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Low hot water pressure

Test hot water volume /pdf
16 steps for finding Hot water pressure problem
Water pressure gauge1) Start with temporary pressure gauge
One that reads up to 100-200 psi and has threads that screw onto hose bibb.
 For example 200 psi Rain Bird P2A or 100 psi Brady BTG 100

I purchased my pressure gauge at local ACE hardware
Buy:
Water pressure gauges
Watts telltale Pressure Gauge 276H300
Temperature pressure gauge
Telltale pressure gauge is left in place for a day, and marks the highest pressure so user can tell if there are pressure spikes that are causing TP valve to leak water, or other possible problems
pressure gauge
Permanent pressure gauge
Or Permanent pressure gauge on cold water line
Pressure over 80 psi can damage tank and shorten life of plumbing fixtures
1/4" pipe thread

Buy:
Pressure gauges at Amazon
Temperature pressure gauge
Resources:
How far hot water travels in 30 seconds
Tank pressure 2) Put temporary gauge on water heater drain valve 
3) Open drain valve, and see if pressure gauge moves
Open drain valve counterclockwise
If there is no pressure, tank drain is clogged

Resources:
How to open clogged water heater drain
How to replace drain valve
4) Turn OFF all water taps
5) Put ear against pipe and listen for water leak
6) Note static pressure when no water is being used
7) Turn ON 2 or 3 COLD taps
8) Does pressure fall?
9) If pressure falls a lot, then supply to house could be clogged
If pressure falls a lot, then supply pipe to house could be clogged.
Run same test on outdoor spigot nearest water meter.
Check if neighbors have same problem. This will show if supply line to house is clogged or water main has low pressure. People on water well: check pressure switch on pump.
Tankless flow rates 10) Close COLD taps
11) Open 1 HOT tap
12) Does pressure fall?
14) If pressure falls a lot, then supply to heater is clogged
With new water heater, Look at heat trap nipples: Remove cold side supply. Check if water will flow when not connected to water heater. Look down into nipple for clog or replace heat trap nipples.
If water will not flow when disconnected from water heater, then look at water heater shut off valve for possible clog, and then go back to split where incoming cold watersupply branches off to water heater.
15) If pressure does not fall, then turn ON 2-3 more hot taps
16) If pressure still doesn't fall, then  hot-side outlet of water heater is clogged.
If whole house has low pressure
Low water pressure
Larger image
Then clog starts somewhere in the incoming cold water line before it reaches water heater, or at cold water tee.
Cold water tee is where cold water line splits: one line supplies cold water to each faucet, other line supplies cold water to water heater.

1) If cold runs fine, but hot water has low pressure, then test with pressure gauge as shown in 16 steps above. AND read about crossover.
Testing will tell if clog is before or after water heater.
2) Use pipe wrench and take apart unions. A union allows two threaded pipes to join together. Take photos of pipes before starting so that pipes can be reassembled easily.
3) Begin by inspecting inside each pipe and at each join.
Pipes can fill with sediment over time.
Sediment can break loose and catch at any joint or elbow
Cold inlet and hot outlet can be clogged with sediment
Cold inlet and hot outlet can be clogged with minerals if water heater temperature is set above 140° F
leaking di-electric union Di-electric unions can clog
Di-electric unions have rubber washer that can leak
Rust and sediment can gather at union.
brass elbow and nipple Use brass connections when connecting copper pipe and galvanized pipe.
Prevent electrolytic corrosion/ deterioration of galvanized pipes and clogs
Use 6 wraps teflon tape on threads
Buy:
Brass nipples at Amazon
Brass elbows at Amazon
Low water pressure can be caused by:
1) Sediment clog in pipe, water heater, or defective shut-off valve.
2) Crossover where bad single-handle faucet cartridge causes cold to enter hot pipe. Hot takes long time to arrive at faucet or never arrives.
3) Clogged faucet areators. Remove and clean areators with CLR calcium-lime-rust remover, or white vinegar, or replace areators.
4) Clogged water filter or water softener. Change filters regularly. Service water softener.
5) Leaking pipe, leaking TP valve, leaking water heater. Shut off all faucets. Inspect for leaks and listen for running water.
6) Broken water main, city water problem. Open outdoor spigot nearest main shut-off to see if pressure coming into house is low. Check if neighbors have same problem. Call city services.
7) Bad water well pump, waterlogged water well. Check pressure gauge on pump. Run water and see if pressure stablizes. Call well service.
8) Bad pressure regulating valve (only if valve is installed). Replace valve.
9) Bad check valve on recirculation sytem or elsewhere along plumbing. Look for check valve and replace or clean with CLR.
If problem is located at one tap or all taps
If problem is located at one tap:
Clean areator and check if problem solved.
Clog will probably be located at low point in water line.
Remove and replace shut off valve.
While shut-off valve is removed. Use stout wire, electrical-wire-puller or drain auger to run into pipe down to next elbow, and then flush line.
Hook air compressor to water line and push air into water line to help release clog. Flush line again. Read more and see image
If problem continues, then pipe has to be traced back to next elbow, and that elbow removed and cleaned or replaced.

If all hot taps have low pressure,
then problem is usually at or near water heater.
Clogs can be found inside the heat-trap nipples at water heater, or regular galvanived nipple, anywhere along the pipe, at elbow, tee, or valve.
Cogs can also happen at check valve, or mixing valve, or pressure valve if these things are installed.
How to save hot water using mixing valve

Another place to check is connection where both copper and galvanized pipe join together.
In case of copper and galvanized, the nearby galvanized pipe deteriorates and needs replacement.

Test for location of clog
Use BTG-100 pressure gauge on outdoor spigot nearest to main shut off to get baseline pressure for house.
If pressure is over 80 psi, then install pressure reducing valve to avoid damage to pipes, plumbing and water heater.
Have helper turn on hot and then cold water faucet inside house and watch for pressure drop for each hot and cold.
Attach pressure gauge to water heater drain valve. Water heater drain valve must be open. Read: if water heater drain valve is blocked
With pressure gauge on drain valve, open hot water faucets. You are looking for rapid fall in pressure. Rapid fall in pressure indicates that clog is between the test point and the incoming cold water tee. If pressure does not fall rapidly when hot faucet is turned on, the clog is after the test point.

Disassemble pipes as needed. Inspect and replace pipes, valves and joints as needed.
Move down the water line and continue inspection and replacement.
Other causes for low household water pressure
water flow rate
Bad faucet cartridge. Read about  Crossover
Leaking TP valve, Leaking water heater Diagnose leaking water heater
How far does hot water flow in 30 seconds
Clogged sediment filter or water filter
Clogged or manfunctioning water softerner
On tankless unit, the water filter must be cleaned each month.
Copper to galvanized fittings not protected with di-electric connections
Old galvanized pipe
Rusty brown water Rusty hot water
Can indicate water heater is rusted out.
Can indicate deteriorated galvanized pipes, which frequently clog at elbows and joints
Heat trap inserts Heat trap inserts, washers, and nipples can clog 
And make noise
Manufacturers include heat-traps so their product appears to use less energy
When installing water heater, remove manufacturer's heat traps.
Read resource about heat traps

Top image shows heat-trap washer. This specific washer is necessary to hold dip tube in place when installing di-electric nipples. To make this washer usable: Push washer over sharpie ink pen and cut off baffles so washer can be used without risk of clog.

Bottom image shows heat trap nipples
Buy:
Camco dielectric heat trap nipples
Dielectric nipples at Amazon

Heat trap washer
Dip tube
Heat trap Remove heat traps:
Heat trap washer can be changed to high heat washer
Water heaters with insert type dip tube might have heat trap washer

Resource:
Read about dip tubes
Combo anode rod Hot side nipple might be connected to anode rod
Replace with combo anode rod without heat traps
Cold side nipple might be connected to dip tube
Replace with combo dip tube without heat traps

Buy:
Water heater dip tubes at Amazon

Resources:
How to remove short water heater nipple
Read about dip tubes
Read about anode rods

Install pex-lined nipples
Available home center water heater department

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Dielectric nipples at Amazon

Resource:
How to remove short water heater nipple
carriage bolt How to remove clogged nipple
Use 5/8" carriage bolt so nipple will not collapse
Remove by turning nipple counter-clockwise

Resources
Read more: How to replace short nipple

Larger image with details
Make your own heat traps
Save $4-12 per year
Use mega-flow water heater connectors
Mega-flow connectors have larger inner diameter pipe to allow greater water flow

Buy:
Water heater connectors at Amazon
High water pressure over 80 PSI
expansion tank Pressure over 80 psi can damage plumbing and water heater
Can damage tank, cause leaks and shorten life of plumbing fixtures.
Install expansion tank on incoming cold water line
Buy:
Expansion tanks at Amazon

Resources:
Leaking water heater

Pressure reducing valve on cold water line
Pressure reducing valve will solve high-pressure problem
Buy:
Pressure reducing valves
Pressure regulating valves at Amazon
Hot water slow to arrive at faucet
Larger image
flow rate of 2 gpm through the water heater is a flow rate of 17.43 inches/second through a 3/4 inch ID pipe
Read
Test hot water volume /pdf
Typical faucet has 2 gpm (gallon per minute)
Typical tub spout has 2-1/2 gpm

Faucet can fill one gallon container in 30 seconds.

2gpm water flow= in 30 seconds hot water will travel a distance of 83' along 1/2 pipe.

If single handle faucet is lifted in center, then equal amounts of hot and cold water will flow, so distance is 41' along each 1/2 pipe.

If single-handle faucet has bad cartridge, hot water or cold water can be slow to arrive: Crossover
 
Use 6 wraps teflon tape
☑ White for water lines
☑ Yellow for gas lines

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Teflon tape at Amazon

Buy:
Pipe wrench at Amazon
Channel locks

Resources:
How to remove rusted element
replace anode rod
Inspect anode each 2-5 years
Buy:
Anode rods at Amazon

Resources:
Replace anode rod
How to maintain water heater
Pressure reducing valve
Pressure reducing valve
Pressure over 80 psi can damage water heater and household plumbing
Buy:
Pressure reducing valve

Resources:
Identify water heater valves
Troubleshoot water pressure
Icon gas valve   
Gas water heater thermostats
If tank is overheating or not heating correctly, replace thermostat
Symptoms: Cold water, uneven temperatures, TP releasing water
Buy:
Gas water heater thermostats at Amazon

Resources:
How to replace gas water heater thermostat
Add another thermostat to water heater
Troubleshoot gas water heater
Pressure reducing valve
Pressure reducing valve
Pressure over 80 psi can damage water heater and household plumbing
Buy:
Pressure reducing valve

Resources:
Identify water heater valves
Troubleshoot water pressure
COLD side Sharkbite flexible water heater connector
COLD side Sharkbite flexible water heater connector

Buy:
Sharkbite water heater connection
Braided water heater line
Stainless steel flexible connection

Resources:
How to install electric water heater
How to install gas water heater
Leaking water heater
HOT side Sharkbite flexible water heater connector
HOT side Sharkbite flexible water heater connector

Buy:
Sharkbite water heater connection
Braided water heater line
Stainless steel flexible connection

Resources:
How to install electric water heater
How to install gas water heater
Leaking water heater

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Impact wrench at Amazon

Resources:
Replace anode rod
How to remove short water heater nipple
Automatic water heater shut off valve
Prevent flood
Automatic water shut off valve
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Water detectors at Amazon
Automatic water heater leak shut off at Amazon
Resources:
Leaking water heater/ steps

Water heater circulation system

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Grundfos at Amazon

Resources:
How to install recirculation system
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