# taco sr503-4 switch



## jmon (Nov 5, 2012)

Furnace is a basic natural gas hot water system. Water gets heated up and sent out and the process continues until zone is satisfied. I replaced the honeywell 832a switch with taco sr503 switch because when the upstairs zone called for heat the downstairs zone also came on making it too hot downstairs. The sr 503 switch is better suited for this. the honeywell 832a switch just turns on the circulators only- not set-up for seperate thermostats and zoning.

installed taco sr 503 switch. wired everything according to schmactic. however, when zone 2 (upstairs) calls for heat, the circulator comes on but does not fire boiler, the red led on 503 switch indicates zone 2 called for heat and the green power led stays lit all the time like it should, and zone 1 red led is off like it should be. I could understand this if the boiler was already at 180 degress or so, but the bolier is cold 0 degrees. All it is pumping is cold water through the baseboard heat. So I turn down thermostat upstairs. 

Now, when I turn on zone 1 downstairs both red leds come on for zone 1 and zone 2 and the bolier is fired and both circulators come on? crazy? Now I have heat in both zones - but I only need heat in zone 2 (upstairs) Now the downstairs thermostat controls everything.

This has me stumped. The bolier is an old lochinvar. It originally had only one zone one circulator. another zone/circulator was added to the same original zone/circulator the boiler came with later for upstairs. The system never really worked like it was suppose to. When upstairs called for heat, downstairs would come also ect. Now the problem is reverse downstairs heat comes on and so does upstairs. However, on the plus side, it is always warm in the house which is nice. 

I contacted taco and told them my problem - they said that's impossible. they had me take off the end wires of the thermostat XX on the 503 switch and touch them together. If bolier fired it was a bad switch which they would replace. The bolier did not fire up. So they said it is not switch - check your termostats they could be conflicting. I have two programmable lux thermostats one upstairs one downstairs. Although I do not have a central air and heating and all that, I am only using two wires red and white and they appear to work fine. checked the wiring and all the wires are hooked up to the right terminals ect.

Trying to get to the bottom of this, I checked the control panel on the bolier itself. The Circulator relay switch was replaced a few years ago with a DPST (double pole single throw - I googled it because I didn't know what the abberviation stood for) - that's what it says on the relay switch anyway. Could that be a possible problem? Double pole single throw would mean to me anyway, both circulators would come on with one throw of a switch. Maybe this needs to be a double throw double pole relay switch here. I don't know. This could be the culprit that has been alluding me all these years. When I call out hvac tech to fix the relay switch i assumed they know what they are doing. I was thinking about replacing both thermostats with a basic honeywell for 2 wire heating system only. But I really don't think this is the problem. hvac techs of the eighties did a lot of gerry riggin to make this system work as a 2 zone system. In there defense, it does work - it just doesn't work correctly. Maybe you just can't set this particular bolier up with seperate zones. It just may have to be configured like this to work. This was all done late 80's early 90's timeframe. techs back then just tried to get things working cheaply and move on to the next job.

Sorry this post is so long - just wanted to give all the information I could.
Hopefully beenthere can help me out with this stumper. Thanks for any advice.


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## Canucker (May 5, 2011)

Are you zoning with pumps? Can you get some pics of the near boiler piping? It would help confirm that you have what I'm seeing in my head.


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## jmon (Nov 5, 2012)

Canucker said:


> Are you zoning with pumps? Can you get some pics of the near boiler piping? It would help confirm that you have what I'm seeing in my head.


 
thanks canucker,

Yes, two seperate taco circulator pumps coming off the same 1 in pipe. I will send photo shortly.


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## beenthere (Oct 11, 2008)

Sounds like there may be a short in you thermostat wires.

Both circulators should be wired to their respective terminals on the 503.


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## jmon (Nov 5, 2012)

beenthere said:


> Sounds like there may be a short in you thermostat wires.
> 
> Both circulators should be wired to their respective terminals on the 503.


both circulators are wired to respective terminals zone 1 and zone 2 on 503 switch. green led is on indicating power to switch. I will run new thermostat wire from thermostats to boiler to see if that is an issue - that is what the rep said at Taco as well. they also said could be bad or incorrect thermostat for bolier. I have two old lux programable thermostats that are for central air and heat they have hook up for 6 wires i am only using the red and white terminal. Should I replace them with a basic heat only 2 wire thermostat from honeywell?


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## beenthere (Oct 11, 2008)

Those stats are ok to use(not a brand I like, but hey're ok).

Disconnect the thermostat wires at the 503. Then jumper each one separately. See if it still does it. if so, then its not in your low voltage side.

Do the circ wires come diretly to the 503 from the circ, or do they go through a junction box first. if through a junction box first, check the wiring inside of it.


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## jmon (Nov 5, 2012)

beenthere said:


> Those stats are ok to use(not a brand I like, but hey're ok).
> 
> Disconnect the thermostat wires at the 503. Then jumper each one separately. See if it still does it. if so, then its not in your low voltage side.
> 
> Do the circ wires come diretly to the 503 from the circ, or do they go through a junction box first. if through a junction box first, check the wiring inside of it.


ok, I did the thermosts wire test here are the results: when end wires were jumped boiler did not fire - zone 2 red led stayed lit, when zone 1 was jumped did not fire boiler - zone 2 red led remained lit, when zone 2 was jumped did not fire boiler also the red led lite on 503 switch went out. When I jumped zone 1 from 503 switch directly to the terminals of the bolier, zone 2 and zone 1 red leds came on and the bolier fired. However, we are right back to the original problem now when zone 2 (upstairs) calls for heat it also energizies zone 1 as well. The downside jumping the system this way is that zone 1 red led stays on all the time because it is be manually jumped right to the boiler. Other words there are two thermostat wires in zone 1 and 2 thermostat wires on the bolier. I did not leave it like that - just wanted to see if I could get zone 2 to fire the bolier and it did by jumping zone1 from 503 switch directly to the boiler. I can't leave it like that because literally zone 1 would never shut off. I am not giving up to try to make this boiler operate correctly. So I put everything back the way it was for now. Still zone 2 does not fire bolier - but circulator comes on, just doesn't fire up the bolier.

Now as for 120vac side of the equation. Here are the results: Zone2 (upstairs) circulator is wired directly into 503 switch, The main power firing up the 503 switch comes from house electrical panel and is wired directly into the 503 switch. zone 1 (downstairs) the original circulator that came with the boiler is wired directly into control panel on boiler first, then goes to 503 switch. It also is connected to; what I call the kill switch that is at the top of the basement when you open basement door - that red switch that says furnace on it. This is the kill switch which prevents the bolier from firing when closed, this is where the power is coming from to power circulator and bolier. So you have 3 120vac lines going into that panel. one for the kill switch (main power), one from the circulator itself, and one from the circulator back to the 503 switch which are all wired together with a huge wire nut. They are in a basic black to black white to white and ground to ground configuation. From there it goes to black and white side (120vac) of a step down transformer and comes out 24 volt on the other side for going to various relay switches. There are a lot of wires in that control panel. I try to send some pics so you can visulize what is going on here - but i don't know how much you will be able to see from them because of all the wires coming together. It looks like one big wiring mess. Could the problem be on the 120vac side at the control panel on furnace? Does that 120vac wiring configuation sound right to you? That's all I have time for right now - got to go to work. I'll check post latter. Thanks a bunch for your help.


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## Canucker (May 5, 2011)

I'm still going to need some pics of the inside of that relay, but it sounds like the end switch on the 503 isn't connected to the boiler or there isn't any power to the boiler itself, so nothing is being lit? I need to see what and how you've got things jumped. It sounds like its easy enough to rewire, just can't picture it right now.(And a pic of the near boiler piping for sure, from your description in the first post, I have a suspicion I'd like to confirm.)


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## beenthere (Oct 11, 2008)

Sounds like the original set up was a master/slave zoning set up.

Run a new wire from the original circ to the 503, so only the 503 controls it.

As above, will need pics of the rest of the wiring to tell you how toi get it wired right.


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## jmon (Nov 5, 2012)

beenthere said:


> Sounds like the original set up was a master/slave zoning set up.
> 
> Run a new wire from the original circ to the 503, so only the 503 controls it.
> 
> As above, will need pics of the rest of the wiring to tell you how toi get it wired right.


ok. will do. Try to get those pics for you.


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## jmon (Nov 5, 2012)

Link to Imgur album here. (pictures of 503 switch and boiler)

For picture Boiler #3,
picture of control box on boiler where everything wires into. you see 2 120vac lines going in - one is the kill switch at top of stairs (main power) and the other is going back to 503 switch, the metal casing is the circulator power line, the black and white side of the step-down transformer. As you can see they are all slave off that one main 120vac power line coming in. It is a wiring mess to say the least.

For picture Boiler #4,
another picture of the control box. Different angle. It's hard to see I know. I'm standing right next to it and I don't know where everything goes.

For Picture Boiler #8,
another angle - hope these pics help you visulize what I'm up against. it's basically 120vac black to black and white to white and ground to ground. I'm not sure of that one wire nut that has a black and white wire together - you usually don't see that, the electrician should have marked that so you know what that is for. Any suggestions as to what that might indicate? But if I wire that zone 1 circulator right to the 503 switch like you suggest, that will be two less wires in that mess. So that means only one 120vac main power from the kill swtich will be going in there now. Therorically it should work. the kill switch would be wired to the primary side (120vac) of transformer. the otherside is all 24volt after that which goes to a bunch of relay pumps, circulator relays etc, finally to the control module and ignition wire which fires the bolier up. just have to be really careful here because if you put 120vac on the wrong side of that transformer all circuits and relays will be fried big time. Well I think i'm up for the challenge. I'm thinking a total rewiring here. Any tips would be helpful. I know I should be very careful not to put 120vac on the 24vac side of that transformer. The black and white side is the primary side which is 120vac correct? The otherside steps down to 24vac. at lease that is what my multimeter is indicating. black and white side says 120vac blue and red side says 24vac that sound right?


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## Canucker (May 5, 2011)

Ok, that,s a big help. Mess of wiring, no good for OCD people like me but its an easy fix from the looks of it. It appears that you have power going to the boiler and to your 503. That's good. Both pumps should be supplied with power from the 503. It looks like you can remove the armored cable on the one pump and get rid of it. Although, in my area, they frown on NM cable for near boiler wiring, you may want to switch yours out. Oh, and do yourself a favour and move the 503 so its not behind that pipe that appears to be the gas line? You'll appreciate it when you rewire it.


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## beenthere (Oct 11, 2008)

The black and white wires wire nutted together, are the switch leg for your switch at the stairs.

The brown relay at the top and just right of center is the relay the circ is wired to. Which you should disconnect and have the 503 control it.


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## jmon (Nov 5, 2012)

ok thanks guys. I will work on that. I knew there had to be a wiring problem somewhere. I will do one step at a time. I will rewire zone 1 circulator so it goes right to the 503 switch like zone 2 does. then the 503 switch will control everything thermostats and circulators. That will get rid of the metal coax wire and the 1 120vac wire going into the control panel on boiler. that just leaves 1 120vac wire going in there, the kill switch at top of stairs. That should get rid of some of those wires. So sum it up - 503 switch will control all theromstats and circulators and the kill switch (emergency switch) at the top of the stairs will kill power to boiler so it does not fire. Correct? sounds pretty basic I'll let you know the results.


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## beenthere (Oct 11, 2008)

The 503 is a fairly simple control. Shouldn't be too hard to get your system to work the way you want.


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## jmon (Nov 5, 2012)

ok guys,
I hooked everything to 503 switch all termostats and both circulators go right into the 503 swtich now. Turned on power, 503 green led came on each zone led light works independly, Both circulators work. One big problem now. Neither of them fires up the boiler. Bolier does not fire but everthing else seems to work fine. any suggestions here at this point.. I have the metal coax capped off right now. along with that other 120vac line you saw in the picture. I did not remove anything from the control box yet. Either That metal coax that came off the circulator or that 120vac line is important. I will have to open the control box latter and trace them out see where they go. Any suggestions, boy this has been a stumper. I can always just hook it back up the way it was. But now the 503 switch works great just doesn't fire up bolier at this point. Switch at top of the stairs is on, all power is on, thermostats are on - can't figure it out. thanks


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## jmon (Nov 5, 2012)

checked the 120 line and circulator metal coax lines. Both lines show no power according to my multimeter. How was this bolier even firing?


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## Canucker (May 5, 2011)

Run the power line from your furnace switch to the boiler. Run a wire from the 503 supply to the same spot on the boiler. Take the black wires and tie them together with one wire on the relay on the boiler. Take the whites and the other wire on the boiler relay and tie them together. Now when you shut the switch off, it cuts power to your boiler and the 503. When its on the boiler and the 503 are powered. You have the lines running from the 503 to the circulators, this is good. Now run a wire from the end switch on the 503 to the boiler control wiring. When this is done, when a room thermostat calls for heat, it starts the circulator and closes the end switch on the 503, which signals the boiler relay to do its job and fire the boiler. I think you've accidentally eliminated the power to the boiler and you still need it. When the 503 is signalling the boiler to start, it looks like it has no power to do that, but the circulators are powered, thats why they're running.


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## beenthere (Oct 11, 2008)

The 2 romex wires that were ran to the boiler, are both needed. one is the power to the boiler, the other is the switch leg. thats why you saw a black wie and white wire, wire nutted together.


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## jmon (Nov 5, 2012)

ok just want to make sure I understand. The furnace switch wire is already there in the control panel on bolier. So thats' taken care of. run another 120vac wire from the 503 switch supply to same spot on boiler. Ok question here - the only 120vac lines I have left on the 503 switch are the end one which is jumpered and zone 3 which I am not using. Do I remove that jumper and wire the 120vac line there - then run it to the same spot on the boiler where the furnace switch is? then tie all the wires together as you mentioned. just wanted to make sure i understand where to wire all 120vac lines. that should take care of the 120vac side.

After that you say to run a wire from the end switch on 503 to the boiler control wiring I assume you are talking about the 24vac lines here the thermostats. Is that correct? The end switch is marked XX. there is already a line from the end switch XX on 503 switch to the red and white terminals of the bolier control panel. So that is done. Right? All I have to do is the 120vac side.

I still have the metal coax and that 1 120vac line that are disconnected now. Do I need them or can they be removed? I am sorry just want to make sure I understand everything. thanks


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## beenthere (Oct 11, 2008)

Post pic of the wires that are currently in the boiler control box.


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## jmon (Nov 5, 2012)

*more pictures*

More pictures here.

In picture #2,
can that wires be removed ?

In picture #5,
is a picture of the thermostat terminal on the control panel coming from the end switch xx on the 503


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## beenthere (Oct 11, 2008)

The romex that is laying on the floor. that should have been the 120 volt feed line. What did you disconnect it from.


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## jmon (Nov 5, 2012)

I am assuming you want me to remove the power line that is coming from the house electrical box that is currently friing up the 503 switch. That power line and the furnace switch power line are hooked up to a standby automactic generator in case of power failure so we can still have heat. It doesn't change anything - just wanted to let you know. You want me to replace it with one coming from furnace switch in bolier control panel. that way you can kill the boiler and 503 switch with one throw of the furnace switch at the top of the stairs. right now the 503 switch has it's own power and the bolier has it's own power. I really don't mind that - I just want the bolier to fire at this point. If I have to do that I will. It seems to me the 503 is lacking something to tell the bolier relay to fire the boiler. i'm still trying to get it straight in my head first before I attempt anything. Just looking for the quickess way to fire up boiler for now to get some heat. thanks.


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## beenthere (Oct 11, 2008)

The end switch is what is suppose to tell the boiler to fire.

Does the boiler have 120 volt now.


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## jmon (Nov 5, 2012)

that was disconnected from the 503 switch zone 1 circulator


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## jmon (Nov 5, 2012)

when you say end switch you are talking about the thermostat wire coming from 503. I took a reading with my multimeter the romex laying on the floor and the romex metal coax have no power readings


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## jmon (Nov 5, 2012)

even with thermostat on that romex on the floor and metal romex coax cable have no power. The circulator is running - but bolier is not firing. So i ssume the bolier has no 120vac at this time.


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## beenthere (Oct 11, 2008)

That romex on the floor came from the 503? Or did it come from a junction box.


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## jmon (Nov 5, 2012)

it was coming out of the bolier control panel and was connected to zone 1 on the 503 switch. I did that when you said to wire the circulator directly to the 503 first. originally It was wire directly to the boiler first then went to the 503.


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## beenthere (Oct 11, 2008)

Ok.

The switch at the stairs is just providing a switch path most likely. probably has no nuetral, which is a common way to wire the switch.

Something feed 120 volts to the boiler panel, and then was wired to the switch. You need that wire back in the boiler panel. So its wired similar to the original pics you posted. 

You can run a 120 volt from the 503 to the boiler. It should be from the same wire that feed power to the 503, not off any zone.


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## jmon (Nov 5, 2012)

if you look at the current pics you see in the control panel all those 120vac wires are slaved together with wire nuts - that's the romex cable you see there laying on the floor. It went from the bolier control box to zone1 on 503 switch.


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## jmon (Nov 5, 2012)

ok, then can I run a 120vac line from main pwr on 503 switch to where that romex wire on the floor is connected to? There is a jumpper on the last 120vac on 503 switch - should I use that one or just add it to the current main pwr which is powering the 503 now.? I believe you can stick two romex cables in those slots.


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## jmon (Nov 5, 2012)

or I can put in a junction box slave them together and use it to power up 503 and then run one right to the boiler. Or I can just use the 503 switch as sort of a junction box also.


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## jmon (Nov 5, 2012)

also just to let you know - I haven't touched anything inside the bolier control box yet. That mess of wires hasn't been touched yet. But I will have to trace that romex cable laying on the floor at some point so I can put that 120vac line coming from the 503 switch to get 120vac back to the bolier so it will fire.


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## jmon (Nov 5, 2012)

I think I got it now. I was reading the 503 instruction sheet. I'm almost there - I think. There is one thing I forgot to do. And it is very important. The 120vac isolated end switch the one with the jumper on it, has to be connected to the aqustat control on the boiler. It says the jumper should be placed between terminals zc and zr which it is already from factory. I am using cold start boiler application as opposed to tankless coil boiler (see instruction sheet). My question is the terminals are jumped which means they will be both hot. How do I connect that to the control panel on boiler? When it comes from the 503 switch both black and white wires will be hot. Do I still hook it up on the bolier as black to black white to white? Or do I remove that jumper on the 503 switch. The instructions don't say.


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## jmon (Nov 5, 2012)

Link to Instruction Sheet here. (PDF)

please look at instruction sheet and tell me what you think? Do I remove that jumper or leave it there? The instructions say leave it there. Don't want to fry any electrical parts. So the romex going into the boiler control panel both wires will be hot. I didn't think you could hook things up that way. thanks for looking. I assume I will be using the cold start bolier app as opposed to the tankless coil bolier alternate wiring.


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## beenthere (Oct 11, 2008)

The ZC and ZR are not for powering the boiler. So keep that jumper there. Put the wires to power the boiler on the same 120 volt terminals that power the 503 itself. The isolated end switch, which is low voltage tells the boiler when to run.


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## jmon (Nov 5, 2012)

ok. thanks I'm glad I chedcked with you first. When I took a reading at the end switch with the jumper on it said 0. When I took a reading on the terminal you just said it reads 120vac. I will put that where the current romex wire laying on the floor goes. That's how the bolier must of got its power to fire. It fact I think that current romex wire laying on the floor is long to reach the 503. I'll just use it. ok , today i will concentrate on getting 120vac to the bolier. So while im in the boiler control panel, would you reccommend removing that metal romex coax cable that went to zone 1 circulator? It the pictures its that metal romex sticking up. Then I can run the 120vac coming from the 503 swtich through there . It would give a little more room there. It would elminate some of that wire congestion. thanks, i'll let you know how things work out.


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## jmon (Nov 5, 2012)

ok. Anther question? I'm in the control panel on boiler. No problem with 120vac I connected just like the old romex that was threre. That is the one if you look in pics has the black and white wire together. That must be how the switch at the top of the stairs shuts everthything off. Ok while tracing the old metal romex connector you see sticking up. The black wire is connected directly to the top right terminal of the pump relay - that brown thing in the pics just above the transformer it says spdt (single pole double throw) on it . What do I do here? I don't want to leave that wire sticking up like that. Can I disconnect that? In oher words take that whole metal coax romex out? Or do I need this for the boiler to fire or pump to work? It's not connected to anything cause I wired that pump right to the 503. I already know all the pumps work the bolier just doen't fire. I belive the 503 should take control of everything now. If I don't need that - I would like to remove it. I don't want to remove the relay switch i can just cap that one wire off and leave it. Then i would be able to get rid of that ugly metal romex coax looking thing. I will wait and see if the boler fires and wait further guidance from you. thanks


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## jmon (Nov 5, 2012)

great news! everything works correctly. Bolier fires, each zone works independly, and the kill switch at the top of the stairs works. Thanks so much for your help. Final thoughts I would like to clean that control panel on the bolier up a little bit. I really don't like that metal romex connector sticking up like that and obviously It's not needed now - everything works fine. Can I put the romex wire there and get rid of that metal thing sticking out of the control box? It would look a lot more professional. Thanks.


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## jmon (Nov 5, 2012)

great news! everything works correctly. Bolier fires, each zone works independly, and the kill switch at the top of the stairs works. Thanks so much for your help. Final thoughts I would like to clean that control panel on the bolier up a little bit. I really don't like that metal romex connector sticking up like that and obviously It's not needed now - everything works fine. Can I put the romex wire there and get rid of that metal thing sticking out of the control box? It would look a lot more professional. Thanks. I'll send new pics when it is all done so you can see it.


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## beenthere (Oct 11, 2008)

Yes, you can move the romex to there.


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## jmon (Nov 5, 2012)

ok, I will remove that metal romex and stick the regular romex cable through there - that will make it look a lot better and get rid of some of that wire clutter. thanks


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## jmon (Nov 5, 2012)

when I remove that black and whit wire from the metal coax romex zone 2 upstairs does not fire and circulator does not run and no red led light on 503 switch. Somehow those wires need to be connected somewhere. I don't understand because they where just stciking out not connected to anything they were going to the zone circulator which is wired to the 503 now. . I put the black wire back on the terminal of the pump relay still nothing the white wire was wiring nuted to another white wire. i'll try and put it back the way it was. and just cap those wires. ant suggestions?


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## jmon (Nov 5, 2012)

put wires back where they where originally in the picture caped them off still zone 2 does not fire and circulator not running. zone 1 works still works fine. if you look in the pics you'll that pupm relay im talking about


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## jmon (Nov 5, 2012)

the black wire is attached to the upper terminal of the pump relay. The other end went to the circulator. The white wire that came from the circulator is nutted togehter with two other white wires one from the 120vac romex i just put there, and one goes to the transformer. I'll wait for furhter guidance from you before i go any furhter. It appears zone 2 has no power at all now


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## Canucker (May 5, 2011)

You're killin' me here. lol. Ok, here goes again. Take the wire thats coming from the switch, connect the black wire to the H terminal on the 503, connect the white wire to the N terminal, right beside it. There is room for 2 wires at these locations, so now I want you to run another cable from the same terminals on the 503 to the relay on your boiler. If I remember the pics, your boiler relay has a white and black wire, wire nut the matching colours together with the wire coming from your 503. Now you should have 120 power going to the 503 and another going to the boiler from the SAME spot. Now, run cable from the relay in the 503 that says zone 1 to the zone 1 pump. Do the same with the zone 2 location and the zone 2 pump. All of these wires on the 503 should be on the same level as the 503 supply. Now, take the wire on the 503 end switch(low voltage wire, small gauge) and connect it to the terminals on the outside of your boiler(They're below where the power feeds in at the boiler, 2 small screws) If you have done this, you will have 120 feed going to 503, then to boiler, separate wires going to each pump from the 503 and low voltage wiring coming from the thermostats to the 503 and a low voltage wire from the 503 to your boiler. Now your boiler will run the way you want it to. Do not remove jumpers, there is no need.


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## jmon (Nov 5, 2012)

Added two more pictures #10 & #11 to the album here.

ok, All that was done just like you said word for word. The bolier works fine - all zones work independly of each other. What I was going through with beenthere was removing that old metal romex cable sticking out of the control. i just wanted to clean up the wiring - it would look more professional. There was a black and white wire still in that metal romex cable. I didn't think I needed these wires anymore, They were just hanging there going to absolutely nothing because that circulator is now wired directly to the 503, and the boiler is working fine. I thought at this point the 503 took total control of everything - so I removed them.The black wire went to the upper right side of the brown pump relay switch, I guess that's what it is - It says SPDT on it (single pull double throw) - just above the transformer if you look at the pics you'll see what I am talking about. The white wire was nutted together with the white wire coming from stairs and white wire from main power of 503. I removed that wire as well. So now the upper right connector of the relay pump switch has nothing connected to it and the white wire have been removed. Then I fired up the boiler to test it again everything work fine except zone 2 would not fire now. So I put those black and white wires that i removed back to where I found them and capped them off. Now the bolier is working correctly again all zones work independly, boiler fires, emgency switch at top of stairs works kills both zones. It makes no sense to me at all. Because those wires go nowhere and do nothing. But the boiler works - so I'm leaving it alone. It must have something to do with how this bolier was originally wired from the factory. Maybe something has to be on that upper right terminator of the pump relay switch even if it is just capped off. remember this bolier is over 20 years old - date of mfr. was 1988. To me; I,m thinking the 503 has total control now, so this pump relay switch in therory insn,t need at all at this point. Am I right here? When it comes to relay switches and transformers I really don't understand how they work. I know 120vac goes in one side of transformer and comes out 24vac to run all the appropriate switches and relays that require 24vac. I want to thank you guys for the help and patience you had with me. I could have never done this without you. Thanks. Here are some pics of the final hook-up.


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## Canucker (May 5, 2011)

Glad it works the way you want now. Any frustration I had was with myself, I figured I wasn't explaining how to fix it properly and it was giving you a hassle to complete what should have been a 10 min job. I sometimes forget that not everyone who comes on here has a full understanding of the basics. This place helps me sharpen my troubleshooting skills, so its good for me too.(Looks good, by the way.)


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## beenthere (Oct 11, 2008)

Makes no sense. But if it only works with them connected. Then so be it.


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## jmon (Nov 5, 2012)

I want to thank both you guys once again for your time and patience dealing with me and my 503 switch and boiler. I could have never done this on my own at my skill level. Everything works and looks great, I didn't blow anything up, and there's heat. Thanks again.


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## beenthere (Oct 11, 2008)

The not blowing anything up, is always a good thing. LOL.

Glad it works the way you want now.


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## jmon (Nov 5, 2012)

amen. thanks


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