If there is a problem with only the hot water in one shower, the problem is most likely in the shower hot water valve. Remove the handle and check to see if you have hot water flow to this point. Make sure that there is no other valve closed.
Blocked Plumbing
Check the kitchen sink, shower faucets, and anywhere else that dispenses hot water. If hot water comes out from the other taps but one, it means a particular hot water line is blocked. Mineral deposits, debris, and sediment are the most likely cause of a blocked faucet.
The lack of hot water for the shower and elsewhere in the home may be down to several reasons. It could be faulty parts in the water heating unit, an obstructed flue, the build-up of sediment or a malfunctioning temperature control.
If your problem wasn't the anti-scalding device, your shower mixing valve has most likely gone bad and is preventing hot water from mixing properly into your shower water. Your shower mixing valve controls the water temperature of your shower by blending together cold and hot water.
What's most likely happening is a problem with the shower's mixing valve. The mixing valve is a control valve that creates the balance in the flow of water from the hot water line and the cold water line and blends the two together for your desired shower temperature.
Hot and cold water can often be caused by an issue with the water pressure in an electric showering system. It might be that limescale has built up in your system and pipework and is narrowing the route through which the water travels.
The usual suspects for this problem are a blocked shower head, kinked or damaged shower hose, or blocked inlet filters in the shower itself. It could also be due to faulty non-return valves. Permanently running either hot or cold.
Your bath may not be heating well due to a clogged pipe or hard water mineral buildup, which prevents efficient heat transfer to the water. It also may simply be that your hot water heater isn't big enough to fill your tub. You can increase the heater's temperature, but watch out for scalding.
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 you place your water heater on a higher setting, the water coming out of it will be hotter, and you won't need as much to reach that same temperature. Raising the temperature setting on your water heater ultimately makes your hot water supply last longer.
Supply points, such as faucets and showerheads, are common points of clogging. Some hot water systems have inlet and outlet filters, which can also clog and reduce hot water availability. In this case, only the affected appliances or supply points will suffer inadequate hot water.
If your water heater loses power, your water heater's reset button can be used to turn the appliance back on. However, your reset button serves as a safety device and turns the unit off when the water temperature gets too hot.
Once you've reset the system, you have to wait for hot water (unless you have an on-demand water heater), but for how long? It depends on the size of the tank, but with any unit, you should be able to get in a hot shower with gas water heaters within 30-40 minutes and with electric tanks, about 60-90 minutes.
Is There a Reset Button on Electric Hot Water Heaters? Yes, all water heaters should have a reset button. They can also be known as the “emergency limit switch”, “emergency cut off (ECO)”, “high-limit safety thermostat switch”, or “electric water heater reset button”.
Low water pressure
If the water pressure to your house drops, this can affect how the hot water pressure is working in your system too. If your shower goes cold after a few minutes, it might be that you've been unlucky enough to be showering just as the water pressure dropped.
A defective mixing valve will allow a cross-over of hot and cold water, even though there are no visible signs of trouble or leak. A plumbing cross-over can cause a complaint such as 'water not hot enough'.
Either way, you need to make sure the electric power to the water heater is OFF before you go on to step two. If the water heater circuit breaker is already in the OFF position, flip it to the ON position as a test. If the breaker immediately flips back to the OFF position this is a sign of a bigger electrical problem.
Disconnect the electricity to the heater.
Most heaters are plugged into a wall with a cable. You may have to unscrew the cable or turn a knob near it to shut off the electricity. If your water heater is wired in directly you'll need to turn it off at the breaker box.
When your thermostat stops working correctly, it can fail to regulate the temperature in your electric water heater properly. This, in turn, will cause your water to heat up to dangerous levels, which will cause the reset switch to trip.
Water Heater Runs Out Of Hot Water Quickly: Possible Reasons Why. As mentioned above, several things can cause a home's hot water supply to run out faster than it should. The three most common culprits are sediment build up, a faulty heating element and a broken dip tube.
Connect a hose to the drainage valve and make sure that you lead it out somewhere safely to drain, knowing this water will be very hot. Into a bucket or outside are your best course of action. Drain and then flush with the cold water valve open until the water runs clear of any sediment.
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.