Adding additional transformer to Honeywell L8148E aquastat

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Old 01-26-12, 06:47 AM
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Adding additional transformer to Honeywell L8148E aquastat

I have replaced the 3 original B&G Modumate zone valves, with the new B&G Comfort-Trol zone valves. Shortly after installing these my transformer burned up in my aquastat. The instructions which came with the new zone valves stated not to use more than three with the aquastat but suggested using an additional transformer to power the zone valves. My question is how do I wire up the additional transformer to the aquastat. Would it be used in series with the built in transformer? I bought a new Honeywell 8148E aquastat and a new 40VA transformer to go with it. I am running a Burnham gas fired boiler with a standing pilot and a vent damper. Any suggestions are appreciated.
 
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Old 01-26-12, 12:35 PM
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Follow figure 2A in this PDF file.

http://completewatersystems.com/wp-c...011/05/604.pdf

NO, do NOT wire the transformer in series!
 
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Old 01-26-12, 03:20 PM
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Thanks for the quick reply, I have another question though, after looking at the diagram on the B&G link, are the "T" terminals on the aquastat already be supplied 24v from the internal transformer? If so what will happen by adding this additional transformer? I don't want to smoke another aquastat!
 
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Old 01-26-12, 03:52 PM
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NO, do NOT wire the transformer in series!
For different reasons that don't need explaining here, don't try to wire two transformers' 24-V secondaries in parallel, either. You need to use separate, 40-VA, unconnected xfmrs for each three (or fewer) valves. The 120-V primaries will, of course, be in parallel.
 
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Old 01-26-12, 04:31 PM
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what will happen by adding this additional transformer?
The additional transformer will power the zone valves, the transformer in the aquastat will power the aquastat. As long as you wire it as shown and make no mistakes, you will not fry the aquastat.

Note that in your aquastat, the "T" terminals are probably labeled "T" and "TV"
 
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Old 01-27-12, 09:37 AM
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Yes, the "T" terminals are labeled "T" and "TV". Thanks very much for the info. I plan on working on it this weekend.
 
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