What should I report if heat stopped after a new thermostat was fitted?
Record both thermostat models, the installed heating equipment and what changed. Compatibility, setup, wiring and unrelated equipment faults require different checks; do not try alternate wire connections.
Preserve the change record
Keep the install date, invoice and old control's model if you have them. Note if heat ever worked with the new one. Describe the screen and what the furnace does when you ask for heat.
A bright screen and Heat message do not prove the new control works with the furnace. It can request heat without a response. Save normal user settings and alerts. Leave installer menus alone.
Confirm the system match
A new control must suit the installed system. A furnace and a heat pump differ. Do not choose their setup from how the wall unit looks. Use the model from an old invoice or manual when possible.
Do not move wires based on their color or an online photo. Leave covers closed and ask for a qualified check of the match and setup. Tell the installer exactly what worked before and what has changed.
Define the correction before buying again
Ask whether the fix concerns the control, its setup or the furnace. Buying another thermostat before that is clear may leave the fault in place.
Tell us who approved the earlier work at the Golden Gate property and who can approve the next step. Check the visit charge and any install warranty. Ask why a new device is needed. Keep its model and setup records after the work.
More about this heating problem
Should I reinstall the old thermostat myself?
Do not use rewiring as a diagnostic trial. Keep the old model information and have the installed control and equipment assessed together.