64Views2Replies

Author Options:

208/240 transformer question Answered

After having several (like 4) thermostats fail in a 6-year period, it finally dawned on me to check the voltage from the transformer and I found it to be a bit over 28 volts. My condo building has 208V service. The transformer in my air handler is a 208/240V one and was wired to the 208V terminal. I removed the wire from the 208V terminal and connected it to the 240V terminal and then found the voltage to be 24.2V. So I have possibly solved the problem of the thermostats failing but my question is, will this cause any damage to the primary (or secondary) of the transformer? Thanks in advance!

Comments

The forums are retiring in 2021 and are now closed for new topics and comments.
0
gmoon
gmoon

5 years ago

This change shouldn't adversely effect the transformer. If the thermostat is working correctly now, then you should be good.

Note that unregulated DC supplies generally should be tested under load, but thermostats usually take an AC (low voltage) supply, so I tend to trust your measurements.

0
Downunder35m
Downunder35m

5 years ago

It should not be a problem but it might be best to leave it as it was and to add a 24V voltage regulator to the thermostat.
That way you don't change the system at all and the thermostat always gets the right voltage even if the mains voltage fluctuates a bit.