Confused on Thermostat Wiring

[patlaw]

Customer has a Totaline P274-1200 thermostat that is bad. The P274-1200 is apparently discontinued, so I'm going to have to replace it with a similar unit. Before removing the old one, I wanted to make sure that understood the wiring. I don't. The HVAC is a one stage cool-two stage heat pump.

Here is the wiring (Figure 14) from the P274-1200 manual (you can click on the image for a zoomed version):

http://i465.photobucket.com/albums/rr20/patlaw_photos/th_Fig_14.jpg (http://i465.photobucket.com/albums/rr20/patlaw_photos/Fig_14.jpg)

Here is a picture of the defecting thermostat:

http://i465.photobucket.com/albums/rr20/patlaw_photos/th_P274-1200Wired.jpg (http://i465.photobucket.com/albums/rr20/patlaw_photos/P274-1200Wired.jpg)

My dilemma is that the white wire, according to the schematic, shows as going to "Y1/W2". In reality, it goes to "W/W1". All four DIP switches are off, as in the diagram. The system has been working for ten years, so the present wiring scheme must be valid.

If you can help me understand this discrepancy, I'll have a better chance of quickly installing the replacement thermostat.

Edited to Add: Here is the link to the P274-1200 Manual (http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/p274-8si.pdf).

[Gunny62]

Residential HVAC Questions and discussions pertaining to HVAC for the home.

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[big sky hvac]

You really shouldn't be concerned with what the wiring diagram shows for the old thermostat. Look at the wiring diagram for the new thermostat and that will tell you how to wire it properly. There is a no DIY policy on this site, so that's the best we can do as far as helping goes. If you're a pro, get your post count up to 15 and apply for pro membership. This will get you into the pro forums where we can give DIY advice and assistance. This probably won't help you right now, but it could help you down the road.

[Atticmonkey777]

I dont see anything "odd" about that thermostat compared to any other thermostat. As long as you know what each wire goes to and what is needed for the application, you should be able to swap stats no problem. But like others have stated already. We can only give limited technical info in the residential forums. Get 15 posts and we can talk in the Tech forums about anything and everything.

[patlaw]

Thanks for the responses. I actually figured it out. The "oddness" was really just labeling confusion. There is nothing unusual about the system.

On a second note, while I'm new, I'm not DIY. I guess I really don't understand the admonitions. If you have to make 15 posts to get a substantive response, what is the anticipate content of the first 15 posts? (I did read the site rules!)

[big sky hvac]

On a second note, while I'm new, I'm not DIY. I guess I really don't understand the admonitions. If you have to make 15 posts to get a substantive response, what is the anticipate content of the first 15 posts? (I did read the site rules!)

The reason for the rules is that anyone at anytime can access the open forum and read what others have written. In the pro forum, only pro's that have knowledge and know the risks and liabilities of the industry are allowed to read and post there. If someone were to give DIY advice on the open forum on how to repair their equipment and they in turn injured or killed themselves, it would put the person giving the advice and this site at fault. That is why there is a no DIY policy. There really are some things in life that should just be left for the pro's to do. The other reason is that we don't get paid to give advice on how to repair stuff. We've all either gone to school or had formal training to learn what we do. There is no reason for us to tell people how fix their stuff when that is what our job is. Why should we take money out of our pockets, we all have families to feed and homes to pay for. I don't see too many doctors telling everyone how to perform open heart surgery on the internet.

[patlaw]

That makes a lot of sense.

[Airmechanical]

you could burn up/destroy parts of your equipment by wiring it incorrectly



.

[big sky hvac]

you could burn up/destroy parts of your equipment by wiring it incorrectly



.

Another very good point I forgot to include.

[patlaw]

I replaced the Totaline with the Honeywell, and it's working great. No problems at all.