What Size Is The Inlet And Outlet On Hot Water Heaters?

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Written By John Roe Stephen

Water heaters need supply lines with a diameter of 3/8 inches and 16-24 inches. It also offers various characteristics that make it more consumers. Although some older water heaters still utilize supply pipes with a diameter of 12 inches.

It does not get much simpler than this for supply line size. Incorrectly sized supply pipes require a lengthy time to fill a tank. Consequently, hot water is delayed.

If you would want to learn more, spend just a few minutes and check out the rest of the article!

If we know precisely what size supply line we need, it will save us time. The standard nowadays is 3/4, although the standard was formerly half.

The same is true of the water supply in the city. If the remainder of the plumbing in the house is smaller, having a larger heater pipe is of little value.

Water heater supply lines should have a diameter of 34 inches. In the 1990s, heater supply pipes had a diameter of 12 inches. However, the low water pressure in the 12-inch supply pipe was an issue. Install a 34-inch supply pipe in the heater if you wish to use showers.

The flow rate is dependent on the correct size. However, it would help if you did not leak the heater. The 34-water heater might malfunction and start leaking from time to time. Water heaters may leak for many different causes.

For several showerheads, body sprayers, etc., a 34-inch supply line is recommended. This supply pipe maintains the necessary water pressure even when all the faucets are turned on.

3/8-inch supply lines are also in demand these days. In comparison to 34-inch supply lines, 38-inch pipes are much longer.

When a 12-inch supply line was used, several users reported poor performance. That is why it is essential to keep an eye on the size of your supply lines.

Inlet Size

Increasing the input size will not improve water flow. As a result, the pressure on your heater’s water line may be too great. With smaller pipes, there is no need to use a larger one. A smaller inlet also means less water flowing through the system.

Outlet Size

An outlet refers to a conduit that drains a tank, cistern, or reservoir. The inlet pipe is smaller than the output piping in size. There is less pressure loss in a giant pipe, so the larger pipe is preferable.

“Friction loss” decreases as water travels through the giant pipe. Water pressure is not affected by having more water in a larger pipe.

Choose the right inlet and outlet line size considering these factors – when comparing various supply lines, there are significant differences.

There is no difference between these two streams of supply. Because of this comparison, you will be able to decide which service is exemplary for you.


Copper supply lines are the strongest and most long lasting. Copper supply lines are almost leak-proof and can withstand high water pressure.

Stainless copper water supply pipes may survive for more than 20 years if they are installed correctly.

Pex water supply pipes cannot handle the total pressure of water. In addition, the temperature is a reality.

If you try to use hot water in a pex water line, it will fracture. After installing the supply line, brown water may also drain. Thirty-four supply lines can handle all the water pressure used. Boiling water may also be passed through it.


Depending on the quality and the length of the supply chain, prices might vary widely. It costs between $6 and $50 for a high-quality 34-inch supply line.

Copper is the ideal material to utilize for supply lines. 24-32 inches is the usual length of the water supply pipe. This will set you back anything from $10 to $30.

12-inch supply lines are much less expensive than 34-inch supply lines. It costs around $20 to buy a good 12-supply line.

The typical length of the water supply pipe is between 12 and 16 inches. Therefore, you should expect to pay $8-15 for a high-quality 12-inch 12-16 supply line.

What Size Water Line Feeds A Hot Water Heater?

Most water heater inlets have a diameter of 34″ or 12″. An inch and a half is a popular measurement in older homes. 34″ is the standard intake size for most heater supply lines nowadays. Generally, tank less water heaters are between 3/8 and 1 inch in diameter.


There is now a clearer picture of the optimal water heater power grid size. When employing a water heater, a supply line with a diameter of 34 inches is ideal. The water flow rate is ensured, and the gallon is promptly filled.

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