Beacon Morris BRT045, Ranco temp controller issues

[turtl631]

I'm in the home stretch of my garage redo, thought I had the heater set but alas not. It's a Beacon Morris 45k BTU gas unit heater and I'm using a Ranco 24v temperature controller for it. Heater worked with R and W1 jumped. I wired up the temp controller and it worked for about ten minutes, showing ambient and triggering heater to run, then they both shut down and there's no power to either. Maybe the transformer is fried? I ran 24v and COM from the transformer on the heater to the corresponding terminals on the Ranco, and NO to R on the heater and C to W1 on the heater.

 

[dfiler2]

R and W1 on the heater just close a loop, like a switch. Not sure what you mean by "ran NO to R and C to w1", if you crossed both sides of the transformer you likely burned out the fuse on the board.

 

[turtl631]

Connected NO and C terminals on the Ranco to R and W1 on the heater. I was under the impression that when the Ranco hits the set point, it closes the relay, so this would complete the circuit between R and W1. Am i misunderstanding how these things work? The 5A fuse did not blow, checked that. Also heater ran fine for about an hour with R and W1 jumpered. Only about ten minutes with the Ranco, then dead.

 

[dfiler2]

Not familiar with the Ranco, if it just closed the connection you should be fine, have you checked to see if there is power at the transformer? If that is a picture of the Ranco it looks like it already has a transformer but you say you ran wires from the transformer on the heater to the Ranco.

Edit: Just looked up the Ranco, and it looks like you had it connected right. I would start checking for voltage on the 120v side of the transformer then the 24v and you'll know if the transformer is ok.

 

[manwithtools]

Just curious why you are using the Ranco unit and not a simple thermostat? Are you sure the Ranco has the correct input power? I see some models require 120 VAC input and some 24 VAC, can't tell what exact model yours is. As dfiler2 said, it's time to check voltages at input and output of transformer of the Ranco and the heater.

 

[turtl631]

I'm using it because it allows you to set a larger set point differential and avoid short cycling. Inspiration here:http://www.garagejournal.com/forum/showthread.php?t=16322

I have the 24v model.

 

[turtl631]

Looks like I'm getting 120v at the transformer input but no 24v output, must be fried. I'll replace and get a separate wall transformer to power the temperature controller.

Will this work okay? http://www.amazon.com/gp/aw/d/B004VMVDTA/ref=pd_aw_vtph_328_1_bs?ie=UTF8&refRID=15KD58N4922MV1HWQF34

 

[manwithtools]

Don't see why the transformer you linked to won't work, but will require some rewiring. Would be nice to find a replacement for the original transformer at a reasonable price somewhere. It would simply be nicer from a packaging standpoint.

I read some of the linked post about the set point differential, I will say that if you have reasonably insulated space that the set point challenges might not be as big as they seem. On the other hand there could be reason for the grater range in certain circumstances.

 

[dreasoner]

What is the VA rating of the Ranco controller? Could you have overloaded the output of the transformer powering both the heater and the controller. Typical furnace will use a 40 VA by itself. Should be able to dig up needed electrical specs.

 

[dreasoner]

Did you Ohm out the secondary winding to see if it is open?

 

[manwithtools]

Quote:

"What is the VA rating of the Ranco controller? Could you have overloaded the output of the transformer powering both the heater and the controller. Typical furnace will use a 40 VA by itself. Should be able to dig up needed electrical specs":

Great point, just noticed you have the 24 volt version of the Ranco. Are you powering it from the unit heater? Was it the heater transformer that quit working?

Sent from my SM-G920V using Tapatalk

 

[turtl631]

Yes, I was powering it from the transformer of the unit heater. I assumed, apparently incorrectly, that the additional load from the temperature controller would not overload the transformer. I have ordered a replacement transformer, as well as a separate transformer to plug into the wall to power my temperature controller. I inspected the fried transformer, and the common 120 volt input wire is melted.

 

[dreasoner]

I would wire in a couple of in line fuses on the secondary of the new transformers just for shits and grins until your sure of the wiring. Wouldn't go anything over 3 amps on the fuse.

 

[turtl631]

Good suggestion. Unit heater wiring is back to stock.