Thermostat Installation and You!
You’re a do-it-yourself kind of person. You’ve done your fair share of home improvements and appliance installation. You know your way around a crescent wrench. You don’t need any help when it comes to thermostat installation.
You’ve got this. You’ll be fine. Everything will be fine. No reason to panic.
Right?
Improper Thermostat Installation & How It Can Ruin Everything
Everything could go wrong, but probably not in the way you’re thinking. While it’s possible to mess up the wiring of the thermostat, that’s not the most common installation problem. The most common way people make mistakes during their thermostat installation is all about location, location, location.
Not Too Hot, Not Too Cold
Here are some thing you should keep in mind when you’re installing any programmable thermostat:
- Do NOT install a thermostat on an exterior wall. If that wall is poorly insulated, your thermostat is going to think it’s either too hot or too cold. You’ll waste energy in summer and winter. Which is bad.
- Do NOT install a thermostat where there is a steady draft. You don’t want your thermostat directly above or below a vent, since that is going to affect how it perceives interior temperature. Again, this is a recipe for wasting money.
- Do NOT install a thermostat in direct sunlight. Ideally, you don’t want your thermostat exposed to sunlight at all. This isn’t always possible, so minimize exposure as much as possible.
- Do NOT install a thermostat behind an obstruction like a door or bookshelf. Even though that spot might meet other thermostat installation guidelines, you’ll come to hate the inconvenience when you want to change the temperature.
- If you’re installing a smart thermostat, make sure it is in range of your home Wi-Fi network. There’s not much point in paying for smart tech if you can’t use it.
You Can Do It
Yes, it’s possible to incorrectly install your thermostat. However, if you follow the aforementioned guidelines, you should be just fine.
75 thoughts on “Thermostat Installation and You!”
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MR COOL
Master of All HVAC
Please help me understand how to program the thermostat on my 18 seer split ac. I can be reached at 954 821 7333.
Thank you
I’ll forward your contact number to tech support.
What are the wires labeled 19rd,20rd,21rd,24rd,22rd and what do they connect to and why no instructions 🤔 when buying this heat strip ? ? ?
Please contact support at 270-366-0457.
Can I put a wired thermostat on my mini split? The mini stat doesn’t read through a Mylar tent to my ac unit and need a wired thermostat.
Unfortunately, that is not recommended.
I’m thinking about purchasing the Advantage 18,000 BTU 1.5 Ton Ductless Mini Split Air Conditioner and Heat Pump (Model # A-18-HP-230A) from Home Depot. Does this model have the USB port to install Wifi up grade?
The Advantage does come with the connecting dongle for a WiFi upgrade.
Would I be able to connect my DIY Enhanced 18,000 BTU 1.5 Ton Ductless Mini-Split Air Conditioner and Heat Pump – 208-230V/60Hz to a third party thermostat?
The Smart Controller may allow for integration with a NEST Thermostat later this year, but at the present time the DIY is not compatible with any third party thermostats.
Thank you!
Hello, was this ever enabled? I’d really like to control my DIY unit with a true thermostat. The built in t-stat is grossly inaccurate compared to 3 thermometers (2 digital,1 non-digital) in the same room. I have tried the manual ‘calibration’ in the app, and it still has issues with keeping the correct temp in the room. thanks!
Is the thermostat in the mr cool advantage units located in the indoor unit head or in the remote control? Also do the advantage units support the hookup of 3rd party thermostats?
The thermostat is in the air handler. Is there a particular device you have in mind?
I have this unit… 18k BTU 16 SEER MrCool DIY Ductless Heat Pump Split System with WiFi Smart Kit – Wall Mounted. I have the temp set at 63 through the remote with the “follow me” feature. The remote thermostat is never up to 63 – typically between 59-61. Outside temps are around 20-40 degrees. The building is well insulated. The app shows a different temp than the remote. I’m at a loss.
That is odd. Give us a call at 270-366-0457, and we’ll see if we can figure out what’s going on.
Am I able to wire in an external thermostat into the air handler bypassing the remote? I have a small indoor cannabis garden and cant risk the wifi controller. From the reviews Ive read it drops signal and the how unit has to be reset when that happens. My plants would be dead if that happened
It should be technically possible to wire an external thermostat to an air handler with the right tools and training. However, it is not something we have done, and not something for which we can provide technical support.
How do you install a remote thermostat for the Mr Cool DIY mini split? Is this even possible?
I’m not wanting a wifi that just sets the temperature on the mini split, but a true remote thermostat, even if it has to be wired.
Glenn
A conventional thermostat cannot be wired to work with a mini-split.
Hi, I have a universal heat pump mrcool 2/3 ton, I can connect a Honeywell thermostat because the manual said no Y wire to thermostat but conddsnser don’t start…. how you wire a thermostat without a Y wire???
Please call tech support at 270-366-0457.
I bought a 2/3 ton condenser and air handler. Why is the thermostat connection so cumbersome? The manual says no Y connection required for the inside unit and for the outside unit no G connection and where exactly on a thermostat should the B be connected since many thermostats out there don’t have B letter inside them. This thermostat connection for both inside and outside unit is the most confusing and non-straightforward that I ve seen. The system is not cooling and does not heat up as the condenser refuses to start just air handler came on and the fan outside too moves slowly. Please assist fully. Thanks
Please call our Tech Support team at 270-366-0457.
Having an issue where the heat pump works for a while then for some reason it stops producing hot air and power to the thermostat goes off. Not sure what is causing this to happen. I’m not seeing any error codes on my outside unit (MDUO18024036) display.
Please contact tech support at 270-366-0457.
How do you wire a Honeywell RTH2300/RTH221 to a 3 ton Mr. Cool universal heat pump without aux. heat?
Please contact tech support at 270-366-0457.
Where to set the heat/cool dip switches on a mr cool 4/5 ton universal heat putmp for the 4 ton setting,? It has 3 capacity settings
Please contact tech support at 270-366-0457.
Can your cielo breeze plus be directly wired by the terms on the back of the thermostat to a wall mounted dyi 9k mini split head?
We would not particularly recommend this.
Have mr cool universal thermostat and mrcool 4 ton universal. Unit ducted what setting is right for telling the thermostat what I have
Please give us a call at 270-366-0457.
Installed a 18K mini last January. Having problems with the heating on the unit. The air conditioning is working fine but the heating is constantly hunting up and down. The bottom louver is constantly in motion. Acts like the thermostat is reacting too quickly. I’ve called tech twice, left my number but no one ever called back. That was three months ago. Probably something simple but need some direction.
We recommend continuing to call us at 270-366-0457 regarding this issue. You may also want to send us an email at https://mrcool.com/contact/.
I have purchased a MrCool 5 ton universal split system and MrCool universal thermostat, the wiring diagrams in the air handler manual do not match the wiring diagrams in the thermostat manual, please provide clarification, thanks Scott
Please give us a call at 270-366-0457 as soon as you possibly can.
What happened? I got the same problem, and my unit isn’t blowing cold air and both lines getting super hot quickly
Please give us a call at 270-366-0457 as soon as you possibly can.
I purchased a new package heat pump unit to replace one that had a bad compressor. I hooked up to the existing electric, thermostat and wiring and duct work. I turn the unit on and the LEDS signal normal operation and will run for a few minutes and shows a anti short cycle fault, but a couple second before that it will blink red only which is a low pressure switch fault. Any suggestions?
Please call tech support at 270-366-0457.
I’ve tried calling all day and it seems like the number isn’t working.
We apologize for this. We are currently experiencing a high number of calls and we’re working on getting back to everyone as quickly as we possibly can. You can also send us an email via our contact page at https://mrcool.com/contact/.
it seems that many folks are having issues with the thermostat wiring, at least on the universal models. Is it possible to publish a how-to for thermostat?
I tried to call Tech-Support during last few days and yet to hear back.
Thank you
Sam
MrCool tech-support engineer called me back with the instructions. Apperantly, I’m using an older install document. If you have a challenge with wiring the thermostat, be sure to use the recent install document and refer to diagram 2.71.
Thank you MrCool…
I’m not seeing a diagram 2.71… Maybe 2.31?
I agree: would like to see a direct demo.
I have mr cool 10kw auxillary heat strip
My thermostat has WE (first stage emergency heat)
And
W2 second stage energ heat.
What connects to W1 on my universal air handler ?
Thanks
The cooling heating cycles work fine
If your thermostat has both a WE and a W2 terminal, we would suggest using a jumper between those two and then connecting to W1 at the air handler.
How to wite and configure a MrCool Universal Wifi Thermostat for a MRCOOL 2/3 ton universal HeatPump? Please share a diagram and the relevant config information.
I’ve sent an email via contactUs form and I’ve been trying Tech support for over a week already.
Please email or call me (the number is on WebSite field of this form.) thank you in advance.
I have forwarded your contact information to the service manager.
I have a 5 ton universal heat pump with the added heating strip. In the outside unit, it says to run the defrost wire into the indoor unit, but there is no where in the indoor unit that references where to connect the defrost signal wire. Also, the two wiring diagrams between the two units don’t match exactly.
Please give us a call at 270-366-0457 as soon as you possibly can.
Due to the frequency of this question just in this thread, it seems like an answer here would be beneficial. Or direct us to a solution online. I too have this issue.
We apologize for this inconvenience, but we recommend getting in contact with tech support at 270-366-0457 for the best advice possible.
I started calling and leaving messages and call back # on the 10th, it’s now the 14th and still no return call!! Unit is Universal 2-3 ton system, installed 6 months ago, heat will come on and run till it satisfies the thermostat, sometimes it will not heat after that, and other times it has heated for 2 days before cycling off. Shutting off breakers for 5 mins resets everything and gets it back going. Sometimes getting h6 (fan speed) code. Assuming I need a control board because fan is free and works fine on reset??
We apologize for this. Let me send your email to the service team manager.
I have a 5 ton universal unit just installed. Installed the nest thermostat and it continues to die. The common wire is run correctly but insufficient power getting to nest to keep it charged. Unit running properly after recharging nest with usb owner supply then dies after 48 hrs.
Please give us a call at 270-366-0457 as soon as you possibly can.
What was the issue, I just installed the 2-3 ton unit and my nest is dieing after a while but only when the unit is not running for a while.
I’m replacing an old R-22 system with your Universal 3 ton. On thermostat wiring (Honeywell RTH7400/7500 SERIES), would I connect the Y and W1 terminals together? Also, there is no D, defrost option with my 3 ton air handler. Is defrost handled with the B thermostat signal (via air handler control board, from condenser temp. signal)?
Thanks, LCB
Please give us a call at 270-366-0457 as quickly as you can for the best assistance regarding this.
I have thermostat wiring issue that seems to be common in this thread. I have emailed and called already with no response. Is there something else I need to do to be contacted?
Please advise,
Thank you.
We apologize greatly for your experience. Would you mind replying to us and sending a reliable contact number so that I can relay it to the service team? The comment with your personal information will not be made public.
Curious if anyone came up with any answers on this. I have the 4/5 ton and having issues as well.
I’m looking for instruction on how to wire up the thermostat there’s no real clear instructions on what wire goes where I have a me cool universal series the heat worked great I go to switch to cool and nothing some clear wiring instructions would be great don’t know why it has to be so secretive on how to correctly place 4 wires
Please give us a call at 270-366-0457 as quickly as you can.
I just installed a 2/3 ton universal heat pump and air handler. Started to hookup the thermostat, manual shows a y wire the units have a D wire instead. Thermostat I am using is a honeywell t5. Please help
Please give us a call at 270-366-0457 as soon as you possibly can.
The “D” terminals are for connecting a wire from (defrost control in the air handler) to the condenser. It’s not a T-stat circuit. Mrcool changed the Universal terminals. What was “Y” is now “D.” They should have simply added a “D” terminal to the air handler, so the T-stat to condenser only “Y” wire could be conveniently landed from the T-stat to the condenser.
If you use the online manual (which I did, as the one in the units are miniature manuals–tiny text), you need to be aware that the online PDF manuals were not updated to reflect this change. The tiny manuals that came with the units are correct.
So, tie the “Y” wire from the T-stat to the wire going to the condenser with a wire nut. And provide a wire from the “D” terminal to the condenser, if the defrost is included (?).
Thank you for posting this!! Luckily my google search wondering what “D” was turned up your reply. Who would’ve thought that the PDF is outdated and the paper manual is up-to-date?! Agreed on the terminal/landing spot. Wirenut/waco it is!
Heat pump not switching on or system not blowing heat. What wire and location does the comm system use to control heat? This is regarding your 2/3 ton 18 seer ducted central system. Why isn’t there a place I can find this info easily? Which controllers are compatible since one isn’t offered by Mr cool?
Please give us a call at 270-366-0457 as soon as you possibly can.
Does D terminal activate the emergency heat strip? I can’t figure out where to tie the E* wire off my nest learning tstat.
Please give us a call at 270-366-0457 as soon as possible.