thermostat not kicking in boiler at night

Eric Wickman

I am having problems with my thermostat, not kicking in the steam control valves at night.
I am using a honeywell, nonprogramable thermostat, which I replaced last Jan.
Am not sure what the problem is as it seems to work fine during the day. I must be missing the cause.
The temperature on the heat kick in was set at 72, the temperature at room temperature was 68, the thermostat is in an interior hall , so the outside areas was on the chilly side.
Any help would be greatly appreciated.
Thanks
Eric W.

Mark Walnicki_2

Hmmm, I wonder if... :-)

Mark Eatherton posted this a few days ago under the "Here is a new one on me" thread:

Date: December 11, 2004 01:37 PM
Author: Mark Eatherton
Subject: Similar story...

Had a lady customer once who kept calling me back because her
heating system would not heat at NIGHT. Everytime I got there,
everything was just fine. One evening she called to complain again, and I
told her not to touch ANYTHING until I got there. When I arrived, I
found a pole lamp parked right in front of her thermostat. It was on, and
the radiant energy from the lamp was keeping the stat shut down... She
told me she always turned the light on at night, and thats when the
heating system would quit working. I advised her to find a new home for
the lamp. Haven't heard back from her since...

Whodathunk...

ME

Eric Wickman

There is no addditional light source near the thermostat.

The temperature in the middle of the hall, is warm, but where thermostat is, it's 2 degrees warmer.
According to how it was set, the heat valves should open and run for a short time, but not unless I manually bump the thermostat up.
This warms the area up then prolongs the next cycle. I waited for an hour for it to go by thermostat, but I had to manually bump it to make heat valves open.

Bill Nye_2

Is it

A HW T-87 round t-stat? If so, did you level the back plate? secure it well? Did you set the heat anticipator to the correct value ?

The thermometer portion of most thermostats are not real accurate, did you check this against another thermometer[known to be accurate] ?

Eric Wickman

It is a CT87A thermostat,yes i rechecked the baseplate level. The thermometer, I used to check the temperature of the hall and closet, I beleive to be accurate. The anticipator is set at 1.2, which manual said was steam setting.

Eric Wickman

I woke at 1:30, this morning, and according to thermostat, the boiler should have been running, cause the steam valves should be open. I turned up thermostat a little and the valves opened. I woke up at 6:20 am and the thermostat, had worked. am stumped.

MIKE6

Nite th

What is your situation? You mention steam valves should be open.Is this an apt or house.If an apt is someone shutting the heat off at nite.

gehring_3

Heat Anticipator


I am not a pro, but I had a similar issue once...

It sounds like the anticipator is not set correctly. The heat anticipator should be set to match the requirements of the controls to which it is attached. The Honeywell instructions generically offer 1.2 as the "steam" setting, but that might not be the correct setting for your particular boiler. Some boiler controls require that the heat anticipator be set at .7 or .1 for example. So, determine what the correct setting is for your particular boiler and then set the heat anticipator correctly. (Just as an experiment, you can try moving it down slightly to see if that helps) But obviously it is better to have it actually set properly per the specs and requirements of your system design.

Eric Wickman

thermostat is in a locked closet, in a 3 story apt. building

Eric Wickman

I will try that and see what happens.

Unknown

Locked interior closet?

Does this closet have any heat loss to cold walls or ceiling or floor?

If not, it will only drop in temperature AFTER the other rooms drop in temperature.

The most drastic drop in temperature is when the sun sets, and the next several hours afterwards, when the radiant energy transfer of exterior walls stops being heat gain and starts being heat loss.

Or it could be something else....

Eric Wickman

Iput a thermometer in the closet, the interior hall was registering 71 degrees, the temp in the closet was 73 degrees.
I am assuming that this trend would be similiar all day.
I can understand the temp dropping at sunset and such.
But when the temperature on the thermostat says 68, and the thermostat is set at 72, it should be opening the steam valves.
I keep adjusting the anticipator.

Matt Undy

Why did you replace the thermostat? Was there a problem with it? What was its anticipator set at. It should be set to the current draw of the controls it is operating.

The anticipator is actualy a small heater that adds more heat to the thermostat coil. Does it turn on the control when you turn it up then turn off soon after without the tempurature having changed (in a slow system like a steam or gravity hot water system it may need to turn off almost entirely on the heat from the anticipator since the stat won't see the heat in a slow responding, oversized system until too much has already been added to the system/building.)

Is the new stat the same as the old? You really need to look at the zone valve and see how much current/power it is rated to draw. Maybe it has an exceptionally high currrent draw.

Matt

Eric Wickman

I moved the thermostat, so I just purchased another, and set the anticipator, the same as the other thermostat.
The reason, I tried moving the thermostat was that I wanted a mid range area, to monitor the steam valves.
The response seems to be right away, except on the 2nd steam valve, as when I look at that vale, the motor is still opening it, but only takes a few seconds to become fully open.