Tony Hwang wrote:
Anthona wrote:
Lately, at various times, I would have to get up early in the morning,
to manipulate my thermostat, because the heat did not come on at
prescribed time...4:45am. the battery is not dead, there is no icon
indicating such. The times are correct..so I thought it cannot be the
batteries..2 AA type. I would clik on the up temperature button to hear
the click of the furnace coming on and then it runs smoothly. This did
not happen daily, only other day or so. Plumber said i have to replace
a section on the furnace for $200 dollars. Then I called the thermostat
company its the TX500 programmable unit. The tech suggested that I
replace the batteries, even if there is no indication of weakness. I
did, and it so far has set up the furnace to come on as prescribed.
Now, although the old batteries were setting the times right and the
temperatures, why should it effect the so called 'switch' of the burner
to come on when its suppose to?

Hi,
When battery is on the marginal state it will acts erratic. Maintaining
clock needs minimal current but to activate discrete logicl it needs lot
more current. Actually battery supplies current to the control loogic
which triggers relays for furnace control. I'd do the same thing if I
were you in this case, just replace battery first and see. Did not
measure the battery voltages? I just replace them at about 1 year
interval even tho manual says it can work a few more days when battery
low indicator comes on. Digital controlled circuits are nothing but
sequencial logic. Just think logical.


Well, my hopes were shattered. It did not come on this morning and
again I had to manipulate the thermostat. and this is with new
batteries. Now, either the plumber was right or I need to replace the
thermostat, which is barely 2 years old. I guess replacement is cheaper
than the plumbing job.