www.hvactechgroup.com - forums

Thanks. Good reply. I can do a heat load and measure air flow easily enough. I had considered over sizing to gain heating capacity. Maybe I will based on air measurements.
Thanks again.

How old is it?  As part of your maintenance did you perform combustion analysis? I can't stress the importance of it enough on any piece of equipment but a particular attention should be paid to a lot of older carrier/bryant furnaces.

It always starts with a proper heat loss/gain calculation.  There are some decent programs that will get you close for free...it's better than nothing.  Size your heat pump to the cooling load trying not to exceed it by much more than 30%.  Variable speed equipment provides a narrow margin of error here so if your true cooling load is close to 2 tons I might stretch it to a 3 ton variable piece of equipment to maximize heating capacity.  Some equipment gives the option to dip switch down from 3 ton to 2.5 which might be preferable, especially on the latent capacity side of the equation (something I think is way overlooked when it comes to actual COMFORT).  As for hooking the MitsAir to your r22 coil, if you're in refrigeration I needn't bring up that mixing oils is not a good idea, even if you rx11 flush it, I wouldn't make that gamble.  I cannot stress the importance of airflow enough in retrofits.  Use one of the many methods to get a good estimate on what your actual airflow is and size your heat pump to that if its less than 2.5/3 tons. 

Lennox has identified that a recent shipment of our S40 Smart Thermostats was stolen during transit from our manufacturing plant and is now being offered for sale through unauthorized channels, including third party e-commerce platforms.
Here is what you need to know:   
•   Any S40 identified as stolen may not be supported by Lennox through warranty claims, replacements, or returns.
•   Stolen units may be blocked from Lennox connectivity and applications and may be fully disabled.
•   Once taken, these actions are permanent.
•   Every S40 thermostat is serialized and tracked at the unit level.
•   Lennox has full visibility into which devices were stolen and when they attempt to come online.
•   Products outside of a Lennox dealer's or authorized reseller's control may have been altered or modified, which may impact performance.
To help protect your business and ensure full product support, S40 Smart Thermostats should be purchased only through authorized Lennox channels, including LennoxPros.com and Lennox Stores. If a source or price appears unusual or below market norms, it may be worth taking an extra moment to confirm the source before purchasing.

Lennox encourages all dealers to continue exercising due diligence and avoid purchasing, installing, reselling, or supporting stolen or unauthorized products. Doing so helps protect warranty eligibility, maintain customer trust, and your partnership with Lennox.

If you encounter a suspected stolen S40 unit or an unauthorized seller, please avoid engaging and report the situation through your Lennox representative.

Lennox is working with authorities to investigate and recover stolen assets and will continue to take steps to protect our products, our partners, and our customers.

Thank you for your continued partnership and for helping uphold the integrity of the Lennox brand.

1. What happened?
Lennox has identified stolen S40 Smart Thermostats that were taken during transit from a manufacturing facility. Some of these units are now being sold through unauthorized channels, including third party e-commerce platforms.

2. How does Lennox know which S40 thermostats were stolen?
Every S40 thermostat is uniquely serialized and tracked at the unit level. Lennox has clear visibility into which units were stolen and when they attempt to activate or connect.

3. What happens if a dealer purchases or installs a stolen S40 thermostat?
Any S40 identified as stolen may not be supported through warranty claims, replacements, or returns. Stolen units may be blocked from Lennox connectivity and applications and may be fully disabled.
4. Can a stolen S40 appear to work initially?

Yes, it may appear functional at first. However, Lennox actively monitors these units, and connectivity may be blocked or the device disabled.

5. Where should dealers purchase S40 Smart Thermostats?
Dealers must purchase S40 thermostats exclusively through authorized Lennox channels, including LennoxPros.com and Lennox Stores.

6. How can dealers identify potential red flags?
Pricing well below market norms, unclear sourcing, inability to verify authorization, or offers through general third party marketplaces should all be treated as red flags.

7. What should a dealer do if they encounter a suspected stolen unit or seller?
Do not purchase, install, resell, or support the product. Report the seller or listing immediately through your Lennox representative.

8. What if a customer brings in or already has a suspected stolen S40?
Do not provide support or attempt troubleshooting. Escalate the situation through your Lennox representative for guidance.

9. What are the risks to dealers who do not comply?
Failure to comply may result in loss of warranty privileges, damage to customer trust, potential legal exposure, and review of dealer standing with Lennox.

10. Is Lennox taking additional action?
Yes. Lennox is actively monitoring stolen units, enforcing protective measures, and working with authorities to investigate and recover stolen assets.

The B139.1.0-24 is adopted on June 2, 2026 in Ontario.

Download the Code Adoption Document FS-280-26 - Here   

The B149.2-25 is adopted on June 8, 2026 in Ontario.

Download the Code Adoption Document FS-281-26 - Here   

The B149.1-25 is adopted on June 1, 2026 in Ontario.

Download the Code Adoption Document FS-279-26 - Here   

Did you ever figure out the wiring for this? Is there a way to control speed using the those 5 terminals?

thank you for helping me with this rough letter. I already did mine.

To whom it may concern,

Please be advised that <name> has been working for <name> since April 22nd 2024.  <name> has attained 4500 hours of theoretical and field experience while performing the service and installation of air exchangers and sheet metal components.  <name> demonstrates the ability to interpret plans and schematics, and shows competency in sheet metal fabrication.

Under the tutelage of <name> (Certificate # & STO Account #), <name> has both installed and serviced residential sheet metal systems.  <name> has demonstrated excellent diagnostic skills in servicing these systems and has also demonstrated the proper usage of the necessary tools and equipment.  <name> practices all safety related aspects required while performing these tasks.

I can accredit that <name> has attained the necessary skills and required hours of theoretical and field experience to challenge the required Certification of Qualification Residential Low Rise Sheet Metal Installer exam 308R.

STO Account #
Existing Sponsor ID #
Training Agreement #

Please feel free to contact me should you require further information.


Thank you,

<name>