2nd Floor is to Hot

Bud13

We have steam heat and the 2nd floor is to hot. There is one zone and the thermostat is on the first floor. We have owned the house for 5 years and this is the first year we have had this problem. All that is different is the Oil company replaced the thermostat in October. Prior one was electronic and when I was replacing the batteries I broke a clip. The new thermostat is not identical to the prior but also electronic. The former owner told us always have the valve completely open and only adjust the air vent valve. The radiators don't all have the same style valves but it doesn't seem to matter if I turn them to 1 or 8 that the heat in the room goes down.

mikeg2015

1) Stack effect. Colder it is out the more air leaks in downstairs and exits upstairs, hot air therefore moves from downstairs to upstairs. At 0F, it's 2F warmer upstairs in my house than at 30F. This is not to be confused with gravity or convective heat rise. With high ceilings and the mass of plaster, I don't have hardly any in both the old homes I've owned. When below above 40F, I can keep the upstairs 3F cooler than downstairs. IN new construction it's not that way.
2) Boiler is oversized for the connected load so it's hard to balance. Radiators are getting fully heated then pressure goes up and the radiators you turned down still end up overheated. However, I think you have Ventrite valves. If so, setting them to "1" should close them and all heating stops. I find that at my low vapor pressures, anything lower than a 4 and I lose all heating.

I wonder if the radiators without ventrites are vented too slow.

Are all radiators getting fully heated across in the coldest rooms? How hot are the warmest rooms.

Try turning the vent upside down in those rooms or if a Ventrite (has a white dial) set it to 1 and see if they are still overheated.

If still overheated, you need to find air leaks and seal them. Start at the baseboards and windows. Basement at the sill plate or rim joist too. IF you have a window you rarely ever use, use the removeable caulk on it or rope caulk.

nicholas bonham-carter

Do the following test:
Set back the thermostat a few degrees for an hour or so to cool down the system. Turn it back on a few degrees higher for a longer burn.
Have a helper upstairs, while you are downstairs holding on to the inlet side of the radiator, while also holding on. Find out if the upstairs is getting steam sooner than the downstairs. Using an IR thermometer would be more accurate, but most people’s hands will let go at the same time of a hot surface.
If there is much difference in the steam arrival between upstairs and downstairs, the you probably need more main, (not rad), venting. Slow rad vents, and fast main vents will get the steam to all radiators simultaneously.—NBC

Bud13

Thank you for the replies. I live in RI and the temp was -5 F last night. The temp in the hottest room on the 2nd floor, our bedroom, was 78. All the radiators are functioning. I moved the vent to the lowest number and it went down to 70 when I had the thermostat at 67, thermostat is on first floor. So hopefully when I lower the thermostat to 60 tonight the temp will be only 63 in the bedroom.

Fred

It just sounds like you need to better balance the radiators/vents. Do you have good venting on the Mains? That would be the first step. Make sure the mains are well vented so that the mains fill with steam before the steam starts looking for a path of less resistance, which may be those upstairs radiators. Once the mains are vented, start adjusting the individual radiators so that each room is comfortable. You may want the room with the thermostat to heat a little faster so as to shut the boiler down a little early and let the residual heat from the radiators finish the heating job.
Also, since this is a new Thermostat, make sure it is programmed for 1 or 2 cycles per hour. They come from the factory with a default of 5 cycles per hour, for forced air systems.