weird HVAC issue

boatman37

Well-Known Member
Jun 6, 2015
4,211
pittsburgh
Boat Info
2006 Crownline 250CR. 5.7 Merc BIII
Previous: 1986 Sea Ray 250 Sundancer. 260 Merc Alpha 1 Gen 1
Engines
5.7 Merc BIII
Not boat related. Started having trouble with my internet a few days ago and it got worse as the days went by. Called my ISP yesterday and they sent a guy out this morning. He replaced all the connections and said the one at the telephone pole was corroded. So now my network is back up....except my wireless. I have my own network with a wireless router but my ISP's supplied modem has its own wireless router, which I have not used. So I went to connect my wireless devices and kept getting 'invalid password' messages. Connected everything to the ISP's router just to get it back up. I have a Honeywell programmable thermostat so connected that to the ISP wireless too. Went back to my office in the basement and felt like it was getting pretty warm. Went upstairs and the furnace is blowing hot air. Checked the t-stat and it says 'Cool' and it was set at 75 and it said it was 77 in the house but still blowing heat. Tried setting it from the phone app, the Honeywell site and the t-stat itself and no change. I turned it off at the t-stat and it kept running. Had to turn it off at the furnace itself to shut it off. The AC fan was blowing on my central air but still heat coming out of the registers.

So thoughts? I find it highly coincidental that both of these failed at the same time but can't see how they are related? I got all wireless devices back to my home router like it used to be so everything is back to how it was. I am totally lost here. Will call an HVAC guy if I need to but not sure that is the issue?
 
Heat pumps have different Tstat outputs than standard furnaces. May need to swap the output setting on the Honeywell.

Had a similar issue with a smart stat install a few years back, took the tech hours to figure out. When cooling was demanded it would also fire the furnace.
 
It's the same t-stat I have been using for the past 5-10 years. Didn't remove it or change any wires or anything. Only change was I ended up changing my wireless password. Other than that everything is back to how it was.
 
When electronics act wonky I always re-boot. Try it with you HVAC system.
 
It's the same t-stat I have been using for the past 5-10 years. Didn't remove it or change any wires or anything. Only change was I ended up changing my wireless password. Other than that everything is back to how it was.
Sorry, to clarify, I'm talking about a digital setting, not the wiring. When a T-stat is in Heat Pump mode but correctly wired to a furnace, it blows hot when cooling is demanded. Maybe it was changed, or reset to a default when you updated the wifi password?
 
hmmm. wonder how to change it back? when i was trying to get it into the wi-fi mode to reconnect i couldn't remember which 2 buttons to push so i tried a few combinations. maybe that changed something? i'll download the manual for the t-stat and read through it. i'll let you know. thanks!

it's a Honeywell RTH6580WF in case anyone is familiar with it
 
I think Function 1 may be set incorrectly at "1" instead of "0":
upload_2019-6-18_14-49-28.png
 
BOOM! fixed. Thanks!. i downloaded the manual and function 1 was set to 1 for heat pump. changed that and all is well!
 

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