage. These ducting systems are so small and crammed into a roofline, that they're hard to build effective baffling systems. The biggest issue is that there just isn't enough room in the roof of these RV's to make baffling and ducting that works well.

That's a great point. I hadn't thought of that. But since I simply stuffed the insulation in there, I guess I could just pull it back out if necessary.

How about a pillow baffle that would deflate when needed on 30 amp? It wouldn't require much room for mechanical systems at all.

Yes, what you did "fixed" the kitchen problem, but Newmars Duct design has been the same for 20 years. Regardless if 1 or 2 or 3 roof AC's. As a Newmar dealer Service tech for 20 years, I have never seen or had such a problem as you found except for my last part of this post. As the other poster stated, you have made your unit a true 3 zone separate system. As he pointed out, you HAVE to have each AC running for your blocked off Zone for that zone to supply cool/heat. While what you did has "fixed" the problem, it is NOT a correct long term fix. You need to contac Newmar and find out what the real problem is as it is NOT correct for a Newmar product. Years ago, Newmar DID have a problem with collapsed ductwork and had to have the complete insulated ductwork replaced on affected coaches. This required removing the roof top (rubber or fiberglass) and removing and installed the new duct assbly's. Also, IF the required roof AC gasket separator is not installed correctly(seperates the intake from the exhaust) then you will get diminished air flow out of the AC. The only way to verify this is to pull the roof AC, have you had any of the roof AC units pulled or replaced? Doug

"holstein13".....I'm sure yours has the elaborate vent covers (large 6' drop down cover) like mine. Maybe you could install a cable or lever to open and close those ducts. The mechanism would be hidden by the covers. You could even slice the duct, and install a slide in tin plate to block the duct. Just pull it out when on 30 amp.

The reality is that you'll probably rarely find yourself on 30 amp and needing A/C. Even if you did, the center unit would probably still blow hard enough to get some air in both directions.

DSDP Don wrote:
Good fix, but one thought. I think a lot of RV's use this ducting system that runs the length of the coach so that when on 30 amp and only one A/C is available, you can get some A/C to all portions of the coach.

In your situation, 3 A/C's, if you were stuck somewhere on 30 amp, you will have blocked off the ability to provide air to the rest of the coach when running the center A/C unit.

I'm guessing in your coach and how you use it, 30 amp camping is not a common thing....same with us, but others may run into an issue by blocking the ducting to the center unit.

A neat solution by Newmar would be some powered baffles that could be turned on and off if there is limited amperage. These ducting systems are so small and crammed into a roofline, that they're hard to build effective baffling systems. The biggest issue is that there just isn't enough room in the roof of these RV's to make baffling and ducting that works well.

That's a great point. I hadn't thought of that. But since I simply stuffed the insulation in there, I guess I could just pull it back out if necessary.

How about a pillow baffle that would deflate when needed on 30 amp? It wouldn't require much room for mechanical systems at all.