T8775C compatible with L8148J Aquastat?


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Old 10-06-09, 01:13 PM
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T8775C compatible with L8148J Aquastat?

Hi,

I have a T8775C (digital round, power stealing) thermostat hooked up to a L8148J aquastat connected to my boiler. Most of the time the thermostat successfully communicates with the aquastat and the boiler/circulating pump kicks on when the temp. drops below the set point on the thermostat. However, from time to time (maybe 1x/week or so), the room temp will be below the set temp. and the boiler/circulating pump won't kick on. To resolve this, I usually have to lower the set temp well below the room temp. and wait a few minutes before raising the set temp. back up above the room temp...then the heat kicks on, usually.

The thermostat is approx. 4 yrs old and the aquastat was replaced 2 years ago for a different problem (circulating pump would go on but boiler wouldn't fire). As the L8148J is a millivolt circuit, could it be incompatible with the
T8775C as this is a "power stealing" thermostat?

Any help would be greatly appreciated.

Thanks!
 
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Old 10-06-09, 05:23 PM
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That is an unreliable thermostat. I recommend a Honeywell thermostat that requires batteries if you cannot supply a C (common) wire to your stat. A non-digital would also work.






 
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Old 10-06-09, 08:47 PM
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Thank you for your response. I prefer digital display...might the Honeywell RTH5100B be more reliable than the T8775?

Please advise.

Thanks again!
 
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Old 10-06-09, 09:33 PM
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Originally Posted by schellas View Post
.might the Honeywell RTH5100B be more reliable than the T8775?
Yes, the RTH5100B will be a better t-stat.
 
 

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