I finally found the model number of my old, Honeywell thermostat (T87F 3855) and it is 24V which is very helpful information. I realize now that I want to return to this very effecient, old standard type.

The only numbers I could find on the transformer (also Honeywell) were A409B1X0) which did not prove to be very helpful. I couldn't find anything on the net. I think the problem may be that its such an old system that they probably don't even make the parts anymore.

Jon -

I don't see what's wrong with asking for help on the cat. I think that most people here are able to help with all kinds of questions. Members seem to have a wide variety of experience and knowledge. I certainly rcvd. the info. I needed and it has saved me a pile of money.

I have no idea how a UK member would have interpreted the info but it was good enough for me.

Since I'm a single mom with very little money to hire tradesman, I often have to do my own work. I make some mistakes but I haven't hurt myself yet. I'm pretty cautious and know when I am over my head. I think that its good to learn about the heating system in your home and not to rely on others to do the work. Same goes for plumbing. Sure, if its a big job, I hire somebody. Its my home and whenever possible, I take responsibility for minor repairs. Whenever I solve a problem (such as this one) my self confidence soars and I enjoy my home even more.