I've posted on here before about the very same system. I hate this system at this point. My wife and i bought this house 5 years ago, and every year I have to fiddle with it to turn the heat off and on for spring and winter, i shouldn't have to. my system is pictured. this year i had to replace the zone valve motor, after doing so, i find the system doesn't turn of the heat, it's running continuously,and doesn't stop when it reaches it set limit of between 62-70 deg., as a matter of fact the thermostat says it's 85 deg in the house! this is the thermostat i have the RTH2510/2410 series, this is the wiring block to it, which following the installation instructions, i connected the colors of my thermostat wires to what i thought were the color letter codes pictured in the casing. turns out the blue wire pictured going to the system is the thermostat wire, so I connected the blue to "the block marked "B" and the white to 'W", of course. but trying to research this brand of thermostat via the internet I found it might be better to connect the blue wire to "R RC", which are jumped, together. I only have one zone valve (ranch house) and two wires to connect to the thermostat. every approaching warm season,
i remove the one white wire from the "Z1" block, because turning the heat setting off on the thermostat, doesn't turn it off, so I'm basically bypassing. Then, every cold season, I have to do the reverse. can anyone help? i can supply more info if need be.