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Determining how many dead-end lines in your home

Determining how many dead-end lines in your home
Easy step by step guide to determine how many dead-end lines in your home.

Determining how many dead-end lines in your home

This guide provides an overview of how to determine how many dead-end plumbing lines you have in you home.  Many homes have more than one dead-end line and may require a second Bridge Valve.  

In some case you may have more than 1 dead-end line but don't care about one of them.  For instance you may have a guest room that is rarely used and you may not want to "fix" that area of the house at this time.  You can always add an additional Bridge Valve down the road.

Plumbers know how to make things work.  However circumstances during construction may alter the way they plumbed your house and it may not seem reasonable after the fact.  A very common example of this is when a bathroom located on the other side of the house from the water heater takes longer to get hot water than a kitchen sink located 10 feet away.  Trying to make heads or tails of this after the walls have been closed and the plumber is long gone can be frustrating - even in new construction.

This guide will walk you through a few simple steps to locate the furthest fixture from the water heater and to determine how many dead-end lines you have.  Even though the test is simple it may take several tries to complete.  Each new iteration of the test must be preceded by letting the water pipes cool down to ambient temperature (usually about 1 hour with no hot water usage).

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One Dead-End Plumbing Layout

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Two Dead-End Plumbing Layout

Where to Start
Step 1:  Allow the hot water lines to cool.

The water lines need to be at ambient temperature before performing this test.

Best time to start the test is early in the morning before hot water is used or wait at least 1 hour after the last hot water usage.

Step 2:  Go to the farthest fixture.

Go to the fixture that you think is the furthest distance from the water heater.  It will be the fixture where there is the longest wait for water to get hot.

Note:  The furthest fixture is not always the one located physically the greatest distance from the water heater.  It's the one with the longest water line feeding it.

Step 3:  Turn on the hot water faucet.

Run the water until it gets hot (not jut warm, but hot).

Note:  It may be helpful to write down how long it takes to get hot.

Step 4:  Go to the next farthest fixture.

Turn on the hot water faucet and note how long it takes to get hot.  If it is faster than normal it is on the same line as the first fixture.  If it takes just as long to get hot it is on a separate line.

Repeat this step until you are satisfied that you know which fixture takes the longest and which one's are on the same line.

Step 5:  Repeat test.

Repeat this test with every sink in your home.

Note:  You can start with 1 Bridge Valve and add more later on if necessary.

What do the test results mean?

Usually several fixtures (if not all) are fed by 1 line.  If you go to the end of the line and get hot water, the rest of the line will have hot water also.  Fixtures that don't get hot water faster are on a different line.

One Bridge Valve will take care of one dead-end line.  If there is a second dead-end a second Bridge Valve will be needed.

More Bridge Valves?

Most homes have a 3/4" hot water trunk line.  That is, the 3/4" line feeds all of the fixtures on a dead-end line.  However the water lines that exit the wall under a sink are 1/2" lines.

The Bridge Valve is installed between the 1/2" hot and cold water lines under the sink.  A 3/4" line has double the capacity of a 1/2".  Removing the cool water from the 3/4" will be much faster if a second Bridge Valve is added.  Typically this cuts the wait in half.

If speed is important to you then a second Bridge Valve will have a big impact.

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