To understand how to fix hot water coming out of a cold water tap, it is best to understand exactly how this can happen. In this article, I will explore some of the reasons that this can happen and some possible DIY diagnostics and fixes.

At Broadley’s Plumbing and Heating, we have been serving South Jersey since 1911. As you can imagine, we have pretty much seen every kind of plumbing problem and situation. We understand when it’s time to call in professional help and when you might be able to perform your own fix.

In this article, we will go over:

• Why the cold water is warm
• Fixing hot water in a cold water line
• FAQs about water line problems

If you are having plumbing issues in South Jersey, give us a call at (609) 390-3907, or contact us online!

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How to Fix Hot Water Coming Out of Cold Tap: Homeowner Guide

Believe it or not, it is not unusual for hot water to come out of a cold water tap. The reasons can vary from a misconnected hook-up to mechanical problems or even hot water pipe proximity problems.

Why is My Cold Water Warm? Common Reasons

Here are some of the most common reasons that warm water can come out of a cold water tap.

• Malfunctioning Thermostat
• Water Pressure Too High
• Copper Heating Effect
• Faucet Cartridge Problem
• Cross Connection

Malfunctioning Thermostat

A malfunctioning thermostat can create temperature variability in the water lines. It can be presented in the following ways:

• No hot water 
• Not enough hot water 
• Slow hot water recovery
• The water is too hot
• The high-limit switch keeps tripping 

In the case of warm water coming out of the cold water tap, it may be the case that your hot water thermostat is operating at too high a level and is radiating heat close to the cold water line.

Water Pressure is Too High

One of the signs of excessive build-up of pressure in the hot water tank is uneven water temperature. Excessive pressure can cause a build-up of steam leading to your water heater’s temperature rising higher than normal. This is a potentially dangerous situation and could possibly lead to a burst tank. 

The following signs are indications of excessive pressure build-up:

• uneven heating
• leaking or corrosion around the tank
• hissing or bubbling noises
• rust-colored water coming from the faucet or showerhead

Any of these signs could be an indication of an excessive pressure build-up in your hot water tank. If you suspect high pressure in your hot water heater, it is important to take safety precautions and take action immediately.

First, turn off the power source to the hot water heater. This will help prevent any further damage or risk of an explosion due to high pressure. If you are unable to locate the power source, contact a licensed electrician or plumber who can assist you with this task.

The Copper Heating Effect

Most plumbers love using copper piping when installing hot water heaters. That is because copper’s excellent heat conductivity allows the hot water heater to quickly and evenly. It reaches the desired temperature and delivers hot water more efficiently thereby reducing energy consumption.

But if the copper pipes are located too close to the cold water lines, radiant heat can inadvertently warm the cold water lines causing the initial burst out of the cold water tap to feel warm. Your plumber may be able to make some small adjustments to prevent the heating effect.

Faucet Cartridge Problems

If your home has a water expansion tank, this piece of equipment relies on a one-way valve to lower pressure on the water meter. Without an operational valve, the hot water flows into your cold water tap. This is an easy way to result in warm water coming out of the cold side.

Cross Connection

A cross-connection happens when a single-handle faucet is leaking internally, or the pipes are incorrectly installed where a hot and cold line are combined by mistake. This could be the reason why you’re having hot water come out of your tap when you’ve turned the faucet to cold.

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Fixing Hot Water in the Cold Water Line

Fixing hot water coming out of a cold water tap may be a job for a professional. Here are a few ways that you can help to determine the problem and possibly address it yourself.

• Turn off your water supply. Before doing any kind of diagnostics it is important to recognize that safety comes first. You don’t want to trigger a massive water leak.
• Check pipe temperatures to look for excessive heat where it shouldn’t be.
• Replace the faucet cartridge. The cartridge may be defective allowing hot water to leak into the cold water lines.

Call in a qualified plumber if these diagnostics don’t yield results.

FAQs: How to Fix Hot Water Coming Out of a Cold Tap

To find a highly experienced service provider for residential plumbing repair in Ocean City, NJ, look no further than your Broadley’s Plumbing, Heating and Air Conditioning dealer.

Can a hot water faucet just have cold water coming out of it?

Yes. There are several possible reasons including incorrect cold water -warm water line hook up, heating effect and more. Your local plumber can help you determine the exact cause.

Why is my cold tap water not cold?

Sometimes the hot water pipe is located too close to the cold water pipe warming the cold water for the initial burst out of the cold faucet.

Can water flow backwards through a water heater?

A pressure imbalance in the plumbing and water supply can cause a condition known as “backpressure backflow”. This is commonly caused by a pressure imbalance in the hot water tank.