Well, it just so happens that the mounting spot for my model 600 will be just beside the water heater. It would be mighty convenient to use the supplied tapping saddle valve right out of the water heater. I also read that it is recommended to use hot water. I wonder though, is it that much of an advantage? I was doind some rough numbers and the instructions say it flows 3gph. that's 72gallons of hot water per day. that sounds awfully expensive and/or wasteful. Can someone chime in on my saddle valve location and also the hot water necessity?

I'm trying to hook up two Honeywell 12 gallon True Steams to my parents' old furnaces (both are Trane XE 70s). The problem is that they only have a five terminal transformer in them (Terminals are R, G, W, Y and one unidentified, but I think it is a B). The thermostat is a new Honeywell non-programmable and the True Steam came with the IAQ humidistat. I don't see a "C" common lead on the furnace, and I understand Trane sometimes used the B terminal for this, but I get error code seven when hooked up this way (HVAC power not present). Measuring the voltage from R to B is zero and R to ground is only about 10v. The only way I can get the 20-30v I am supposed to get is between R and W on the furnace. When I hook it up this way (connecting Furn W to True Steam C), the error code ceases, but the True Steam has only the green power light on and pushing go, clean, reset, etc., has no effect. The unit simply sits there even though the IAQ is calling for 45% humidity and the ambient air is only at 35%. I haven't tried hooking up the wiring on the second unit until I get this one down, but they are identical save for the second furnace having two additional wires running out to the A/C (furnace No. 1 has no A/C). Anybody familiar with the XE 70 line or how to hook up a True Steam to a basic (no PC board) furnace? Thanks in advance.