If there is only cold water coming from the tap, it is likely your water heater, especially if the cold side is working fine. There are various reasons why water heaters do not heat properly. It may be due to a leak, a build-up of sediment or it could have become unplugged. Try to fix it by flushing the water heater.
Close cold water valve, open a hot faucet on the closest faucet, then be sure all faucets are closed. If you're quick, you can loosen the element, screw it out, quickly pull it out and put the new one in. You many lose a cup of water if quick. If you're not sure, drain the tank.
If you are getting hot water but not cold water then the cartridge could be clogged or faulty. The best thing to do is remove the cartridge and clear the cold water input to the valve body. What you can do is turn off the hot and cold shut off valves under the sink.
A likely explanation is that your faucet might be clogged. Over time, mineral deposits build up inside the plumbing fixtures after repeated use. This blockage doesn't allow the hot water to flow correctly. The problem becomes more prominent when combined with other plumbing issues, such as low water pressure.
A broken or burned-out heating element (immersion) could be the culprit for cold water in the hot water tap. As we use our water heater, the heating element gets worn out over time, which reduces its efficiency and lowers the maximum water temperature, until it completely stops heating the water.
There are several reasons why you might not have hot water, ranging from common problems, such as a problem with your water or power supply, boiler settings, thermostat, timer, recent power cut to more complex issues, such as boiler pressure, a potential airlock or frozen pipes.
Check the upper thermostat if there is no hot water or the supply is insufficient or too hot. If the thermostat is damaged, it should be replaced. Even if the thermostat is set correctly, lack of regular maintenance can lead to problems because of sediment accumulation.
Usually there are two main causes: The water is sputtering out of the faucet, possibly because an airlock has been created that is preventing the hot water from flowing out of the tap, or there is a problem with your water heater.
There might be a blockage or a leak in the pipes that supply hot water to your sink, resulting in a lack of hot water flow. Additionally, check if there are any closed or partially closed valves in the hot water supply line that could be restricting the flow of hot water to the sink.
First, find the shut off valve for the hot water and see if it's closed. If so, opening the valve could remedy the situation. But if the water still remains warm for only short periods of time, you may have a blockage or obstruction in the pipes or a problem with your bathroom shower valve.
Likely, the heating elements inside your water heater are broken or not working properly—or, potentially, your thermostat is incorrectly set. If those aren't the issue, it's possible the power source for your electric water heater has been interrupted—this is commonly caused by a blown fuse or tripped circuit breaker.
Water Line Blockage
Mineral buildup can block the water lines leading to your kitchen sink. When one of these blockages occurs in your hot water supply, your sink faucet will only be able to provide you with cold water. If no water comes out, you know that you have a clog in the hot water inlet.
Possible Issue: One of the most common culprits for this predicament is a malfunctioning differential valve. This valve is responsible for controlling the flow of hot and cold water in your plumbing system. When it's not functioning correctly, it can lead to an imbalanced water supply, leaving you with cold water only.
The simplest possibility is that the valve under the sink is closed. This can happen if someone recently worked on the faucet and forgot to turn the water back on. The fixture could also be clogged, dislodged, bent, or broken. The worst-case scenario is that you'll have to replace the faucet, which isn't a big deal.
One of the primary reasons for no water coming out of a tap can be blocked pipes due to the build up of sediment or debris, which obstructs flow. This can include rust, heavy metal deposits, or limescale.
No water from hot water pipes suggests a serious issue such as a major blockage or a shut-off cold water supply. Checking for frozen pipes, especially during cold weather, is a good starting point as ice can cause blockages that prevent water flow.
This is typically caused by a malfunction in the valve or a failure in the plumbing that connects the valve to the water heater.
While there may be many reasons why your tap's hot water function isn't working, the most common problems are leaks, limescale build-up, and boiler pilot light malfunctions. If you've got an Instant Boiling Water Tap, you might find that the tank which boils the water has been unplugged.
A lack of hot water can be caused by a variety of issues. In electric water heaters, a power loss or heating element failure can cause water to no longer heat in the tank. In gas water heaters, a faulty gas connection, a bad pilot light, or a bad burner can cause no water to heat.
You could be having a blockage in the faucet, an issue with the water heater, or a faulty faucet cartridge. You should examine each part until you find the exact cause of the issue with your kitchen sink.
If your hot water runs out too fast, you may have an issue with: Too much hot water demand from multiple sources at the same time. Sediment build up inside of your water heater tank. A broken dip tube.
Thermostat Malfunction
The ideal temperature for a water heater is somewhere between 120⁰ F to 140⁰ F. In some instances, all you have to do is readjust the temperature or hit the reset button to get your hot water running again. However, it's possible your thermostat is damaged and requires a repair or replacement.