Improving 2014 Parkliner air conditioner

[trasko]

Forgive all the posts and data, but I found something useful. See the attachment. It is a table showing the "Net Free Area" calculations for certain vent types. This is generally used for attic venting calculations but seems relevant here.

To use the chart you can look at the vent & mesh type and then run calculations. For example: the exhaust vent on my Parkliner has 2 holes 6x7" which adds up to 84 in^2 of area. However, they are covered with 1/8" hardware cloth and aluminum louvers. That means the NFA drops to 40% of the otherwise un-obstructed area. So now we're talking 33.6 in^2.

The "intake" vents are 6 holes w/ 1/8" hardware cloth and no louvers. This calculates out to 40 in^2.

I'll be basing my calculations on these numbers. I need to triple these numbers at least because 1) it was insufficient before; and 2) the higher BTU unit needs more air.

[Eddie Longest]

Just a thought. Scamp glasses in a support maybe 1/4" thick inside in the trolly top to support the A/C. On the older Escapes they glassed on the separate A/C support cap over top of the trolly top. The Parkliner has a reverse (sunken) trolly top. You could glass in a support on the outside and it not really be visible and not need to have a perfect finish. Then you could go with a standard RV A/C. Maybe get pictures of the support on newer trailers with A/C. Before cutting up your trailer.
Eddie

[trasko]

Been awhile since I updated. Project got slowed down due to home life. I'm not going to write a bunch this time. Hopefully the pictures explain everything.

I made a bunch of committing cuts to the trailer so hopefully this proves successful. Initial testing I've done is unclear since the weather is so mild right now. The A/C works fine but that doesn't really matter when the temp is 74F. This Sunday is calling for mid/high 80s so that will be temperatures similar to when I gathered as my "before" dataset.

If everything works as I hope it does I'll assemble it more permanently and be done.

[daleeb]

Originally Posted by trasko

Been awhile since I updated. Project got slowed down due to home life. I'm not going to write a bunch this time. Hopefully the pictures explain everything.

I made a bunch of committing cuts to the trailer so hopefully this proves successful. Initial testing I've done is unclear since the weather is so mild right now. The A/C works fine but that doesn't really matter when the temp is 74F. This Sunday is calling for mid/high 80s so that will be temperatures similar to when I gathered as my "before" dataset.

If everything works as I hope it does I'll assemble it more permanently and be done.

Looking better for both in and out. Will the large exhaust be problematic for road splash water? Going to be following this for sure.

[trasko]

Originally Posted by daleeb

Looking better for both in and out. Will the large exhaust be problematic for road splash water? Going to be following this for sure.

Who knows regarding the splash, but I would think not. I had the original holes open to the elements for about 2 weeks and during that time there were at least 5 heavy downpours during the afternoon thunderstorms we get this time of year. I didn't notice any water inside.

On the plus side the original ACU had a hole drilled in it's bottom and it would just drip into the bulkhead below where the vents are and then drain out of another hole near the wheel well. So any water that does get in the vent will follow the same path. There is some electrical in there (12V and 120V) as well as the shower drain line but nothing I expect to be problematic. I used a "weather rated" electrical box to do the 120V extension joint since I saw one at the store and figured there is a chance of water in there.

[trasko]

In separate news I've been working on the fridge. It's a little 1.8 ft^3 Dometic 3-way (I think it is Dometic). During our big summer trip the performance was disappointing but from what I've heard not entirely out of the ordinary. It can do 35-40F below ambient. But we were regularly hitting 95-100F and so regularly having food at 50-55F for long periods.

The fridge in the Parkliner is held in only at the front panel by 6 rivets. During this A/C project I have pulled out the fridge, cleaned it up real good (inside the box but also the burner/chimney/fins/etc), tweaked the metal baffles and replaced the rivets with rivnuts so I can more easily service it. I ended up testing it and still not getting great performance.

I have a stick on thermometer I put at the top part of the door. It reads ~40F when it's 80F outside. However the floor of the fridge with a couple bottles of water reads 33F. So... Perhaps that's okay and I've been reading a maximum temp. of the fridge vs. something more typical on the inside.

Yesterday I pulled the fridge out again (thanks rivnuts!) and "burped" it per some threads I've seen on the RV forums. Short version is: flip it upside down, on it's side, on it's back, etc for a few minutes per turn and then reinstall. Don't start for 1 hr after the "burp." I'll go check on it later today to see if that had any effect. If not I'll likely leave it alone for the next 3 seasons and look to get a compressor unit next summer.

[trasko]

This project is done. It was more work than I thought it would be and I would have done things differently had I known.

First: I think it was a success.
I'm not sure as I'll need a 90F+ day to prove to myself that the A/C can cool to a comfortable level in that situation. Given the forecast for the next 10 days I expect that will have to wait until next summer. I will explain WHY I think it will work, though.

1) I've proven that an extra fan circulating air takes care of the "A/C on the floor" problem.
2) I've increased the capacity of the ACU from 5000btu to 8000btu.
3) Most importantly, I've significantly increased the "venting" (intake & exhaust for the "hot" side). From 40/33 in^2 up to 140/110 in^2 "Net Free Area."
4) I've greatly improved the sealing between the 3 zones of the ACU.

Lastly, I have one more trick up my sleeve: if the tripled vent area is still insufficient on very hot days I can remove some of vents (I used rivnuts) and can double the NFA of them. That means I can go as high as 240/220 in^2 NFA which is 6X more than from the factory.


What would I do different next time?
I think almost all of the problems with the factory A/C are due to venting. 1) not enough NFA both for the hot exhaust air and for the replacement air. 2) Mixing between "replacement air" that should be sucked into the exhaust and "cold side" air which should NOT be sucked out of the conditioned space (but was).

I think the small capacity of the ACU (5000btu) is actually sufficient for the space. And given the very tight space constraints one should avoid trying to fit something bigger like I did. I believe that was a mistake. Although the unit was not super expensive (~$300) it was by far the single largest expenditure of the project. The rest of the components were likely around $100 (screws, rivnuts, vents, caulk, special blades for jigsaw, etc).

So next time I would:
1) pull out the ACU to give me room to work w/o removing the cubby
2) cut some holes like I did in my project.
2a) increase size of exhaust holes (and use rivnuts w/ new vents)
2b) add additional "intake" space (also using rivnuts)
2c) cut holes in fore side of ACU cubby and shower floor cubby to allow replacement air a path to the ACU (this is scary!)
2d) I would not cut a hole for the "scoop" like I did unless I felt strongly I needed the small extra NFA (~30 in^2). I think it is helpful but too much effort and risky beacuse any imperfections are very visible.
3) Take great pains to seal the 3 "zones" from each other (hot exhaust, hot replacement air, cold). Using incense or smoke pen to track down any leakage from one to the other.
4) re-install ACU like from the factory

This plan would avoid the expenditure of a new ACU and all the mess and headache of removing the cubby from the trailer (scraping old caulk, exposing rivet holes, pulling back carpet, etc). My gut says for 1/4 of the work and 1/4 of the cost you would get 3/4 of the improvement I will get. And if you're still not satisfied you can copy my plan and none of the work you have done would have been wasted.


For now I have put everything back together, caulked it and put all the trim back in place. Vacuumed everything and wipes all the fiberglass/wood dust out. I'm done and likely won't know the true verdict on this project until next June/July.

[Doggonehappy1]

Wow! So well written and explained. It is definitely a huge annoying problem and we do appreciate you going in as a pioneer hacking and clearing a road and sharing so that we too can travel with a cooler Parkliner experience. ⭐️⭐️⭐️⭐️⭐️[emoji1319][emoji1319][emoji1319][emoji1319][emoji1319][emoji5]

[JohnH-StLouis]

I'm the new owner of this Parkliner. Once it gets warm enough to need the air conditioner i'll post a reply as to how it's working.

[Doggonehappy1]

Looking forward to hearing from you.

[Wayne Collins]

We have a 2016 with the same A/C. As I see it, the "hot" side just doesn't get enough air circualtion to vent the heat to outside.
A row of round holes under the floor for intake, and a wimpy grill at the side for exhaust.
the vertical panel below the front of the dinette seat gets very hot.
I will read your story thoroughly. to see if I can improve mine.
I was advised to crack open the roof vent let hot air out, so the "cooler" air can gradually work its way up to bed level.

[Wayne Collins]

Originally Posted by trasko

My Parkliner came with what I believe all of the first few years worth of them came with: a 5000 BTU window unit made by Frigidaire.

Model LRA050XT7. Fridigaire website says it is discontinued but I see it for sale on Amazon currently for $165. It may be available by other manufacturers. It is distinct compared to most modern window A/C units in that it uses manual dial controls -- almost everything is electronic these days. It is also the SMALLEST window A/C I have found in a few hours of research. Even compared to other 5000 BTU models it is consistently smaller in at least one dimension.

It is installed in the port side front under the "side dinette" seat. It faces towards starboard blowing pretty much straight at the door. The blower portion is about 16" off the floor -- so pretty darn low. It's an efficient use of space which I appreciate. It is slightly angled towards the center of the living space which helps keep the control knobs away from your legs and looks nice aesthetically.

In terms of its installation: it's in there pretty tight. There is no extra room and it is fussy to get it out. There is a wooden block on the front you screw into place which prevents the unit from coming out which is the only direction it can possibly move. Also of note on the picture of the A/C you'll see a small tab on the right side of the cool-air intake which is what you pull to remove the mesh filter. You cannot open that at all when the unit is installed. Even if you pull the A/C half-way out you still cannot remove the filter. Not the end of the world but... not great either. I'll expound more about the details of the install in the next post where I go into the research I did -- both online and in person.

In regards to its operation, the unit always fired up immediately and began to cool quickly. It was remarkably quiet outside of the trailer. You can hear it but if there is any other ambient noise going on it is hard to notice. Inside the noise is moderate. Enough you can't whisper to another person and expect to be heard but you don't need to shout, either. Watching a show on tiny laptop speakers is not a problem.

One thing that is confounding in this whole endeavor is if you sat down right in front of the unit (like my kid did!) it blew cold. Real cold! If I went to the exhaust vent on the outside it was blowing pretty darn hot. So it was "working" in that it was pushing some cold air into the cabin and pushing hot air out of the vent. But at the same time I knew that it wasn't getting the temperatures down much at all even when given many hours to do it.


So in conclusion of where I started: I liked the A/C in many respects. It's size/weight, the low noise and its location where it doesn't create more drag on the roof or impinge upon headspace. The only problem is that it doesn't actually cool down the trailer!

close-up of the A/C unit (ACU)
Attachment 146743

external exhaust vent circled in yellow
Attachment 146744

general idea of where the ACU is located; this is from our messy first shake-down trip with the trailer.
Attachment 146745

unfortunately your post is reproduced 3 or 4 times. the duplicates could be removed…

[JohnH-StLouis]

Yesterday was warm/hot for this time of the year in St Louis. It was 90 degrees. My trailer was in full sun. I had the AC running for the entire day.

With the AC unit near the floor there is no way for it to cool the hot air that's up higher. I put a thermometer on the floor and measured the air temperature at 63 degrees. Depending on when the compressor kicked on with the AC, the outlet temp from the AC was around 54. The temperature of the trailer as measured from the top of the stove was 92.

I took the grill & filter off of the front of the AC and then played around with removing the temp sensor that's in front of the evaporator and moving it farther up/away, so see if I could get the AC to keep the compressor running longer. It worked for a short time, but the evaporator would quickly start to ice over.

I then placed a small fan on the floor and directed it to blow upward. The fan isn't very powerful. It can run off of D cell batteries or a 500ma plug. It did almost nothing for helping circulate the air and the temp inside only went down to 91.

I then placed a larger Lasko High Velocity Pivoting Utility Fan on the floor and set it to low speed. It moves a lot of air. After about 1hr the temp for the trailer dropped to 74 degrees at the top of the stove and 71 degrees at the floor.

The downside to this setup is that the fan takes up floor space and blocks the door to the bathroom. The other minor issue with this particular AC unit is the placement of the air outlet. It's partially behind the door. It causes part of the top of the fiberglass bench to be cooled and form condensation. I think i can correct this by adding some insulation on the underside of the bench.

I'll continue testing later this summer when it gets hot again. Next 10 days are cool again and I leave for vacation after.

[Wayne Collins]

That's about it for ours too.
I mentioned previously that you could crack open the roof vent with the fan on slow. That lets the hot air out - BUT - then must draw in outside "hot" air to make up the difference.
Your A/C unit seems to be back under the dinette seat. Ours is out even with the edge.

[Markz]

I crack open the roof vent and use a top shelf mounted fan to blow the remaining hot air down to circulate the air inside the cabin.

[JohnH-StLouis]

Follow-Up post:

The window AC performance hasn't been great for any days when the temperature has been above 90 degrees. Even with the large fan on the floor the trailer gets very warm and the humidity stays high. A few days in late spring the temp was 94 to 96 and the trailer was in the low 80's. I then decided to remove the window AC and install a roof AC.

For the roof AC I had to make a few decisions. First, where to put it. Second, which unit. Third, how to install it.

1. Where to put it: The easy spot would be in place of the rear fan, since most roof AC units fit into the standard 14x14 fan opening. However I didn't want to give up the fan. The fan works great for the majority of the time when we are camping. Plus the trailer doesn't have much roof length behind the fan.

The next location is the roof hatch. The hatch opening is 21-3/8" square. This means patching it in but also reinforcing it and making the roof thicker. Roof AC units have a minimum thickness. The roof's fiberglass is a bit over 1/4" thick. AC's usually need a minimum of 1.5".

2. Now that I had picked the install location, next up is which unit. I looked at installing a Dometic Penguin 2, but it had some downsides. Weight is about 120 lbs and its a bit wide (I plan to install solar along the sides of the roof). I heard good things about Rec-Pro's Houghton AC units so I researched them. Benefits are weight at 67lbs, lower width, and very quiet when running. So that was my pick.

3. Last is how to install it. I removed the old hatch and sanded off the gel coat down to the fiberglass where i'd be attaching a new frame. The roof needed to be reinforced and also made thicker. So I made a small wooden frame and attached it to the fiberglass using marine adhesive. Then i attached a piece of 3/4" marine grade plywood to the top, fiberglassed over it and onto the trailer roof, and lastly used gel coat. This made the roof extremely strong (easily supporting the weight of myself and my brother). The gel coat isn't smooth, but since you'll never see it I wasn't worried. And, it will be covered up by solar panels anyway.

I then measured where to cut the 14" hole and made sure it was centered in the existing opening from the inside. The Houghton's interior vent & return air grill is nearly the same size as the old hatch. I only needed to trim it out at the corners. I used some white PVC sheet that I had on hand. (I'm not totally convinced with how it looks. I may switch it out for birch plywood to match the rest of the trailer)

Finally, I removed the window AC under the seat and filled in the hole with finished plywood (no photo currently)

Performance: Yesterday at noon it was about 96 to 97 by afternoon with 54% humidity. The inside of the trailer started at 89 degrees and within 45 minutes it was down to 80 and 26% humidity (felt noticeably cooler due to the low humidity) By 1hr 30min it was 76 and 27% humidity. 2hrs it was 74 degrees.

Later in the late afternoon & evening when the outside temperature was 90 the inside of the trailer was in the mid 60's and it felt cold.

If the weather here ever reaches 100 or higher i'll retest things and post how the performance is.

So far this has made a huge improvement with how the interior of the trailer feels.

[trasko]

Hi John. It’s disappointing to hear about the performance of the A/C changes I made. I’m glad to hear you’ve corrected it and have a comfortable trailer to enjoy. Happy trails.