Wiring transformers in parallel

I need to wire a “Zone valve” for my uncle heating hot water system and I need to hook up an additional transformer (24v) for the added zone valve.
I have been told to hook up the additional transformer in parallel to the old transformer to get additional current. I was cautioned to make sure the transformers are wired in “phase”, but I am not certain how to check this out. Has any one ever wired transformers in parallel? How do you verify the transformers are in phase?
Thanks
:cry:

It is not a good idea to parallel two different transformers, even if they are both 24 volt because they are not identical and current will circulate between them. It will be less expensive in the long run to replace the original transformer with one of a higher rating.

FYI: To check phasing, connect one lead of the 24 volt secondary to the other then measure the voltage between the other two. If the voltage is zero, OK. If it is not zero, it should be 48 volts, not OK.

Wiring transformer's in parallel

I agree with russlk in paralleling transformers. Be very careful. If the the transformers are the same manufacturer and the same part number it should be no problem. I have connected as many as 4 in parallel with
great results.