Does the house heater stay cold even with the heating on? Does your car's engine temperature exceed normal operating limits? In both cases there may be air pockets that prevent normal water / fluid recirculation. Fortunately, this is a common and easily solved problem. With a few tools, both the car radiator and the home heater will return to full efficiency.
Steps
Method 1 of 2: Bleeding a Heater
Step 1. Check the heater
This must be purged if there are pockets of cold air in the upper elements. Therefore, when you turn on the heater, the heater remains completely or partially cold to the touch. Unfortunately, a cold heater could also be a symptom of more serious system problems. Before proceeding, check for other common malfunctions, such as those listed below. Remember that heaters can get very hot, always protect your hands.
- If you have several heaters in the house, touch them to see if all of them are cold or lukewarm. In this case you could have a much more extensive problem for the whole system; the boiler could not work properly or there could be an accumulation of dirt and sediments in some part of the system. Read this article.
- If the problem is accompanied by a leak of water under the radiator, then there is a weak spot in the radiator where the water is coming out. Turn off the heating, tighten all the nuts / bolts you find near the valve. If this does not solve the problem, the nut may be corroded and must be replaced. Call a professional technician.
- If the heaters on the upper floor of the house do not work, but those on the ground floor do, then the system could have problems with the pressure to push the hot water upwards.
Step 2. Find the radiator key
If you have decided that it is advisable to purge it before proceeding to other actions, then you must find the key that opens the relief valve. At the top of the radiator you need to locate something that looks like a drain valve that has a small square indent that can be turned with a special wrench. The latter is easily purchased in hardware stores. Get the right size wrench for the model of heater installed in your home or, alternatively, look in your toolbox for a small wrench that is suitable for turning the valve.
- Some modern heaters have valves designed to be opened with a simple flat screwdriver.
- Before continuing, make sure you have the radiator key, a screwdriver, a wrench, or a combination of tools suitable for opening all the valves on any radiator in your home. When purging one heating element, it is best to proceed with the others as well.
Step 3. Turn off the heating
Make sure that the main switch is turned off before proceeding with the purging operations, otherwise the boiler will continue to pump air into the system. Before removing the air you have to wait for the content of the radiators to stabilize. Wait for the heat to dissipate, then touch the radiator to see if it is still hot; if it is even partially, you have to wait a little longer before moving on to the next step.
Step 4. Open the heater valve
Make sure both the inlet and outlet valves are open. Insert the wrench (or screwdriver) into the vent screw and turn it counterclockwise to open it. You should hear a hiss emitted by the air coming out.
Opening the vent valve allows the hot air to escape, which in turn will be replaced with hot water by means of the pipes that connect the radiator to the boiler
Step 5. Collect what is dripping from the heater
As the air comes out, it carries some water with it, so there may be splashes during the purging phase. Keep a tea towel or cloth under the valve to catch them or alternatively use a bowl or plate.
Step 6. Wait for a stream of water to come out of the valve
When you see a steady stream of liquid coming out (and not a mix of air and spray) then you are sure that all the air in the heater has been released. Close the vent screw (turning it clockwise) and make sure there are no leaks. Use a rag to wipe away any drops that wet the radiator.
Step 7. Repeat the procedure for all the heaters in the house
To be sure that the system has been cleaned of all the air, you must purge all the heating elements in the house. If you want to keep your system in good condition, remember to bleed the heaters once a year and in any case after any repairs or modifications.
Step 8. Check the boiler pressure
By removing excess air from the system, you have lowered its pressure. If this is too low, the hot water may not reach all the heating elements (especially those on the upper floor). To restore the pressure, you will need to top up the water in the boiler.
- For home heating, the pressure usually needs to be between 12 and 15 PSI. The greater the pressure, the greater the path that the hot water is able to travel, which is why this value must be proportionate to the size of the house; a particularly high or low house will need, respectively, a boiler with higher or lower pressure.
- If your boiler has an automatic refill system, it should be able to maintain 12-15 PSI without any intervention on your part. If not, you will have to add water manually until the pressure gauge indicates the right pressure.
Method 2 of 2: Bleeding the Car Radiator
Step 1. Check your car for symptoms that indicate a malfunctioning radiator
The car radiator can have problems for exactly the same reasons as a home heater: air pockets that prevent the circulation of the coolant. This prevents the antifreeze from traveling through the cooling circuit, causing the engine to overheat. If you notice one or more of the following marks on your car, the radiator may need to be bled:
- The temperature warning light on the dashboard indicates very high values.
- The liquid boils out of the radiator.
- The engine emits a strange, sweet smell (due to leaking antifreeze which then burns).
- However, it is a good idea to bleed the radiator after maintenance, such as replacing parts of the cooling system. During mechanical work, air may be introduced into the radiator, always check the thermostat on the dashboard after making any changes.
Step 2. Locate and loosen the radiator vent valve
Some models have this valve built into the cooling system and it works by releasing trapped air. Consult the vehicle maintenance manual to find the exact location of this valve. In general it is located at the highest point of the system since the warm air, by nature, tends to rise.
- To bleed the radiator with this valve, you just have to loosen the latter until you hear the hissing air coming out. Use a cloth to catch any splashes of coolant, then close the valve again when a steady stream of coolant begins to leak.
- Some cars are not equipped with a relief valve, but don't worry, it is always possible to carry out this type of maintenance.
Step 3. Start the car after removing the radiator cap
Another simple technique for bleeding the radiator is to run the engine at idle with the cap removed (great if your model does not have a breather valve). Let the engine run for about 15-20 minutes. The air pockets will be forced to circulate in the cooling system and will come out of the opening.
Step 4. Lift the car
Air naturally tends to rise, so if you raise the front of the car with the radiator higher than the rest of the cooling system, you can speed up the air out. With great care he raises the car with jacks; cars usually have one, but if yours does not have one, you can buy it in the auto parts store. Make sure the radiator cap is removed or loosened before lifting the car.
On some models, the radiator may not be in the front. Consult the vehicle maintenance manual
Step 5. Wash and fill the radiator
After bleeding it, it is always a good idea to top up with coolant. The trapped air artificially increased the pressure inside the system, so it is likely that you were driving a car with little liquid. Remove the old coolant and add the new one according to the instructions in the maintenance booklet. Here are some guidelines:
- Wait until the engine is completely cold.
- Place a drainage container under the radiator valve.
- Add water to the radiator until it is full and then drain it from the valve under the car.
- Close the drain valve and add new coolant, usually a 50% mixture of distilled water and antifreeze is fine (do not use tap water as it releases mineral deposits).
- Purge the radiator again to remove the air that was introduced with the flush and top up.
