Oil burner/taco valves

ROBBINJE1

I have a Honeywell aqustat l7224u it has a 24 volts to terminal TT also I have a remote 24 volt transformer that is connected to the terminal TT, is that ok for two transformers connected in parallel 

EdTheHeaterMan

NO

You need to show the diagram or pictures of the wiring

TT on that L7224U control is for a thermostat to open and close the circuit.

When Zone valves get involved it can cause the smoke to leave one or both of the transformers.

What zone valves are you using?
Are you using a zone control panel?
...or just wiring the zone valves and transformer with that spaghetti of wires and wire nuts?

We will help you to get it right.

Jamie Hall

T-T can be connected ONLY to the contacts of an aquastat or thermostat, or dry contacts of a relay. If you haven't already fried your control, you will by your description. NEVER APPLY AN EXTERNAL VOLTAGE TO T-T

Jamie Hall

Double post. And the answer here is the same as the other one: no, it is not correct.

Big Ed_4

The red wires from zone valve are wired in Parallel to tt . The remote transformer it wired in series to thermostat and zone valves , Transformer -RH in thermostat- W in thermostat -yellow wire zone valve .Other yellow wire zone valve - common transformer . The one in the aquastat will power the control with oil , with gas it will power the gas valve .. Tip , wire in a three amp fuse to protect the transformer .

Erin Holohan Haskell

Jamie Hall said:

Double post. And the answer here is the same as the other one: no, it is not correct.

I merged these double posts. Thanks.

EdTheHeaterMan

What Zone valves do you have? Honeywell



The wiring on some of there are different than the wiring on others.

also if you place a 3 AMP automotive fuse on the R terminal of your transformer then place all the wires removed from the R terminal on the other end of the fuse with a wire nut, you will save your transformer from failure while trying to connect to the system. Just in case you make a mistake

ROBBINJE1

ROBBINJE1

This picture is of what I have on oil burner in regards with two transformers in parallel 

Jamie Hall

The remote transformer, assuming your sketch is correct, is powering the thermostat and the zone valve. I don't see another transformer?

EdTheHeaterMan

This the second time you started a new discussion with the same question. You will not get a different answer no matter how many times you ask. Now that I know what zone valves you have I can offer this.

Your wiring should look like this

Just because there are only 3 terminals on the Taco 571 actuator does not put the transformer in the Honeywell aquastat in a series circuit or a parallel circuit with the zone valve transformer.

Your diagram looks exactly like the factory diagram.

The problem will arise if you attempt to add a smart thermostat that requires the use of the C terminal from the zone valve transformer

OR

If someone swaps the #2 terminal with the #3 terminal on subsequent zone valves actuators. or you swap the R and the W on the thermostat, there may be a problem with transformer failure.

For the system wiring to not have a conflict with the transformer in the aquastat and the transformer for the zone valves you MUST make sure that all the #2 terminals are connected to the same T terminal in the aquastat and all the#3 terminals are connected to the other T terminal on the aquastat. I recommend that the R terminal on the transformer connect to the R on each thermostat and the W from the thermostat be connected to #1 terminal on the zone valve. The following illustration will be a problem.

Although any of the above wiring diagrams may be acceptable individually, when you combine different wiring designs on the same system, there Will be a problem with the transformer failure.

@Erin Holohan Haskell please merge this dicussion with https://forum.heatinghelp.com/discussion/189591/oil-burner-taco-valves#latest

EdTheHeaterMan

This the second time you started a new discussion with the same question. You will not get a different answer no matter how many times you ask. Now that I know what zone valves you have I can offer this.

Your wiring should look like this

Just because there are only 3 terminals on the Taco 571 actuator does not put the transformer in the Honeywell aquastat in a series circuit or a parallel circuit with the zone valve transformer.

Your diagram looks exactly like the factory diagram.

The problem will arise if you attempt to add a smart thermostat that requires the use of the C terminal from the zone valve transformer

OR

If someone swaps the #2 terminal with the #3 terminal on subsequent zone valves actuators. or you swap the R and the W on the thermostat, there may be a problem with transformer failure.

For the system wiring to not have a conflict with the transformer in the aquastat and the transformer for the zone valves you MUST make sure that all the #2 terminals are connected to the same T terminal in the aquastat and all the#3 terminals are connected to the other T terminal on the aquastat. I recommend that the R terminal on the transformer connect to the R on each thermostat and the W from the thermostat be connected to #1 terminal on the zone valve. The following illustration will be a problem.

Although any of the above wiring diagrams may be acceptable individually, when you combine different wiring designs on the same system, there Will be a problem with the transformer failure.

@Erin Holohan Haskell please merge this discussion with https://forum.heatinghelp.com/discussion/189591/oil-burner-taco-valves#latest

ROBBINJE1

Thanks for your response, I was only questioning the fact that there is two 24v sources on terminal TT on the Honeywell controller,it seems different then I am used to, I am a retired electrician/ consultant and paralleled many bigger transformers, they were always the same impedance. Thanks again for you help  

Erin Holohan Haskell

EdTheHeaterMan said:

@Erin Holohan Haskell please merge this dicussion with https://forum.heatinghelp.com/discussion/189591/oil-burner-taco-valves#latest

Got it. Thanks.

Jamie Hall

ROBBINJE1 said:

Thanks for your response, I was only questioning the fact that there is two 24v sources on terminal TT on the Honeywell controller,it seems different then I am used to, I am a retired electrician/ consultant and paralleled many bigger transformers, they were always the same impedance. Thanks again for you help  

There aren't, really, if you actually follow the circuits through. The zone valves have three terminals. The upper two -- one and two -- require power (from that transformer shown) to operate the valve. The lower two -- two and three -- are a simple end switch. Now it happens that terminal two is shared between two completely separate circuits -- not a design I care for much, but there it is. So one circuit is the external transformer, the thermostats, and the zone valve motors. The other circuit is the internal transformer, the zone valve end switches, and the boiler control.

Perhaps if you think of terminal 2 as the neutral in a conventional 120/240 VAC power wiring it might help.