Need help please with wire connectors to get hydronic heater to function.

monkeymachine

Hello friends,

I have been trying to get my family's hydronic heating system back online. My dad has been helping me because he is more technical and has had some experience with this heating system when he lived here.

Note. I have tried researching a solution myself and have failed to find a solution. This is my first post ever on a forum.

When I supply the heating system with power and a call for heat through the thermostat, it does not kick on unless the wire connectors (circled in yellow) are jumped with external power. Suspecting they needed power, my dad had jumped these wire connectors with 24v from the transformer on the wall. He says it bypasses the safeties of the heating system to force it on.

He says that the system needs to be wired correctly so that the safety systems in place can function correctly and allow the heating system to turn on.

He says he does not see how the safety mechanism(circled in black and red) is getting power to function correctly. He says that either the last two wire connectors(circled in yellow) need to go someplace for power or else these wires are for diagnosing/testing the system in which case he is more unsure how the safety mechanism(circled in black and red) is getting power.

I believe the safety mechanism(circled in black) he is referring to is a high limit aquastat. The model info is White Rodgers 11B02-1 Style V20. It seems to have a surface type temp sensor. I don't know what the safety mechanism (circled in red) is (I don't have the cover plate with model info), but the aquastat above it connects to it and this mechanism seems to have a sensor probe into the pipe it attaches to.

Two wires ultimately run down from this mechanism(circled in red) to attach to wires(circled in blue) at the bottom.

Main questions.

-Do these wires(circled in yellow) need to connect someplace? Where to?
-What does the unit circled in red do exactly?
-How do these units(circled in black and red) get any power? Is there something else needed to correctly wire the safety mechanism(circled in black and red) to the heater to allow the heater to function correctly?

Other relevant information.

-The heater is a Dunkirk Radiator Corp Series XEB-5, Boiler Model. No. XEB-5.
-The aquastat relay is a Honeywell L8148A.
-I attached a photo of the wiring diagram that was attached to the heater.
-I attached a pdf of the white rodgers aquastat I found on supply house which contains a wire diagram as well.
-I included closeup photos of nearby units for more info.

Zman

If you temporarily cross those wires, does it fire?
Any idea what they were connected to in the past?
The safeties on that are probably wired in series (daisy-chained). You can use a multimeter and figure out what is breaking the circuit.

JUGHNE

Have those loose ends of wire always hung out like that?
Does the inducer fan run during any of these experiments?

I am thinking you should get a boiler control person there to fix and check this up.
Not a plumber and maybe not a HVAC furnace person but a hydronic boiler repairman.

monkeymachine

Zman said:

If you temporarily cross those wires, does it fire?
Any idea what they were connected to in the past?
The safeties on that are probably wired in series (daisy-chained). You can use a multimeter and figure out what is breaking the circuit.

Crossing the the wires does not help.
Don't know where they were connected to. My younger brother who lived in the house in the past said that a technician may have came over in the past and put those wires(circled in yellow) on.
My dad says he thinks the high limit aquastat needs to be wired with the aquastat relay to the heater for the circuit to be complete/correct. He says there may be something missing or not wired in correctly perhaps from the technician who possibly came in before.

EBEBRATT-Ed

@monkeymachine

You have the wiring diagram there to follow. The one component that I don't see is a 120-24 volt transformer which is wired to B1 & B2 on the Honeywell aquastat relay.

I think you will be better off calling a service tech in for help.

monkeymachine

JUGHNE said:

Have those loose ends of wire always hung out like that?
Does the inducer fan run during any of these experiments?

I am thinking you should get a boiler control person there to fix and check this up.
Not a plumber and maybe not a HVAC furnace person but a hydronic boiler repairman.

We don't think the loose ends of wire have always hung out like that. We think a technician may have came in the past and put them on and left them.
The inducer fan turns on when I turn up the thermostat with nothing else attached to the wires(circled in yellow). After jumping the wires, the inducer fan turns on along with the rest of the system.

monkeymachine

EBEBRATT-Ed said:

@monkeymachine

You have the wiring diagram there to follow. The one component that I don't see is a 120-24 volt transformer which is wired to B1 & B2 on the Honeywell aquastat relay.

I think you will be better off calling a service tech in for help.

My dad will take a look at that wiring when he stops by this evening. He says that there is still the problem of the whole thing not being wired in series.

HVACNUT

Jump the thermostat terminals on the aquastat. What happens?
Those wires go to the thermostat, as well as something else. Where else do those wires go?
Also what is the purpose of the clamp on aquastat on the pipe?

rick in Alaska

If you do jump the terminals in the aquastat, take at least one of the wires off first. Some thermostats with an anticipator will fry right away if you don't.
Rick

STEVEusaPA

I just had this conversation with a control expert. He claims jumping the thermostat without removing the wires will not hurt the anticipator. But it will mess with any learning thermostat and throw off the algorithm.

monkeymachine

Thank you so much for the responses. We're going to get a service tech to come in. I will update afterwords.

EdTheHeaterMan

You are missing a part. My guess is when the new Aquastat was replaced, the repairman discarded it. It is a 24 V transformer.

It looks like the part on the right of this picture and it gets mounted in the unused hole indicated

You can get the part from a local suppyhouse. the part number is AT140A1000

The black and white wire coming out the other side gets wired to B1 and B2