Adjusting AC distribution in Dutch Star

[rg neumann]

The two AC units in our Dutch Star do an excellent job of cooling the coach. However, the rear AC unit discharges too much air in the rear bathroom. Of course the temp of the rear unit can be raised significantly but then the bedroom is uncomfortably too warm. Can the four ducts in the bathroom be controlled with an adjustable baffle to reduce the air flow?

[Mr_D]

Had the same problem in our '02 DSDP. Ran the front on high and the rear on low. to kind of even things out.

[TonyDi]

Originally Posted by Mr_D

Had the same problem in our '02 DSDP. Ran the front on high and the rear on low. to kind of even things out.

That's exactly what I do too!

[shaman52]

Your rear bath likely has 4 round ceiling registers. The ones without foam are the return air. The other two are supply air ducts. To do a test take out one foam filter and install it in the supply air register. If this works well buy another foam filter and put in the one return air that is now lacking one.

Your other option is to install one or two adjustable supply air registers. They can be found here. Heat Vent 4" White Dampered Plastic - RV Wholesalers Parts Store

Good Luck!

[MD-Keith]

I bought two of the dampered vent covers for the rear bath and then was advised by my service tech not to use them. He said that any restriction of the A/C air flow could result in a freeze-up of the A/C unit in hot and humid conditions. Living in FL where it is always hot and humid, I now simply adjust the fan speed as needed. I remain at a loss as to why changing fan speeds did not occur to me earlier...

[JFXG]

Originally Posted by shaman52

....The ones without foam are the return air. The other two are supply air ducts. To do a test take out one foam filter and install it in the supply air register.........

Methinks you got things a little twisty here. The foam filters go in the returns, catching the dust brought up from the living area; the cold supply air is unfiltered.


John & Diane, fulltiming since '12
'02 DS, FL, Cat, '04 Element
NHSO RVM103

[Mr_D]

Originally Posted by shaman52

Your rear bath likely has 4 round ceiling registers. The ones without foam are the return air. The other two are supply air ducts. To do a test take out one foam filter and install it in the supply air register. If this works well buy another foam filter and put in the one return air that is now lacking one.

Your other option is to install one or two adjustable supply air registers. They can be found here. Heat Vent 4" White Dampered Plastic - RV Wholesalers Parts Store

Good Luck!

On both our Dutch Stars the filters were in the return air ducts, not the output. That's the same way our home air con is set up too.
I bought filter material at a local store owned by Kroegers. Just cut it to fit, washed them as needed.

[shaman52]

1. Temporarily moving one filter from the rear area return and installing in nearby supply air throttles the supply air to the rear. This is to see if this increases the supply air to the bedroom. If this works you know the rear supply air could be throttled down. This is a crude form of balancing the supply air duct system. Not twisty at all.

2. Whether your Newmar has three or two Heat Pumps or A/C units they are all connected together on a common supply and return duct system. That is why you get some conditioned air in the rear when only the front unit is operating.

3. What is needed is re-balancing of the supply/return duct system. Turning down the fan speed limits your cooling/heating potential. Newmar may have provided more rear supply air to the rear, as the diesel engine below can provided significant heat flux as it cools down after a long run. When stationary this extra cooling is not needed.

4. Re-balancing the duct system is a common practice in residential and commercial Heating Ventilating Air Conditioning (HVAC) systems. To do correctly you would need a flow-hood or spot velocity meter to evaluate the Cubic Feet per Minute (CFM) on both return and supply air. If done correctly evaporation coil flow would be enough to prevent evaporator freeze-up mentioned by your RV tech.

I replaced all three Penguins on my roof of my 2007 MADP model 4528 and did not see any evidence of system balancing by Newmar. Balancing may be required and not re-balancing.

Without instrumentation all we do is make logical guesses and hope what we do will work.

Good Luck!

[handstjg]

We just purchased our first MH, a 2008 Kountry Star and we live in the desert.

Which makes us very interested in the best solution to the AC units.

I love the idea of the 4" "Directional" vents. Our supply and return are within inches of each other and the conditioned air cycles from supply to return very quickly. Not allowing enough time to cool far enough down from the ceiling unless we run on high speed all the time.

With the directional vents we could aim both the supply and return vents to their respective outside walls and allow the conditioned air to stay long enough in the living area to allow us to slow down the fans.

Thanks again for all the input it is very helpful to the rookies of the world…