Voltage drop at tstat

[Rox9142]

I have 24 volts at my common on control and I only have 10 volts at thermostat . What would cause this voltage drop ?

[BBeerme]

Loose connection, not measuring the voltage proper, an excessively long run of stat wire for the gauge, a load drawing too many amps or a combination of any of the above.

[timebuilder]

I have 24 volts at my common on control and I only have 10 volts at thermostat . What would cause this voltage drop ?

Are you an HVAC tech or the homeowner?

[riggija]

Are you saying you have 24v across r-c at unit and 10v across r-c on tstat with common hooked up to stat?

[Rox9142]

I'm a tech

[pecmsg]

I'm a tech

[2sac]

Why does the common have voltage?

[timebuilder]

I'm a tech

I try to avoid giving a lot of technical advice in the open forum areas.

Use the link below to learn about our FREE pro membership that allows you to post in the Pro forums, where we routinely address these questions.

[rjk_cmh]

Post only one thread, not dozens of them.

[beenthere]

I have 24 volts at my common on control and I only have 10 volts at thermostat . What would cause this voltage drop ?

What terminals were you on at the stat when you got the 10 volt reading.

[akal]

What's ur transformer s va rating and what is your total va required do they match up ?