Need help with wiring thermostat -

clydesdale

Something is not happy with my thermostat wiring. I have 5 or wire thermostat wire going from a new thermostat to control my simple Modine garage heater that is hooked to my hot water boiler. I have a red wire, white and blue. The blue and white wires seem to have power. When I cross the white and red, I get the water circulating. But, I cannot seem to get this thing to work. I originally put the red in R the white in W and the blue in C. This powers up the stat just fine. But, when i called for heat, it blinked twice and that was all she wrote for that stat. I got a new stat and boiler guy said switch the red into W and the white into R. When I do this, I do not get power at the stat. Any thoughts?

clydesdale

My boiler transformer has a C and R terminal. The boiler guy hooked a blue wire from the R on the transformer to the blue wire in my thermostat wire bundle going to my thermostat. Could this blue wire need to be hooked to the C on the transformer instead?

HVACNUT

You're second post is a little confusing.
There is a stand alone transformer at the boiler or is it part of the aquastat or a switching relay?
I'm guessing a separate transformer and zone valves?
We might need some pics for this one. Thermostat, aquastat, switching relay(s) and connected wiring.

clydesdale

Here is the transformer. Thanks.

Zman

It sounds like you have a zone circ? Does it have a relay?
What tells the fan to turn on?

clydesdale

This is the wiring for the garage zone value.

clydesdale

In that wiring picture you will see two bundles of brown thermostat wire. One bundle goes to the stat and uses the blue, red and white. The other just uses the blue and goes to the transformer. The blue of the transformer is mated to the blue of the zone valve. I greatly appreciate all help. Thanks. The fan turns on by a aquastat at the Modine. It will kick on after hot water has circulated a bit. I think I have the lingo right on that.

Zman

The power needs to go from the R on the transformer to R on the t-stat. From the W on the t-stat you go to one side of the zone valve motor (yellow wire on Honeywell) The other side of the zone valve motor wires to the C on the transformer.
Think Power supply - switch- load-back to power supply.

Jolly Bodger

Like @Zman says. And if it is a digital thermostat, a third wire from C on the transformer to C on the thermostat. The R-C terminals provide the power circuit for the thermostat.

clydesdale

It is digital. The problem may be that the common goes from the R on the transformer to the c in my thermostat. If you look at the first picture, you will see the blue common goes from the R on the transformer. Do I need to switch this to the C ? The stat will only get power if I have the white wire in W and the red wire in R. I have only tried having the blue wire in C. Thanks.

Jolly Bodger

Was the old one Digital? If not the Red wire may be broken and the reason the Blue wire is on R. Try moving the Blue wire to C. That would be the correct wiring.

EdTheHeaterMan

I consider myself pretty good at control wiring but I can't make heads or tails out of this Modine heater from the picture of the transformer and the picture of the wire and a hand!

What is needed to be sure you don't fry any more electronics is a better idea of the actual places the wires attach.

not a picture of a couple of wires with a wire nut on them.

Pic of thermostat wire sub-base with the wires connected
Pic of what the thermostat controls (zone valve, circ relay, aquastat)
pic of what is on the pipes that go to the modine

If I could see what you got I can give you a job specific diagram.

I helped others with wiring problem, but need more info. see this post for how specific I can get on wiring
https://forum.heatinghelp.com/discussion/comment/1578144#Comment_1578144

clydesdale

OK, I will take more pics. I had used a regular battery operated thermostat for the test of the heater last year and it worked fine. The boiler guy then came back and added the C wire so that I could have this Wi Fi thermostat. I have not been able to get it to work. But, if we manually cross the red and white, the pex gets warm. I did not leave them crossed long enough to trigger the fan on the Modine.

Jamie Hall

Remember that electricity is colour blind. You need a wire which goes from common on the transformer to common on the thermostat. You need a wire which goes from hot on the transformer to hot on the thermostat (usually R, Rh, Rc) you need a wire which goes from the switched terminal on the thermostat (often W) to the hot terminal of the controlled device. You need a wire from the other terminal of the controlled device back to common on the transformer.

EdTheHeaterMan

Damn! I was going to say that Color Blind line. I used it in all my "Electric for HVAC tech." classes.
... ALSO... a wire is not a one way street!

it might go the other way (referring to sequence of operating and back feeding thru a device to cause operation of something or frying transformers and so on)
Because I now AC flows both ways 60 times every so often. (like per second)

mattmia2

Can you draw out a schematic showing the terminals on the xfmr, the zone valve, and the tstat showing what wires are connected where, especially the valve and xfmr and any wires between just the xfmr and valve, and between the valve and boiler?

EdTheHeaterMan

Look at post to see how a incorrect wiring job could make electricity go the other way to make something work.

https://forum.heatinghelp.com/discussion/176516/furnace-only-runs-with-fan-on-manual

In that case electricity intended for the fan to operate constantly via the fan-limit control... inadvertently powered up an oil burner primary control...

In your case I believe there is a situation where wires are just in the wrong places and you are applying 24V to contacts that have no load connected. From source to contacts that close back to source. This is a description of a "Dead Short" or a "Short Circuit". This scenario is going to Fry something for sure!

clydesdale

Blue is traced from the transformer all the way to the stat- blue is blue the whole way.

On the thermostat plate- red touched to white gives 26 volts. Blue to white gives 26 volts.
Blue to red gives zero volts.

However, the red from the transformer becomes white going to the thermostat.

The white from the transformer goes to the zone valve.
The red from the thermostat goes to the other zone valve wire.

At the transformer, the R terminal has a red wire, the C terminal has white and blue now. We switched the blue to the C terminal as previously suggested.

My brother is thinking that the red and white need to be switched at the thermostat.

Suggestions, thoughts, please help. Thanks for your help.

hot_rod

A simple sketch of the components, or pics of each would help.

You have a power stealing stat? Requires 3 wires R, W and a color, call it B blue

You have a stand alone transformer? R and C goes to the stat, C also goes to the zone valve, it's motor needs a common

B the switched leg of the t-stat also goes to the zone valve as the this energized the motor.

the Modine may have it's own transformer or fan center (relay with transformer)

if so the end switch on the zone valve would make that connection to start the fan. The fan probably has a temperature switch so the blower only runs when the coil is hot, so powering it may not cause the fan to run until it sees boiler water.

that leaves a boiler call needed, either from the Modine via an end switch or from the stat.

the boiler may also have its own transformer?

really not much we can add without knowing all the components, in a drawing or with pics.

This is a common transformer, stat, zone valve with end switch to call on a unit heater.

Zman

Zman said:

The power needs to go from the R on the transformer to R on the t-stat. From the W on the t-stat you go to one side of the zone valve motor (yellow wire on Honeywell) The other side of the zone valve motor wires to the C on the transformer.
Think Power supply - switch- load-back to power supply.

If you need a common, run another wire from the c on the transformer to c on the t-stat. Don't get too hung up on the wire colors.

clydesdale

Here is a pic of drawing.

Zman

Switch the R and W on the T-stat.
And buy your brother a beer

EdTheHeaterMan

The first thing that jumps out at me on @hot_rod diagram is ... If the red wire in on thermostat R terminal and the white wire is on thermostat W terminal, then you are going to fry something! But the letter C in the thermostat is a bit ambiguous/confusing.


@clydesdale diagram Is the way you want to do it after you switch R and W on the thermostat (see Diagram)... You need to power R on the thermostat all the time. W will turn on the zone valve motor when the thermostat calls.

...BUT it is important that all other zone valves match. Sometimes if a zone thermostat and zone valve are wired slightly different, they will work fine separately, but if both zones call at the same time you will get problems



If service tech Carl likes to do Zone Valves one way, and Service Man Joe comes and fixes the indirect water heater zone in the summer a different way, then come October a thermostat or transformer gets fried. It is because Joe did not follow Carl's design. Joe's way works all summer, then Joe blames Carl for doing it wrong. But Carl was there first!

POINT BEING. ALL ZONES MUST BE IDENTICAL

If Transformer R gets connected to Thermostat R on one zone... all other zones need to be the same.

Check the other zones for the way they are wired.

EdTheHeaterMan

Especially when there are several 24 V transformers involved.

Murphy's Law # 63 If you have multiple control transformer on one thermostat control system. Your mis-wiring will burn out the more expensive transformer! (you know the one on the $400.00 circuit board)

HomerJSmith

Zman's right. And right about the beer. too.

clydesdale, the charging circuit on the T-stat is thru the R & C connection. The ZV operation is thru the R & W connection. There is no circuit between the W & C connection on the T-stat. Both the charging circuit and the ZV circuit get their power from the R connection on the transformer and the path back to the C connection on the transformer. One thru the charging circuit and one thru the ZV.

Your drawing show that the only time the T-stat Charging circuit is powered is when the ZV is operating and the voltage is low because the ZV motor is zapping it.

Your diagram works perfectly for the ZV and when you jump the R & W on the T-stat you are just closing a ZV circuit energizing the motor.

HomerJSmith

If you have two transformer controlling one circuit as, EdTheHeaterMan says, both transformer must be on the same electrical sub-panel buss. There are 2 busses in a panel. Connect 2 transformers to different busses and you get 220V thru equipment that is supposed to operate on 110V. That pretty much fries everything. That being said, the transformers must be the same polarity and phasing when hooked together. How to do it? see below.

clydesdale

Thanks guys. I owe my big brother way more than a beer at this point in life. Thank you to all of you as well. This forum has always been very helpful. Thanks again.