Honeywell RTH8500 install....

switching from an old Honeywell T87F (dial type) thermostat.... on th old tstat it was:
Wire - Terminal Red - R White - W Green - G Yellow - Y Grey - B (but this wire wasn't connected to the transformer on th other end)
I tried just using the recommended wiring scheme that honeywell's sit said, which is the same as above with the exception of the B termina and the Grey wire. No go, wouldn't turn on the fan, heat, or A/c unit
there is a common terminal on the transformer that doesn't have a wir connected from the set that goes to the thermostat (the grey wire i just taped back and not in use). i tried hooking that grey wire to th common terminal on the transformer (in the furnace) and connecting tha to the C terminal on the backplate, but still no dice.
any advice would be great. thanks
-- midnight
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
midnight wrote:

You've probably fried the transformer.
hvacrmedic
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Was the new stat compatible with the system? Time for a VOM and check voltage. If the transformer is not putting out then you will need a new transformer as well.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

And I think they are saying you shouldn't have connected it.

traced it to the transformer and went to a supply store where they said it was part of the control panel and was about 200 dollars.
I whined a bit and he offered me a plain transformer for about 10 dollars,.
It looks sort of funny mounted elsewhere inside the furace but it's been working for more than 20 years.
Remove NOPSAM to email me. Please let me know if you have posted also.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.