Thermostat heat only oil burner. Replacement woes

stap24

Hi eveyone . Im new to the forums. Im really at a major loss here. Im hoping someone can help here . It may be very basic , i hope.

I want to replace my old Honeywell thernostat from the 70's to a digital one.

I have heat only. Oil fired burner. Line voltage.
The box behind the tstat contains 2 romex lead wires. 5 in total . 2 black coupled , 2 white coupled. And one more standalone white and of course a ground. My original spring tstat has two screws for the wires. The one standalone white and a jumper from the 2 whites tied together. After i removed the stat i figured out when touching the stabdalone white to the coupled whites it kicks the circulator on. The two blacks complete the burner connection.

What my issue is every line voltage tstat i get, when i make the exact same 2 wire connections copied from the original, and i call for heat, i hear the tstat switch on but nothing happens with my system. Im baffled.... if anyone can offer suggestions PLEASE HELP

thanks so much everyone!
Phil

Jamie Hall

You need to trace all five of those wires individually. On a 120 volt system, a black wire should be hot (may be switched) -- 120 volts. A white wire should be neutral; if it's hot, or can be connected to hot through a switch, it should be marked black or red. The ground should be either bare or green. It doesn't sound as though your wires are properly colour coded -- and who knows what they are hooked up to.

The thermostat is a switch...

Trace them all back, and figure out what connects to what.

stap24

Jamie ,

Thanks so much for getting back to me . Yes the ground is bare. I know what you mean its a switch, thats why for thr life of me i cant understand why this simple spring thermostat that functions to either make contact to turn the circulator on etc or off, cannot be duplicated with a dam digital... i will trace them all out. Thanks again for the reply man.

Jamie Hall

Question: does the lovely new digital contraption require a common wire to power it by any chance? Some do... some don't.

Zman

Another way to deal with it would be to convert to 24 volt.You would need a simple relay with 24 volt power source like the taco pump controller http://www.supplyhouse.com/Taco-SR501-4-1-Zone-Switching-Relay.

With a 24 volt system you could use your existing ground wire as a common and have a your choice of a wider selection of 24 volt t-stats.

stap24

Hatteras guy. And everyone thanks for helping out.
The stat is a T451A Honeywell

stap24

True! see this is the thing. The two coupled white wires , like you said will do nothing. I dont have voltage off them. They had (i say they as the old owners) the two coupled wires with another lead wire coming off of them to the stat now if i touched the one single white wire to the coupled wires which is the same way they went on the stat... the circulator kicks on....

stap24

Here is a pic of the wires in the box as it came off the stat

stap24

Also jamie the new stats ... all of them i tried have batteries .. . The only stat i didnt try was one made specificaly for electric heat whic i do not have .

stap24

You said it man lol . Idiots.. im no electrician by any means but will do basic work as it is straight forward FOR THE MOST PART, when done correctly the first time. but this thing is driving me insane. Im pretty sure that copper wire coming off the 2 coupled wires when grounded and tested, had no juice but the single white wire did. Ill check again in the morning to be sure. As i was doing this like 2 days ago. I also took pics of the circ box wiring ill include it. Again i really appreciate the help. Sad thing is ny father is a retired master plumber and contractor etc . He had a stroke a few months back and while he is like 95 percent better thank god. He isnt quite in the zone yet and i cant bother him with this as he gets pissed because he cant remember .

EBEBRATT-Ed

Somebody has cobbed this up. I am wondering if someone tried to "tap" onto the burner circuit to get power for something?

Either way it needs rewiring.

You have a black wire running through a mounting hole in the back of the box that is a short circuit waiting to happen.

Either rip it apart and fix it or run a new wire and new thermostat. Make sure any abandoned wire is left safe, dead, taped up, wire nutted etc.

stap24

Hi Ed ... Thanks for weighing in! . Im not sure what they did..That wire looks like its coming from the hole in that pic. Its not though...Ill attach a more clearer pic. The two master romex leads are coming up through the bottom correctly

Jamie Hall

Do yourself a big favour. Go down to the basement, where those two Romex and one white wire reappear. Find out what they are connected to. At least one of those white wires should be a neutral -- possibly both of the Romex ones. If so, they are OK as is. If not... if any of the three white wires is connected to a hot connection, or to a switch or motor or relay, identify if clearly downstairs -- at least wrap black or red electrical tape around it (use red on one and black on the other, if there are two hot or relay or switch etc.). Go back upstairs and identify which white wire is marked red downstairs, if any, and which is marked black, if any, and mark them similarly. Now go back downstairs and identify exactly what each of the two black wires is connected to then go back upstairs and label them clearly as to what each is connected to.

The rule is if, and only if, a wire goes back to the neutral connection on your switchboard without going through any switch or other device, then and only then it can be white (note that they can be daisy chained with wire nuts or other suitable connectors). Otherwise, it must be marked black or red anywhere it is exposed.

Now... one of those wires you have marked should have power to it. Another should go to your relay or zone valve. Those are the two for the thermostat.

stap24

Yep that worked. Since like you said earlier they reversed the nuetral and hot... i just have to swap the jumper cable to the black i guess?

stap24

Here is where im at now if i touch the jumper from the black to the single white the circ starts..... now heres the new stat! If i connectvthe red to white and black to black and call for heat... nothing!!!! Here is a pic

stap24

Here is a pic of wiring and 120v stat

Jamie Hall

Please find out what all the wires in the wall do. Mark them correctly and label them. Before you electrocute yourself or burn something down...

EBEBRATT-Ed

Ok so the wire does not come through the box hole so that's good. I must say I have never seen a cable with 2 white wires in it.

I find it easier to use different color sharpies to mark wire colors. Easier to do that try and wrap tape inside a box and more permenent.

Robert O'Brien

Long Island, by any chance? Two zones by any chance?