A/C ducting on 3570RS

[kenwessels1451]

We are full-time in our new 2016 BH for a month now. We love the floor plan but there seems to be a design flaw in the a/c ducting. The front ducting doesn't go through to the rear. The rear a/c cannot keep the rear cooler than 10 degrees below when it hits 90 degrees outside. No help from the front a/c. The temp from the vent is 55 degrees. I've been in touch with Joshua at HL customers svc asked if the engineers could brain storm to come up with a fix. Since the skylight is in the way maybe a smaller skylight allow the duct to go through or ?. If any other 3570 owners have a fix please chime in. I'll advise what Joshua gets back to me with. I can't belive they would leave us owners to sweat it out.

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[jimtoo]

Hi kenwessels1451,

Welcome to the Heartland Owners Forum and to the family. We have a great bunch of folks here with lots of information and all willing to share their knowledge when needed.

Hopefully it's a small problem, maybe just a cutout blocking the flow of air. Maybe some of our other members will have some suggestions for you also. Let us know what happens.

Enjoy the forum and your new unit.

Jim M

 

[BouseBill]

We ran both the front and rear....and put a small fan in the hallway to blow some of the cool air from the bedroom to the living area. It did seem to help.
And yes it would have been nice if Heartland had tied the two together!! When it was 111 outside we could get the living area down to 91 when the bedroom was nice and cool.

 

[kenwessels1451]

It will be 100 here Fri and Sat. We'll be using a fan in the hallway to help. Thanks

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[Dave_Burrow]

I also have a 3570RS and had issues with the HVAC. I live in mine in south Georgia during the week to avoid a 150 mile round trip daily commute. We bought the unit last December. We had issues with the air conditioning in the late spring and summer when we had an early heat wave this year. We had about the same 10 degree difference from inside to outside when it got hot outside. I looked at the Dometic documentation that came with our unit from the factory and saw that they require a minimum of 4 vents the size of the ones in our Heartlands for a 15,000 BTU unit like ours. Our 2015 1/2’s are the first of the Bighorns to incorporate the Whisper Quiet Air. They moved the AC unit to the roof but did not add any additional registers in the ceiling. The registers that used to all be dedicated to cool air supply are now split with 3 for supply and 3 for return in the living room. Moving the unit to the roof eliminated the direct air return into the unit in the ceiling and reduced the noise. I tried to talk to the factory about the data in Dometic’s manual but was told that that requirement didn’t apply to their installation. The only way I can see that they could say that the requirements don’t apply was if they counted the registers in the bedroom in the total for each system. They are not really available since the skylight over the shower does block the ceiling duct for the cool air supply; leaving each system on its own from a cool air register standpoint. I think the return air duct is continuous so technically that side may be OK per Dometic’s requirements.


I talked to a friend who works for Trane in the commercial air conditioning business. He told me that they do not like to see cold air coming out of the discharge vents more than 20 degrees cooler than the air that is returned. (This does not mean that you can’t get but 20 degrees below ambient.) If the cold air is more than 20 degrees cooler than the warm air that went back to the unit there is too little air flow over the coils and cooling performance can be increased with more air flow coming out at a slightly less cold temperature. This fits with Dometic’s call for more vents being required. My friend said the heat transfer inside the unit just works better with more airflow and less temperature change. You get more of the unit’s BTU’s transferred into your interior air. When the unit has adequate air flow it can begin to cool the interior and slowly the return air temperature starts to drop. As it drops you start moving the inside temperature down and you are able to get your interior temperature more than 20 degrees below the outside temperature. This goes on until your thermostat sees your temperature at setpoint and then it cycles the unit to hold things steady.


We couldn’t do anything about the break in the duct for the skylight in the bathroom but we could add more registers in the ducts as we have them. We ordered 7 extra registers from Heartland’s parts people. They only cost between $50 to $60 total so it wasn’t very expensive. They did want a photo to assure that they sent us the correct item. They are easy to install. All you need is a 6” hole saw (If you have to buy this too it costs about another $50 from McMaster Carr or maybe you can rent one at Home Depot). Just be careful using that hole saw on your ceiling. It generates a lot of torque on the drill as it cuts that big hole in the ceiling. Hold it steady and tight or it will try to walk all over the ceiling and scar it badly. Once the holes are cut you get as much saw dust as possible out of the duct and install the new vents using 3 small screws each. We added 2 new supply and 2 new return vents in the living room, 1 new supply into the bathroom and 1 new supply and 1 new return in the bedroom. The vents in the living room were added just forward of the forward most extension of the fan blades of the ceiling fan and the second set was added on either side of the roof vent up near the pantry wall. We have the coffered ceiling and these locations look ‘proper’. The bathroom supply vent was added between the ceiling light and the shower door. The two vents in the bedroom were added between the existing vents which put them right over the bed. If you look at the Dometic installation instructions you can work out that some of these locations are not exactly where they would prefer them but I felt like I was in a situation where life gave me lemons. This was the best lemonade I could make based on where I started. Dometic recommends 4 vents minimum and 8 maximum per unit. I now have 5 pairs in the living room and 4 pairs on the bedroom.


Unfortunately our living room unit developed a Freon leak while I was waiting on the vents to arrive and its cooling performance suffered even further. We used the additional vents and keeping the shades down to survive the rest of the summer. Heartland did provide a warranty replacement for our living room unit but it took a long time for me to be able to get my Bighorn into the shop (my fault, not theirs). I now have two good air conditioners but the peak of the summer heat is gone and I cannot say definitively that I have no more issues. I was able to survive with the extra vents and the damaged air conditioner through the summer so I expect to be pleased with the total system performance next year. I can say that we have noticed much better air distribution in the living room with the added vents. It always used to be warmer near the door than anywhere else in the camper but now there is almost no change as you walk from the bedroom to the sofa.


This was an inexpensive fix for us. I wish Heartland would come to terms with this issue but they may never have built a unit before with Whisper Quiet Air and a bathroom skylight that interrupts the air duct. Also Whisper Quiet Air is new to Bighorns with the changes that came out with the 2015 ½ models so they still have a bit of experience to gain installing it in this line. It’s a bit like the old advice to ‘never buy a new model car the first year that model is introduced’…but we really like the new features including the air conditioning.


One other item, our air conditioners had problems with the freeze sensors in the coils of the units on the roof. This allowed the bedroom unit to freeze solid (Its freeze sensor had fallen completely out). We had to run the fan on high speed all the time to keep it from freezing until we found the sensor out. There is a space in the coils for the sensor and all you have to do is reinsert it in that fairly obvious spot. The sensor for the living room unit was not inserted all the way and pushing it in prevented the small freeze ups that were occurring. Once the Freon leak developed there was nothing that could stop the periodic freeze ups.


Sorry for this being long winded but I hope it helps.

NOTE: See follow up post #12 in this thread.

 

[kenwessels1451]

Adding the extra vents makes sense when these a/c units can use up to 8 each. You're increasing the flow better than 30% in the living room and more in the bedroom. I'll put this on the to do list I have when the trailer goes in the shop this February. I'm not having freeze ups on the units but I'll add checking the sensors too. Thanks

I did have a question I asked HL two weeks ago if the ducting at the a/c can be reworked to make the door side the a/c outlets and the street side the intake. Then the skylight blocking the outlet duck a non issue since the duct on the intake is not blocked. I'm calling HL tomorrow since emails over the last month haven't provided any help. I'm not able to check the a/c myself but if anyone has that can chime in and advise if this is possible it may also be a solution so the front a/c can help the living room.

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[danemayer]

Adding the extra vents makes sense when these a/c units can use up to 8 each. You're increasing the flow better than 30% in the living room and more in the bedroom. I'll put this on the to do list I have when the trailer goes in the shop this February. I'm not having freeze ups on the units but I'll add checking the sensors too. Thanks

I did have a question I asked HL two weeks ago if the ducting at the a/c can be reworked to make the door side the a/c outlets and the street side the intake. Then the skylight blocking the outlet duck a non issue since the duct on the intake is not blocked. I'm calling HL tomorrow since emails over the last month haven't provided any help. I'm not able to check the a/c myself but if anyone has that can chime in and advise if this is possible it may also be a solution so the front a/c can help the living room.

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It won't hurt to call Heartland to discuss, but temper your expectations knowing that the engineers have designed the system a particular way and have tested it that way. Heartland supports it that way. They probably won't want to help you do something they can't support.

 

[kenwessels1451]

Will do
Thanks

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[donr827]

Great explanation Dave. Maybe HL will take a look at your posting.
Don

 

[BouseBill]

I would hope that if a customer ordered the parts from Heartland they would be more than willing to sell them. If the system can be made to work more efficiently, no skin off their nose...right?

 

[kenwessels1451]

HL just called and Joshua's conversation with Bill in engineering was although he wasn't in on the original design said there's definitely a flaw. Engineering can offer no solutions. He said the a/c units can't be setup to redirect the inlet and outlet to the opposite ducts. Also as stated earlier in the thread they won't support what the consumer does since they didn't design or test it.

This maybe this was one reason the 3570 was dicontinued.


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[Dave_Burrow]

I think it is time I posted a follow up to my long post from last November (reply # 5 to this thread). First off a couple of things have changed with us so I am not quite as up on this issue as I might have been. I am no longer living in my 3570RS 4 nights a week. I had a job change and now we only use the unit on weekends. We were in the unit for the weekends of both Memorial Day and July 4th. These were near 100 degrees here in south Georgia and both our sites were in total sun. It was hot! Our bedroom stayed cool but neither of our systems were able to hold to their set points during the day. By about 10:00am each morning the actual temperatures began to climb above their set points. By mid afternoon the living room was in the upper 70's and the bedroom was a degree or two less. These results were better than we had last summer before we added the extra vents. The afternoon of July 3rd the living room temperature did get up to 82 but there 10 to 12 folks in the camper and people were coming and going so I can't blame all of that on the HVAC issue.

There are a few things I noticed and I do have plans for next steps.

First of all we tried to get ahead of the heat issue. We set the thermostats down to about 70 by 9:00am and set the fan speeds to high to maximize the efficiency of the HVAC units. We also kept the shades pulled down to block as much heat from the windows as possible. I replaced the light bulbs in the fixture over the dining table with LED's and I am going to replace the ones over the sink. The incandescent bulbs give off a lot of heat. We also have to accept that our residential refrigerator puts heat into our living room but there is nothing we can do to help that issue.

I saw that if we ever got a few clouds we could gain a little ground on the internal temperature. That means to me that radiant heat from the direct sun light was a major contributor to our problem. Also I have found that when we go to pick up our camper for trips that the internal temperature is not real hot. The trailer is still in the campground where I stayed and the site is very shady. When I go get the unit tomorrow I will see if the systems are holding the temperatures at setpoint. I should get there about 10:00am (forecast temp=88 with heat index of 103). I leave the HVAC systems on 75 with the fans in auto so they are not going to be working at their best due to the lower air flow. I will update this post after the weekend.

What next... I need slide toppers. I have wanted them for a while due to leaves but I also think they would stop the direct sunlight from hitting the tops of the slides. These are not insulated as well as the roof and let in a good bit of heat. The air space under the slide toppers would provide some insulation but I think their main advantage would be to provide some shade. They would block the direct sun light. Beyond the slide toppers I want to get heat rejection film on my windows. 3M makes a film and I have purchased another film from Camping World. That 'install it yourself' film worked great on our first camper. We has dual pane windows on our second camper and they let in a lot of radiant heat. They were also bad to put film on as it makes the window itself absorb the heat and this can damage the window. This is not an issue with single pane windows as the heat can get back outside. I am going to price professionally installed film on the windows in the living room. I think that will help quire a bit.

I would like feed back from others. If you have slide toppers do you have heat issues? Remember, we are talking about Bighorns that have the Whisper Quiet Air. If you have the large ceiling air return for your HVAC you don't have the same problem that I am dealing with.

Has anyone added heat rejection film to their windows? What are your thoughts on your results? As best I can remember in our first camper the film really cut the heat from direct sun light. You could not see into the camper at all during the day due to the reflective film. Also at night you could not see out of the windows if there were any inside lights on but you could see in from outside.

Have others found better or different solutions?

Thanks.

Dave

 

[danemayer]

While you're looking at slide toppers, you might also look into window awnings. If you can keep the sun from ever hitting the windows that should reduce the radiant heat quite a bit. Maybe someone who has window awnings can comment on how effective they are in direct afternoon sun.

 

[cookie]

I'm with Dan on the window awnings.
I installed one over the two large windows on the door side of our 3585RL.
My brother did the same along with adding one to the off door side where he has a large window in his 3610RE.
It does help with keeping the heat of direct sunlight out.

We also have the slide toppers and I believe that they help as well. As you said, they do provide some shade for the top of the slideout.

Peace
Dave

 

[TravelTiger]

I ordered some self-install window cling samples that were supposed to cut the heat transfer as much as 45%. These would go on the inside of the window. I applied the 5 cling samples to the inside of one window that gets direct afternoon sun, and used my infrared temp gun to see the difference. The only difference I could tell was about 3-10 degrees cooler than no film at all. I wasn't sure that was a significant enough difference for the cost and hassle of installation, so I did not order any film.

I am considering solar screens for the western facing Windows instead.


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[danemayer]

Erika,

We have solar screens on the outside. They help, but not as much as I had hoped. If I were spending the money again, I'd try window awnings and would probably do a self-install. And if we were still in Texas for the 8 month summers there, I'd have them already.

 

[SNOKING]

HL just called and Joshua's conversation with Bill in engineering was although he wasn't in on the original design said there's definitely a flaw. Engineering can offer no solutions. He said the a/c units can't be setup to redirect the inlet and outlet to the opposite ducts. Also as stated earlier in the thread they won't support what the consumer does since they didn't design or test it.

This maybe this was one reason the 3570 was dicontinued.


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Well I have a 2017 BH3575el and the supply air duct is on the door side and return air is blocked in half by the bathroom sky light on the off door side. Which is supply and which is return is base on how the plenums are constructed in the ceiling and not on how the A/C units work. So they are correct in that it can not easily be changed on an existing unit. Our front unit has 2 return and 3 supply vents. I have a third register to install in the bathroom as an additional return. I currently have the supply side blocked between the to units. This thread has me thinking I will remove those blocks along with the fact that the front unit does a lot of short cycles now(do the thermostats have a differential setting?). My living room unit has 4 supply and 4 return vents.

I am also experimenting with direction of the vent fins. It seems that having the fins across the flow > fins across ||| might be causing the first half fins encountered to push air over the second half set. So I change them so air flow > sees fins = like this dumping air left and right, not front to back in the trailer.

So going forward I think maybe an another addition bedroom return vent giving it 4 with the bathroom one I already have to install, 2 to 4 additional living room vents and removing the blocks I put in the supply side are in order!

Looking at our living room ceiling adding vents near the fantastic fan and in front of the paddle fan just in front of the coffered ceiling cross piece seems like good locations.

Thanks Chris

 

[SNOKING]

Just found this 6" hole saw.

https://www.amazon.com/EazyPower-Hole-Saw-CornHole-Boards/dp/B000YC1XUK

How ever in measuring the vent I have to install 5 7/8" would be better. Here is an adjustable one.

https://www.amazon.com/Klein-Tools-...=1-1&keywords=Klein+53731+Adjustable+Hole+Saw

Chris

 

[TravelTiger]

Well I have a 2017 BH3575el and the supply air duct is on the door side and return air is blocked in half by the bathroom sky light on the off door side. Which is supply and which is return is base on how the plenums are constructed in the ceiling and not on how the A/C units work. So they are correct in that it can not easily be changed on an existing unit. Our front unit has 2 return and 3 supply vents. I have a third register to install in the bathroom as an additional return. I currently have the supply side blocked between the to units. This thread has me thinking I will remove those blocks along with the fact that the front unit does a lot of short cycles now(do the thermostats have a differential setting?). My living room unit has 4 supply and 4 return vents.

I am also experimenting with direction of the vent fins. It seems that having the fins across the flow > fins across ||| might be causing the first half fins encountered to push air over the second half set. So I change them so air flow > sees fins = like this dumping air left and right, not front to back in the trailer.

So going forward I think maybe an another addition bedroom return vent giving it 4 with the bathroom one I already have to install, 2 to 4 additional living room vents and removing the blocks I put in the supply side are in order!

Looking at our living room ceiling adding vents near the fantastic fan and in front of the paddle fan just in front of the coffered ceiling cross piece seems like good locations.

Thanks Chris

Chris,

I ended up replacing all our vent covers with the BigPort vent covers, with the 1/4" flange. These don't fit the hole as the hole is slightly larger than needed, but they cover it.

A little challenging to install with four screws each, and aligning with a hole that's bigger.

But because they don't intrude into the duct and the louvers are not as angled, they seem to dump more air into the room. I tested with a windspeed app on my phone, and did see some improvement.

Drawbacks of these vents are that the foam filters are sold separately. But you can use your old filters, if you cut a hole on the center for the center post design of the new vent.

They don't match or blend well with the OEM vents. So if you have any OCD, you'll have to replace all of them. $$$

The fin section is removable to remove the foam filter, but takes some effort.

http://www.dwincorp.com/products/11/Bigport-9850-Louvered-RV-AC-Ceiling-Vent


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