Dreiha Atmos 4.4 Home Install

[Galileo]

4 hours ago, Geronimo John said:

The houghton IS a great unit.  But if they have not gone back to their SET 1 configuration with a remote thermostat and where the fan shuts down when the compressor shuts off then that is a significant concern for most owners.  WHY?  Most owners will not want to risk making the two mods to fix these SET 2 issues. 

Once the mods are made, then I still feel that the HOUGHTON 13.5 k unit is GREAT.  It however does not have a condensate drain system as of last week when I I checked.  But the larger 15K does.  

That said, I think the 15K unit is oversized for even hot weather use and would not recommend it as such.  Also check the height difference.  The 13,5 is a reduction over the Dometic OEM on most OE2's.

Dunno why the mfrs of RV air conditioners haven’t included the features that even cheapo window units have. Though sometimes I like a fan running all the time just for circulation sake, most of the time I want the fan to shut off. That said, I want the fan to run until the evaporator coils have equalized in temperature before the fan shuts down. I forget what they called that setting on my last window units, but it was nice. 

If/when the fan and compressor shut down at the same time, you have all that nice cold just wasted there in the housing. May as well blow it out into the area you’re trying to cool, right?

I think a lot of folks buy too many BTUs and it’s counterproductive from what I’ve read. If you cool the room (trailer) too quickly, you don’t move enough if the room air across the evaporator coils to adequately dehumidify the air. That’s (more than) half the battle in making interiors comfortable when it’s hot and humid. As I understand it, there’s a new generation of high efficiency a/c’s that use another method of reducing humidity.

[Geronimo John]

2 hours ago, Galileo said:

Dunno why the mfrs of RV air conditioners haven’t included the features that even cheapo window units have. Though sometimes I like a fan running all the time just for circulation sake

Yes and YES.

The key to your, mine, and a boat load of owners is the ABILITY to choose Off or On of the fan.  The Houghton Set 2 units do not so provide.  Hence serious humidity issues caused by this AND the fact that on the Set 2 they mount the thermistor (that controls the compressor on/off) is mounted inside the unit and does not very well reflect the cabin temperature in the middle of the cabin.  

Such a huge mistake for likely 90% of the US market.  But it is just fine for 90% of the AU market there it is hot and dry....

They chose, and continue it appears to not give a hoot about the USA 90%.  At least not yet I hope.

Why?  Their unit is a really great unit otherwise.

GJ

[jd1923]

1 hour ago, Geronimo John said:

The key to your, mine, and a boat load of owners is the ABILITY to choose Off or On of the fan.

The Atmos does this too, but sitting in Ron’s Oliver at the Texas Rally, where temps were mid 80s, not summer humid, his A/C dropped temp from OFF to very comfortable and humidity dropped by 11% at the same time! (In 20-30 minutes) I remember numbers and our friend @Ronbrink has all the temp sensors and gadgets, an extremely well-equipped Oliver!

So why does one create humidity and the other does not? Kevin at SDG told me it’s cause the condensate is expelled to the exterior. They both do that.

If Australia is hot and dry, same here in Arizona. I want the humidity but NOT fan noise. I figure when it’s cooled off and the fan is running, I’ll be in bed and hit the remote to power off the system! 🤣

[Ronbrink]

I just saw this fairly recent YT video by The Fit RV, wherein SDG installs an Atmos 4.4 in their EKKO Transit. Not tech savvy, so if interested do a search for this:

 

Edited March 14 by Ronbrink

[Geronimo John]

On 3/13/2025 at 4:29 PM, jd1923 said:

So why does one create humidity and the other does not? Kevin at SDG told me it’s cause the condensate is expelled to the exterior. They both do that.

If Australia is hot and dry, same here in Arizona. I want the humidity but NOT fan noise. I figure when it’s cooled off and the fan is running, I’ll be in bed and hit the remote to power off the system! 

ASSUMPTION:  From the internet,:  Swamp coolers are primarily used in the dry, hot climates of the Southwest United States, such as Arizona, New Mexico, and parts of Utah and California, and are less common in areas with higher humidity." Keeping in mind that not all occupants in these states use them, as is evident the number of AC in those states.  For this post, I'm saying I think that in the USA, for mechanical cooling in the USA, let's estimate that 5% of USA cooling units are Swamp Coolers.  And the other 95% use regular refrigerant A/C's and/or Heat Pumps for mechanical cooling (AC). 

Now to your above thoughts:

The AC evaporator coil has the capacity to store well over a quart of water on its very large amount of heat transfer surface.  You turn on the AC and it is dry.  As humid air passes over the coil, it condenses water from the air and it stays on the  coil.  Eventually the coil is saturated, and it begins to drain water out of the AC unit.  As it continues to run the process continues and water flows out of the unit.  This is true for all AC units. 

For the Houghton Set1, and most USA air conditioning units, the fan and compressor units cycle together.  This keeps the condensate on the coil between runs.  The humidity in the cabin is lowest just as the unit shut off the compressor. The humidity will then rise naturally due to occupants and their activities.  But this typically is a slow process and before it gets out of comfort range,  the control system cycles the compressor back on.  Comfort is assured for 95% of USA applications.

But for Houghton's Set 2 units and similar designed units, when unit Thermistor/T-stat reaches set point, they shut off the compressor but not the fan.  The condensate then gets evaporated into the cabin.  For 95% of US applications this is not good.  This can be demonstrated with any heat pump.  Just turn the heat pump on in "Cool" mode, and run the unit until you see condensate exiting the unit.  Then switch the Heat Pump to heat and FEEL the humidity as the heat pump inside coil heats and evaporates that entrained condensate.  You will be amazed.  And can then fully understand one of the problems with Houghton Set 2.  

Your scenario in AZ is very much like what the AU Houghton typical customer wants.  You are spot on. BUT most OTT owners are FAR more concerned with too much humidity and heat.  As such, you likely would LOVE the Houghton Set 2 units....Until you took a vacation to most other USA locations. 

So, as you mentioned 🙂     This is why I have made the case for Houghton to provide a selector switch serving the supply air fan and compressors so as to allow the occupant to switch them accordingly to their needs.  This would greatly benefit the vast majority of USA users and the bottom line for RECPRO and HOUGHTON.  Combine this with a remote thermistor/T-stat and it would fix the cycling issue as well.  Doing so would make it easy for all of the USA Market to use their product out of the box.  

And if they really really wanted the Air Stream and OTT customers to smile big, redesign the lower pan of the unit to allow for gravity drain of the condensate without needing an electric condensate pump like they have now added to the 15K BTU unit.  Again they took the wrong design path.......  Until such design improvements are made, their amazingly wonderful unit would not seem to be suitable to those chose not to execute Mod 1 and 2.  But for those that can, it is a GREAT unit.  

GJ

Sorry for the above response from deep inside the rabbit hole.

 

Edited March 15 by Geronimo John

[Geronimo John]

On 3/14/2025 at 2:31 AM, Ronbrink said:

I just saw this fairly recent YT video by The Fit RV,

Good, but long, video.  Thanks for sharing.  It appears that the Atmos 4.4 design is very well done.  Has many of the same concepts used by the Houghton.

Two design details for further update by Atmos owners:

In the video they did not make it clear that when the heat pump is in cooling mode, that the fan does not have to run when the compressor is off.  This is a deal killer if the Supply Air Fan and the Compressor cycle together.  Unless you are one of the 10%ers as discussed already.

The other detail that potential purchasers should be aware of is the unit's height.  Here is a comparison:

• Dometic Penguin II  9 1/2"
• Houghton 9"
• Amos 11.14"

For most not a problem.  For some that 2.5" could be if you have a 10' entrance height.  Just measure and be sure especially if your entrance to the storage factify has an UP ramp as you back in.

Looking forward to learning about the cycling of fan and compressor topic.

GJ

 

[ScubaRx]

On 3/13/2025 at 7:30 PM, Geronimo John said:

Why?  Their unit is a really great unit otherwise.

GJ

That’s like saying, “Other than all that Mrs Lincoln, did you enjoy the play?”

[jd1923]

19 hours ago, Geronimo John said:

In the video they did not make it clear that when the heat pump is in cooling mode, that the fan does not have to run when the compressor is off.  This is a deal killer if the Supply Air Fan and the Compressor cycle together.

They cycle separately but the interior fan is always running when powered on, compressor fan only running when the compressor is running (though likely runs for a period after for cooling).

When observing @Ronbrink's Atmos at the Texas Rally, it was just after noon and about 80F. Ron and Brooxie were outside in the shade with the A/C OFF. They had not yet run the A/C that day. Ron, Ken @mountainoliver and I went inside. Ron turned on the Atmos and we talked for 20 minutes or so, hearing every word said with a very light fan sound in the background. Just a faint sound so that it was not apparent the fan was running. In this short time the inside became quite comfortable and according to a humidistat that Ron had (do trust Ron for all the required gadgets), humidity dropped by 11% while the temp broke under 70F.

One thing all these YouTube guys get wrong with sound testing is the valid comparison is dBs produced on LOW fan, not high. I'm generally not sleeping with any fan on. But if we need cooling at night the fan will certainly be on low. If you're concerned about dBs, you would run the fan on low. What is the low-to-low fan noise comparison?

The Dometic Penguin II is LOUD regardless of fan position and on our unit, the difference between high or low fan is negligible. Comparing low to low fan, on my ears no dB phone app, the Dometic is 3 to 4x louder than the Atmos on low fan.

I just emailed Kevin at SDG with questions about availability and the SoftStart. I hope to order ours early April and get it installed by May. Will not have summer temps but on sunny afternoons I will run amperage tests (on inverter) and sound tests, before and after, the best I can. I'll start a new mod thread when I do.

[Ronbrink]

1 hour ago, jd1923 said:

They cycle separately but the interior fan is always running when powered on, compressor fan only running when the compressor is running (though likely runs for a period after for cooling).

You are correct on both instances, and a mention that the rear fan continues to run until the compressor is cooled down, supposedly to add longevity to the unit. A couple of things, the Dry feature is very effective in keeping interior cabin levels comfortable when relative humidity conditions are very high outside. It is also my understanding that the condensate and evaporate coils have separate drain pans, each having drain holes to both sides to ensure condensate water flows out regardless of the trailer’s orientation. I’m not sure if that is common or unique to the Atmos. 

 

[Geronimo John]

17 hours ago, ScubaRx said:

That’s like saying, “Other than all that Mrs Lincoln, did you enjoy the play?”

Spot on!  Those of us who have completed Mod 1 and Mod 2 for the Houghton's really like them.  But having to do the mods to get there is not realistic for most of the audience with Mrs. Lincoln.

7 hours ago, jd1923 said:

They cycle separately but the interior fan is always running when powered on

Same darn mistake Houghton made.  Where was the ATMOS designed an where manufactured?

6 hours ago, Ronbrink said:

It is also my understanding that the condensate and evaporate coils have separate drain pans, each having drain holes to both sides to ensure condensate water flows out regardless of the trailer’s orientation

The Dometic Penguin II also had bi-lateral drainage.  But it was an internal drain down a tube to near the port side tire.  The Houghton and if I am reading your note correctly both flow the condensate over the roof.  Please confirm.  IF so, then both of these units are not quite as good in the condensate drain design as the  Ole Dometic.

All over-the-side drainage designs have to be bi-lateral.  Reason is that with Heat Pump's you may well be operating the system in freezing temp's.  If they were not bi-lateral designs for flow, you would have a condensate pond inside the roof top unit on the low side.  Such ponds in freezing weather can cause serious problems.  

I wonder how long it will be before we have Houghton type Mod 1 and Mod 2 for the Atmos units?

Edited March 17 by Geronimo John

[Ronbrink]

20 minutes ago, Geronimo John said:

The Houghton and if I am reading your note correctly both flow the condensate over the roof.  Please confirm.

That is correct, and thanks for explaining another aspect of the bilateral drain design. 

 

24 minutes ago, Geronimo John said:

I wonder how long it will be before we have Houghton type Mod 1 and Mod 2 for the Atmos units?

I read this morning of a video wherein a mod was done to have the fan only run when the compressor is running in Cool Mode. An Atmos owner (not Oliver) stated in the Sprinter forum that he was going to do the mod, but no further report to date. Such mod would void the warranty. 

[Geronimo John]

1 hour ago, Ronbrink said:

Such mod would void the warranty. 

Most likely.  If you want to get an idea about what is required for the Houghton's, it very likely would be similar for the Atmos units as well.  

The Mod to turn supply air fan on/off with the compressor is just a ACR style relay.  I had proposed this long ago and one of the SOB owners ran with it.  GSM Bear was very helpful in the process.  

The Mod to remote the thermistor that controls when the compressor comes on / off is just an extension of the cable of the existing thermistor or just buying one with a longer tail.  Normally an easy mod if your trailer has an easy path to where you want to be sensing cabin temp.  In the case of OTT's, it was a tough nut to crack.

There is EXTENSIVE "Deep Rabbit Hole" posts on those two topics.  Some of my thoughts and a lot of others are attached below.  Warning:  it gets deep into it in the attachments.  But in actuality it is not impossible for a talented and courageous electrical tech to accomplish these mods.  But as you said, "Such mod would void the warranty so one is for sure at risk.  

Last thought is that if a person were so inclined to do the mods, I would run the unit for a full season just to make sure it is good to go, then decide to proceed "at risk".

GJ

 

Houghton Single Line Relay Wiring Diagram from GSMBear.docxGSM BEAR V2 RecPro Houghton Interior Fan Mod v2.pdfHoughto 3400 Humidity Relay Mod (13 JULY 2024).docx

[rideadeuce]

We went down with the kids to visit my nephew last night in Birmingham, AL. 3 hr drive. The Oliver is very well suited for city boondocking. We parked with no hookups at his apartment complex in a great spot that very few TT/TV combos could have reached. We had 100% batteries (920 Ah) when we arrived due to the solar and DC/DC charger working great finally.

During the night, it dropped down into the low 40s. We had the heat set at 68 AUTO on the Atmos and I have to say between the quiet and new Tochta mattresses it was probably the most pleasant night I have spent in the Oliver. Comfortable and quiet. Great combination. 

The Auto mode on the Atmos works very well heating or cooling. I have said this before but I like the fan on more during cooling for the air circulation in the cabin. Doesn't get stuffy. 

I did kick on the heat with the dedicated Honeywell thermostat that sits where the old AC control was and it fired right up. 

Edited March 22 by rideadeuce

[Ty J]

Tosot A/C installed this winter just finished also. Looks similiar to Greer. Very similiar to Atmos. Caught amazon at weak moment Prime day (900.00) and just finished install. Pretty simple if you have a good back mine is not had most of my friends help get a/c on roof with painters scafolding. Has great reviews on dehumidifying. Not needed up here in mt but maybe able to retire someday and head south. Picture below of unit on top is not mounted(FYI) Just set on top. Hardest part was leveling a/c because of factory bump. Could not modify drain lines to get them to work without ton of modifications.

Here is a few pics. I installed with 100.00 dollar tosot soft start. I was told really did not need, but decided to install for running on my lithium. Heater works great. (Slow warm Heat 850watts not warm enough to test a/c quite yet. Pulling 900 watts on high but still cold up here in Montana. Great job on Atmos.

[Ronbrink]

On 3/29/2025 at 10:48 PM, Ty J said:

Looks similiar to Greer. Very similiar to Atmos. Caught amazon at weak moment Prime day (900.00) and just finished install.

GREE manufactures several like units including your Tosot, they are all seemingly the same as the Atmos. You got a very good deal and current pricing on Amazon is now $100 higher, but still a value buy. Others may be interested in knowing what added costs there may be, specifically tax and shipping if applicable. The TURBRO soft start is interesting and value priced, as well, however I would be concerned with its quality. And yes, you are better off having a soft start device if running on LFPs, good move and install! You may want to add an informational ‘Signature’, go to Account Settings.

Edited 14 hours ago by Ronbrink

[jd1923]

12 hours ago, Ty J said:

Tosot A/C installed this winter just finished also. Looks similiar to Greer. Very similiar to Atmos. Caught amazon at weak moment Prime day (900.00) and just finished install.

Can you please confirm if the Tosot you have runs on R410A or R32 refrigerant? With R32 it means it is equal to the Atmos today. The Gree last year was advertising R410A and it's hard to know what you're getting since this Amazon ad and other sources often do not specify. See this article for the superiority of R32:
https://aircondlounge.com/types-of-refrigerant-in-air-conditioning/

Still a good "Spring Deal" on Amazon now at $1, 020 + tax, delivery included. Wish we lived in one of your no sales tax states! With the high AZ sales tax, this comes to $1,105. The Atmos is $1,350 + $150 shipping + tax (both numbers without StartStart).
https://www.amazon.com/TOSOT-Conditioner-Non-Ducted-Rooftop-High-Efficiency/dp/B0CDWR5RP9/?th=1

The Turbro soft start you show in the picture is $84 plus tax, also on Spring Sale today:
https://www.amazon.com/TURBRO-Installation-Compressor-S15-Plus/dp/B0DK8BXHWH/

[Ronbrink]

2 hours ago, jd1923 said:

Can you please confirm if the Tosot you have runs on R410A or R32 refrigerant?

I was wondering the same so went into the Tosot Owner’s Manual prior to my last reply to @Ty J and read R32. Hopefully he can offer further confirmation per your request. 

Edited Sunday at 07:38 PM by Ronbrink

[Ronbrink]

19 hours ago, jd1923 said:

Can you please confirm if the Tosot you have runs on R410A or R32 refrigerant? With R32 it means it is equal to the Atmos today. The Gree last year was advertising R410A and it's hard to know what you're getting since this Amazon ad and other sources often do not specify. See this article for the superiority of R32:
https://aircondlounge.com/types-of-refrigerant-in-air-conditioning/

Still a good "Spring Deal" on Amazon now at $1, 020 + tax, delivery included. Wish we lived in one of your no sales tax states! With the high AZ sales tax, this comes to $1,105. The Atmos is $1,350 + $150 shipping + tax (both numbers without StartStart).
https://www.amazon.com/TOSOT-Conditioner-Non-Ducted-Rooftop-High-Efficiency/dp/B0CDWR5RP9/?th=1

The Turbro soft start you show in the picture is $84 plus tax, also on Spring Sale today:
https://www.amazon.com/TURBRO-Installation-Compressor-S15-Plus/dp/B0DK8BXHWH/

Not to further confuse the issue, but just viewed another like unit offered on Amazon, FOGATTI. What caught my attention was the much higher CFM air flow and EER ratings on this unit compared to the Tosto. I seem to remember reading that the Atmos had comparable high CFM, but need to research for confirmation on that. NEway, would be good to know if there are in fact subtle differences in these very similar units and thus, some actually better than others; also the reason for the price disparity. Just say’n!

Edited Monday at 11:56 AM by Ronbrink

[Ronbrink]

3 hours ago, Ronbrink said:

I seem to remember reading that the Atmos had comparable high CFM, but need to research for confirmation on that.

I did a brief search of Dreiha Atmos 4.4 specific information, but found no formal references regarding actual CFM or EER ratings. I did however, find this statement on the Sprinter forum, not conclusive but remember reading this when I was considering the Atmos. I will say this unit will blow my hair when standing at the wet bath doorway, not so with the former DPll!

 

I also recalled wherein @rideadeuce included this unit sticker in his writeup on the SDG install. Interesting enough, it shows ‘SANZ DREIHA GMBH - GERMANY’; when researched the location is Bremen, Germany. Another fact I remember reading, the Atmos was German engineered.

Furthermore, Page 7of7 of the Dreiha Atmos 4.4 brochure also shows other ‘SANZ’ affiliates; SANZ Kenway and SANZ Clima, headquartered in Fairmount, Minnesota and Madrid, Spain, respectively. SANZ Kenway “custom designs and manufactures mobile air conditioning and heating components and systems…”; SANZ Clima has factories in Spain, USA (Fairmont, MN), Germany, Brazil and Poland. Could this be the origin of the Atmos 4.4 and not China (think GREE branded knockoff products), perhaps even Made in the USA? I know, another ‘can of worms’!

 

Where was the ATMOS designed an where manufactured? @Geronimo John once asked. Maybe getting closer to a definitive answer, but then….

 

Edited Monday at 03:00 PM by Ronbrink

[CRM]

44 minutes ago, Ronbrink said:

I did a brief search of Dreiha Atmos 4.4 specific information, but found no formal references regarding actual CFM or EER ratings. I did however find this statement on the Sprinter forum, not conclusive but remember reading this when I was considering the Atmos. I will say this unit will blow my hair when standing at the wet bath doorway, not so with the former DPll!

 

Personally, I would worry about how high the CFM's are since any 15k unit is going to give you as much or more than needed inside the small space of an Ollie. I'm more concerned with how low the CFM's can go at it's lowest setting for controlling humidity and I couldn't get that info on the Atmos when I was researching it. 

[Ronbrink]

19 minutes ago, CRM said:

Personally, I would worry about how high the CFM's are since any 15k unit is going to give you as much or more than needed inside the small space of an Ollie. I'm more concerned with how low the CFM's can go at it's lowest setting for controlling humidity and I couldn't get that info on the Atmos when I was researching it. 

Once the Oliver is brought to a desired temp, in Cool Mode the fan can be set to its lowest setting to address your concern. For high humidity conditions, Dry Mode is very effective, and the fan only operates at low speed and cannot be adjusted. I don’t know why the air flow CFM range is seemingly unavailable. 

[jd1923]

3 hours ago, Ronbrink said:

Another fact I remember reading, the Atmos was German engineered.

I read this too, last year when you first made us aware of this model. I'm thinking the Bremen Germany SANZ DREIHA GMBH created the design and brought it to China to manufacture. Once the CCP got their patent-violating dirty mitts on it, they stole the design and manufacturing processes and are competing with the German company (under the various trade names of Gree, Tosot, Fogatti...) that brought them this technology (China has done this with everything, in my experience from 30 years ago with Motorola).

They all have identical Air Distribution Boxes (ADB), you have to know they were built in the same factory. Perhaps Fogatti added something new. They write re an "Auto Sweeping Motor" in the ADB (see picture 6 on Amazon listing). Is this something extra, that the Atmos does not have? Like @CRM stated, extra CFM is unnecessary in the Oliver and if that's truly an extra motor, mounted below the ceiling, all it would do would be to add noise creating the extra air flow. In the same pic, they advertise the greater airflow can reach the length of a 36' trailer. I doubt it but...

Still hoping to get a confirmation of refrigerant type from @Ty J! You took a lot of pictures. Did you get one of the refrigerant label? Please post one. It would be great to compare it side-by-side to the DREIHA Atmos label Ron posted above.

Edited Monday at 04:16 PM by jd1923

[CRM]

2 hours ago, CRM said:

Personally, I wouldn't worry about how high the CFM's are since any 15k unit is going to give you as much or more than needed inside the small space of an Ollie. I'm more concerned with how low the CFM's can go at it's lowest setting for controlling humidity and I couldn't get that info on the Atmos when I was researching it. 

Sorry, tried to edit my original post and reposted by mistake. Changed "I would" to "I wouldn't" 

Edited Monday at 04:44 PM by CRM
I'm dumb...

[Ronbrink]

47 minutes ago, jd1923 said:

"Auto Sweeping Motor"

I’m certain this refers to the same gear drive motors for the front and rear ADB  ‘up & down swing’ angles of the Atmos, no pics.

Edited Monday at 04:55 PM by Ronbrink

[Ronbrink]

48 minutes ago, jd1923 said:

I'm thinking the Bremen Germany SANZ DREIHA GMBH created the design and brought it to China to manufacture. Once the CCP got their patent-violating dirty mitts on it, they stole the design and manufacturing processes and are competing with the German company (under the various trade names of Gree, Tosot, Fogatti...) that brought them this technology

Or they reverse engineered!