Thermostat problem

[ajhuta]

When client turns on above stove hood vent. All Honeywell thermostats in house rises on display and client is concerned that heat will not go on when cooking. I was there and the thermostat went from 66 degrees to 77 in 5 minutes and even in back bed room. It seemed crazy.

 

[MAC702]

A lot more detail will help. We can't see what you are able to see. Where is the hood being vented to? How big is this place? Where are the thermostats located? Are they manual or digital? Are they located at air returns for a central air system? First instinct is to follow the air flow, but I've never heard of this phenomenon before. What kind of heat is the stove producing into that hood at the time?

 

[ajhuta]

Thermostat problem

Hoot vent is just on. No heat is being produced. They are electronics digital non programable t-stats located even in a couple of back bed rooms with door closed. No change in temperature. No real air movement. Say temp is set for 68 degrees and it’s 66. When hood vent is turned on and display climbs to 76 the heater will not come on until hood is turned off and display goes back to normal. Thinking hood motor supply is in on the with other heating wires and producing some type of interference. Maybe 1500 square foot house. Wires could be bundled house thirty years plus.

 

[MAC702]

What does an independent thermometer next to the t-stat do?

These are 24V t-stats on control voltage, not line voltage? What type of central air is this?

 

[retirede]

Thermostat problem

Do you see any other issues such as dimming or brightened lights?

Just wondering if you have a bad neutral connection somewhere that causes the voltage to the thermostats to go WAY out of spec when the Whois is energized.

 

[ptonsparky]

You /we need to know what changed. The set point or the actual room temperature? Digital displays or old analog with pointer. Heat type?

Details.

 

[kwired]

May be a long shot, but you aren't by chance drawing warmer air from someplace else through the wall and across the thermostats?

If you are exhausting air from a space make up air has to come in who knows what paths it may be taking?

At same time unless you run the fan all day are those rooms going to suffer signigicant loss of heat before you aren't running the fan anymore?

 

[rlundsrud]

I would make sure that the 24 volt control Transformer that feeds these is wired correctly. By that I mean make sure the common on the secondary side of the Transformer is grounded and you have proper isolation from the 120 volt system. Those stats use half wave rectification to convert the AC to DC and if they're not properly isolated from other systems you can couple the 60 hertz signal onto the DC side. Once that occurs it can do some weird things to the electronics.

Without more information, this is admittedly somewhat anecdotal. Hopefully this will help.

 

[ggunn]

May be a long shot, but you aren't by chance drawing warmer air from someplace else through the wall and across the thermostats?

If you are exhausting air from a space make up air has to come in who knows what paths it may be taking?

At same time unless you run the fan all day are those rooms going to suffer signigicant loss of heat before you aren't running the fan anymore?

In a related story...

In the building I work in the thermostat is in a hallway that is open on both ends and not in the room where the registers are. It never accurately reads the temperature in the room where our desks are, so winter or summer, with heating or air conditioning, I am constantly donning and removing the sweater that lives on the back of my chair through the course of the day.

 

[LarryFine]

In a related story...

In the building I work in the thermostat is in a hallway that is open on both ends and not in the room where the registers are. It never accurately reads the temperature in the room where our desks are, so winter or summer, with heating or air conditioning, I am constantly donning and removing the sweater that lives on the back of my chair through the course of the day.

In my home, I set the fan to 'on' instead of 'auto' for that reason. The thermostat can only maintain the temperature where the thermostat is. It doesn't know the temperature in the rooms unless that air is constantly being brought past the thermostat.

 

[MAC702]

I can see not having a choice in the workplace, but in your home, go with a permanent and actual solution. There's the old school way, which any residential service electrician can do, and move the thermostat. Or the latest generation of WiFi thermostats, like the Nest Gen 3, can use a wireless remote sensor that can be placed in the actual room you wish to monitor the temp.

 

[hbiss]

I really can't see even thinking about this problem until and unless you place an accurate thermometer next to each thermostat to measure the actual temperature. What kind of heating system? Is it forced hot air? It could be that the fan is just redistributing hotter air from another location for some reason. Maybe pulling air back through your ductwork and through your furnace, if that's even possible.

Don't know, but I doubt at this point that this is electrical.

When did this start happening? That's another big question that needs to be answered. You say house is 30 years old.

-Hal

 

[MAC702]

...What kind of heating system? Is it forced hot air?...

Don't know, but I doubt at this point that this is electrical. ...

Ditto.