Replacing ducted ac with nonducted unit.

[ttwitc9516]

Have any of you done this? I'm not a fan of my ducted ac. It doesn't seem as efficient and now that one of my unit has faild it seems like a logical time to make the change. Will a nonducted unit bolt in place? I can just ignore the ducting.

[dougrainer]

rodsterinfl wrote:
I only run it on high. I learned quickly that it will freeze if I don't. It can run all day on high but for some reason, freezes up after so long on low. The fan runs on high while the temp is at one-half. Good checking point though. I've been reading about a difference in more recent AC units being noisier than older ones. That too could have an impact. My current coach is an '06 with a Penguin unit. Now there is Penguin II.

I did change my air distribution unit to the new style with the five direction airflow instead of the all front/back. That was a much needed change for comfort at night or even when sitting.

You need to do your test with the MOST COMMON AC units, RVP(Coleman) and Dometic. Advent advertises their 13.5 and 15 will cool as high as 16 to 17k. That means to me, they use a HIGHER rpm fan to accomplish that. So, since I have only seen 1 advent in that past 2 years (most mainstream RV OEMs do not use them) I cannot state that Advent is as quiet as a Dometic or RVP. Doug

[2oldman]

I put a roof air ND on an old Prowler trailer in about 1995. That was loud.

[rodsterinfl]

I only run it on high. I learned quickly that it will freeze if I don't. It can run all day on high but for some reason, freezes up after so long on low. The fan runs on high while the temp is at one-half. Good checking point though. I've been reading about a difference in more recent AC units being noisier than older ones. That too could have an impact. My current coach is an '06 with a Penguin unit. Now there is Penguin II.

I did change my air distribution unit to the new style with the five direction airflow instead of the all front/back. That was a much needed change for comfort at night or even when sitting.

[2oldman]

rodsterinfl wrote:
5 as opposed to my 62dB/62dB/61dB in my non ducted 26' system. Granted there is a .5-1.5dB difference.

Make sure the ND one was on high fan.

[rodsterinfl]

Ok, shopping, I returned to CW again today but this time I took my sound meter with me. I went in two units both with ducted air systems running Advent units with four total exhausts in one model and a 17 foot duct. The other was a smaller model and a different duct layout but also having four exhaust vents. The readings in both trailers was 60.5 dB/60.5/60.5 in the 31' and the other ducted unit 60/60.5/60.5 as opposed to my 62dB/62dB/61dB in my non ducted 26' system. Granted there is a .5-1.5dB difference. The human ear is supposed to only be able to judge difference above 3dB.

I had to go back to look at the units and compare while the question was in my mind. It could be the ones I looked at but according to what I am finding, there is a difference in distribution but not necessarily in loudness level. I know that some people have reported hearing their compressor inside the coach, I cannot hear any of that, just wind noise from the fan. That too is what I heard on those units but non localized which also showed up on the readings as the same at front, middle and rear.

Either the Advent unit blowers are louder than others, the models I looked at were just not like other RVs with ducted AC or ducted air is not really quieter. I know I am driving this into the ground but there are a couple of reasons, a family members insistence and the salesman's claim at of course a greater expense. To me, they are both loud but it is a temporary habitat lucky to even have AC. On the other hand, the wallet $$$ and decision are important too.

[2oldman]

rodsterinfl wrote:
Is ducted cooling really quieter?

As one who has had both, I can testify the ducted is MUCH quieter.

Then again, the trailer I installed the non-duct was smaller than my 5er.

[wa8yxm]

I would not do it.. REASON.

First the greater "Effiency" of the non ducted is a myth, what you get is faster air flow standing under the thing, this can be accomplished with a box fan or even a clip on fan. Which is how I do it.

Second, many folks complain about the noise... Way noisier.

[dougrainer]

I have NEVER heard the claim that ducted versus Non ducted is quieter. The reason they have ducted is simple. With slide outs and different floor plans, you can get the COLD air to the various parts of the RV. With a Non ducted, the air just blows out forward and rearward of the Unit. Kind of hard to get cold air to the rest of the RV. IMO, from working on RV's for 35 years, Ducted IS slightly quieter. BUT, if quiet is your concern then do NOT buy an RV. When I purchased my current house, one of the MAIN requirements was the outside AC units be FAR away from the Master Bedroom. My old house, the HP was just outside the Master Bedroom window and you had to listen to it all year long. I was amazed at how many new and used houses, the idiot builders install the AC units outside the Master Bedroom. NOT smart, but you put a compressor and fan motor 8 inches over your head in an RV and you expect quiet??????? Doug

[rodsterinfl]

Is ducted cooling really quieter? I am not so certain. I believe it better distributes the conditioned air but the noise level improvement is questionable. I have a non-ducted Dometic unit. I have measured it at 62dB at full run from the floor directly under the unit, from the front of my RV 62dB and in the rear 61db all with the meter pointed toward center each time, sitting at belt line heights on each end- Sofa back and nightstand (in my floor plan)

Today, but without a meter, I looked at a new RV with ducted AC. I switched it on and the blower noise was astounding. The noise came from everywhere- not localized. It was as if I was in a passenger jet during travel. The unit was an Advent AC. I wish I had meter readings. but I can tell you it was as loud as mine but seemingly worse.

I believe they need to come up with a better AC solution for RVs.

[ttwitc9516]

I cut a hole in the metal plate that is inside the motorhome on the unit that does work and put a 4x12 floor register in it and just let it dump into the main compartment and it works great. I can close it when I want to use the ducting to transport air into the rear and the bathroom. On that note, the opening into the duct work had collapsed and was getting about 60% airflow. It probably won't be enough when it gets into the 90's but that will give me time to get another unit installed in the rear.

[ctpres]

Main problem with ducted air is ducts run thru ceiling which is heated by sun. So discharged air is warmer. And many ducts are just channels cut in foam with ceiling panel glued to foam. Glue fails or not properly glued and air leaks out everywhere. We installed rear unit as non-ducted. Use ducted front for low cooling needs and when really hot turn on the non-ducted rear for really cold air. Works great for us.

[ttwitc9516]

Golden,
I've had the same thought. You kick them on and cold air comes out and you don't think about whether either of them are operating at diminished capacity. I'll probably stay with the ducted unit and try to find the vented cover. I do like that they are quieter.

[Golden_HVAC]

rgatijnet1 wrote:
It seems to be that most ducted AC units are quickly installed at the factory without the benefit of the installer taking his time to actually seal all duct leaks at the unit.

My AC unit was marginal until I removed the cover and, using AC duct seal, was able to actually seal the ducts so that the cool air actually went where it was supposed to go. After doing that, I am glad that I have the ducted AC system and the airflow is sufficient now to distribute the cool air throughout the coach.

I agree that you might have had a bunch of cold air escaping the cold air duct and just returning to the A/C inlet, causing several problems including ice on the evaporator.

I also had to remove the interior cover of my buddy's Bounder and cut away some excess styrofoam that was in the fresh air duct, blocking proper air flow. I just used a kitchen knife, and cut away a section about 2" thick and 2" wide that seemed to be blocking air flow, and it improved air to the rear vents.

To the OP, Did you consider that your original A/C has not been working correctly for some time? It might be slightly low on freon for a long time, and therefore giving reduced capacity all that time. I have found that ducted A/C is much more quiet, and distributes the air all over the RV, not just into the area below the A/C.

You can buy a replacement interior cover for the ducted A/C that opens a vent directly below the air filter, and blasts cold air into the RV. This might be a great advance to your ducted A/C unit.

Or if you live in a very hot area, and don't typically use 30 amp services with marginal voltage (or already have a voltage booster to get over the low voltage problem) you can get a 15,000 Btu ducted A/C with about 10% more capacity than the typical 13,500 Btu model. This combined with perhaps a marginal A/C unit that you are replacing might give you 30% more capacity than your non-functional unit had.

I would stay with ducted A/C just because they are so much more quiet!

Fred.

[Dog_Folks]

Double post. Sorry.