Broken thermostat or am I missing something? When does thermostat trigger boiler to make heat?
Outdoor temp is 53F.
Thermostat lower gauge indicates indoor temp of about 50F.
Red slider is around 65F
Why is the heat not kicking on? Heat is not on.
I know heat/boiler works b/c it will make steam if I exaggeratedly move the red slider to 80F.
Also, boiler fires up to keep tankless coil water heated.
But why isn't the boiler turning on as soon as room temp falls below 65F?
Broken thermostat or am I missing something obvious?
AC is not connected to this thermostat, just oil fed steam boiler.
I moved the blue slider to touch the red at 65F and still nothing.
Comments
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Sounds to me like the thrmostat is either way out of adjustment — or busted. Or… not familiar with that model, but is their a changeover switch form cooling to heating which might not be set right?
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England1 -
That looks like an early Chrontherm stat? The blue was the temperature during setback, the red was the normal operating temperature. Slide them both past 65 or so. Does it kick on?
Is there a clock dial on the left or inside with pins to set the schedule?
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Boiler kicked on when I pushed it to 68. I had assumed it was 50F in the house, but the little display of room temp is just a spring. Not connected to system at all. For display purposes only. So, it might have been 67 for all I know. Next step is to compare room temp actual vs. temp slider. Could be calibration, as stated above.
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Push the levers together. There's no setback so it's reading the Blue lever. Push them together at your desired setpoint.
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The spring is a bimetal thermometer. Some of them have an adjustment to dial it in to actual room temperature.
You are correct, it is not connected to the functionality of the stat. But it would be nice if it was accurate. Like a clock.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Can you explain what "no setback" means?
Blue lever gets priority?
I was thinking blue=AC and red=heat.
I might need to read the owner's manual.
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There should be a clock with pins to place and make setback times to save fuel. The Blue indicator is the setback temperature, and the Red indicator is the "comfort" temperature. If you push the Red and Blue indicators together, it overrides the setback.
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Make sure its level also. Its got mercury tubes inside of it that will be waaay off if out of level
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If you take the cover off completely (both the cover and the door you have lifted in that photo) you will have two mercury bulb switches. Those switches are attached to a bimetal spring that changes its coil based on the temperature. (Just like the thermometer you say does not do anything). You can set the position of the mercury switches with the blue or red lever. By setting the blue lever to 65° you will see that the mercury bulb will rock to the left as the temperature drops below 65° and rocks to the left when the temperature rises above 65°. There is about a 1-1/2° to 2° differential on that swing from left to right and back again.
Item 14 are the mercury bulbs on the bimetal coil. The way a bimetal coil works is there are two dissimilar metals bonded together and spun into a coil. As the temperature changes one of the metals expands at a different rate than the other metal. This causes the spring to change shape based on temperature changes. The coil will get larger or smaller on a rotating motion. That rotating motion will change the angle of the mercury switch.
There is also a heat anticipator adjustment that will provide a small amount of “FAKE” heat inside that thermostat to anticipate that the temperature may rise above 65° a little too far on some gravity heaters, and make the room 67 or more after the burner shuts off. That is adjustable based on the type of heating system you connect the thermostat to. I is number 12 on the photo and has a more detailed illustration (Fig. 8) just below it. On that same note, The onboard clock also generates a little heat and the calibration of the thermostat takes that into account. So if the clock motor is no longer operational, then your calibration will be off to the cold side by a few degrees.
If the small red and blue pinwheel at the lower right of the clock (number 8 on the photo) is set on blue, then the blue lever is what the thermostat is set on. When the clock spins and you have one of the blue or red pins inserted at a given time, the small pinwheel will change to the Red lever to control the temperature. As each hour passes the clock may change from the red lever setting to the blue lever setting based on where the pins are set on the 24 hour wheel. Since you have no pins in the clock wheel, the thermostat will never change from blue to red or from red to blue. By placing both the red and blue levers together. You are basically eliminating any set back because both levers will be set at the same temperature
I hope this helps in understanding your thermostat.
As long as you don't need WiFi control of your system, and you can compensate for the accuracy of the calibration, you have a superior thermostat for a boiler like yours. Don't get rid of it!
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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I disagree. No newer thermostat will be as reliable or as last as long. So long as you don't break the mercury bulbs there is no hazard. None. Zip. Nada.
Stop scaring people, @HomerJSmith , or if you must pick something real.
Edit: cone to think of it, @CoachBoilermaker , if you're really terrified of it, I'll take it.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England1 -
As I recall some of them became noisey, you could hear the gear train mechanism at work.And the clicking when it flipped in and out of setback.
looks like you are not using the setback, may as well get a nice large face, user friendly digital stat.
Ecobee if you want a WiFi type thermostat.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
Thanks for the info, guys.
With this upcoming first winter, I will need to decide on what schedule I want to heat my house.
It is just 2 of us in the house.
When we are at work all day, I can have a low temperature mostly to prevent the pipes from freezing? (What's a good empty house all day temperature??)
Then set it to turn on at 5pm. Then maybe low again at 10pm bedtime (space heater in BR? Instead of heating rest of empty house all night?)
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Do you agree with GPT??
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For your heating schedule, you're on the right track with lowering the temperature when the house is empty and possibly using a space heater at night. Here's a plan that could work well:
Daytime (when you're at work):
- Setback Temperature: A common recommendation is to keep the house around 55°F when you're away. This is warm enough to prevent pipes from freezing while still saving energy.
- Pipe-Freezing Concerns: As long as your house is well-insulated and the temperature stays above 50°F, the risk of pipes freezing is low. You can also set up your thermostat to have a "minimum temperature" in case the weather gets especially cold.
Evening (when you return home):
- Comfortable Temperature: Set the thermostat to start warming up around 5 p.m. so that the house is at a comfortable 68-70°F when you get home.
Nighttime (bedtime):
- Setback Temperature: For sleeping, it's often more comfortable to lower the temperature again. You could drop it to 60-62°F around 10 p.m. and use a space heater in the bedroom if needed. This would save energy by not heating the rest of the house unnecessarily.
- Space Heater in Bedroom: Using a space heater in just the bedroom is an efficient way to stay warm without cranking up the heat for the whole house overnight. Make sure it's a safe, energy-efficient model.
Weekends/Days Off:
- If you're home during the day, you could adjust the schedule to maintain a comfortable temperature, or just manually override the thermostat as needed.
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The common logic is that for every degree you can lower the temperature in your home your heat loss will decrease by 3%. So when you set your thermostat to 70° for comfort, changing it to 69° will yield you a 3% lower gas bill. That is what was advertised in the 1970s anyway. Now by setting your thermostat to 68° because President Nixon told you to, you would save out country from being dependent on OPEC and reduce your oil or gas bill by 6%. If you could turn your thermostat down 5° lower for half the day, (62° at night and 62° when away from home) you could save an additional 7.5% (5 degrees x 3% got 1/2 of the day = 7.5%). So the Chronotherm was reintroduced with a battery back up so the clock didn't loose time.
then there were the folks that said this was all a government hoax and you lost all your savings when you turned up the thermostat to recover from the lower temperature. I have looked at this and did some unscientific tests on my own home back then and came up with this:
If you lower the thermostat 5° for 3 hours then raised the temperature back up to the comfort temperature, you will probably not save that much. But any lowering of the thermostat more than 3 hours will result in a savings. To set back the thermostat 5° for 8 hours, there wil be 5 hours of actual savings. So when you go to work for 8 to 9 hours (including travel) you will save 2% When you set back 8 hours while sleeping you will save another 2%. That is a total of 4% if you remember to do it. and that is the reason for the setback thermostat.
In the 2000s we called it a programable thermostat. Today we call it a smart thermostat
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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@Jamie Hall , I'm not saying it is a hazard or that I am scaring people. I merely stated , if you discard the old mercury thermostat, to discard it environmentally.
Bi-metal thermostats do get out of calibration and wear. If you have a thermostat calibration wrench and an accurate thermometer, good.
The newer electronic thermostats are, I think, more accurate, responsive, reliable and easier to read.
We stopped driving around in Ford Model 'T's even tho some still drive on the road.
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Not saying the modern digitals aren't good. They are, and have a lot of features people really like — and particularly with faster responding heating systems such as forced air or many heat pumps they really can save you energy. Maybe even enough to pay for them.
They are reliable, too — in the sense that while they are working, the do work. However, I doubt we will see too many pushing much past the 20 year mark…
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England1 -
@Jamie Hall, I guess we will find out in 20 yrs , I won't be around to see it. Of course, if there's a 3rd World War they will only have to last for 15 min.
P.S. I have some digital White-Rogers (Emerson) thermostats that are pushing 20 yrs.
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True enough, @HomerJSmith . Be an interesting 15 minutes, though…
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0
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