Question

What's the best temperature to set my hot water baseboard heating to when I leave the house?

Asked by Ryan Smith
Bozeman, MT

With hot water baseboard heating, is it better to keep the heat at 60+ degrees when you leave the house so it doesn't take as much energy to heat the house up to 65+ degrees? What we have been doing is dropping the temperature to 50-55 degrees when we leave the house. I'm looking for the most cost-effective way to use hot water baseboards.

Answer

William J. Martin, AIA, LEED AP-H

Answered by William J. Martin, AIA, LEED AP-H

Westwood, NJ

WJM Architect

November 21, 2010

The heating system you are describing is a hot water heating system where water is heated in a hot water boiler and then circulated by an electric pump through tubing or piping to fintube convectors in each heated room or space.

  • There the heat energy moves from the water and heats up the metal fins of the convector. These heated metal fins cause an air current that rises through the fins as air is heated.
  • This draws cooler air in from the floor and up and into the convector, creating a warm convective air current in the room. The cooler water then circulates back to the boiler to be re-heated.

Your question is about managing this system in a cost-effective way. I am assuming your question refers to a daily routine where you turn down your thermostat as you leave and then turn it back up when you arrive home from your day out. If you are planning to leave for longer periods, there may other concerns not addressed here.

  • It is a common myth that by reducing the thermostat for only a few hours, it will take more heat to bring your home back up to the desired temperature. This is incorrect.
  • Reducing the thermostat setting will always save energy and money.

Install a programmable thermostat

First, I would recommend you install a programmable thermostat. The thermostat can be programmed to lower the temperature setting just after you leave your home and then raise the setting just before you arrive home. This allows for maximum comfort while saving energy.

  • I am a fan of simplicity, so I would recommend buying a thermostat that is simple to use and not overly computerized, unless that is what you desire.
  • Try this link for additional information about programmable thermostats.

I would recommend you turn down your thermostat as you leave home and then turn it back up when you arrive home, as decribed above. If your lifestyle is such that you leave in the morning and come home at night as a regular routine, substantial energy and money can be saved by setting the thermostat to lower the heat when you don't need it on.

Typical savings

Generally speaking, for each degree Fahrenheit you permanently lower your thermostat you will see about a 3 percent reduction in your seasonal heating cost.

  • In other words, if you lower your thermostat from 65 degrees F (18.3 degrees C) to 64 degrees F (17.7 degrees C) for the whole heating season, you would use 3 percent less heat.
  • This means typical savings are about 1 percent per degree F setback for each eight-hour period.
  • In other words, if you lower your thermostat from 65 degrees F to 64 degrees F for an 8-hour period every day during the whole heating season, you would use 1% less heat.

In your case, lowering the thermostat from 65 degrees F to 55 degrees F (12.8 degrees C) for an 8-hour period every day during the whole heating season, you could use 10% less heat.

Programming the thermostat

You say the comfortable temperature when you are in the house is 65 degrees F. Since hot water baseboard heating delivers heat fairly quickly, you could easily set the thermostat lower than 60 degrees F (15.5 degrees C) provided you program and account for the time needed to bring the temperature up to coincide with your arrival home. This allows for savings of energy and cost without sacrificing comfort.

  • You may also wish to set a lower temperature at bedtime and program the heat to come on before you rise from bed in the morning. This allows for additional savings overnight when you are warm in your bed sleeping.
  • Depending on the severity of your local climate, you should be careful not to set the lower temperature too low. The gradient between the temperature outside and the lower temperature inside could cause pipe freezing and other problems if the thermostat is set too low for too long.

Ceiling fans

Incidentally, with hot water baseboard heating systems, I also recommend you install good Energy Star rated ceiling fans in the major rooms and bedrooms.

  • Since heat will rise to the ceiling, reversing the fan's blade-spin will move air upward, pushing the heat gently down the walls, evening out the heating in the room and creating a more comfortable, evenly heated space.
  • Try this link for Energy Star ceiling fan tips.

Following these recommendations will allow you to save energy and cost without sacrificing comfort.

 

For more information:

Read Steve Saunders's Q&A "Does a programmable thermostat really save 20% on my utility bills?"

Tagged In: heating cooling

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