Q–In a two-flat with one boiler providing heat for both units through radiators, and with the thermostat in the second-floor apartment, will the first floor be much warmer?
Can you explain how this works and what temperature variation could there be if the thermostat is set at 72 degrees?
A–Actually, the first floor will probably be cooler than the second floor as heat rises naturally. This is especially true if the ceiling and the walls of the second-floor apartment are well-insulated, said Mark Burger, a senior technology specialist with the U.S. Department of Energy’s Chicago Regional Support Office.
So to get the downstairs a toasty 72 degrees, you’ll probably need to set the upstairs thermostat to 78 degrees. That would be not only uncomfortable but a waste of energy.
There are several ways to balance the system so that both units are a comfy 72 degrees, said Burger.
First, see if either level has more radiators. “Often, they put more radiators on the second-floor apartments to keep them warmer,” said Burger. If there’s an additional radiator or two on either level, you could consider closing those off so they don’t put out unneeded heat and waste energy.
Next, consider having radiator vents installed on the downstairs radiators. A radiator air vent permits air to be forced out of the radiator as steam enters. The radiators warm more quickly, and the boiler runs less, saving you energy dollars.
Some vents are adjustable, doing the opposite: The radiator will fill with steam more slowly, and won’t be as hot.
Overall, the vents allow steam to be more evenly distributed throughout all the radiators in the two apartment units.
You can also consider installing thermostatic radiator valves, or TRVs, which also help control the amount of heat emanating from your home’s radiators.
A TRV is a temperature-controlled valve that works as an adjustable air vent. It can raise or lower the temperature of a room by restricting the air flow through the radiator air vent and controlling the amount of steam entering the radiator.
This is done via a temperature setting knob on the TRV.
TRVs are more costly. They start at about $50 each to install and the payback will take a few years.
Moving the thermostat to the first floor wouldn’t make a difference, said Burger. Again, if you set it to 72 degrees downstairs, it will probably be 78 degrees on the second floor. And if you’re renting out the apartment downstairs, putting the thermostat there would give control of it to your tenant.
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