Suggestion for better cooling

[KirbyRVA]

We have a 2018 384GK-R Solitude. Our bottom step up to the bedroom has shoe storage as I suspect many GD 5th wheels have. If you look in the back of the shoe storage area, you will see that the back is open to the basement. We were having trouble maintaining desired temp in a hot and humid location, Myrtle Beach, SC. Heat index of 98-99 outside and the best we could do in afternoon in the living area was 76-77 F on high cool, awnings deployed, two shade trees, shades closed on sunny side of rig. The hallway also felt warmer and humid.

If you feel near the shoe storage area, there was a lot of warm and humid air coming out of that space into the living area. So I used some flexible foam in the back of that space to close it off. What a difference. Within 45 minutes the temp in the living area came down to 73 and we no longer felt the warm air in the hallway.

Grand Design told me they designed it this way to allow air flow from the basement to help keep the furnace from overheating during heating. I am not sure why since our furnace is in a box at the bottom of our pantry and I would think a return register there would work just as well. Anyway, they said it was fine to close the opening during cooling season.

[OffToHavasu]

Yeah, you will need to open it up when using the heater. Different models have different return location. For your model, that the return to the basement for the furnace.

[Country Campers]

Not sure if the Solitudes have this or not , behind our toilet in the bathroom there is an open register to the basement , lets a lot of cold air down into the basement. When not heating I think it is fine to close off any vent or passage that leads to the basement or anywhere else that cold air cold be leaving the cabin.

Brian

[KirbyRVA]

Yeah, you will need to open it up when using the heater. Different models have different return location. For your model, that the return to the basement for the furnace.

Been thinking through this and, while I am no HVAC expert, I am mechanically and technically skilled. During heating GD is pulling cold air from the basement into the heated space. According to them, this helps 'cool' the furnace. It would seem to make more sense to put a return opening inside the living area near the furnace close off the opening under the steps, and put a small one way (flapper) vent in the basement wall to exhaust any hot air/relieve pressure. Considering other poor design and execution decisions GD made when building this coach, I suspect they just made a choice that was cheap and easy.

[OffToHavasu]

Whether or not it it's a poor design choice or cheaper route is a moot point. The fact is, it is the way it is designed and that in order for heating to operate properly it will need to be opened up.

[KirbyRVA]

Whether or not it it's a poor design choice or cheaper route is a moot point. The fact is, it is the way it is designed and that in order for heating to operate properly it will need to be opened up.

Agree until I can devise an alternative. We also had cold air coming from under the steps this past winter so I plan to poke around in the basement and see if I can provide another way to get return air to the furnace without pulling cold air into the living area. Gotta be a solution.

[KirbyRVA]

We've been in our spot here in Myrtle Beach now since July 5. It has been pretty hot this summer and I am convinced that the two 15,000 BTU AC units are just not sufficient to cool the rig properly in hot weather. Over the past few days temps peak at about 88 -91 with a heat index of 95 or so. We have our awnings deployed but the driver side of the rig has no shade and is exposed to the afternoon sun. I invested in the snap on sun shades for all of the windows on the driver's side and the big rear window. We also pull the interior shades before noon. We keep the filters on the two AC units clean. I have checked both units with a good HVAC thermometer and both are within specs, producing output temps at least 20 - 22 degrees lower than inlet. I've checked and adjusted all the ceiling vents....none are blocked, air flow is good, output temps good in all of them.

In spite of our efforts, temps in the living area rise to 76F by mid afternoon. We supplement with a small fan. As soon as the sun sets, temps drop to our desired set point which is usually 73.

So, I am of the belief that it is a function of insulation (too little, poorly installed, not the best type, etc.) in the roof. Grand Design claims they do a really good job insulating the Solitude. There is only so much you can put in a 2" thick bonded sidewall so rigid foam is all anyone can do. I suspect the issue in my rig is whatever is, or isn't, in the roof structure. Also, I still think Grand Design should offer the option of a third AC in any 5th wheel 40' or longer.