View Full Version : thermostat for second zone doesn't control boiler?

02-22-2012, 08:09 PM
Hi - I have a two-zone forced hot water baseboard heating system with gas-fired burnham boiler that is used to heat the basement (one zone & thermostat) and a family room on first floor (second zone and thermostat). Problem is that the family room won't heat properly unless the thermostat in the basement is set high enough that it is calling for heat also. So if we set the basement thermostat to 55 or so, there is essentially no heat in the family room. When the family room thermostat is calling for heat, the circulating pump runs, but the boiler doesn't fire. Basement thermostat seems to control both its circulating pump and the boiler just fine. Looks like it might be wired so that the boiler itself is only connected to the basement thermostat. Is this likely the problem? is there a simple way to re-wire so that both thermostats can fire the boiler? Looks like the second zone (family room zone) may have been added later...Is it possible that this boiler can only accomodate one thermostat control? Just bought this old house, and slowly finding all kinds of crazy issues...

02-23-2012, 08:52 AM
There aren't enough details on the system or how it's controlled to answer the question. By referring to "...the circulating pump..." seems to imply that it's a one pump system, where as "...its circulating pump..." implies two?

Model name & number & vintage of the boiler?

02-23-2012, 01:51 PM
What you may need is a zone controller box. Lots of people make them. Taco and Honeywell come to mind. Basically, you wire your thermostats to that box, and it OR's their inputs to then control the rest of the system, so that either one OR the other thermostat can activate the system (or both at the same time). But, you may not need one, depends on what you have. What you have may have it built-in, or it could be made to work easily. As Dana said, would need more info to figure it out.

02-23-2012, 06:36 PM
Thanks to both of you. the boiler is a Burnham series 2 model 202. There are two circulating pumps - one for each zone. The thermostat for the misbehaving zone is connected to a honeywell RA 832a controller. WHen the thermostat calls for heat, the relay actuates and the circulating pump comes on, but boiler doesn't fire. I looked at it more carefully tonight - looks like the relay in the 832a is not closing the control circuit that actuates the flue damper & boiler (put the ohm meter across those connections in the controller and it is still an open with the thermostat calling for heat and the circulator running), but it is closing the 120V to the circulating pump. Does this sound right? Can the relay be replaced or does the whole 832a box need to be replaced?