Heating System Coming On By Itself??

coreyndstuff

I have a steam boiler that seemingly is kicking on by itself. As I sit in my living room next to my thermostat which is in the OFF position, I can hear my radiators spitting air.

We have a forced hot water pump hanging off the side of the boiler which is called from a room upstairs, however the radiators up there are cold.

I have a dedicated high efficiency hot water heater, so it shouldn't be the domestic water kicking it on for heat.

Nothing else as far as I can imagine is connected to the thing - but it's no only turning on, but reasonably turning off too when the temp hits about 72-74.

What could be kicking it on? I even swapped out the thermostat, thinking maybe it was bad - but the behavior remains. It's 31 out, been pretty much in the mid 40's all day... and my house is toasty, but the thermostat has been off all day!

What can I do to determine the source of this?

EdTheHeaterMan

What is the chance that there is another device completing the burner circuit?
Are you sure that you have a Steam boiler with steam radiators AND a hot water loop that uses a circulator on the top floor? It can be done but it might be done wrong causing this unusual heating condition.

The burner should not operate unless there is a completed circuit from a thermostat calling for heat, the limit devices are all in their normal closed position... like the LWCO is sensing enough water, the pressure control senses low pressure. the room thermostat senses room temperature lower than the thermostat setting and the thermostat in the HEAT position.

What thermostat are you using?

What can I do to determine the source of this?

go the the burner control and see why it is getting powered. (Gas heat, is the gas valve getting 24 Volts). (Oil burner, is the primary control getting a closed circuit on the T T terminals)

Perhaps some photos of the boiler and the thermostat might help top determine where to start looking. Is there a wiring diagram on the boiler somewhere? A picture of that would be a big help.

dko

Are the radiators upstairs heated with the hot water?

is there an aquastat telling the boiler to fire until it hits a certain temp limit? Was this setting raised by anyone recently?

Depending on how its all wired, if wired out of order, your 2nd floor zones can be closed and not calling for heat but still fire the boiler to satisfy aquastat. Normally set to heat the water a little but not long enough to steam. 

Faulty, improperly wired, or tampered aquastat is just one possibility and one of the things that could be found completing the circuit as above comment has stated.

Mad Dog_2

Start at the Line voltage supply and work through every circuit, disconnecting the wires, and see what kills it.  Question? Are you atleast a working electrician or boiler guy?  If not, you can easily get zapped, fry a perfectly good control or several.  Ask me how I know...tuition!   Mad Dog

kcopp

IS there a tankless coil in the boiler that you get your hot water from?

coreyndstuff

here are some photos of the setup.

Tim_D

It is likely cycling itself to satisfy that aquastat for the hydronic zone which is set rather high. They are not exactly precision instruments and it is possibly over shooting. Also, it is not in the boiler water and will not correctly sense tha boiler temperature unless the zone is calling for heat. Relocate the aquastat so that it is in the boiler water and set it for 180 and I suspect that your issues will go away.

coreyndstuff

@EdTheHeaterMan

What is the chance that there is another device completing the burner circuit?

That's kind of what I thought was going on. It feels like some other condition is clicking it on.

Are you sure that you have a Steam boiler with steam radiators AND a hot water loop that uses a circulator on the top floor? It can be done but it might be done wrong causing this unusual heating condition.

I am 100% sure it is steam + boilers, with a hot water pump radiator setup for an addition room they added back in the 50's.

What thermostat are you using?

Simple honeywell programmable thermotat. No fancy thermostats. In the forced hot-water room, it's one of those old mercury thermostats.

go the the burner control and see why it is getting powered. (Gas heat, is the gas valve getting 24 Volts). (Oil burner, is the primary control getting a closed circuit on the T T terminals)

Thank you - i will do this!

No wiring diagram as far as I could see :(

@dko

Are the radiators upstairs heated with the hot water?

Just in one bedroom + bathroom that was added on.

is there an aquastat telling the boiler to fire until it hits a certain temp limit? Was this setting raised by anyone recently?

We wouldn't have touched the aquastat - however we have been lowering the temp of the thermostat in the room that controls the hot water pumped heating. Like 60-62, my wife likes it cold in the bedroom lol.

Things were working pretty well for probably 2-3 years. It does seem like this started happening when she started turning the temp down in the bedroom.

Faulty, improperly wired, or tampered aquastat is just one possibility and one of the things that could be found completing the circuit as above comment has stated.

This does make sense...

@kcopp

No tankless coil - we have a totally seperate unit for domestic.

And i'm not technician :) just trying to figure out if it's something as a homeowner I can tweak. If it's requiring anything more than poking at something or changing a thermostat, i'll call a pro :).

coreyndstuff

Tim_D said:

It is likely cycling itself to satisfy that aquastat for the hydronic zone which is set rather high. They are not exactly precision instruments and it is possibly over shooting. Also, it is not in the boiler water and will not correctly sense tha boiler temperature unless the zone is calling for heat. Relocate the aquastat so that it is in the boiler water and set it for 180 and I suspect that your issues will go away.

This is pretty logical, it seems easy enough to turn that aquastat down to 180 and see what happens? As for relocation, i'll talk to my plumber.