"Lieutenant Scott" wrote in message
newsp.wanqbqizytk5n5@i7-940...
On Sun, 04 Mar 2012 17:42:30 -0000, John Williamson
wrote:

Lieutenant Scott wrote:
On Sun, 04 Mar 2012 16:55:27 -0000, Harry Bloomfield
wrote:

A resistor in the room thermostat housing

But it's wildly inaccurate. And there seems to be no adjustment for
them.

It's a very cheap way to improve the responsiveness of the system. I
once disconnected one, and found out that re-connecting it it made a
noticeable improvement to my comfort in the room with no noticeable
increase in heating costs.

It was a single small room with a blown air calor gas powered heating
system, but the same principle applies to a central heating system as
used in my house.

I think the resistor in this one is making too much heat. It never
switches the heating on for very long, and I don't think it's good for a
central heating system to be cycled on and off repeatedly. I much prefer
it to come on for an hour at a time.

Thing is, if it's on for an hour at a time you'll get shedloads of
overshoot. With the resistor it switches more frequently so you get a more
even temp i.e, smaller hysteresis about the set point.