Need source for 24v Transformer - 4600-01V04AD31 and Oil Primary Control - R7284U

PM_15106

Armstrong Oil Furnace - LUF80C84/95D16-1A
Serial - 8403F13475

Need source for 24v Transformer - 4600-01V04AD31.
The transformer is starting to bum/buzz loudly and is very warm/hot to the touch.



Also need a source for the Oil Primary Control R7284U.
I'm replacing a R7184B-1032 and I see that the R7284U is what should be used.

I read where the R7284U LIMIT must be powered for the unit to work.
Does the new R7284U include a jumper to connect to the adjacent L1 spade?
Or do you just splice into the L1 and wire to the LIMIT?
Thanks for your help!

SuperTech

Supply house.com should have those parts. Wiring the R7284U depends on the wiring of the furnace.  Also setting up the R7284U depends on the furnace.  It's not ready to go out of the box. 

mattmia2

hot and buzzing sounds like it is overloaded or the output is shorted(although some amount of hot is normal if you are drawing near its limit). buzzing cam also be normal if the parts get loose. checking what current is being drawn and the output voltage is the first step.

PM_15106

SuplyHouse.com does not have the 24v Transformer - 4600-01V04AD31.
Any ideas as to where I can find one?

mattmia2

they may not have that part number but they certainly have a 40 va 120v primary 24v secondary foot mounted transformer. if you want one with the fan and ac terminals you can buy a fan center and take the transformer off of it

109A_5

Hello @PM_15106,
I think you will find that transformer unit is not made any more. They have come up with something better, no screws.

4600-02M12AE52 - Aftermarket Upgraded Replacement for Tyco Furnace Transformer
https://www.amazon.com/4600-02M12AE52-Aftermarket-Upgraded-Replacement-Transformer/dp/B079LPHHYN

You may have to go with a unit with wires and use some wire nuts for the connections. Many options but an exact replacement probably will be NOS if you can find it, I could not.

PM_15106

109A_5 - Thanks for the link to the transformer.
Looks like it will fit and is wired the same using spade connectors.

Question - the transformer installed now appears to be quite warm even when the furnace is not running,
Apparently, it is wired so that it has voltage constantly applied.
Is that correct?
Seems that it should only need power once the furnace starts to run.
The furnace had a recent service and all the operating specs, temp, etc. were checked and set.
Not sure if this was something that the tech missed.

109A_5

Hello @PM_15106,

On a warm day (or when you don't need the boiler) disconnect the wires on the secondary of the transformer, see it it cools down in a few hours. A warm transformer may be OK, but not hot. You could measure the load current too. Standby load current should be zero or very low.

Typically 120 to 24 VAC HVAC and similar doorbell type transformers run continuously. Most old doorbell transformers will be stone cold. If the transformer is not powered up all the time and the control power is 24 VAC what would power up the transformer at a call for heat ?

It seems over the years to cheapen transformer manufacturing they have reduced the turns on the primary and secondary maintaining the correct turns ratio also making the wires as thin as possible. The side effect is they run warm even with no load. Less expensive to make (less copper per transformer) and the manufacturer does not pay the electric bill of the end user.

mattmia2

an electronic thermostat or other microprocessor controls might be running all the time and drawing fro the control transformer. if something is overloading the transformer the secondary voltage will fall below 24vac so measuring between r and c will indirectly tell you if it is overloaded. also might be a vent damper that is sticking.

EdTheHeaterMan

By looking at this wiring diagram in the I/O manual for your furnace, It appears that the 24v Transformer - 4600-01V04AD31 almost always has 120 V power to the primary terminals. The normal operation of the furnace requires this to have power so the secondary 24 VAC is available for the thermostat to power any heating, cooling or fan relays to operate. As a result of having constant power to the primary and secondary windings, one of the byproducts of using electricity in this way is heat energy. To determine how much heat is generated you would need to do some advanced calculations to answer that question. I never needed to do those calculations because I did not care about this particular nominal byproduct of electrical energy use.


This diagram shows the path of 120 V from the source (Red Box) in black, thru several connectors, limits, and relay terminal wire connections ending at the 120 VT primary on the transformer. The return path to the source (Red Box) is indicated in a light gray line to indicate the white common wire.

To further understand the diagram of your furnace I have indicated the 24v Transformer - 4600-01V04AD31 in a blue box. (2 blue boxes). The green box indicates the R7284U Primary safety control. (sometimes called a Protecto-relay)

In your situation as a professional I would substitute a Carlin 70200 relay for the R7284U. the Carlin has many more diagnostic features that were not available when the R7284U was introduced.

I would substitute a https://www.supplyhouse.com/Rheem-47-19807-04-Transformer-Fan-Center-90-113?_br_psugg_q=47-19807-04 for the 24v Transformer - 4600-01V04AD31 in order to have all the terminals indicated in the photo you provided.


My question would first be "what is wrong with your heating system" before I replace any of those parts. If the only answer is "that you think it is a little hot to the touch" or "it is making a humming noise", my reply would be "It ain't broke, Don't Fix it!"

I might also add that the reason your heater is humming is because it forgot the words to the song it was singing.

PM_15106

Had a chance to return to the furnace.
With power on and furnace not running - the transformer is 102F.
Also noticed the the Oil Primary Control, right where the R7184B in printed is 94F.
I believe that these temps are excessive given that the furnace has not been running for several hours.

A few days ago, the transformer was buzzing loudly, like a warning from a piece of equipment.
A sharp tap from a screwdriver quieted it down to where it is what I would think is an acceptable hum.

I did like like the line about "I might also add that the reason your heater is humming is because it forgot the words to the song it was singing." from EdTheHeaterMan and many thanks for the schematic!!!

It will be most helpful as I work to get the furnace sorted out.

Jamie Hall

Both the buzzing and the relatively high temperature tell me that something is drawing power from that transformer -- probably near its rating -- on the 24 volt side. Might be worth finding out what...

PM_15106

So - as I look at the schematic, the Oil Primary Control is downstream from the transformer so that component is what is drawing power from the transformer.

EdTheHeaterMan

After a close look at the Armstrong wiring diagram, I am not sure i agree with it. It appear to have the 24 V transformer connected to R and C of what appears to be the older R8184M ProtectoRelay. That relay has a 40 VA transformer included in it. this would put both transformers in direct connection (hopefully in phase) to create a 24V 80 VA power supply? If the wires get reversed so the C goes to R and the R goes to C that would be a 48 volt dead short. (Just ask the expert @109A_5)

Maybe I am reading it wrong.

By taking this factory wiring diagram from the Armstrong I/O Manual
And placing a primary control with the W G Y R C terminal board like the R8184M in the place where the Primary control appears in the diagram, anyone can see that these two transformers are connected in a way that will cause at least one of the transformers to smoke! Look at how the transformers in the violet circles are connected to each other.
uUnless the W G Y R C are not attached to the primary as the diagram shows, there is something really wrong here. No wonder the transformer is making a loud humming noise. I would certainly forget the words to any song with an electrode up my you know what!

EdTheHeaterMan

Ask enough questions and you will find the answer. Look at the actual furnace wiring diagram here
Now look at the thermostat connection on the diagram especially Rh and W going to the primary control.
Now look at the customers actual wiring of the thermostat hereNotice anything between rthe R and the RC terminal that should be removed?

Maybe that is why the transformer is always hot even when nothing is operating. I wonder if that is a power stealing thermostat?