Why You Have Hot Water In Some Faucets (And How To Fix It)

Having hot water in some faucets but not in others can be endlessly frustrating. You turn on a faucet expecting a steady stream of hot water for your morning coffee or shower, only to get an unpleasant blast of cold. Even worse, the issue seems to randomly affect different fixtures in your home over time. Before calling an expensive plumber, it helps to understand exactly why this occurs and try some DIY troubleshooting steps first.

Common Causes Behind Losing Hot Water in Select Faucets

There are several possible root causes for losing hot water flow in some sinks and showers but not in others:

• Clogged faucet aerators or screens
• Sediment buildup and clogging in pipes
• Inadequate home water flow rates
• Trapped air or "airlocks" in hot water lines
• Old, worn out, or faulty shut-off valves
• Broken diverter valve in boiler system
• Electrical issues with hot water heater unit

Before assuming the worst case of a failing water heater or extensive plumbing repairs being needed, focus troubleshooting on the most likely culprits behind uneven hot water distribution in your home.

Start With Inspecting Faucet Aerators and Screens

The aerator at the tip of faucets plays a crucial role in controlling water flow. Aerators contain a small screen that catches debris flowing through pipes. Over time, this sediment and mineral buildup can clog the screen, blocking water flow.

Since sink faucets typically get more use, their aerators tend to clog faster than other fixtures. Especially in older homes with galvanized steel pipes or homes with hard water, regular aerator cleaning is a must.

Warning signs of a clogged aerator and screen are lower water pressure, intermittent splashiness, and loss of hot water supply coming from the tap. Thankfully, cleaning or replacing faucet aerators is an easy, inexpensive DIY fix.

Step-By-Step Guide to Cleaning Faucet Screens

Fixing a hot water flow issue from sediment or debris caught in the faucet aerator and screen takes just minutes. All you need is an adjustable wrench, some white vinegar, and a small brush.

1. Turn off water supply lines under the sink
2. Unscrew the faucet aerator head counterclockwise
3. Carefully remove screen insert from housing
4. Soak screen in white vinegar solution to dissolve mineral deposits
5. Gently scrub screen with small brush to dislodge sediment
6. Rinse screen under running water until debris free
7. Replace screen in aerator housing
8. Hand tighten aerator head back onto faucet
9. Restore water supply and check flow rate

Take care not to lose any small washers or gaskets within the aerator when taking it apart. Replacing the entire aerator head is an easy alternative if the screen proves too challenging to clean.

Pipe Sediment Buildup Can Also Lead to Clogs

While faucet aerators trap a good deal of mineral sediment from your home's water supply, they cannot catch all debris flowing through the plumbing system. Tiny amounts of residue gradually coat the inside walls of pipes and can accumulate over years.

Eventual sediment buildup causes friction and turbulence in pipe fittings. As water struggles to flow through narrow openings, pressure and volume decrease. Hot water lines seem especially susceptible to mineral deposits and corrosion.

Warning signs of pipe sediment issues are lower water pressure from all fixtures, including both hot and cold supply lines. However, hot water flow tends to get impacted first. Hearing banging noises as water moves through pipes points to heavy limescale or rust accumulation.

Using a Pipe Flush Valve to Clear Mineral Deposits

Pipe flush valves offer an easy DIY solution for clearing out accumulated mineral sediment without disassembling plumbing. Installed just like any other valve fitting, opening the valve creates turbulence that dislodges and flushes out debris.

For especially problematic areas, detach the faucet aerator before opening the flush valve to allow bigger pieces to pass. Catch any flushed out particles in a bucket to prevent drain clogs.

In addition to periodic pipe flushing, installing whole house sediment water filters extends the life of your plumbing. Filters continually capture abrasive debris, preventing buildup accumulation on pipe walls over time.

Check Your Home's Water Flow Rate

Having sufficient water flow and water pressure plays a big role in maintaining comfortable hot water supply throughout your home. Minimum flow rate specifications vary by fixture type and local building codes. Typical single family homes need:

• Sink Faucets - 1.5 to 2.0 GPM flow rate
• Showers - 2.0 to 2.5 GPM flow rate
• Bathtubs - 4.0+ GPM flow rate

New low-flow fixtures now available can operate on even lower GPM ratings. However, if your home still utilizes older, standard flow rate faucets and showerheads, low water volume can definitely contribute to loss of hot water supply at some fixtures.

Using a Water Pressure Test Gauge

Verifying your household water pressure takes just minutes with an inexpensive water pressure gauge that connects to outdoor hose bibs. Water pressure impacts both flow rate and volume. The ideal range is 50-70 PSI.

Consistently low pressure under 50 PSI makes it difficult to run multiple fixtures at once without noticeable loss of water volume. Lower pressure causes more rapid cooling of hot water as it moves through pipes, reducing supply at farther faucets.

Adjusting Fixture Settings to Compensate

Making small tweaks to temperature and pressure settings at problem faucets can help compensate for borderline low flows:

• Increase hot water temperature setting
• Reduce maximum flow rate if adjustable
• Use low-flow or water saving faucet accessories

However, upgrading to higher water flow rate fixtures may be required long-term, especially in homes with undersized or outdated supply lines. Installing recirculating hot water pump systems greatly improves delivery while reducing water waste.

Do You Have an Airlock in Hot Water Lines?

In addition to debris and mineral buildup impeding water flow to fixtures, small air bubbles can also get trapped inside plumbing pipes. While not technically an "airlock" like what occurs in car fuel systems, the effect is similar. Air pockets block the free flow of hot water to faucets.

How Do Airlocks Happen in Plumbing?

Small air bubbles infiltrate through microscopic leaks or gaps in fittings all the time without issue. However, changes in flow velocity, pressure shifts from quick fixture shut-offs, and turbulence passing through elbow joints causes bubbles to join and stick to pipe walls.

Most air bubbles that form pass through the system when water runs. But over time, difficult-to-reach pockets enlarge as more air accumulates. Sections of piping that loop up and downhill are notorious spots, since rising air naturally gets caught.

Signs of an Airlock Cutting Off Hot Water

Symptoms of an airlock that has built up enough volume to block water flow mimic other clog issues like sediment buildup. Warning signs include:

• Intermittent loss of hot water flow
• Significant droplets in pressure and flow strength
• Gurgling noises coming from hot water lines

However, the problem arises only with hot water supply, not cold water lines. Running a hot water faucet for several minutes may temporarily improve flow before air pockets shift and water stops again.

Bleeding Pipes to Get Rid of Trapped Air

Removing built-up air pockets causing hot water supply problems involves opening strategic points along the plumbing to purge or "bleed" the air out.

1. Locate accessible highpoint along hot water lines
2. Connect small hose securely to create outlet
3. Route hose ends to large bucket
4. Open downstream fixture to allow air release
5. Close fixture after steady flow runs bubble free

Repeat the process along different pipe sections until water performance normalizes. Adding auto air vents permanently at suspected problem areas prevents future airlock recurrence.

Do You Have Partially Closed Shut-Off Valves?

The various valves installed throughout your home's plumbing system play a huge role in directing and controlling water flow. Older globe valves frequently get overlooked as a source of issues. But worn, faulty, or partially closed valves can cause infuriating loss of hot water problems.

How Valves Impact Hot Water Distribution

Two types of shut-off valves contribute to balanced hot water distribution - fixture supply valves located under sinks or behind appliances, and main circuit valves for each zone.

Supply valves tune flow to individual fixtures. Similar to a volume control knob, opening or closing them adjusts water volume. If valves supplying hot water piping gradually fail, it diminishes flow unevenly.

Zone valves manage overall circuits, making it possible to isolate sections for maintenance. But age related issues can lead to valve seats not fully closing or opening properly.

Finding and Replacing Problem Shut-Off Valves

Start inspecting valves closest, testing them first. Symptoms to check valves for include:

• Excessive handle loosening needed to achieve full closure
• Water continues dripping after full closure
• Valves getting stuck open or closed

Bad valves require replacement to restore precise flow control. Upgrading older compression valve styles to 1/4 turn ball valve models brings huge reliability improvements.

If unsure, calling a plumber to survey all home valves takes the guesswork out of locating problem ones degrading hot water distribution.

Could a Broken Diverter Valve Be To Blame?

Houses utilizing a boiler setup for generating hot water rely on special diverter valves to handle directing flow between various fixtures or heating zones. If the diverter valve breaks, it can cut off hot supply unexpectedly.

Understanding Diverter Valve Operation

Diverter valves provide a "traffic cop" function within boiler systems. Using input data from sensors, automated commands shift internal chambers to change flow pathways. This allows managing delivery to heating units, hot water storage tanks, and household fixtures from the same boiler.

For example, as the heating system thermostat demands hot water, the diverter valve channels flow from the boiler through that zone's pipes. When temperatures equalize, the diverter then switches to sending hot water to the domestic supply tank and household faucets instead.

Symptoms of Diverter Valve Failure

Problems within the diverter valve's internal operating components lead to an inability to correctly reposition flow channels on command. This manifests outwardly as:

• Loss of space heating or hot water at times
• Hot supplied to some fixtures but not others
• Lukewarm water temperature complaints

Visually inspecting for leaks near the diverter valve while intentionally activating heating and hot water modes helps diagnose issues. Modern digital diverter valves feature status lights indicating internal settings.

DIY Quick Fix vs. Valve Replacement

Before replacing the entire control valve, try freeing stuck components first. Tap gently along valve body while toggling modes to jar obstructions loose.

Use an Allen wrench to detach electrical control heads, exposing valve internals underneath. Check for debris interfering with seals and clean with water spray if buildup present. Ensure no loose parts got displaced from proper position while reassembling.

However if electric power or mechanical components themselves fail, diverter valve replacement becomes necessary by a trained HVAC technician. Newer thermostatic mixing valve models provide the highest reliability and precision.

Could Electrical Problems Be Preventing Hot Water?

Electric hot water heaters rely on internal control boards and sensors to govern heating cycles properly. Like any appliance, electrical issues can develop over time that cut off operations.

How Electrical Systems Operate Water Heaters

Thermostat circuits continuously monitor tank temperatures with sensors, triggering heating elements to switch on when dropping below setpoints. Near bottom, immersion heating rods radiate heat into the water.

Control boards orchestrate all electronic functions and commands. They integrate sensor data to optimize energy efficiency based on usage patterns using solid state logic programming.

Symptoms of Electrical Failure

When critical circuits fail, all functionality ceases. Warning signs of an electrical issue are:

• Complete lack of heated water supply
• Noticeable changes in typical temperature
• Sediment leaking from tank joints
• Burning plastic smells

However, if problems develop slowly over time, you may notice hot water only reaches some fixtures farther from the water heating source.

Checking Electrical Components

Start diagnosis with a voltage meter to check for power reaching key components like heating elements and circuit boards. Loose wiring connections often cause arcing and burning.

Remove and inspect control boards for physical signs of short circuiting. Test continuity across sensors using a multimeter. Replace any damaged parts.

For older tanks, consider upgrading entire water heating systems. Modern heat pump electric and hybrid hot water heaters achieve better efficiency and reliability than early models.

When To Call In A Professional Plumber

While many hot water problems stem from minor fixes you can tackle yourself, certain issues do require professional work:

• Low water pressure under 50 PSI
• No hot water reaching any faucets
• Faults inside concrete slab foundation piping
• Sewer gas odors coming from drains

Seeking professional assistance right away also makes sense if you lack plumbing experience, the issue quickly returns after fixing, or you want whole home replumbing.

Finding a Reputable Plumber

When selecting a plumbing company, check reviews and ask about:

• Licensing
• Insurance coverage
• Customer satisfaction ratings
• Sample pricing for common repairs

Established local companies often give free consultations and firmer quotes compared to gig economy handymen.

While no plumbing system runs trouble-free indefinitely, you can dodge many headaches by:

• Cleaning faucet aerators and showerheads regularly
• Flushing hot water pipes once a year
• Replacing old valves and supply lines
• Tuning up water heaters annually

Investing a little effort into preventative home plumbing care saves time, money, and frustration over the long run. But even well-maintained systems still occasionally hiccup. Now having a better understanding of why hot water inconsistency happens arms you to diagnose and fix issues promptly.