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Themostat

Jennifer Jackson
Jennifer Jackson Member Posts: 7
in THE MAIN WALL
Hello out there, I live in NYC in a brownstone, one year ago I replaced a mercury themostat with a digital.  I recently had a energy audit in the house and was told that a themostat with mercury is better.  My heating system is steam with radiators.  Any comments?  The themostat is located in room on the street level on inside wall.  Does it make a difference?  Please explain, I have no problem changing back.  Also are there any recommendations on model.

Comments

  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,578
    thermostat rated for steam
    1. most people here like the honeywell "visionpro" set to 1 cycle per hour. it is digital, but works well with steam, when set according to instructions. it can also have a remote sensor, so you could have the base at one location, and monitor another location. maybe your present thermostat is not rated for steam, but the fact that it is digital is not inherently bad, unless there is not a setting for steam heat.maybe the energy auditor was talking about the inadvisability of night setback instead of mercury.
    the location should be alright as it is on an inside wall, but is it free from drafts when the front door is opened?-nbc
  • Unknown
    Unknown
    Thermostat

    The old mercury thermostat probably had a device know as an "anticipator"  which helps prevent overshoot and saved fuel. The anticipator senses the set target temperature and cuts off the burner just before the target temperature is reached and the system "coasts" to the desired set temperature. Without the anticipator, the thermostat turns the boiler off at the moment the set temperature is reached  and the system coasts beyond the set temperature for a short time. Cutting off the boiler early and coasting to the set temperature saves fuel.



    If you have the old round one you could use that or as NBC mentioned, a lot of people are using the Vision Pro as it has a function where you can set the boiler cycles per hour. This serves the same purpose as the anticipator. Most digital thermostats (from the home center type stores) don't have an adjustable cycle function and with a steam system, having a thermostat  with an adjustable cycle function is very beneficial.



    As most people buy a digital thermostat for its setback function, I might mention that with steam heating,  it has generally been found that to using a large setback temperature differential burns more fuel.  It appears to be more economical to maintain a temperature with no more than of around a 5 degree setback than trying to make up a large setback temperature difference. (I use 65 during the day and set it back to 58 at night.  I use TRVs in rooms that I want colder -like for sleeping)



    For more information on your steam system I would strongly suggest you to get a book called "We Got Steam Heat". It's easy reading, humorous and written for the homeowner. It's a "must" for anyone owning  a steam heating system! It's available on this site.  Use this link:

     http://www.heatinghelp.com/products/Books/5/61/We-Got-Steam-Heat-A-Homeowners-Guide-to-Peaceful-Coexistence



    - Rod
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