I recently had insulation blown in on my 2 story home. The difference of course is amazing. But, the temperature on my 2nd floor is substantially different than my 1st floor. Basically, the 2nd floor loses heat much faster than the 1st floor. When the radiators heat up the house, the house heats equally but as times goes on, the 2nd story eventually gets about a couple of degrees colder than the 1st story. It's significant. Is this normal for an old house that had new blown in cellulose added? Or should I demand the contractor to come back? (The contractor said it was normal.)

Any time you change the insulation levels there will be some shift in load balances, and balancing the first & second story to run as a single zone is always a subtle issue. Most newer heating systems will separately zone each floor to deal with it.

There may be ways to reconfigure the heating system to re-balance it even as a single zone, and it may require moving the thermostat. But without a room-by-room heat load and radiation calc and a better description of the heating plant it's hard to make reasonable recommendations, and even then it's not always amenable to a "design by web forum" approach.

The top floor always has more exterior surface area to lose heat from than the first floor, but the first floor is where infiltration air leaks in due to "stack effect" in winter. When you added the cellulose wall insulation the walls got tighter (less leakage), but the surface area ratios didn't change.

Windows often dominate the heat loss of insulated walls. If you have single-panes + storm windows, replacing the storm windows on the upper floor with the tightest low-E storms you can find it WILL make difference, and you may be able to restore balance more cheaply than breaking open the heating system. A ~$170-200 low-E storm replacing a clear-glass triple-track over a single-pane double hung takes the configuration from about U0.5-U0.6 to about U0.32-U0.35 for much less labor & cost than a U0.34 replacement window, cutting window losses by about a third.

To accomodate the faster heat loss on the 2nd floor, I've opened up the radiators on the 2nd floor. That helps a little because now the 2nd floor gets hotter than the 1st floor as the radiators EDR is larger. But as the time passes, the 2nd floor gets colder and colder while the 1st floor maintains it's temperature. For example, I come home and turn on the heat to 72. Within an hour, the 2nd floor heats up to 74 while the 1st floor with the thermostat heats up to 72. But, after 4 hours, the 2nd floor gets to 70 degrees or lower while the 1st floor maintains it's 72 degrees. Evidently, the 1st floor is holding the heat better. I guess my question is did the insulation contractor put enough blow in on the 2nd floor? Should there be such a temperature differential? (For example, by 4 am, it will be 72 degrees on the 1st floor but 68 degrees on the 2nd floor.) Or is this normal with all blow in projects?

Your first floor has a heated space above, the second floor has a cold space above, so you have more heat loss on the second floor. there could be air leaks into or through the attic, and/or air leaks in the basement driving the stack effect dana1 mentioned. Hire an energy auditor to do a blower door test to find the air leaks and repair them. If the attic is the location of the new insulation, was it air sealed and tested before the new insulation was added? Was the old ceiling air sealed prior to installing the new insulation? Is there an insulated & air sealed attic hatch or stair? These allow lots & lots of air leaks & heat loss. Adding insulation doesn't help as much if there is lots of air leakage.

Lots of air leakage through the attic would tend to pull the warmer air up from below, which would even out the difference between the lower & upper floors rather than cooling the upper floor. While air sealing the attic is always a good idea, it's probably not the treatment for the symptom.

If the attic isn't well insulated it's worth adding as much as can reasonably fit, but even with only R20 in the attic the window losses from the second floor with U0.5 or higher windows are likely to outweigh ceiling losses, and contribute more to discomfort.

The upper floor has about 2x the exposed exterior surface area of the first floor, but you can't exactly stuff 2x the insulation in the upper floor walls and go 5x as deep in the attic to achieve better balance. You may be able to even it up some with window upgrades, but it's still not as good as separate zoning. This isn't just an issue with houses with retrofitted insulation, it's an issue with ALL multi-story houses. But adding insulation very often changes the balance of heating & cooling systems- it's normal. So, if it had been reasonably well balanced for the draftier less insulated condition, it's not surprising that the balance has shifted a bit. It doesn't mean the contractor didn't do his job, but to check it out in more rigorous fashion, buy yourself a $50-100 pistol-grip infra-red thermometer and start scanning the walls and ceilings for cold spots where there shouldn't be. Fireblocking, extended window/door headers and other framing anomalies can and do get missed sometimes, and if you have several 10s of square feet of uninsulated wall cavity on the second floor and full-fill on the first that could be a contributor.

Also stick your head in the attic- the top of the insulation should be fairly even and smooth over the entire space, no big sinks or gaps.

If the thermostat is located on the first floor it will never adequately control the temp on the second floor, and with higher upper floor losses it will cool before a thermostat on the first floor calls for heat. If you move the thermostat upstairs you might be somewhat overheating the first floor, but you may be able to block convection on some of the downstairs radiators to throttle back their

Is this a pumped hot water heating system or is it steam?

Dana,

It's very interesting that the 2nd floor has 2x the surface area. It seems that you are saying that the only true way to make it comfortable is to create 2 zones. Of course, that's not practical here but it's something I'll definitely consider if I install a new heating system.

With respect to checking out the cold spots, i'll do so. I can borrow a heat gun from a friend who has one. What should I be looking for specifically? Is there a certain method that you suggest? For example, do you recommend looking at under windows or around joists? How many cold spots warrant the contractor coming back and reblowing? How big does the cold spot have to be? etc etc?

This is a one pipe steam system with the lowest radiator vents already attached on the 1st floor. There really nothing I can do except for perhaps cover the radiators themselves. If I close the radiator valves, I won't get any heat at all!

The top story has the surface area of the roof losing heat, the first floor does not, therein lies the surface area difference.

With the IR thermometer at a few inches distance from the wall on a cold night you should be able to detect where the studs are. Look at the bays above and below windows in particular. The sash weight cavities are usually behind the window trim-casings, but above and below the window you should have wall temperatures similar to other random parts of the exterior wall. Look carefully at the stud-bays a foot to 16" away from the window casings on each side to see if there was any additional framing to support the window that may have blocked a complete fill. If the bottom of a stud bay is a few degrees warmer than the top, it didn't get a complete fill. (This stuff is remarkably obvious with an infra-red camera, but those are harder to borrow. :-) )

The ceiling temps should be pretty consistent everywhere, with perhaps cool spots near where it intesects exterior walls, depending on how the band joists were done there may be inherent thermal bridging there, but at 10" in from the exterior wall it should be pretty similar to the temps in the middle of the ceiling if there's full coverage on the attic floor (but that's usually easily spotted by just looking in the attic.)

You can try boxing-in half the fins on each radiator on the first floor and get a feel if that approach would work for getting better balance. It's a real pain to reconfigure all the plumbing to swap radiators, but since you now have more radiator than you get all the heat you need at lower temps, a good system designer could probably convert it to a low or mid-temp pumped hot water system broken into two loops, if it's already plumbed optimally. That's a bit beyond the scope of a design-by-web-forum approach though, and it won't be cheap. (If you don't have air conditioning it might be cheaper and better to put a 3/4 ton mini-split heat pump upstairs to cover the difference, but that too would take more analysis.)

You might try splicing the thermostat wires and just drape the wire in the stairs as an experiment to see if moving the thermostat to the top of the stairs maintains better comfort upstairs without roasting the first floor. Modest period of overheating are usually more comfortable than underheating, and the insulated house will be using a lot less fuel even if the downstairs is running 74-75F sometimes.