I have a five year old Weil McClain WGO 3 oil fired hot water boiler, in my new cape home that was built in 2000. It will heat only to 66 on one zone when it gets below -30. To get it to 70 I have to crank the wall thermostat to 85 at 7 am and by 9 pm it will be 70 and slower keep going over 70. Then i can turn it down to 73.This is on the first floor which is on one zone. Home is about 40' by 40'. I have boiler set to 210 high limit. Should I cut the one zone 70 feet in half? The upstairs zone 30 feet works great if i turn it to 75 in minutes it that temp. Could the wall thermostat be bad? The technicians can't find anything wrong with the boiler. The heat lost came out OK, BTU's are three times the size it needs to be for my home (for later expansions) and there are enough registers. Weil McClain said its ok to set the 210. There are two shut off valves in the cellar. The technicians bleed the lines three different time over the the years. There is no noise like when there's air in the lines.
It's base board heat, ten feet long under all windows there 1" off the floors and about 6 inches in height. They each have one 3/4" pipe going in one side.There is only one water valve for each zone which is above each circular valve, next to the boiler. The two circular ( two zones one on each floor) valve sound the same ( very quiet) when running. I was thinking I may switch them to seem if one is bad, what do you guys think? The water maker that is next to the boiler works great. We never run out of hot water. Boiler runs at 15 psi and starts at 190 then stops at 210 degrees. It runs for 10 minutes 3 times per hour. So if the pump is good should i replace it with a multi speed pump first?
I just checked the water temperature at the boiler zones with a cheap meat thermo.( ZONE 1 IS THE PROBLEM WITH ONLY HEATING TO 66 DEG.) At zone 1, with 70 feet of base boards which is on the first floor, just above the boiler. At the beginning of this zone I got 162 to 190 degrees at the end I got 134 to 154 degrees by the circular pump. Pumps are 1/25 hp. Right know it set to 73 and heats to 70, temp outside is 0. This zone has never worked correctly .
Any other ideas guys?
Thanks,

Mike


[Edited by mlizotte on 01-30-2005 at 12:15 AM]