120V to 24V Transformer Blew

One of my transformers for my honeywell valves blew unexpectedly. I didn't think that there was any kind of short circuit in my wiring, but after being on for about 3 minutes it blew. With my recent rewiring, the two transformers that I have are actually not touching. Would that have caused an issue? or do I need to revisit how I have them wired. I know they have 120 V coming in. They are not grounded though.

Sounds like it was wired backwards

Passed too much current on the secondary side is my guess. Got a diagram you can show us? It's good idea to fuse the secondary to prevent this in the future.

Test the ohms on your gas valves. If one is really low its shorted and will blow another transformer. Replace the valve in that case, the transformer and add a fuse. If you have any other coils like actuators check them also. If you don't know what the ohms should be you can install the fuse first and start plugging things in until the fuse blows and you found it.

Here is how I have everything wired.

I just saw that you are in Charlotte. Are you a CBM member? There are plenty of members with the skills to solve this problem and wouldn't mind helping, including myself.

I'm actually about to join

could it be a ground issue? the pump is the only thing grounded on my system, but its the only component that has a ground wire on it.

do both valve wires go to the transformer? or should one go back to the neutral bus?

No takers?

sgraham602 said:

could it be a ground issue? the pump is the only thing grounded on my system, but its the only component that has a ground wire on it.

do both valve wires go to the transformer? or should one go back to the neutral bus?

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Both valve wires got to the transformer, no neutral connection.

I assume the wire on T11 of the controller should be red (hot)? Is that a 24V AC xfmr wired to 24AC valves? What is the amp rating of the xmfr and your valves?
Both wires from the xmfr go to valves. Grounding is usually not required with these valves but check your manual. What's the valve model#?

Poobah58 said:

I assume the wire on T11 of the controller should be red (hot)? Is that a 24V AC xfmr wired to 24AC valves? What is the amp rating of the xmfr and your valves? Both wires from the xmfr go to valves. Grounding is usually not required with these valves but check your manual. What's the valve model#?

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Yes. T11 is the is a hot wire. The xfmr is a 24V output (which I verified with a volt meter). Not sure what the amps are...I'll have to check. Should both wires on the transformer go back to the Love controller?

I'm wondering now if I have my controller wired correctly as well? I have seen diagrams that have the transformer being wired directly from the hot bus, with one lead then going to the gas valve and one common going to the controller and to the other side of the gas valve.

there is also a good chance I am making this way more complicated than it is.

how should i interpret the below??

You could try powering the xfmr hot thru the switch (keeping it energized). Then run the 24v thru T10-11 contacts to the gas valve. Transformers (a big coil) hate being de-energized. You should fuse the hot out to the valve.

so to do that I would run the a wire from the 24v side of the transformer into T10 and from T11 to on side of the gas valve?

would a 1A fuse be sufficient if I did it that route?

sgraham602 said:

so to do that I would run the a wire from the 24v side of the transformer into T10 and from T11 to on side of the gas valve?

would a 1A fuse be sufficient if I did it that route?

Click to expand...

Yep. Fuse depends on the valve current draw.