Digital thermostat

[WanderBred]

Honeywell TH1100DV1000/U Pro 1000 Vertical Non-Programmable Thermostat https://a.co/d/0ULqGXV
Well this one work for turning on and off my furnace only?
And thanks.

 

[Centex]

Not sure about the Honeywell, but FYI this less expensive Lux Pro PSD010B definitely works for furnace-only control as a replacement for the 2-wire Dometic furnace-only thermostat (proven in my 2021 5.0 with no factory AC, also installed by several other members here)

Tip - as seen in the attached, both of my thermostat wires are blue; not sure if it makes any difference but tape/mark the one going to Lux terminal W1 before you pull it from the original thermostat to keep 'em straight just in case

https://www.amazon.com/dp/B002SR9PH...trial&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw&th=1

 

[WanderBred]

Thanks

 

[JohnK-ESC]

Not sure about the Honeywell, but FYI this less expensive Lux Pro PSD010B definitely works for furnace-only control as a replacement for the 2-wire Dometic furnace-only thermostat (proven in my 2021 5.0 with no factory AC, also installed by several other members here)

Tip - as seen in the attached, both of my thermostat wires are blue; not sure if it makes any difference but tape/mark the one going to Lux terminal W1 before you pull it from the original thermostat to keep 'em straight just in case

https://www.amazon.com/dp/B002SR9PH...trial&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw&th=1

This information might be the breakthrough I am looking for to connect a heat only thermostat to the furnace as part of a transition from the Dometic rooftop aircdonditioner to a Houghton.

So if I am reading the wiring diagram correctly, the +12v blue wire from the on/off switch at the furnace should be connected to the +12v terminal at the digital thermostat, and the -12v wire at the furnace sail switch should be connected to the W terminal at the digital thermostat.

Alan, am I understanding this wiring correctly?

John

 

[SRS]

Honeywell TH1100DV1000/U Pro 1000 Vertical Non-Programmable Thermostat https://a.co/d/0ULqGXV
Well this one work for turning on and off my furnace only?
And thanks.

My Trailer doesn't have AC and this Honeywell thermostat is the one I installed in my trailer. works great, you just need to remember to change the batteries once a year.

 

[WanderBred]

Thanks

 

[Centex]

This information might be the breakthrough I am looking for to connect a heat only thermostat to the furnace as part of a transition from the Dometic rooftop aircdonditioner to a Houghton.

So if I am reading the wiring diagram correctly, the +12v blue wire from the on/off switch at the furnace should be connected to the +12v terminal at the digital thermostat, and the -12v wire at the furnace sail switch should be connected to the W terminal at the digital thermostat.

Alan, am I understanding this wiring correctly?

John

John, attached above are the wiring diagrams for my situation (with the indicated furnace model number and no factory AC). I'm not expert in this arena and don't want to guess about yours that came with factory AC.

Good Luck!

 

[Ron in BC]

Tip - as seen in the attached, both of my thermostat wires are blue; not sure if it makes any difference but tape/mark the one going to Lux terminal W1 before you pull it from the original thermostat to keep 'em straight just in case

I've never worried about polarity when hooking up this type of thermostat.

Such an improvement over the factory original.

Ron

 

[GinoandLinda]

One of the few things that made us go "huh?" when we saw the 50's vintage thermostat our new Escape in '22. Even our 2015 Rpod came with a nice, modern Dometic digital thermostat. Escape could do better by putting a digital unit in.

 

[Ron in BC]

I'm not sure "huh" was the term that I used.

I had one in my Scamp that I used for awhile always wondering if I was going to snap off the little lever. Not to mention noting that the temperature reading was pretty approximate.

The digital is so nice by comparison and you don't even have to look at it to adjust it up or down a few degrees. Just count the beeps.

Ron

 

[JohnK-ESC]

John, attached above are the wiring diagrams for my situation (with the indicated furnace model number and no factory AC). I'm not expert in this arena and don't want to guess about yours that came with factory AC.

Good Luck!

Yes Alan I realize my situation is different than yours so an abundance of caution is in order on my part when looking at your wiring diagram. Thanks for the reminder.

After posting earlier on this thread I noticed from photos of the original factory supplied Digital thermostat that the yellow wire, usually associated with cooling was connected to the ground terminal of the factory supplied Honeywell thermostat and the black wire, usually -12V or common was connected to the R10 terminal, R10 usually being a communication terminal. Sure enough, the yellow wire rings to ground on an ohm meter, and there is no continuity to ground in the black wire. It makes me wonder if I should be connecting the black wire to the W terminal on the new AA battery powered Honeywell thermostat. I need to do some more research on that before I risk frying something.

Thank you Alan for responding to me.

John

 

[JohnK-ESC]

Centex I can report to you that your your post #2 in this thread was the information I needed. I jumped from the blue +12v wire in the ceiling to the R terminal on the AA battery powered digital thermostat and from the blue -12v wire in the ceiling to the W terminal on the digital thermostat which successfully operated the furnace from the thermostat. Thank you for your very helpful post.

I'll now be looking for a way to route my wiring while leaving the original overhead air conditioner and Dometic thermostat routed for the next owner in the event they want to revert to the original factory air conditioner/furnace thermostat configuration. Not sure how I'll accomplish that. Any suggestions would be welcome.

John

 

[MVA]

I replaced the thermostat and rewired the furnace in our E19 in preparation for replacing the original Dometic AC unit. A couple of things I learned that may be of use to others:
- The only electronic thermostat I could find that the company specified applicability for 12 vdc is the White-Rodgers (aka Emerson) 1E78-140 thermostat. Hence, I went with that unit.
- The furnace current draw through the thermostat is about 0.7A. Higher than I expected, so make sure your wire size is appropriate if you are replacing the thermostat.
- After almost 9 years, I came across the first wiring issue in our trailer. It took me some head scratching to figure out how ETI wired it. In short, ETI tied the 12+ VDC trailer power to both the furnace power line and the thermostat + line, effectively bypassing the built-in 5A breaker in the furnace. They then ran a separate 12+ VDC line directly to the Dometic control box in the AC unit that should have been the thermostat + line from the furnace. Long story short, it is all rewired, the breaker works (and is now in the circuit), and the new thermostat is functional. AC unit will be removed later. You may want to check your wiring if you are so inclined.

 

[John in Santa Cruz]

I have a Honeywell digital thermostat for my furnace only setup... Let me find some old pix that might remind me what it is specifically, its worked great for many years now. This model has probably been superceded but they are all pretty similar. Mine is an RTH5100B 'deluxe non-programmable'. Honeywell suggests the RTH5160D1003 is a direct replacement.

those 2 AAA cells last for several years at least, and it gives low battery warnings for months before you have to replace them.

The two lower buttons on the front, the left one just turns on the display backlight so you can see it in the dark, the right one turns the heat off and on. the up/down buttons on the right increase/decrease the heat setting 1 degree at a time. It always shows the ambient temp, the heat setting is shown when the heater is enabled.. There's some jumpers inside that set it for heat only vs heat+AC vs whatever else it can do. for the Escape heater, you just have the two wires white+green, these go to W and Rc respectively.

 

[JohnK-ESC]

The furnace current draw through the thermostat is about 0.7A. Higher than I expected, so make sure your wire size is appropriate if you are replacing the thermostat.

MVA, which size wire are you using at the thermostat? I replaced our Dometic thermostat with a AAA powered Honeywell set to furnace control only. The blue wires throughout our furnace wiring which used to terminate at the air conditioner but now terminate at the thermostat are 14 awg stranded copper. This is heavier than I would have expected for signal wire, certainly for .7 amp draw. The thermostat terminals are actually too small for 14 awg wire.

John

 

[MVA]

Good question. In reviewing pictures on this site of folks that have replaced the Dometic AC unit, the wire size from the Dometic control box (physically within the Dometic AC unit) to the digital Dometic thermostat is not consistent. Some trailers appear to have 16 AWG to 18 AWG size wire. Our trailer was unfortunately 24 AWG. Fine for a digital control thermostat but inadequate for an analog thermostat drawing 0.7 amps. Hence, my comment to check your specific trailer wiring size. I ran a pair of 18 AWG lines from the new thermostat directly to the furnace.

 

[John in Santa Cruz]

My 2014 vintage furnace, the thermostat is at indeed 13.x V when open circuit, and the closed circuit current draw is 158 mA (0.158 A) when the thermostat is on (ok, I unplugged the thermostat and connected my Fluke in 'amps' mode directly across the green and white wire to turn the furnace on and measure the on current...)

 

[JohnK-ESC]

Well John that's an interesting idea and one I'd like to try, but I'm not sure I have the requisite system understanding to try. I too have measured 13.x V at my thermostat where I connected a + blue wire to the R terminal and a - blue wire to the W terminal, but I'd be measuring current without knowing if my + and - blue wires equate to your green and white wires. The furnace runs and heats normally for more than 10 minutes with no damage to the thermostat, fuse or circuit board. Maybe I leave well enough alone?

 

[John in Santa Cruz]

the multimeter in 'amps' mode acts like a jumper wire, so you just connect the meter terminals to the green and white wires (or your blue wires, whatever), polarity doesn't matter if its a digital meter, and when connected, it will turn the furnace on, and read the thermostat current.

note most meters, for DC Amps, you have to move the plus terminal from the normal position to an Amps only position AND switch the meter to DC A(mps). make sure you switch it back to a volts setting or off, and move that meter cable back to its normal position when you are done.

 

[John in Santa Cruz]

meter in normal mode: