Boiler/Transformer/Thermostat


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Old 10-24-05, 05:49 PM
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Boiler/Transformer/Thermostat

Hi,

When I tried to fire up the boiler for my hot water baseboard heating system, all I got was a hot transformer. I cut off the power to the system when I first noticed a 'burning' smell near the boiler. The smell turned out to be from the transformer, which also was pretty hot. My guess is that it's fried, the question is why?

The only thing that has changed since last heating season is the addition of an electronic set-back thermostat. I suppose it's possible that I wired the new thermostat incorrectly. Could this cause the transformer to overheat and fry itself? I've double checked the thermostat wiring and it seems to be OK, but I'm not an expert.

The transformer has two primary wires that connect to the regular 120v electrical system and I believe it's supposed to be outputting 24 volts on the other side. After it cooked itself I turned the circuit breaker back on and used a multimeter to check for 24 volts on the transformer's terminals. There was no reading at all.

Will replacing the transformer solve my problems, or should I expect the next tranformer to also get cooked since the problem is elsewhere.

Please let me know if there's more information needed.

It's getting cold here in NJ and I sure could use some heat in the house!

Thanks,

Dave
 
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Old 10-24-05, 07:05 PM
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Fried transformer

It is entirely possible the thermostat wiring fried the transformer. Is this boiler gas or oil fired & what does the transformer power? When you replace the transformer, put a 5 amp automotive fuse in line on the low voltage side. It could save you another transformer. Since you live in N.J., I presume you also have A/C. Does the same thermostat control both the heat & A/C? If so, you need to make sure the jumper between Rh & Rc on the stat is removed.
 
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Old 10-24-05, 07:27 PM
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Grady,

Thanks for the reply.

The transformer looks like it powers the boiler which is gas fired. I don't have central air, the thermostat is only for the boiler.

I originally did not have the jumper between RH and RC when I first tried to fire up the boiler. I installed a jumper after doing a little research. Could this have been my problem?

BTW, where would I find a replacement tranformer? Home Depot? Plumbing supply? Electric supply?

Thanks again,

Dave
 
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Old 10-24-05, 07:37 PM
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Thermostat, transformer

With no A/C, the jumper makes no difference one way or the other.
You do have one wire to Rh & the other to W, do you not?
If you have Taco zone valves or B&G zone valves, many digital thermostats are not compatable with them.
You should be able to get the transformer at Lowes, Home Depot, an HVAC supply house (for sure), a plumbing supply house (Maybe), or electric supply house (maybe).
 
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Old 10-24-05, 07:48 PM
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The thermostat is a LUX 1500. It's connected right now with a red wire to RH jumpered to RC, a white wire to W and a green wire to G.

The zone valves are Taco valves. I think the model number is 571-2.
 
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Old 10-25-05, 06:35 PM
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Lux 1500

I just downloaded & read the installation instructions for that stat. It says nothing about hydronic systems. Many digital thermostats are not compatable with Taco zone valves. What is the green wire for? You only need two wires. The problem may be with the stat or it could be with the wiring. Before replacing the transformer, find out what each of those wires is for. I suspect you have created a dead short. Disconnect the thermostat before replacing the transformer. I suggest you call Lux to check on the compatability of the thermostat with Taco zone valves.
 
 

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