The relays and transformers below are available at local refrigeration supply stores but most refrigeration supply stores will only sell to businesses they typically will not sell to home owners. These items can be purchased at Amazon

Relay 24vac coil with
NO (normally open) contacts
Relay 24vac coil with
DPDT contacts
Contactor 24vac coil
1 pole 40a contact rating
Contactor with
24vac coil 2 pole 40a contact rating
Encapsulated Pam Relay Transformer 120vac
40VA No breaker
Transformer 120, 208, 240, 48075VA With breaker Plug in 120vac to 24vac transformer
Delay on make relay Delay on break relay

HVAC And Home Automation Books

Home Automation Home Automation
Smart Home HVAC
HVAC Alexa smart Home

Zone Controllers

Honeywell HZ311 3 zone controller Honeywell HZ311K 3 zone controller kit
Honeywell HZ322 3 zone controller Honeywell H322K 3 zone controller Kit
EWC NCM300 Zone controller

Wifi Thermostats

Nest 3rd Generation Learning Wifi Thermostat ecobee3 Wifi Thermostat with Remote Sensor
Honeywell RTH9580WF Wifi thermostat White-Rodgers 1F86U-42WF Emerson Sensi Wi-Fi Thermostat
Ecobee3 Lite Lyric T5
Venstar T7900 Honeywell 9000
Honeywell Lyric Vine Thermostat
Schneider Electric Wiser Air Wi-Fi Smart Thermostat Lux Products GEO-WH Wi-Fi Thermostat
Honeywell RTH6580WF Honeywell RTH8580WF1007

Add a wire products

Venstar Add A Wire connects to "K" terminal on thermostat and separates into Y and G signals
FAST-STAT Common Maker Thermostat Wire Venstar ACC0436 2-Wire Kit for all 24VAC Thermostats

General HVAC Products
Tool to straighten out outdoor condenser coil fins Jumper Test Leads

18/8 Thermostat wire / 18 gauge 8 conductor 250 Feet 18/2 Thermostat wire 50 Feet
18/5 Thermostat Wire 250 Feet 18/6 Thermostat cable 30 feet
18/5 Thermostat Wire 50 feet 18/8 Thermostat Wire 50 feet

The meters and test equipment below are not the items that a typical HVAC technician would own but would be good for home use.

AC / DC Digital Volt Meter AC / DC Digital Volt Meter
Etekcity Lasergrip 774 Non-contact Digital Laser Infrared Thermometer Etekcity MSR-C600 Digital Clamp Meter, Multimeter with Voltage, AC Current
Signstek UNI-T UT210E Handheld RMS AC/DC Mini Digital Clamp Meter Resistance Capacitance Tester

The meters and test equipment below are some of the equipment that a professional HVAC technician would own
115 Compact True-RMS Digital Multimeter Fluke 323 True-RMS Clamp Meter
Fluke 116 Compact True-RMS Digital Multimeter Fluke 116/323 KIT HVAC Multimeter and Clamp Meter Combo Kit
117 Compact True-RMS Digital Multimeter Fluke FLUKE-117/323 KIT Multimeter and Clamp Meter Combo Kit
Fluke 373 True-RMS AC Clamp Meter FLUKE-375 FC 600A Ac/Dc Trms Wireless Clamp
Fluke 376 True-RMS AC/DC clamp meter Fluke 381 remote display True-RMS AC/DC clamp meter with iFlex
Fluke 62 mini infrared thermometer Fluke 561 HVAC Pro Infrared Thermometer
Fluke 971 temperature & humidity meter Fluke 975 Air Meter
Fieldpiece AAV3 Anemometer Air Velocity and Temperature Accessory Head Fieldpiece ARH4 Digital Sling Psychrometer Accessory Head
Fieldpiece ADMN2 Dual-Port Manometer Accessory Fieldpiece HS33 Expandable Manual Ranging Stick Multimeter for HVAC/R
AC Non-contact voltage tester