Thank you Dana and Smithtb, for the information - sorry for the delay in responding; had difficulty logging on (also using dial up internet connection, which is proving to be very painful). Had the contractor who installed the baseboard heating (2 zones, one long and the other shorter with thermostat located in the shorter zone) now back over on a couple of occasions - still not working properly. The boiler is 20 years old (manufactured by firm based in Burnaby, British Columbia - no longer in business) initially used for slab heating. This is what is now happening: Boiler cycle consists of water temperature (at boiler) initially at 160 F; then when thermostat is turned up (starting the circulator) the boiler temperature drops to 120 - 130 F and essentially remains at that temperature indefinitely. The boiler keeps firing almost continually like this with the temperature in the longer zone achieving only a maximum temperature of 62F, which is really not adequate. When the circulator does stop (which is only for a couple of minutes at a time) the boiler temperature does build up some, but as soon as the circulator starts again the boiler temperature once again settles to the 120 - 130 F range. Checked the limit control settings and they are at 160F MIN and 180F MAX. Not sure that the individuals being sent over by the contractor are thoroughly versed with the electronics of the system. Any additional comments would be much appreciated. Thank you.