What happens when the cold water is turned off and the fan of the gas water heater is started?

When the cold water faucet is turned on and off, the gas water heater will start. This is caused by the reverse flow of water pressure. The water inlet pressure and water supply pressure of the water heater are balanced. When the cold water tap is turned off, the water pressure of the water heater will decrease. When the cold water faucet is closed, the water pressure in the main pipeline will flow to the place with low pressure (water heater pipeline), causing the water heater fan to start when the cold water faucet is closed. A one-way valve can be installed at the water inlet of the water heater, which can generally solve this problem. The air from the water heater pipeline to the end of the hot water pipeline should be evacuated.

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When there are multiple hot water outlets that need hot water, how many tees are there in the hot water outlet of the water heater (if there are several hot water outlets, how many tees are there). If it is a newly renovated house, you can ask the water and electricity installers to embed concealed pipes in the wall. If it is an old house, the requirements are not high, just install open pipes.

After installing the tee, you can divert the hot water to the places you want to use, including kitchens, washbasins and other places that need hot water! You need to use hot and cold taps to control the start of the water heater. As long as you turn on electricity (or ventilate the battery) and turn on the tap of any hot water outlet, the gas water heater will start automatically.

As for the installation of the mixing valve, it is not contradictory to the water heater. The water mixing valve has two ports, hot water on the left and cold water on the right. After installation, the water mixing valve can be moved to the hot water end (left) to start the water heater! If the water is hot, turn right again and you'll be fine.