Taco Switching Relay Fried Twice--Tstats at fault??

wmgeorge

So just connecting the Rh and W wires no issues, but when You wire the programmable
in with C wire things burn out. Hmm. On those old panels I do not believe they had a C or now its Black wire called out. So where is that common wire picked up?

ratio

wmgeorge said:

So just connecting the Rh and W wires no issues, but when You wire the programmable
in with C wire things burn out. Hmm. On those old panels I do not believe they had a C or now its Black wire called out. So where is that common wire picked up?

This. If it works fine on batteries but not with the C wire attached, look at the C wire. My guess after just skimming things is that the C wire, isn't; or possibly the C wire off a different, out of phase, transformer.

Jamie Hall

On the wire test -- you have to test all four, wire to wire and wire to ground (so -- red tp white, green, blue; white to green, blue; green to blue and red to ground, white to ground, green to ground, blue to ground) and all those tests much 1 megohm or greater.

And I think you and I, at least, agree that the Ecobee isn't the problem -- and they take so little power it's very hard to see how it could overload the transformer.

wmgeorge

We cannot seem to get an answer, so does this unit have a AC or air handler hooked up also?? Granted the OP may not think it matters but when your troubleshooting, Everything Must be Considered. Speaking as someone who has been chasing naughty electrons since 1962.

jac34

Jamie Hall said:

On the wire test -- you have to test all four, wire to wire and wire to ground (so -- red tp white, green, blue; white to green, blue; green to blue and red to ground, white to ground, green to ground, blue to ground) and all those tests much 1 megohm or greater.

And I think you and I, at least, agree that the Ecobee isn't the problem -- and they take so little power it's very hard to see how it could overload the transformer.

Want to make sure I'm following this wire test. When you say ground, what do you mean? I have the whole wire off any connections and was just testing wire end to wire end with a probe on each end. How am I testing a color wire to ground? I only get numbers close to 0 when its the same wire with a probe at each end.

jac34

wmgeorge said:

We cannot seem to get an answer, so does this unit have a AC or air handler hooked up also?? Granted the OP may not think it matters but when your troubleshooting, Everything Must be Considered. Speaking as someone who has been chasing naughty electrons since 1962.

This particular stat is only running boiler for heat on 1st floor, nothing else.

Jamie Hall

jac34 said:

Jamie Hall said:

On the wire test -- you have to test all four, wire to wire and wire to ground (so -- red tp white, green, blue; white to green, blue; green to blue and red to ground, white to ground, green to ground, blue to ground) and all those tests much 1 megohm or greater.

And I think you and I, at least, agree that the Ecobee isn't the problem -- and they take so little power it's very hard to see how it could overload the transformer.

Want to make sure I'm following this wire test. When you say ground, what do you mean? I have the whole wire off any connections and was just testing wire end to wire end with a probe on each end. How am I testing a color wire to ground? I only get numbers close to 0 when its the same wire with a probe at each end.

What I'm looking for is -- when the wire is in place, but not hooked up at either end, there should be no connection (resistance greater than 1 megohm) between any of the four wires and any other of the four -- that's the first part -- or between any of the four wires and "ground" -- that is to say, the ground connection of the house switchgear -- most easily, probably, the bare copper wire in a handy junction box, although in most cases all the metal associated with a boiler is bonded together and could be used.

Your end to end test on the same wire is useful -- it indicates that the wire is intact -- but it doesn't identify any possible shorts between wires.

The underlying premise is that something, somewhere, shorted out the transformer -- that is, managed to connect the two output connections (the 24 VAC connections) directly to each other. That is -- directly through a wire or wires, of course. And the question we are trying to solve is what and where is that connection? With the wire testing I'm trying to eliminate -- quite systematically -- the wires between the Taco board and the thermostat.

Every possibility I can eliminate is a step ahead.

There is one possible misconnection to the base of the thermostat -- not the thermostat itself -- which could be a problem: if the common wire and the white wire are swapped at the base, when the thermostat asks for heat it will make a direct connection between the red -- hot -- wire and the common, which will short the transformer. However, if the temporary replacement is working properly connected to the red wire and the "white" wire (it may not be white), that would seem to not be the case. Sadly, there are a number of other misconnections which are possible and which could cause the trouble -- and the only way to track them down is to systematically go through the whole thing, wire by wire, connection by connection, to be sure that one has found the problem. Among other things it is essential to understand how it should be wired, obviously!

SuperTech

Maybe I missed something, but in the last picture you posted you have a wire to RH as well as RC but I don't see a G wire or Y wire that go along with RC. Maybe that is the problem?

jac34

SuperTech said:

Maybe I missed something, but in the last picture you posted you have a wire to RH as well as RC but I don't see a G wire or Y wire that go along with RC. Maybe that is the problem?

This stat is only running heat from a boiler, no a/c or anything else. the other wires are going to the board for 24v power to run the ecobee stat

Shane_2

If the Ecobee is only controlling one zone of heat only, why are 4 wires needed? And why is anything hooked up to Rc? Isn't that Red cool?

SuperTech

Shane_2 said:

If the Ecobee is only controlling one zone of heat only, why are 4 wires needed? And why is anything hooked up to Rc? Isn't that Red cool?

Exactly. It looks like RC and common are on different wires. 

jac34

This is how the wiring was set up and installed for yrs with no issues. When our boiler was replaced in 2018 the installers set everything up and has been fine since 2018. All of sudden, the stat is blank and the transformer blew over the weekend.

The green and blue were connected on the relay board as shown in pic attached, red/white run the circulator for that zone. Never had a problem with this set up so I can't answer the questions as I didn't connect it that way.

U can see in the pic where the wires from that Tstat are going, the green (common) and blue are going into the 24v terminals and the red/white are on the zone control for the circulator.

jac34

jac34 said:

This is how the wiring was set up and installed for yrs with no issues. When our boiler was replaced in 2018 the installers set everything up and has been fine since 2018. All of sudden, the stat is blank and the transformer blew over the weekend.

The green and blue were connected on the relay board as shown in pic attached, red/white run the circulator for that zone. Never had a problem with this set up so I can't answer the questions as I didn't connect it that way.

U can see in the pic where the wires from that Tstat are going, the green (common) and blue are going into the 24v terminals and the red/white are on the zone control for the circulator.

Forgot to mention, they fuse you see is what the tech put on after his theory that the ecobee was the issue and this was there to protect the board...which it did not b/c it blew again when I put it on

Jamie Hall

Maybe we are getting somewhere. Besides concluding that your tech. is obviously well out of his depth.

An Ecobee set up for heating only needs ONLY three wires. Normally they would be red, to rh; white to wh, and green to common. At the other end -- the board -- rh would be to the one of the hot controlling terminal on the controlled zone, and white to the other controlling terminal (I'd have to look at the specific board for labels) and green to common.

I haven't the slightest idea what you are using that fourth wire for, but it could be a problem...

wmgeorge

FYI Normal T'stat wiring color code and landing point same color is: Red Rh Heating power wire to stat, Red Rc Cooling power wire to stat, W1 or just W heating terminal W2 2nd stat heating terminal Green on G is Fan control to furnace or air handler NOT 24 volt common. Blue on B may be Heat/Cool changeover and I have seen used to switch a damper motor, C is Black terminal used to bring the Other (common) side of the transformer to the new digital T'stats that need power to run instead of battery.

IF your using green tstat wire from the panel connected to G which is the fan terminal as Common or Black there is your problem.

jac34

This is how ecobee recommends it be wired which it has been all this time with no problems so I don't think it would just randomly fry the transformer. They looked at that wiring and had no issue with it. See pic from ecobee website which is how it's wired.

Also included a close up of how the blue/green wires were wired on the board into the 24v terminal.

Jamie Hall

The highlighted description in the Ecobee instructions above applies to using an external 24 VAC transformer to power the Ecobee in the event that the controlled device -- in this case the Taco board -- does not have a transformer.

The Taco has a transformer. Providing additional power to the Ecobee other than through the R connection has the potential to create some possible short circuits through either the other connections on the Taco board or through the Ecobee. This would let the smoke out of the transformer.

Since we otherwise seem to be making little progress, we may have to use a bigger hammer. Put a fuse rated at no more than 1 amp, fast blow, on all four wires and connect up the system. Then when the fuse blows you won't fry the transformer and you will know where to start finding the short.

wmgeorge

Maybe you did not read what I wrote. The G wire terminal on the Tstat can not be used as a power connection of any kind, it feeds only the Fan relay on a furnace or air handler. Feeds from the R terminal or Rc. 
The C or black terminal on the tstat is where the other side of the power transformer should be. Thats it. If you are feeding power into the G wire that is Wrong.

jac34

Jamie Hall said:

The highlighted description in the Ecobee instructions above applies to using an external 24 VAC transformer to power the Ecobee in the event that the controlled device -- in this case the Taco board -- does not have a transformer.

The Taco has a transformer. Providing additional power to the Ecobee other than through the R connection has the potential to create some possible short circuits through either the other connections on the Taco board or through the Ecobee. This would let the smoke out of the transformer.

Since we otherwise seem to be making little progress, we may have to use a bigger hammer. Put a fuse rated at no more than 1 amp, fast blow, on all four wires and connect up the system. Then when the fuse blows you won't fry the transformer and you will know where to start finding the short.

Why are there two wire connectors on the 24v transformer if you only need one? Just curious why they were both in there and the tech told me to connect it back up the same way? It also says for boilers with zone valves; I have 3 zones using circulators, would that be considered the same set up as a zone valve?

Also did the wire test you suggested and the only time I got a reading was when same wire was tested end to end. The other tests to ground just showed 0L

jac34

wmgeorge said:

Maybe you did not read what I wrote. The G wire terminal on the Tstat can not be used as a power connection of any kind, it feeds only the Fan relay on a furnace or air handler. Feeds from the R terminal or Rc. 
The C or black terminal on the tstat is where the other side of the power transformer should be. Thats it. If you are feeding power into the G wire that is Wrong.

Thanks, it's going into C, not G...not using G at all

jac34

Jamie Hall said:

The highlighted description in the Ecobee instructions above applies to using an external 24 VAC transformer to power the Ecobee in the event that the controlled device -- in this case the Taco board -- does not have a transformer.

The Taco has a transformer. Providing additional power to the Ecobee other than through the R connection has the potential to create some possible short circuits through either the other connections on the Taco board or through the Ecobee. This would let the smoke out of the transformer.

Since we otherwise seem to be making little progress, we may have to use a bigger hammer. Put a fuse rated at no more than 1 amp, fast blow, on all four wires and connect up the system. Then when the fuse blows you won't fry the transformer and you will know where to start finding the short.

He put fuses on both sides of the transformer but they are 5 and 3 amps so not sure if I should try it again for fear of another failed transformer and I lose heat again. I was on the phone with them today and they aren't coming out right away since I have heat and we are in a dispute over the bills I received so far...these guys installed my boiler and rezoned my house and did a great job back in 2018 so I'm confused why they are having such a hard time with this one.

wmgeorge

What is the Va of the transformer ? I would try a 2 amp or smaller. Ok I understand no connection to G, good news. Now guessing that that Blue and Green on the board is the transformer 24 vac, can you confirm with a voltage reading? Red & White are the zones? Red wire there Should be the same as Blue wire connected just above.  No reading between?  Guessing again that green feeds the  Tstat  C or Black terminal . 

Daveinscranton

I have followed this thread.  I do believe that you are sneaking up on it.  With sage and kind help.  From very capable people.

My advice is philosophical in nature.  Most of my misfortunes in life, I have played a part in.  Painful admission.  Almost all.  

When this is resolved, and it will be, I would immerse myself in basic electronics and controls books and studies.  Time better spent than disputes over money etc.  Leads to unhappiness.  A great education is being had.  Education is expensive.  One way or another.  I have a mountain or two of ruined parts.  Part of my education.

These problems are more easily deciphered hands on.  Last thought is persistence.  Without frustration or anger.  It will work.

Best wishes 

jac34

Daveinscranton said:

I have followed this thread.  I do believe that you are sneaking up on it.  With sage and kind help.  From very capable people.

My advice is philosophical in nature.  Most of my misfortunes in life, I have played a part in.  Painful admission.  Almost all.  

When this is resolved, and it will be, I would immerse myself in basic electronics and controls books and studies.  Time better spent than disputes over money etc.  Leads to unhappiness.  A great education is being had.  Education is expensive.  One way or another.  I have a mountain or two of ruined parts.  Part of my education.

These problems are more easily deciphered hands on.  Last thought is persistence.  Without frustration or anger.  It will work.

Best wishes 

Appreciate the kind words and couldn't agree more. I'm trying to learn so I don't have to depend on others all the time, would rather just understand it myself. The problem is time, which I've spent way too much here, but as you say, education is expensive and time is money.

I do appreciate all the insight here as I do not know 1/3 of what most do on here but I find it interesting so here to listen and learn...

jac34

wmgeorge said:

What is the Va of the transformer ? I would try a 2 amp or smaller. Ok I understand no connection to G, good news. Now guessing that that Blue and Green on the board is the transformer 24 vac, can you confirm with a voltage reading? Red & White are the zones? Red wire there Should be the same as Blue wire connected just above.  No reading between?  Guessing again that green feeds the  Tstat  C or Black terminal . 

The blue (Rc on ecobee) and green (C on ecobee) on the board is coming from the Tstat which is what is powering it, green is labeled common. Red/white are going to the zone 1 control.

The first 2 pics below show the specs for the transformer: One labeled taco is the original one that is tied to the board. The one labeled temp is what they put on after the board transformer died. The last pic shows the close up of the red/white wires coming from Tstat.

wmgeorge

Too late here to think it all out and its as I suspected. The Blue should feed the R or Rh not Rc as it should be  the Red (and marked as such) wire.  I suspect its the same as the Red wires feeding the Zones but I need to do a bit more thinking and research. 

coby

I don't like that your sending power to rc and rh. This may be your issue. If you have ecobee 4 unhook the blue wire from rc and put the red wire in rc. leave blue wire unhooked and see how that works. If you have a ecobee3 unhook the blue wire from rc and leave the red wire in rh. that will work for ecobee 3. leave the w and c wires where their at. That may be your issue. Also check that the ecobee is set up in the settings correct. Let me know.

SuperTech

Your tech should have installed the Taco SR504 EXP. Each thermostat connection has its own R,W and C terminals. That would make the wiring simple and easy. That current zone control wiring is a mess and isn't correct. 

wmgeorge

Found the diagram and added color and text, you only need 3 wires to the Tstat. Remember this was designed for a simple T87F before digital, you do not need the blue wire which is really a RED wire. They sell and I use wire markers all the time. Home Depot has a professional wiring supply department.

You need to verify all with a good meter and I would put as suggested not over a 2 amp fuse on the 24 volt secondary, if you have a 1 amp for troubleshooting please use.

wmgeorge

Added pictures of the DIY fuse holder for automotive fuses and wire markers.

jac34

wmgeorge said:

Found the diagram and added color and text, you only need 3 wires to the Tstat. Remember this was designed for a simple T87F before digital, you do not need the blue wire which is really a RED wire. They sell and I use wire markers all the time. Home Depot has a professional wiring supply department.

You need to verify all with a good meter and I would put as suggested not over a 2 amp fuse on the 24 volt secondary, if you have a 1 amp for troubleshooting please use.

Thanks for the info. Got a level 2 support tech from ecobee on the phone today that seemed to clear some of this up.

The current 4 wire set up that I've been running is fine, if you only had 3 wires and didn't want to run a new wire, you can use your diagram above. He explained that the 4th wire just isolates it, but that's how it was always connected with no problems.

Last night just to rule out the Tstat base, I unhooked the temporary battery operated Tstat (not connected to the transformer) and put the ecobee base plate back on with the kitchen ecobee that never had any issues; worked fine, no fuses blew. I checked the 2 terminals at the base plate that are coming from the COM (green wire) and 24VAC (blue wire) on the board and got a 24v reading at the base plate. Went another step forward and put the original "culprit" ecobee back on the base where it all started...worked fine, no fuses blew.

So it's working as it was with the temporary 40va 24vac transformer that they installed as a temp fix. So it's back to it's original set up. Questions still unanswered are what caused the original transformer to fail and what caused the replacement to fail quickly once I put the ecobee back on it??

Ecobee tech had a few thoughts...the original transformer on both taco boards was 15va, they recommend 40va, especially if you are running circulators. The temp transformer is 40va so maybe that's why it's now fine? And I checked the transformer on the other air handler that took the ecobee fine and it is also a 40va. He thought that maybe the 15va couldn't handle the 3 circulators + the ecobee which is why they recommend wiring it separately into a plug in transformer for dedicated power or upgrade the board that has dedicated common terminals for each zone as someone mentioned above. But again, had it set up this way for 3 yrs no problem. I understand why it may have eventually failed, but not the second transformer that went up in minutes.

The next unanswered question may be answered above. What caused the second one to go when I put the supposed "culprit ecobee" back on the base? Maybe the load was too much and killed it quickly?? We will probably never know but the HVAC tech is sticking to his guns that the ecobee killed it. Which I guess in some ways it did if the va rating was too low, but then again, they installed this board originally and then put the same one on a second time. They are blaming me for connecting it back up so I guess we will have to work this out. I see their point, but why don't they know these things considering smart thermostats are a very common type of Tstat these days and they do this every day?? I'm not trying to rip anyone off, I appreciate what they do, but don't see how I am responsible for the $350 charge for a second board they installed. Wouldn't they thought to possible wire the Tstat on dedicated power or put in a board that could handle it??

Any input is appreciated and thank you all for your help. My head hurts after all of this but I def learned some things. I'm just going to wait and see what this does and if the 40va fails then I'm at a loss again.

wmgeorge

The diagram I posted is straight from Taco why would you need the blue wire?? Its the same as that Red wire in the Zone connections?  The wires should be marked correctly, in my 60 years of wiring, if not marked someone will connect it wrong and burn something up.... again.

jac34

wmgeorge said:

The diagram I posted is straight from Taco why would you need the blue wire?? Its the same as that Red wire in the Zone connections?  The wires should be marked correctly, in my 60 years of wiring, if not marked someone will connect it wrong and burn something up.... again.

Good question, don't think I really know either but that's what ecobee tech support said and that's how the professional tech connected it. I sent them pictures and they said it was fine. I didn't set it up originally, only took pics of how it was wired before I reconnected it and just put it back the way I found it.

When they put the new board back on, they told me to connect it that way too so if it's wrong, then that's on them. Still trying to understand why they even put this board in originally if it doesn't have the power needed to run everything. I may just purchase the SR504-EXP myself and put it in myself. Enough wasted time already...

wmgeorge

I agree on leaving the 40 VA transformer in and I would place the fuse suggested in the circuit. The 15 VA might of been just fine 30 years ago, but not today.

Zman

I had a similar issue a few years back and it turned out to be a short between Rh and common probably caused by a pinched wire. Fortunately, I had an extra conductor as you do and was able to make it work.

jac34

wmgeorge said:

I agree on leaving the 40 VA transformer in and I would place the fuse suggested in the circuit. The 15 VA might of been just fine 30 years ago, but not today.

Board only 3.5 yrs old. Guess it got tired fast 

HomerJSmith

I did ask you what that black (blue actually) wire was connected to the Rc connection on the base and I didn't get an answer. If the latest group of pics is correct and the blue wire is connected to the C connection on the Taco, there's your problem. The Rc is like the Rh connections, they are both the 24 Vac power connections not the C common connection. The C (the green wire) connection on the Ecobee should be connected to the common where the blue wire is connected. Disconnect the blue wire on the Ecobee and from the Taco common as it isn't needed and connect the green wire to the common. Read my third post. You have a direct short on the secondaries of the transformer. That's all the news fit to print! Of course, "I'm often wrong, but never in doubt."

Heck, what's the green wire to the 24 Vac connection on that Taco terminal? You could have drilled out the pop rivets on the transformer and used a nut and bolt to put in another transformer, easy peezy.

Jamie Hall

An overloaded transformer may not fail immediately, or even relatively quickly. The way they fail is damage to the insulation on the windings, and that comes about from overheating. The transformer is built to take a certain rated current without raising the temperature to the point where the windings are damaged, but if the transformer is asked to carry more current, it will overheat. A short peak usually isn't a problem, but long term overload, even a very small one, will eventually degrade the insulation to the point where the windings short out -- and that's the end of that. This can take several years, even!

wmgeorge

HomerJSmith said:

I did ask you what that black (blue actually) wire was connected to the Rc connection on the base and I didn't get an answer. If the latest group of pics is correct and the blue wire is connected to the C connection on the Taco, there's your problem. The Rc is like the Rh connections, they are both the 24 Vac power connections not the C common connection. The C (the green wire) connection on the Ecobee should be connected to the common where the blue wire is connected. Disconnect the blue wire on the Ecobee and from the Taco common as it isn't needed and connect the green wire to the common. Read my third post. You have a direct short on the secondaries of the transformer. That's all the news fit to print!

What pictures are you referring to? The wiring diagram I posted above is correct.

HomerJSmith

wmgeorge, Yes you were. I did look at that. I should have joined Zman and given you an agree. Mea Culpa.