Houghton a/c youtube re: humidity issues

[GAP]

On 12/17/2022 at 3:48 PM, Geronimo John said:

Certainly an odd design.  I know that on some A/C systems it is normal to run the fan after compressor shut down for a short time to lower the head pressure.  Sort of like an unloader in a shop air compressor.  The intent for those set-ups is to decrease the re-start torque.  But to run it continuously after compressor shut down boggles my mind as well.  

If the fan running while the compressor is off is the source of the problem, would it make sense to have chosen a smaller unit?  Would the 9.5 BTU in an Elite 2 run the compressor for longer periods, removing more moisture from the air?  I would also guess that the smaller unit running for longer would have a similar power draw to what the bigger unit would use running for a shorter time.

 

[Geronimo John]

I call your attention to the last paragraph of my late December post:

               

So it appears we all pretty much agree that the problem is humidity evaporating off the coil due to the fan running continuously.  The cause is a design change by Houghton, likely to benefit Aussie owners who have far less of a humidity issue than we do in the USA.                           

             

Since the question can not be answered by RecPro, time to bypass them and ask Houghton directly what specifically needs to be done to switch our Type 2 units to Type 1?

I'm focused on the condensate issue.   Someone want to tackle this issue directly?  

GJ

 

[SeaDawg]

I'll look forward to the answers you get.

May not be a huge deal for you, as you are in the west, but very important for many .

And, I'm sure you just want to know. 

Said the wife of another engineer.. .

[Geronimo John]

8 hours ago, GAP said:

If the fan running while the compressor is off is the source of the problem, would it make sense to have chosen a smaller unit?  Would the 9.5 BTU in an Elite 2 run the compressor for longer periods, removing more moisture from the air?  I would also guess that the smaller unit running for longer would have a similar power draw to what the bigger unit would use running for a shorter time.

This was discussed in a previous thread.  For hot summers, likely a 9.5 unit would be too small for most owners.  A perfect solution would be an 11K BTU unit, but Houghton does not have a low profile one.  But the fan would need to be cycled with the compressor regardless.  Part of that discussion included thoughts concerning insulation changes OTT made recently.  I would love to know some specific's about that topic!

As far as energy consumption, a smaller "right sized" unit running longer will provide better humidity control than a larger unit run/stop.  ESPECIALLY if it is a Set 2 Houghton unit!   And in doing so generally uses less energy.

 

[Geronimo John]

19 minutes ago, SeaDawg said:

Said the wife of another engineer.. .

LOL.  I know the feeling as the husband of a Masters level Electrical Engineer.  She is a special rare bird in our vintage.

[SeaDawg]

Too bad there is no manual j for travel trailers. 

Too many variables. 

[CRM]

8 hours ago, GAP said:

If the fan running while the compressor is off is the source of the problem, would it make sense to have chosen a smaller unit?  Would the 9.5 BTU in an Elite 2 run the compressor for longer periods, removing more moisture from the air?  I would also guess that the smaller unit running for longer would have a similar power draw to what the bigger unit would use running for a shorter time.

 

I have a Coleman 9.2k BTU in my Elite 2 and would replace with the same if/when it decides to give up on me. So far all of my camping has been in my home state of Florida and mostly during hot and humid weather conditions. Pretty much runs continuously on 90+ days, but always brings the temps and humidity down to comfortable levels within an hour or so of setup, and holds it for the duration. Uses around 10amps on AC and 16 amps on the 6k BTU heat strip.  

[bhncb]

4 hours ago, Geronimo John said:

Since the question can not be answered by RecPro, time to bypass them and ask Houghton directly what specifically needs to be done to switch our Type 2 units to Type 1?

I'm focused on the condensate issue.   Someone want to tackle this issue directly?  

You're closest. 😀

[Geronimo John]

1 hour ago, bhncb said:

You're closest. 😀

Likely for sure.  But I best not start "Another" project.

Besides I think you were the BEST and most knowledgeable person to post on this thread!  Just look at those pictures of your second spare unit!

  🙂  Gotcha!

GJ

[Geronimo John]

5 hours ago, CRM said:

Pretty much runs continuously on 90+ days,

As it was designed to do. 

However, for owners traveling to MUCH warmer states, where summers see temperatures often in the 100's and at times well over 110 degrees, a 9K BTU unit in an OE2 would not work well at all.  Hence the middle ground of 11K Btu recommendation for trailers with the upgraded? insulation package and owners that don't go out there where it is real hot.

As an owner with an "Older" 2018 that does not have the rumored  (Yet to be confirmed)  insulation upgrade, that is "out there" all the time where it gets real hot, even 11K BTU unit likely is undersized.  Hence my decision to go with the 13K BTU Houghton.    

As has been said before, each owner's relevant experience is based upon their use of their trailer.  My hope is that those looking to go with a different A/C is to take our recommendations with knowing where and what we expect to see in heat loads to the AC when making their decisions.

Thanks for your point of view. 

PS:  Sure wish I knew in detail what that rumored insulation "update" is.  It may even sway me to ponder for a second or two about a 11K BTU in 110+ areas where I have shore power that can allow me to run the unit 24/7.  But then, an hour or two to cool down then would need to be considered too.  I hope you are not now as confused as I am.  🙂

GJ  

[bhncb]

10 hours ago, Geronimo John said:

Likely for sure.  But I best not start "Another" project.

Besides I think you were the BEST and most knowledgeable person to post on this thread!  Just look at those pictures of your second spare unit!

  🙂  Gotcha!

GJ

Do we really need another fool’s errand to go along with adapting those Dometic drip pans?

Ouch! Watch for it.

[Geronimo John]

Might be worth the question.  But if it as half as complex as the drip plans have turned out to be, it's not worth the effort.  

But then it may just be swapping a wire on a relay.  

GJ

[bhncb]

2 hours ago, Geronimo John said:

Might be worth the question.  But if it as half as complex as the drip plans have turned out to be, it's not worth the effort.  

But then it may just be swapping a wire on a relay.  

GJ

OK you wore me down. Sent Houghton an email asking about the evap fan control and option for internal condensation. We'll see how responsive their are.

[bhncb]

On 1/19/2023 at 1:46 PM, bhncb said:

OK you wore me down. Sent Houghton an email asking about the evap fan control and option for internal condensation. We'll see how responsive their are.

The General Manager of Houghton responded  to my questions with the following:

Thanks for reaching out with your queries.

To answer your questions regarding the Houghton A3400 and A2801:

1 – There is no option or modification available to collect condensate and direct it to an internal drain.

2 -  There is no option for stopping the inside fan when the compressor has stopped in Cooling mode. We do this very deliberately to maintain air flow over the return air temperature sensor. This ensures that the unit will respond appropriately to the cabin temperature. If the fan is stopped then the unit is no longer sensing the true air temperature of the living space and may not turn on again until the space is unacceptably hot. We have used this arrangement in the Australian climate for many years. Our northern states are hot and tropical, similar to Florida, and our units have excellent performance in these conditions.

However, we are aware that this arrangement is not typically what you encounter in the USA market.

I am very interested in better understanding your concerns about the inside fan remaining on once the compressor has stopped.

Can you help me to understand the source of your discomfort?

 

[Geronimo John]

I

On 1/23/2023 at 7:32 AM, bhncb said:

The General Manager of Houghton responded  to my questions with the following:

He honestly does not know?  I'll PM you some thoughts later this weekend.

GJ

[Tummy]

First time poster here.  I've been following these Houghton threads on this forum for quite a while since we installed a Houghton 3400 in our class-b last summer.

Last week I installed a relay to fix the humidity problem by allowing the low speed fan to get power only when the compressor is on. Auto mode works a lot better now in testing.

This is the relay I used but any relay with a 120v AC coil should work.  https://www.amazon.com/dp/B087G6D24G Two pack because I like to have spares.

There are multiple ways and connectors you can use to do it, but I used Wago three wire connector to connect the wire marked COMP to one side of the coil.  Then another connector to add the N1 wire to the other coil terminal.  Then connected the Fan low wire on the normally open terminal.

I still have a problem where the thermostat is not at all accurate, but I'm trying something this weekend to try and improve that.

[GSMBear]

On 4/6/2023 at 9:07 AM, Tummy said:

Last week I installed a relay to fix the humidity problem by allowing the low speed fan to get power only when the compressor is on. Auto mode works a lot better now in testing.

Tummy -- are you also known as FloridaAmbient on YouTube?  🤔
If so, I appreciate the video you made about this solution.  And if not, I still appreciate hearing from someone else that an additional relay to cycle the interior fan on/off with the compressor is doable.  Have you seen improvements with interior humidity?

I'd love to move the temperature sensor to an external location to see if that improves cycling and temperature matching between the set point and actual temperature.  Once my AC runs for 90 minutes or so, then the temperatures seem to match fairly closely.  Until then, it shuts off 2 or 3 degrees above the set temperature.  My RV is an Airstream so I do have some space between the inner and outer aluminum skins.  But there are lots of obstacles along the way even with one of those wire fishing thingies.

Here is the video:

 

[Geronimo John]

On 12/16/2022 at 4:01 PM, Geronimo John said:

If multi speed, say three speed (Hi, Medium, Low) then why not add a fan speed selector switch with the same number of speeds.  Then power the fan speed selector switch input from the compressor power feed.  Circulation fan would run only when t-stat is calling and the compressor relay is energized.  Fan would run at the speed that was set on the selector switch.  When the t-stat reaches it's set temperature, the unit control board will shut down both the compressor and fan.  Humidity problem greatly reduced.  Seems to me that this could be a simple mod.

Tummy:  That's the same conclusion I came to in December.  Thanks for posting your results.  I have the relay in hand and would sure love to see a detail installation diagram for connection.  I can figure it out, but seeing it would save all of us a lot of time and worry.  Thanks again!

Geronimo John

[GSMBear]

RecPro Houghton Interior Fan Mod.pdf

(Disclaimer -- I'm an owner of an Airstream rather than an Oliver.  My Airstream came equipped with a 13.5K Dometic AC with heat pump.)

I finally had a chance to document the steps for modifying the factory wiring for the Houghton/RecPro A3400 air conditioner to prevent the interior fan from running continuously.

Houghton's intent for running the fan continuously is to keep interior air running across the thermistor sensor located in the return air duct for more accurate cycling of the compressor and therefore a more accurate overall interior temperature.

The problem, for me, anyway, with this design is that the air being circulated is blowing across the wet cooling fins and that moisture is quickly reabsorbed into the air and returned as humidity into the living space making it uncomfortable.  I'm not sure why this isn't a problem in the more hot/humid areas of Australia where the unit is manufactured.  The General Manager who responded and is quoted upstream didn't seem to understand the humidity issue that I and others have experienced.

This wiring modification solves the humidity problem nicely but, since interior air is not blowing across the thermistor temperature sensor continuously, there is a greater swing with interior temperatures before the compressor cycles on to cool again.

Overall, I'm pleased with the change. The humidity issue was a real problem for me and I'll learn to adjust to the wider temperature swings (about 4 degrees F) with the compressor cycling.

When time (and courage) permits, I might try snipping the wires of the thermistor sensor and adding an extension so that I can relocate the thermistor in an external location away from the interior of the AC unit. I still have the RJ45 "phone" cable leading from the 14" AC roof cutout area to the original location of the Dometic CCC2 thermostat that is no longer in the equation. Maybe that wire will be used to extend the tip of the thermistor to a new location.

The instructions are in the attached PDF document for anyone interested.

[Geronimo John]

On 10/6/2022 at 1:18 PM, CRM said:

Their humidity problem is undoubtedly being caused by either the unit being oversized (my guess) or they aren't running it in dehumidifying mode or low speed fan setting (if that unit has such features) while operating in humid conditions.  

EDITS IN GREEN:  

Ok, now that I have my Houghton 3400 heat pump installed and have run it in 106 degrees full sun on our OE2, I can respond with a professional M.E. opinion:  The 13.5 KBTU Houghton 3400 is NOT oversized for hot running conditions.  I would not recommend a 11,000 BTU unit for an OE2 if you go to hot places,   

Secondly, again in my opinion the humidity problem is certainly caused by re-evaporation of humidity on the coils after the compressor is shut down.  Frankly IMHO, this is a bad design element of Houghton units for USA use where humidity issurs are common.  But for the dry Aussie Land it makes sense. 

As such, I am doubling down on my long-ago suggestion of adding a relay tied to the fan low speed and compressor as a trigger (Mounted in the upper unit) to shut off the fan when it auto cycles to low speed while on auto.  This suggestion is exactly what another AS owner (GSMBear) posted last month on their web site and one of our owners posted on ours.  

I took a deep dive into that video and the relay part is relatively easy.  But one also has to know how to relocate the room air sensor from the supply air duct to the ambient area.  Detailed info on this must be known before just adding the relay.

GJ

[CRM]

11 hours ago, Geronimo John said:

Ok, now that I have my Houghton 3400 heat pump installed and have run it in 106 degrees full sun on our OE2, I can respond with a professional M.E. opinion:  The 13.5 KBTU Houghton 3400 is NOT oversized for hot running conditions.  I would not recommend a 11,000 BTU unit for an OE2 if you go to hot places,   

Secondly, again in my opinion the humidity problem is certainly caused by re-evaporation of humidity on the coils after the compressor is shut down.  Frankly this is a bad design element of Houghton units for USA use where humidity issurs are common.  But for the dry Aussie Land it makes sense. 

As such, I am doubling down on my long-ago suggestion of adding a relay tied to the fan low speed and compressor as a trigger to shut off the fan when it auto cycles to low speed while on auto.  This suggestion is exactly what another AS owner posted last month on their web site and one of our owners posted on ours.  

I took a deep dive into that video and the relay part is relatively easy.  But one also has to know how to relocate the room air relay from the supply air duct to the ambient area.  Detailed info on this must be known before just adding the relay.

GJ

 I was specifically talking about the original video in this thread where the unit was installed in an pickup bed camper. The Houghton is grossly oversized for their application.

Edit: Also, testing at lower temps with high humidity will be a truer test to see if the unit is oversized or not. I'd really like to know how this Houghton performs (post fan mod) in an E2 under these conditions as I'd like to upgrade to a heat pump myself if and when my Coleman finally gives up. 

[GSMBear]

On 8/2/2023 at 8:25 PM, Geronimo John said:

This suggestion is exactly what another AS owner posted last month on their web site and one of our owners posted on ours.  

I took a deep dive into that video and the relay part is relatively easy.  But one also has to know how to relocate the room air relay from the supply air duct to the ambient area.  Detailed info on this must be known before just adding the relay.

I am the Airstream owner you might be referring to.  I'm Ho'onanea on the Airstream forum and I'm GSMBear on this forum.  I've been all over the place looking for whatever information I can find on the Houghton A3400.

I'm not sure I understand your reference to "relocate the room air relay from the supply air duct to the ambient area."  I'm not an engineer.  From what I have seen looking up into the return air duct, there is an inexpensive sensor that I believe is called a thermistor.  I'm not aware of a relay being involved.  Am I missing something?

I would like to experiment with relocating the thermistor to an ambient area that is not in the direct flow of air coming out of the plenum.  I have a perfect place for it and I even have some wire that runs from the 14" roof cutout through the aluminum ribs (think "trusses") of the roof and down the wall to a location where the original Dometic CCC2 thermostat was located.  (Keep in mind, this is an Airstream rather than an Oliver.)

I bought a thermistor with a longer wire that I think is the same kind that Houghton uses.  I had planned to plug it into the circuit board and route it into the return air duct and test it in an ambient area.  Unfortunately, it's a little misleading about how to get wires from the exposed portion of the rooftop unit into the sealed portion that can be seen by looking up from the inside when the plenum is removed.  Could not find an easy way to do it and I did not want to remove the factory seal of the Styrofoam enclosed area.  So I abandoned the experiment.

My brother is the electrical engineer.  He's not shy about using a soldering iron above his head in tight quarters.  So the plan when he visits next is to snip the wire of the factory thermistor (yikes!) and he will solder a new length of wire to each snipped end allowing the factory tip of thermistor -- where the actual sensor is -- to be relocated.

He says soldering the wires is important because a thermistor measures resistance and soldering the wires is the best way to minimize the addition of resistance.

[GSMBear]

On 8/2/2023 at 9:00 PM, CRM said:

I was specifically talking about the original video in this thread where the unit was installed in an pickup bed camper. The Houghton is grossly oversized for their application.

As an owner of the Houghton A3400, I'm not in agreement that the unit is grossly oversized for the pickup bed camper in the Joslyn Journey's video.  That's a fairly large pickup camper and it has two slide outs.  Their initial video is about the humidity problem and my experience shows this is solved by cycling the fan with the compressor.  Shorter cycles can occur from oversized units reducing the amount of time for humidity to be removed from the air.  But again, my experience shows the lion's share of the humidity problem is from the factory design of continuous cabin air flow over the wet fins allowing humidity to be reabsorbed and cycled back into the cabin.  With the wiring/relay modification that I have done, I now have cabin humidity readings comparable to the interior of my home on the same property.

[CRM]

3 hours ago, GSMBear said:

As an owner of the Houghton A3400, I'm not in agreement that the unit is grossly oversized for the pickup bed camper in the Joslyn Journey's video.  That's a fairly large pickup camper and it has two slide outs.  Their initial video is about the humidity problem and my experience shows this is solved by cycling the fan with the compressor.  Shorter cycles can occur from oversized units reducing the amount of time for humidity to be removed from the air.  But again, my experience shows the lion's share of the humidity problem is from the factory design of continuous cabin air flow over the wet fins allowing humidity to be reabsorbed and cycled back into the cabin.  With the wiring/relay modification that I have done, I now have cabin humidity readings comparable to the interior of my home on the same property.

It's been a while, so I don't remember the actual numbers, but I do remember that the cubic feet of space in their camper was much less than an LE2 and that is was also a fully foam insulated 4 season camper. The big giveaway that their issue (IMHO) is caused by an oversized unit was that it always short cycled at night, even on low fan. Shutting the fan down in between cycles would more than likely help some, but if they're short cycling and never getting the humidity down to begin with I don't see how it could ever solve the problem in their truck camper.

I'm far more interested in learning how this Houghton performs in a low temp / high humidity environment in an LE2 for use as a possible replacement of our Coleman 9.2k unit down the road. Our Coleman, which for now works perfectly, is pushing 15 years old and I really like the idea of switching to a heatpump to eliminate the use of the the propane heater when power is available. 

[Geronimo John]

On 8/6/2023 at 11:51 AM, GSMBear said:

I'm not sure I understand your reference to "relocate the room air relay from the supply air duct to the ambient area.

GSM:  I edited my post above for clalrity.  You were correct as I used the wrong word.

Cutting and splicing Thermister Wires:  It has been a really long time since I was playing with thermisters, so my foggy memory may need your update.  

My recollection is that the thermister changes resistance based upon temperature.  The mother board of the unit is set up to interpert resistance and map it to a temperature setting and unit response.  If we cut the wires to the thermister and extend them, that would change the overall resistance of the thermister and original wire resistance as seen by the mother board.  Would that cause other issues?

GJ