Houghton a/c youtube re: humidity issues

[mtt]

hobojoe sent me a message asking for more details about my design and I am happy to share it.  First, I need to mention that working with high voltage can be very dangerous and has the potential to cause serious injuries including death.  I recommend hiring someone with the correct skills if you do not have them. I am a fourth-generation engineer in the electrical,  electronic,  radio communication, and computer fields and I am a senior member of the IEEE so I feel qualified to make these changes. Always ensure your RV is disconnected from AC power and that any inverter that might be powering your air conditioner is turned off before working on your air conditioner.  I am not responsible for any damage you might do to your RV, air conditioner, or yourself.  Making these changes will most likely void your warranty. 

Links for the wiring diagram and parts are below. I used the P1-5 program of the timer and set T1 to 45 seconds and T2 to 360 seconds, There has been some discussion about not wanting to purge the remaining cold air.  If you want to avoid the purge you could use the P1-4 program and set T1 to 360 seconds and T2 to 45 seconds. The program on the timer can only be set while it is powered with AC.  After it is set up it will remember the settings when it is powered off.  If someone wants to try both of these settings in a very humid environment I would be interested in the results.

Please reach out through the discussion thread if you have any other questions.

wiring: https://trontamer.com/dl/wiring.png 
timer: https://amzn.to/3XGyA6O
relay: https://amzn.to/3W2nacw
cable: https://amzn.to/45GcxPy

[GSMBear]

4 hours ago, hobojoe said:

Have a question concerning low speed fan wire in the above diagram going to NO of the relay and a new wire from COM to where wire was removed on circuit board. An earlier post with attachment v2 shows thin white wire removed and attached to COM port, then new wire from NO to where wire was removed from circuit board. Am curious which is correct or will either one work?

I apologize for unintentionally creating confusion.  The schematic diagram posted above was meant to illustrate the ports for the coil sensors. It also has the conceptualized wiring plan for the new relay.  The conceptualized plan was drawn prior to knowing what my wire color choices were going to be limited to based on my wire supply.  Please ignore the wire color labels in that diagram.

To be more precise about your question though. . . 

When you open the cover to this control box, you will see the thin white wire from the factory connected to the low fan speed blade.  You want to remove it from that blade and reattach it to the COM blade on the new relay.

Then, take a section of your own wire that you'll need to supply (about 10") and connect one end to the low fan speed blade and the other end to the Normally Open (NO) blade of the new relay.  In the pictures from the v2 PDF document, both of these wires are white with the new wire that I had to supply being the thicker wire.

Hope this helps and I apologize for creating the confusion.

[Nan]

Hope someone can answer this: Installed the Houghton, but want to be able to use the factory heater so I bought a Honeywell thermostat Pro 1000 that says "Heat only"..does anyone know how to wire this thermostat for the old heater use?  If I interrupted this tread, I am sorry.  Thanks.
 

[hobojoe]

Thanks to all-much appreciated. Am waiting for Amazon deliveries to start this project but once completed will report back results of installation.

[mtt]

53 minutes ago, Nan said:

Hope someone can answer this: Installed the Houghton, but want to be able to use the factory heater so I bought a Honeywell thermostat Pro 1000 that says "Heat only"..does anyone know how to wire this thermostat for the old heater use?  If I interrupted this tread, I am sorry.  Thanks.

I took a quick look at the datasheet for the Honeywell thermostat Pro 1000.  It is a home 24-volt AC thermostat.  This type of thermostat is not designed for RV use and they are very hard to adapt for RV 12-volt DC use.  The good news is that most RV heaters use a simple two-wire control system.  The link below is for a simple RV thermostat that would be very easy to set up. The second link is for a digital thermostat that looks like it is designed for a two-wire heater control.  I am going to order the digital thermostat to test it with my two-wire heater and I will report back.

https://amzn.to/3VFdmna

https://amzn.to/4cGNyhv

 

Edited June 26 by mtt

[hobojoe]

Question for MTT, wiring diagram, low speed fan wire: Should I piggyback wire from low speed spade on circuit board to COM of relay? No need to relocate factory wire ?

S2: Wire from S2 goes to NO of relay and branches to "IF". Could you give a little more detail as to what "IF" is and how connection is made.

Thanks much

Edited June 26 by hobojoe

[mtt]

1 hour ago, hobojoe said:

Question for MTT, wiring diagram, low speed fan wire: Should I piggyback wire from low speed spade on circuit board to COM of relay? No need to relocate factory wire ?

S2: Wire from S2 goes to NO of relay and branches to "IF". Could you give a little more detail as to what "IF" is and how connection is made.

Good questions.  Let's start with the second question. IF  stands for the internal fan. This is the one that runs inside the RV.

The wire that currently comes from the internal fan that is connected to the LOW terminal is disconnected and it is rerouted to S2 of the timer and NO of the relay.  A new wire is connected from the LOW terminal to COM of the relay.

[hobojoe]

All power disconnected from RV

Removed the cover from the 2801 AC, located the metal electrical box and removed cover. I was able to locate terminals for Low fan, compressor, and looking for possible location for new timer/relay box. 

Thanks again for your quick response to my questions. When it comes to electrical the only dumb question (for me) is the one I don't ask. In this case I would have done some real damage "assuming" I understood how to proceed.

 

[hobojoe]

Curious if the "box" used to mount your timer and relay is the same plastic device that has to be removed to get into electrical box? Just have to cut out the plastic dividers to allow room to install devices? 

The 18/4 in the parts list can be used to make connections from circuit board to devices?

Edited June 27 by hobojoe

[mtt]

On 6/27/2024 at 6:34 AM, hobojoe said:

Curious if the "box" used to mount your timer and relay is the same plastic device that has to be removed to get into electrical box?

Yes, that is the same plastic box and I did remove about 2/3 of one of the dividers to mount the timer.  I also cut two small slots on each side to catch the mounting clips of the timer.  

For your information, I have seen at least one YouTube video where someone removed and discarded the plastic box to mount something else in its place.  This is a bad idea as the plastic box/spacer has a purpose.  It is there to ensure that the air flows correctly over the coils.

[hobojoe]

Amazon delivered all the parts yesterday and this morning was able to complete install of timer and relay. Data will be from a Houghton 9.5 BTU, model 2801AC, mounted on a 2018 Casita Spirit Deluxe. Camper always parked under large carport where we formerly had our 5th wheel. Outside temps today were in the mid 80s and humidity was around 52%. Inside temp of Casita was 83 degrees.

First test was to run unit on high fan, set to 68 degrees. After about 30 minutes inside temps didn't go any lower than 73 degrees. The unit would cycle compressor off for 3 minutes-consistently-  then cycle compressor on. On times of compressor would vary from as high as 3:15 seconds to low as 2:57 seconds. This is so annoying! We were never going to get to set temperature with compressor off half the time!

Lowered temperature on unit as low as it would go, 60 degrees. Compressor off time didn't change, consistently off for 3 minutes. Compressor on times were as high as 3:36 seconds and low as 2:52 seconds. Inside temp got down to 72 degrees. At end of compressor on time supply air was always around 54 degrees with humidity around 44%. At end of compressor off time of 3 minutes supply air had risen to about 62 degrees, humidity risen to 48%. 

Second test was to try new relay and timer. Set unit to low fan (Not Auto) and changed set temperature to 72. Relay and timer working good. Ran this way for one cycle and shutdown power to adjust T2 time from 360 to 180. Long off time of compressor allowing too much temperature rise. By this time temp inside Casita has risen to 79 degrees, humidity at 51%.

Third test with T2 set to 180: Compressor came on and stayed on for 4 minutes, supply temp 40 degrees at end of cycle, humidity 44%, Casita at 77 degrees. Fan on 45/off 3 minutes/ fan on 45/compressor starts. cycles on for 2:59 seconds, humidity at 45%, temp at 77. Fan on 45/off 3 minutes/fan on 45/.About 5 seconds into off time compressor comes on for 3 minutes, humidity 44%, temp at 77. Fan on 45/off 3 minutes/fan on 45/off for about 27 seconds then compressor came on. On for 2:50 seconds, humidity 45%, temp 77. End of test. Will do more tomorrow.

I don't understand the 3 minute compressor off time when unit operating on high fan-to me this makes no sense and will never get to set temp. Just when the air is feeling really good the compressor shuts off. Challenge: solve the 3 minute compressor off time!

Timer/ relay on low fan: This has promise, I ran out of time but tomorrow I will be playing with T1 and T2. The air was not as humid inside camper. Again any thoughts, ideas, suggestions would be appreciated. This unit is MUCH quieter and worth fighting for. 

 

 

[hobojoe]

For those of you that have this unit, does it operate same as mine ? As described in the first test?

[GSMBear]

8 hours ago, hobojoe said:

For those of you that have this unit, does it operate same as mine ? As described in the first test?

It's been a year since mine was out-of-the-box new and installed but it does sound familiar to the time when I did not have the compressor fan relay mod and relocated indoor temperature sensor in the equation.

I just used mine this weekend (it's in an Airstream, not an Oliver) parked in full sun and low 90s for the highs.  When set to auto, my fan will come on high for a short while and then taper down to low as it gets cooler inside.  During the hot part of the day, it would run on low for quite a while (an hour?) which was fine with me.  It's very quiet and it kept the inside temperature at a comfortable 74 degrees which was the set point.  At night, I like it cooler.  I would set it to 70 degrees and it would maintain that.  On cycles during the night were frequent and short.  I don't know what the interior humidity was because I've stopped measuring it as that problem seems to be solved.

My application is different from yours, though.  I do not have the timer mod installed in mine but I do have the fan relay mod.  Moving the indoor temperature sensor was a pretty easy task with my RV but might be significantly more difficult in the Olivers and Casitas.

[hobojoe]

Started AC on high fan, set to 60 around 6:45 this morning, temperatures 79 and humidity 76%. Unit ran beautifully, compressor on for 12:30 with supply temps close to 40 degrees, humidity dropped to 49% at end of cycle. Changed set temp to 73, adjusted fan to low, cycled off. Also T2 was changed to 120 prior to start this morning.

On low fan unit went through 10 cycles or almost 30 minutes until compressor came on, and then it only stayed on 1:34. During off time humidity had risen from 49 to 64%. Let unit cycle on low fan and the temperature maintained but humidity remained in the low to mid 60s.

For our climate here where the humidity can be a problem, if the compressor is not on, the problem with humidity will remain or made worse by inducing moist air when compressor off and fan running.

For my next test will setup unit to operate with relay only. 

Correction: Since I posted about an hour ago outside temperatures have risen to 89 degrees. Before making additional changes to Timer/relay decided to check how things were performing in camper. I had left unit on and I was pleasantly surprised to find set temperature (73) was good, humidity down to 52%, and unit was cycling through low fan setting. Will continue to monitor unit performance at current settings and report back.

What Changed: If you look at outside temps of initial test this morning they were 10 degrees cooler at 79 degrees. Unit met set temp, cycled off, and took almost 30 minutes to cycle back on. During this off time fan was blowing moist air into cabin. 

Does this make sense?  

 

Edited July 1 by hobojoe

[CRM]

26 minutes ago, hobojoe said:

Started AC on high fan, set to 60 around 6:45 this morning, temperatures 79 and humidity 76%. Unit ran beautifully, compressor on for 12:30 with supply temps close to 40 degrees, humidity dropped to 49% at end of cycle.

 

If I'm following correctly, the compressor would only run for 3 min at a time yesterday but ran for 12:30 straight today? I wonder why? Also, may be perfectly normal for this unit, but a temperature differential between cabin temp and supply air over over 30 degrees seems too high to me. If the supply air is at 40 degrees the actual evaporator temp is most likely very close to freezing the condensate on the fins.

[hobojoe]

I wondered same thing, compressor stayed on until set temperature was met. On the 3rd test yesterday, for one cycle after changing T2 to 180, supply temp got down to 40 and compressor ran for 4 minutes. In a hurry to capture data between cycles I thought perhaps I had read temperature of supply air wrong. The only difference I can think of from yesterday and today is today I started the unit with set temp at 60 and high fan. Yesterday unit had ran for awhile, and not getting down to set temp, I then lowered set temp as low as it would go-but the compressor cycled anyways. Will try to simulate longer compressor on time to see if it will repeat.

[Johnny5NoDisassemble]

On 6/30/2024 at 8:31 PM, hobojoe said:

For those of you that have this unit, does it operate same as mine ? As described in the first test?

I installed a Houghton 2801 AC on my Parkliner trailer. The compressor also cycles on/off about every 4 minutes. I don't understand why.  I'm wondering if one of the temperature sensors isn't calibrated or working properly and the AC thinks the indoor temp has been reached or coil temp is too low.

I modified my AC to install a relay on the low speed fan to try and reduce the humidity, but with the short cycling it's not making much difference.

[CRM]

2 minutes ago, Johnny5NoDisassemble said:

I installed a Houghton 2801 AC on my Parkliner trailer. The compressor also cycles on/off about every 4 minutes. I don't understand why.  I'm wondering if one of the temperature sensors isn't calibrated or working properly and the AC thinks the indoor temp has been reached or coil temp is too low.

I modified my AC to install a relay on the low speed fan to try and reduce the humidity, but with the short cycling it's not making much difference.

What Houghton really should be doing is working on a new control board for these units. One with Dip switches to be able to select whether the fan runs or not with the compressor and the ability to use a standard wall mount thermostat. One for compressor run time would be a bonus, though that problem might solve itself with a standard thermostat.

 

[hobojoe]

I settled on the timer/relay setup with details provided by member MTT for the 2801 9.5 BTU installed on our 2018 Casita. After several tests settled on the following P1-5 timer settings: T1-45, T2-120. Times are in seconds. We are leaving for a 10 day trip to Minnesota later this month so will have actual performance to report back how unit performed on the road, different climates. 

Also tried changing thermistor location with details provided by GSM. With new thermistor from Amazon the installation was very simple on the 9.5, was able to follow same path as factory thermistor to route wire from control box to inside. With timer removed, tested operation with relay and new thermistor relocated to cabin at different locations, I found for my situation the timer provided better temperature consistency. 

With  timer/relay setup installed I would start unit and adjust set temperature to 60, run on high fan until set temperature met, then with remote change set temperature to desired level and  low fan. From there unit performed good, cycled off/on, humidity low, and temps were good. Am going to stay with this setup until we complete out of town trip. If time allows I would like to play with T1 setting of 45 seconds, perhaps increase to 60 seconds.

 

[Johnny5NoDisassemble]

On 7/5/2024 at 9:52 AM, hobojoe said:

After several tests settled on the following P1-5 timer settings: T1-45, T2-120. Times are in seconds.

 

So after the compressor turns off the fan runs an additional 45 seconds, then turns off for 2 minutes, and the fan turns back on for 45 seconds & cycles like that until the compressor comes back on?

How often does the compressor cycle back on? 

[hobojoe]

Correct. 

Compressor cycle depends on outside temperatures, as temps rise compressor cycles on more frequently. We have been in a heat wave here, in the 90s most days, these settings have worked good for now. We will be on a 10 day trip soon and the real world test will be if wife is happy lol.

At end of compressor run cycle the supply air is at 40 degrees so I decided to adjust T1 up to 60 seconds to clear more of this cold air from unit and into cabin. This new setting doesn't seem to be causing humidity issues but it seems to help compressor cycle on more as outside temperatures rise and more consistent temps inside camper.

[hobojoe]

The Recpro 9.5 kept us cool while on trip to Minnesota. It was 92 degrees first day there then cooled off nicely. On the days we had to run A/C the Recpro is quieter than the Coleman Mach 8 it replaced so that is a plus. The cycling on/off as described in previous post didn't seem to bother us and we definitely slept better at night due to lower noise levels.

However: (1) if the unit could be controlled by a wall thermostat that would be the way to go. (2)The unit is not as loud as the unit it replaced but the days and nights we didn't have to run the A/C was much more pleasant. That is to say in a Casita which is only 17' long, with the unit mounted on roof over the bed, when it is off your glad it is off. (3) Having low speed fan cycle on/off is definitely the way to go. The compressor on times when set to low fan really depends on outside temperatures, the hotter it gets the more the compressor cycles on. (3) We always started unit on high and set temp to 60 to get camper cooled then switched to low fan setting and adjusted temperature to desired level.

 

[jd1923]

1 hour ago, hobojoe said:

We always started unit on high and set temp to 60 to get camper cooled then switched to low fan setting and adjusted temperature to desired level.

Is this required? Should not be so in a well engineered A/C. When set temp is several degrees lower than actual temp, the A/C should be full on, no compressor cycling. 

[hobojoe]

Well unfortunately that is what happens, compressor will start to cycle before reaching set temperature so to keep compressor on and humidity low we set temp to 60 until reaching about 72 degrees in camper.