Hi William, hope you are having a nice day

On 26-Mar-05 At About 07:34:36, William W. Plummer wrote to All
Subject: Thermostat circuit

WWP From: "William W. Plummer"

WWP Are all thermostat circuits powered by a 24 vac transformer? For
WWP both the heating circuit and the cooling side?

Not all. some are 24 volt, some are 110 volt and some are even less than one
volt. some 24 volt systems use 1 transformer and some use one for both heat
and cool. this is why it is really important to know what you have and how to
wire it.

-= HvacTech2 =-


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Are all thermostat circuits powered by a 24 vac transformer? For both
the heating circuit and the cooling side?

William W. Plummer wrote:
Are all thermostat circuits powered by a 24 vac transformer? For both
the heating circuit and the cooling side?

Generally, yes ... if you are referring to a wall mounted thermostat in
a modern home. But you've not given enough specific information to
guarantee that answer in every possible situation.

Better to get the model numbers of the heating/cooling equipment
involved, get the schematic/wiring diagrams for them and make sure.

Jeff
--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"As long as there are final exams, there will be prayer in public
schools"

In some instances you have one transformer that powers both heating and
cooling and in others,you have separate transformers. This is why sometimes
you'll see in the thermostat RC and RH with a removable jumper
"William W. Plummer" wrote in message
...
Are all thermostat circuits powered by a 24 vac transformer? For both the
heating circuit and the cooling side?

William W. Plummer wrote:

Are all thermostat circuits powered by a 24 vac transformer? For both
the heating circuit and the cooling side?

Some heating-only thermostats are powered by the thermocouple that
senses that the pilot is still lit. These generate very small voltages,
in the millivolt range, and this is called a "millivolt system".

A cooling system will always use a transformer.

A combination heating-cooling unit, or a heat pump will usually have one
transformer, but separate units may have two, which the appropriate
thermostat will treat separately.

--
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No. Some are 110 volts or 220 volts.

--

Christopher A. Young
Learn more about Jesus
www.lds.org
www.mormons.com


"William W. Plummer" wrote in message
...
Are all thermostat circuits powered by a 24 vac transformer? For both
the heating circuit and the cooling side?

"William W. Plummer" wrote in message
...
Are all thermostat circuits powered by a 24 vac transformer? For both
the heating circuit and the cooling side?

No, they are not. There are several different systems in use that you
may see. The most common are; Milivolt control, Low Voltage (i.e. 24
volts), Line voltage (115 volts). There can be one or two transformers
depending on unit configuration. That said, the most common control system
for heating and cooling today is a single transformer 24 volt system.

Joseph