We purchased five new Honeywell RTH7400Ds to replace our thermostats on our 1960s zoned gas boiler/hot water baseboard heating system (we actually have six zones, but we assumed one was to the greenhouse that we don't use). We installed them in the fall, and for awhile all seemed to go reasonably well. But this week we are starting to have doubts. We can't seem to get any room about 65 no matter what we set the thermostats at (even setting up to 90), and we have some some rooms with stone cold baseboards. We are not sure if this is a problem with the thermostats, or with some other part of the system, but since we have recently been monkeying around with the thermostats, we suspect our own handiwork. First, as I understand it, there could be two issues: wiring and configuring. Only the heating system is controlled by these thermostats (air is on a completly different thermostat). I had originally assumed this must be a three -wire system, but the heating guy who came to service the boiler for me in the fall said that it was a two-wire system, though they apparently used three-wire to do the wiring, just not hooking up the green wires. Sure enough, when I removed the old thermostats, there were two wires hooked up (R & W), and the green wire was just lying in there unconnected. So we wired the red to R and the white to W (after MUCH research on this and other forums because of course the old thermostat was not marked!). I am not too concerned about this, but I am long-winded in case you want to "check my math" on this. I am less confident about the configuring. In the initial setup procedure, one is asked to designate what type of heating system one has(setup #170)--and there are 10 options. I had it narrowed to one of 2: #3 Heat only with no fan (Conventional)--"gas, oil, or electric heating without central air conditioning. No wire on the G terminal on new thermostat." or #5 Hot Water Heat Only (Conventional):"Gas or oil hot water heat with three wires connected to new thermostat or for normally closed hot water values with wires connected to R and Y on new thermostat." None of the others seemed to match our situation since we don't have air conditioning on this thermostat, nor do we have a heat pump, and I don't think we have multi-stage heating and cooling (drifting out into deep water here.....). I have tried both options (though I notice that #5 refers to wires at R and _Y_ on the new thermostat--should that white wire I have going to W really be going to Y?). If I choose #3 Heat only with no fan, I am then asked to make a choice at setup #240: Again, there seem to be two options: "5--Gas or Oil furnace (less than 90% efficient)" or "3--gas or oil hot water, Gas 90%+ high-efficiency furnace" I have tried 3 variations: #3 at Setup #170/#5 at Setup 240, #3 at Setup #170/#3 at Setup 240, and #5 at Setup #170 (which doesn't require a choice at 240). None of them seems to improve the situation. It's not that we don't have heat at all--some of the radiators give off heat, and we can get most of our rooms to 62-65 with it being in the 40s outside--but it almost seems as if the thermostats have no effect on whatever is happening. Can someone tell me if I have it wired right, and if I've made the right choice in configuring? If we could rule out a problem with the thermostats, we could then move on to troubleshooting the rest of the system. We have also tried bleeding all the radiators until hot water runs (though some of them never get to hot water, but just lukewarm). We've found no air in any of the radiators. Thanks!

I bleed the raditaors on my old hot water sytem and after several weeks the air returns and it is very noisy. Any ideas as to what the problem is. The air is coming in from somewhere???Thank you Guy