coldguy wrote:
Mikepier wrote:
I agree with Paul with something additional to add. You claim that
when
the T-stat is off the 2nd floor would be boiling, and when you turn
the
T-stat up, it's cold. All this started after you replaced the
T-stat.
Could it be possible that you mis-wired the T-stat and that it is
in
"cool" mode. Anotherwords you wired it up as an A/C thermostat so
when
you turn down the T-stat, it would actually turn on your boiler
instead
of turning it off, and vice-versa when you turned up the T-stat it
would turn off the boiler.
A good way to check is to remove the wires from the t-stat and
short
them together. If you start to feel heat coming up to the second
floor,
that means that everything is fine, you just have to wire the
T-stat
correctly.

Hey there, thanks for the advice, I will definitely try shorting the
cables together. Just to clarify, the thermostat that was behaving
badly was the old one, and I didn't want to imply that it always
behaved the opposite of what I set it to do. I was just trying to say
that sometimes the heat was as expected, other times it was very warm
or cold, irrespective of what we put the thermostat to.

Oh, one last thing about the wiring. When I change the thermostat from
a very low target temperature to a high temperature, I can audibly hear
the boiler 'click' (and vice versa, when I go from up to down). Which
is why I was leaning away from the wiring being bad... it at least
sounded like the boiler was reacting to the request for more or less
heat. I'll still look into it more, though.