3750FL cooling question

[Ozz]

quote]Originally posted by Steve and Brenda

Hi all,

Getting warm here in Dallas and our new 3750FL does not seem to get as cool as our other Montana's did. This is our first front living room unit, the bedroom stays cool but the living room reache into the 80s during the heat of the day regardless of what I do to reduce the load on both air conditioners.

What I am wondering is - anyone else with a front living area experiencing the same issue and what have you done to correct it? I did not get slide toppers like usual on this model, went into full time mode early and did not get a chance to install them. Other than that, we are operating as we usually do.

Sure can use some advice.
[/quote]

Hello Steve and Brenda,
I am a HVAC guy, been doing it all my adult life. I would get the slide-out covers, as that will help. Keep that Sun off. Start the A/C early, if you elect to turn it on later in the day, keep the shades down, consider reflective covering for the windows, that will help a bunch. Run both A/C units, get a fan and set it in the doorway from the bedroom up.
If you can stand the noise, use the 'Dump damper' the large bottom sliding vent on the A/C. I added adjustable vents, modified them and can direct air wherever I need it, It helped us a bunch, that slide-show was just on here somewhere.
Good luck.
Ozz

[Clemson1881]

seanjackmc, I see in your profile that your are in Detroit. If you ever travel down South in the Summer months make sure you have two A/Cs. One will only keep your rig in the high 80s on a hot, humid day down here.

[Art-n-Marge]

How about the capacity of the A/C units? I have seen they can be from 9,000 BTUs to about 15,000BTUs. Maybe you can upgrade the capacity and hopefully get more air up there if the power is available?

We spend most our time in the living room and wouldn't be too happy if it was too warm.

As for Bingo's picture, that's a bummer that it looks like the front space isn't vented properly. Maybe you should consider swapping an A/C with the Fan in the living room. The bad news is you might increase the height of the rig, but it seems the goal is to get any A/C as high as possible and let it drop down to cool a rig instead of trying to get cool air pushed up.

[bncinwv]

I think Ozz and I have mentioned that with dual ac's (op and us), the only practical solution is to simply add a fan into the mix. With that being said, we do have the slide toppers, but even so moving the air around in the rig does not require a large fan, I would think a desktop model sitting on the kitchen counter would provide some quick noticeable relief
Bingo

[Artemus Gordon]

It got 100 degrees here last week. In addition to the both air conditions, we supplemented with the ceiling fan in kitchen entry. After some testing, we also found by directing all the air, from both units to ducts, the flow was increased into the LR. Stayed nice and even throught the Montana. I suggest you experiment with the combination of opening main vents at the air units, and diverting through ducts. We have two 15,000 BTU units and found with a little experimenting a good flow can be achieved ! The big kitchen fan can move alot of air! Oh and yes the bedroom, does get cold, just the way I like it!

[kab449]

Experimented this weekend and found that if I set the rear bedroom unit at the temp I was comfortable sleeping and set fan to continuous low speed everything cooled evenly and efficiently.
The rear unit would cycle the compressor as it easily cooled the rear. With the fan running on low all the time it would not allow any cool air from the front unit to travel rearward and actually increase flow to the ducts in the front living room.

With the fan setting on auto on the rear unit and the front unit running there is a significant amount of air that makes it all the way to the rear bedroom vents and drops the flow forward.

[seanjackmc]

Just got back from a great weekend on michigans west side. Duck creek rv resort was terrific. It got up in the high 80's on Sunday and we were able to keep the Monty cool however the ac unit never cycled off. We are heading to Virginia beach in two weeks and I think a second unit may be in our future. Without hijacking this thread any suggestions for a additional unit? Right now our is over the kitchen dinning area and I'm plumbed for the rear bedroom.
Thanks
Sean

[Ozz]

Get the 15K unit, just a few dollars more than the smaller unit. Duo-therm is my choice, they are sold everywhere, and any tech is used to working on them.
That is the road I took, I am a HVAC tech.

[bncinwv]

Dual 15K units here. We go to Myrtle in the heat of July and August and have no problems maintaining the temperatures where we need.
Bingo

[seanjackmc]

Cool thanks for the help, Ozz being an hvac guy is adding a unit a DIY project or something better left to a pro. I'm somewhat handy but have no experience with this sort of thing.

[mazboy]

i have a 3150, 2 AC units, both ducted. i had a similar problem with my bedroom my A/C not putting out cool air, (
solutions were: 1. set bot A/C temps differently. or, 2. move, or block the sensor in bedroom.

they both are good answers.

[Clemson1881]

Adding a second A/C to a unit such as yours (prewired and framed) is very easy. The hardest part is getting it on the roof. With your unit going on the back of the trailer you should get a Dometic 15K regular profile with built in electronic controls. You may have to have it ordered as most dealers keep analog control units in stock. Also make sure you get the ducted ceiling assembly. Again most places will try to sell you on a direct blow assembly. That is not a good option to go on the back of your trailer. You need to be ducted. When you get the right unit you will need to remove the ceiling vent. The wiring is already there. You just plug in a couple of wires and you're connected to your wall thermostat. It's not very hard for someone just a little handy.

[Clemson1881]

Mazboy, the best solution to the issue you mention is keep the units running on continuous fan. That will keep the cold air from the opposite unit from blowing on the thermostat sensor and keeping it from going back into the cooling cycle. It's creates a barrier of air to seperate the units output from each other. They should have not put the zone 2 sensor so close to the duct or return that is affecting it. But the continuous fan will solve the problem.

[Ozz]

quote:Originally posted by seanjackmc

Cool thanks for the help, Ozz being an hvac guy is adding a unit a DIY project or something better left to a pro. I'm somewhat handy but have no experience with this sort of thing.

If it is not in your comfort zone, I would hire it done. I think that would be the way to go for you, if you can swing the expense.
Good luck with it.

[seanjackmc]

Ozz, thanks for the honest opinion. While I would live to think I could do it myself I realize my limitations! My time is money and not having to send my trailer in to redo my ac job would make sense. Any ideas what a install should run?
Thanks
Sean

[Ozz]

I would guess if a shop is set up for it, probably around 3 hrs, one man, 1 hr for a helper.
Rates?? probably $75-100 hr shop time. You might find some HVAC guy with refrences in Craigs List for $50.00 hr...with plenty of refrences..
Good luck, never easy to find a good honest installer.

[seanjackmc]

Thanks, camping world is running a special to install for $75. Seems like a good deal. I just wonder what extra they will find to charge me with.
Sean

[Clemson1881]

They will charge you extra to remove the existing vent for sure.

[Big Dave]

I just thought I would add my 2 cents worth on this discussion!
I have been living in my 2013 3750FL since I bought it in December 2012. For the last month our temps here have been running between the high 90's up to 108 degrees.
My living room gets up 78 to 80 everyday
I do have the 2 ducted vents in my living room.
I do not have slide toppers.
I have tried to open the dump on the unit in the kitchen.
I have tried to run the fans on auto.
I have the ceiling fan in the Kitchen running and blowing down.
I have not tried to run the fantastic vent in the front room!

The best results I have obtained so far is to have the fan for both air conditioners run on High, close the dump vent on the Kitchen unit and force as much air as possible through the ceiling ducts.
Yes as others have said my bedroom is the coolest room in the trailer.

This is my first Montana and my first Fifth wheel, other than some minor issues and the refrigerator cooling coils going out, I love this fifth wheel!

[Captain Joe]

Big Dave,
I share your experience. I had a 2011 3750FL and we could not keep the living room cool in 90 degree plus weather. We tried everything. We only have the two vertical vents up there. We kept both airs (15K and 13.5K) on high and the compressor never shut off in the kitchen. The bedroom would cycle. We have slide toppers. The DW loves to sit at the dining room table or desk when my son and I are watching TV in the Man Cave (living room). She is freezing in the dining room and we are sweating in the living room. We tried everything.

We fixed the problem by trading in our unit and purchasing the 3725RL.

Keystone made the mistake by putting the front air in the kitchen vs. the living room. I expect they were worried about the look, losing some ceiling height, and the overall height of the unit. If I kept our 3750, I would have added a third air and a separate power cord and replaced the fantastic vent in the living room. Our new 3725RL has no problem keeping us cool. Why? The airs are where they are supposed to be. There are plenty of vents in the bedroom and it has the same ceiling as the 3750.

I really liked our 3750FL. Being 6'4" tall, I never hit my head and I was very comfortable, except for the heat. Now, I hit my head going into the bedroom and bath with our new 3725RL, but I am at least cool doing it.