Heaters are an essential appliance at home and commercial buildings. They help to keep the environment in the room warm. The thermostat is an integral part of the heater to control the heat and to control it.
Sometimes you may see that the heater is still on when the thermostat is off. You may ask what is causing these issues and how to solve it. Let us discuss the reasons behind this particular issue and how to solve them.
Heater is still on when the thermostat is off? (With solutions)
There are multiple reasons why a heater will stay on when the thermostat is off. It may be caused due to a shorted wire, storage in the thermostat of the heater, a faulty control board, mistakenly open gas valve, broken furnace and at last a damaged or broken thermostat can cause this problem.
There are multiple reasons when a heater is still on when the thermostat is turned off. Although it is hard to pinpoint the actual reason behind this issue at one try, you may go through all the possible scenarios to narrow it down.
Let us help you know the reasons why a heater is still on when the thermostat is off. Also, let us provide you with the solutions for these reasons with step-by-step solutions if possible for a better understanding.
Shorted or bad wire or thermostat in the heater:
This is the most common issue in a heater. This often happens to a heater’s thermostat as it uses continuous electricity to operate. This may also occur due to aging as well.
Many things can indicate a shorted or bad wire. Among all the types of damaged or shorted wires, the following are the most common: burnt wires, disconnected wires and shorted wires. All of these wires can be fixed following some simple steps:
Remove the protective cover of the thermostat:
The thermostat has a protective cover at the top. Use a screwdriver to remove the screws of the protective cover. Removing the cover will provide access inside the thermostat.
Check for any shorted wires or thermostat:
After removing the panel, check for any wires which are shorted with other wires or terminals. You should also check if the thermostat is shorted with any cables or not. This is the standard solution for this issue.
If there is any shortage, remove it and secure the wires correctly.
Unscrew the terminals of the connection:
After fixing the shorted wires, it is time to reseed the connections in the terminals. Remove the screws of the terminals using a screw. Disconnect the connecting wire from the terminal.
Splice of the wire and reconnect them:
After disconnecting the terminal, slice the protective plastic cover over the wire. When you slice open the wire, it will expose new and fresh wiring.
Cut the old wiring part and connect the new wire heads to the terminal. Screw the terminals back again.
Place back everything as it was:
After doing all of the above, place back the board after setting the wire appropriately inside. Check if the thermostat panel is working properly or not.
A faulty control board:
A damaged or faulty control board is a common issue for which the heater stays on even when the thermostat is off. A control board is the heart of any heater and this is the control center of the heater itself.
If the control center is damaged or faulty, it may not take the commands appropriately. As a result, the heater may stay on even when the thermostat is turned off.
It is often advised to consult with an HVAC expert to replace it. But if you want and have the skills of performing electrical repairs, it is an easy task to replace the control board.
Here are the simple steps that you may follow to replace the control board of your heater:
Remove the screws of the control board:
The first thing to remove the control board of a heater is to remove the screws of the control board. To do that, you will have to use a screwdriver and find all the screws on the control board.
Depending on the model of the control board, it will have 4 – 6 screws. Remove the screws and store them safely.
Disconnect all the connections:
After you open the control board, there will be multiple connections connecting the board. Disconnect all the connections of the board from the terminal.
You will have to use a screwdriver and disconnect all the connections from the terminal.
It is noteworthy that there will be a blower motor wiring as well. You will have to remove that carefully as well.
Remove the old board and replace it with a new one:
After disconnecting all the wires, remove the old board carefully. After removing, purchase a similar control board from your nearest electrical shop and connect that with the terminals of the heater accordingly. Screw the terminals correctly.
Screw back the new control board:
In the end, place back the new control board and screw it back on the heater properly using the provided screws of the control board. Screw it tightly and check if it is working properly or not.
Jammed gas valve:
Sometimes due to carbon buildup or just simple aging, the gas valve can be jammed open. This may cause the heater to stay on even when the thermostat is off. This issue is a rare problem and may require a complete change of the valve as a result.
There are various ways to resolve this problem. Before solving this issue, it is important to turn off the gas connection.
Here are the simple steps to resolve this issue:
Check if something is stuck in the gas valve:
First of all, you will have to check if something is stuck in the gas valve.
Try to remove the blockage:
If the gas valve is jammed, try to remove the blockage that is causing it to be jammed.
Try to close it manually:
After checking that, you may try to close it manually. But you have to be careful about not putting too much pressure while trying to close the valve. It might break the valve.
If yet unsolved, you will have to change the valve with the help of an HVAC expert.
Damaged thermostat:
The thermostat may get damaged eventually if it gets old. It may get damaged due to other reasons as well. But whatever the reason is, this may also cause the heater to stay on when the thermostat is off.
You can replace the thermostat by yourself easily. Simple steps to do so have been given below:
Turn off the thermostat:
You will have to turn off the thermostat from the heater at first.
Remove it:
Then you will have to remove it by unscrewing it from the wall and detaching it from the wires that it is connected to.
Purchase similar thermostat:
After doing that, you will have to purchase a similar thermostat suggested by your heater manufacturer.
Connect the new thermostat:
After purchasing it, connect the new thermostat with the wires that connect with the heater. Place it on the wall and screw it properly.
Enable the power at the heater to the thermostat so that it can operate properly.
When should I contact an HVAC expert?
If you are facing issues like the heater is still on when the thermostat is off, you should contact an HVAC expert. Heaters are complicated appliances and require a lot of patience and experience to repair.
If you do not have the proper knowledge for this kind of work and if you do not have previous experience with HVAC appliances, you should consult with an expert.
A heater may cause various kinds of risks if you repair it without the proper knowledge. As a heater uses electricity to operate properly, there is a chance of you getting electrocuted if you do not maintain the necessary steps.
There is a chance of a fire as well. As a heater uses gas to heat the room, you may start a fire or damage the appliance if you do not take the necessary steps to prevent them.
Even diagnosing a heater is difficult for an average person, so it is better to call an HVAC expert if you have issues with your heater.
How much will this cost to fix?
This will cost you around 50$ – 700$ depending on the issue of your heater. An HVAC expert may charge you around 50$ to perform a basic diagnostic of the heater. Depending on the heater’s problem, it may cost you around 100$ – 700$.
If you need to change the furnace or thermostat, the electrician may charge you separately for the spare parts. For repairing the control board, it may cost you around 125$ – 700$.
Final thoughts
Various reasons can cause the heater to stay on when the thermostat is off. Among those issues, shorted wires, faulty circuit board and damaged thermostat are common issues. Even though there are straightforward solutions for all of them, it is better to contact an HVAC expert to solve the problems.