Upgrade thermostat

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Kheren

Kheren

Well-known member
Joined
Jun 19, 2017
Posts
135
Location
Pinetop, Az.
Hi all, it?s been awhile since I?ve been on. I want to upgrade my old analog dometic duo therm to a digital. I?ve read hundreds of suggestions so far, I think the Honeywell may work? Not sure of the pros and cons of being programmable or not. Also, I see to add a toggle switch to be able to use fan speeds. What if I just keep it on low fan? What do you do with the wires if they do not go on a toggle, like to bypass that option? Any suggestions? Please write like you?re talking to a child as my electrical knowledge is zero, ha! Thank you!
 
You do not need to add the switch.  But you need to use high speed fan and not low speed.  Low speed at times will not move enough air across the AC coils which could cause them to ice up.  This has happened at times on our bedroom AC.  Not fun.
Adding a micro toggle switch is no big deal.  I installed the Hunter Douglas for about 25 dollars several years ago and it works great.
 
Oh ok, I keep it low now too, should I not? I figured it saved on electricity. Did you drill hole for toggle into the wall below or in the frame to the new thermostat? Thanks!
 
Here is a photo of the Honeywell thermostat I used to replace my Dometic Duo-Therm analog thermostat, I added a small toggle switch to the side of the thermostat body where there was a mostly blank space inside the thermostat housing (I did have to remove a couple of plastic ribs to get it to fit though (I simply twisted them out with a small pair of needle nose pliers).

Ike

p.s. note the Honeywell thermostats like mine have a safety feature built in so they will not start heat if the temperature is below freezing, this is so that if there is a power outage in an unattended house that the heat will not turn on and thaw out burst frozen pipes.  This is not a big deal for me, I just carry a hair dryer to warm the thermostat if needed.

p.p.s. here is a link to the type of switch I used https://www.ebay.com/itm/The-Install-Bay-by-Metra-IBMTS-20-Leads-On-Off-Mini-Toggle-Switch-5-pack/181449646400 note it only needs to be a SPST switch as both the lo and hi wires can be connected at the same time for high fan speed, no need to open the low fan connection when you connect for hi
 

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Oh I like that, the toggle on the side is much nicer! I assume all wiring tutorials I find online will be easy to do, I hope. Thanks so much for the photo!
 
Here is a write up that seems to include all the information you need in one place if you are half way handy with doing wiring and electronics


http://www.modmyrv.com/2012/01/03/mod-100-honeywell-digital-thermostat
 
Kheren said:
Oh that link looks way different than the other switches I?ve seen used?
Click to expand...

I opted for ones like those as they had pre-installed leads, I can solder, but why go to the the trouble of pulling out the soldering iron if you can get switches with pre-wired pigtails for $1 more.
 
Here are some a little bit cheaper:

https://www.ebay.com/p/5pcs-Security-Alarm-Pre-wired-On-off-Mini-Toggle-Switch-Fast-USA/22025009115?iid=254130839550

AND:

https://www.amazon.com/HonsCreat-Pre-wired-Industrial-Equipment-Emergency/dp/B07JP4GFJ8/ref=sr_1_37?keywords=mini+toggle+switches+with+wires&qid=1552593510&s=gateway&sr=8-37
 
I?m looking at this one? Any advice, pros, cons?
Honeywell TH5110D1006 Honeywell Non-Programmable Thermostat, Up To 1 Heat/1 Cool https://www.amazon.com/dp/B000GGPMO2/ref=cm_sw_r_cp_tai_GdRICbRD0QPYT
 
That looks like the little brother of the one I used, (I have a heatpump so needed a thermostat that would support at least 2 heat sources), overall it works well, I installed mine a bit over 2 years ago, my only complaint is it goes through batteries fairly fast, I think it uses a pair of AA's which I have to replace about every 8-9 months, compared to the Hunter brand thermostat with smaller non-backlit display that I have in my sticks and bricks house (installed about 12-15 years ago), which only needs new batteries every couple of years.
 
I have done this upgrade.  Have the model/serial number for the T-stat and AC and call Dometic. They will tell you what you need to do to change the T-stat to digital.  Dometic uses 7.5v dc for power and the control box in the ceiling should be changed also. 

I like this mod because it starts the fan first for 5-10 secs then starts the compressor and reverses the process on shut down.  This is easier on the start up amps. The analog starts both full bore and shuts them down them down the same. 

Doing this mod this way will cost more then rigging it with a big box store T-stat but will be easier on the equipment. Hopefully saving you money in the long run.
 

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Going with the Dometic digital thermostat conversion will also cost MUCH more than converting to a Honeywell or Hunter residential style thermostat as it also requires replacing the control board mounted in the ceiling, as well as probably running new wires for the modular jack on the back of the Dometic digital thermostat .

Bobtop46, in what possible way would it be easier on the equipment?
 
Well I?ve seen MANY rv goers do this will no negative results that I?m aware of so I don?t consider it ?rigging.? I will keep the original in case anything goes wrong. I see no reason to pay that much more when a residential one will suffice. Fingers crossed.
 
Isaac-1 said:
Going with the Dometic digital thermostat conversion will also cost MUCH more than converting to a Honeywell or Hunter residential style thermostat as it also requires replacing the control board mounted in the ceiling, as well as probably running new wires for the modular jack on the back of the Dometic digital thermostat .

Bobtop46, in what possible way would it be easier on the equipment?
Click to expand...

Mostly from starting both the fan and compressor at the same time.  Seems more graceful one at a time.  I didn't have to run any new wires the T-stat didn't have a modular jack.

I could be wrong, I've been wrong before and will be wrong again. 
 
Anyone have tips on stabilizing the toggle switch? Parts aren?t here yet, so maybe it?s as easy a a screw? Hoping to put it inside the mounting like said above. 
 
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