How many amps is the Honeywell HWLHZ370 - Honeywell HWLHZ370 Ceramic Electric Compact Heater

Here is a link to that manual.

ST9400A & ST9400C Programmer - Honeywell

https://www.honeywelluk.com/documents/Installation-Guide/pdf/835.pdf

Depending on the age of the Vista 10, yes, but you'll have to be quite knowledgeable to make the necessary program changes. Be advised that there have been a number of compatibility issues since Honeywell started changing component designs in recent years without changing the part numbers...good luck.

Honeywell has made a huge number of thermostats over the years. Directions for each are specific to each model. Your model number will begin with the letters, T, TH, RTH, C, or CT and is on the back of the thermostat.
Once you have the model number, you can obtain the owner & programming information by supplying it on the Honeywell webpage, here.
If you are having trouble, either contact Honeywell directly - or repost here.
Good luck!

Mis-wiring.

WARNING: When the thermostat is reset, all parameters (clock, configuration

and schedules) return to their default settings.

?? Open the thermostat's door.

?? Press and hold the Pgm button.

?? Insert a pointed object (e.g., paperclip) in the reset opening.

Remove it when the thermostat's screen becomes blank.
?? Wait one second and release the Pgm button.

http://customer.honeywell.com/techlit/pdf/69-0000s/69-1855.pdf for complet instructions

Here is a link that might help. It's shows the operation & installation manual.
http://www.honeywellcentral.com/ssi/pdf/honeywell/2087D-2092D.pdf

Go to honeywell.com
Under red welcome sign
Bottom red highlighted box literature/image search
Type in thermostat model number
Click on arrow to right
Then click on the PDF files owners manual / installation instructions
If you can’t find what you want, the bottom left and bottom of web
Page, they have homeowners assistance and Home products to get the help you need.

you need to program the thermostat for the reversing valve "O" it will tell you how to do this in the manual. you will need to chang from "O" to "B" or "B" to "O" depending on how its set.

Can you see an amp draw rating on the fan motor itself?