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Thanks for responding. The controller has two "R" terminals with nothing connected.
The "B" terminal has a wire on each terminal. I believe this makes up the
24 volt circuit to start and fire the boiler. The "W" terminal has a wire
on each terminal - I believe one is stage one and the other is stage two.
I did lift what I believed was stage one wire and the boiler turned off.
Please explain why this would indicate changing the temp controller?
Also whenever I had stage two going, I turned the controller all the way down and it would NOT TURN off.
These parts cost approx. $277.00, I would like to get this right. Is there any other part that would cause this problem?
I pulled the brown wire off the gas valve and the unit shut down - which is what it is supposed to do.
What is the other way to verify this is the part that needs replacing?
Hello again! Thanks for the excellent rating.The control operates by breaking the circuit the two wires that go to the switch ... verify the switch by looking at the wiring diagram on the temperature control.... by removing one of the wires you are simulating the switch opening. So we know that it is the control failing to open the switch when it should.You should try that a dozen times or so... it takes a while to format ones thinking patterns in these regards.... then it becomes obvious. _________________.if it is failing to break the circuit that energizes the gas valve when the temperature of the boiler water is above the thermostats set point.... then either the contacts are fused closed...or the sensing element is not sensing the water temperature.If the sensing element is 3/8 or 1/2" diameter copper bulb, it is full of refrigerant. When the refrigerant warms up it puts pressure on a diaphragm inside the controller and that is mechanically linked to the switch that the wires are connected do.If the sensing element is electronic it is called a 'thermistor'.. and is 1/4" in diameter, chrome plated as a rule and has an insulated set of wires going to it.... *not a thin copper tube.Let me know which you have, . We can go from there.Phil
I have the 3/8" diameter copper bulb. According to the schematic one "W" terminal on the controller goes to the first stage and the other
"W" terminal goes to the second stage. It looks as though the two "R"
terminals make and break the 24V control voltage.
Please tell me if you think there is any other part in this system that could give this symptom before I purchase the controller, etc. tomorrow. This would be an expensive mistake and very disappointing.
The only other components to choose from, in my opinion, would be the
gas valve and maybe the electronic controller. It seems as though the
temp controller is the component that actually removes the 24V to turn
the boiler off ---- IS THIS CORRECT?
Thanks for your help. I will be installing the temp controller tomorrow,
so I may have a couple more questions.
Thanks for the follow-up suggestion about using the heat conductive
paste. I figured I needed this whenever I removed the old one. I was
hoping there would be enough residue from the old bulb! I did not
realize I needed this.
I installed the temp controller on Monday and everything has been
fine. I will keep you posted.
Thanks for being so conscientious - your help is appreciated.