Question? Just ask us!
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
InspectAPedia ® Home
AGE of WATER HEATERS
ALTERNATIVE HOT WATER SOURCES
ANODES & DIP TUBES on WATER HEATERS
ANTI SCALD VALVES
APPLIANCE DIAGNOSIS & REPAIR
APPLIANCE EFFICIENCY RATINGS
AQUASTAT CONTROL Functions
BACKDRAFTING HEATING EQUIPMENT
BACKFLOW PREVENTER, HEATER WATER FEEDER
CARBON MONOXIDE - CO
CHECK VALVES, WATER SUPPLY
CLOGGED SUPPLY PIPING
CROSS CONNECTIONS, PLUMBING
DEBRIS in WATER SUPPLY, Water Heater
DRAIN a WATER HEATER TANK
ELECTRIC WATER HEATERS
FLOODED WATER HEATER REPAIR
FREEZE-PROOF A BUILDING
GALVANIC SCALE & METAL CORROSION
GAS BURNER Flame & Noise Defects
GAS FIRED WATER HEATERS
GAS PIPING, VALVES, CONTROLS
HEATING COST SAVINGS METHODS
HOT WATER SUPPLY
HOT WATER IMPROVEMENTS
HOT WATER DELIVERY SPEED UP
HOT WATER EFFICIENCY IMPROVEMENT
HOT WATER PRESSURE EXPANSION RATE
HOT WATER PRESSURE LOSS
HOT WATER PROBLEM DIAGNOSIS
HOT WATER QUANTITY IMPROVEMENT
HYDROGEN SULFIDE GAS
INDIRECT FIRED WATER HEATERS
MANUALS & PARTS GUIDES - HVAC
MIXING / ANTI-SCALD VALVES
NO HEAT - NO HOT WATER: HEATER DIAGNOSIS
NOISE, WATER HEATER
ODORS IN WATER
PIPING IN buildings, Clogs Leaks Types
RELIEF VALVE LEAKS
RELIEF VALVES - Water Heaters
SCALE REMOVAL, WATER HEATERS
SEWER GAS ODORS
SOLAR HOT WATER HEATERS
TANKLESS WATER HEATERS
THERMAL EXPANSION of HOT WATER
THERMOSTATS, WATER HEATER
TIMERS for ELECTRIC WATER HEATERS
WATER HEATER ALTERNATIVES
WATER HEATER ANODES, DIP TUBES
WATER HEATER AIR INLET
WATER HEATER DEBRIS FLUSH
WATER HEATER DRAIN PROCEDURE
WATER HEATER EFFICIENCY
WATER HEATER FLUSH PROCEDURE
WATER HEATER NOISES
WATER HEATER PROBLEM DIAGNOSIS
WATER HEATER COMPARISONS, PROPERTIES
WATER HEATER SCALE
WATER HEATER SAFETY
WATER HEATERS for HOME HEATING USE?
WATER ODORS, CAUSE CURE
WATER PIPES, Clogs Leaks Types
WATER PRESSURE TOO HIGH: DANGERS
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER QUANTITY IMPROVEMENT
WATER SOFTENERS & CONDITIONERS
WINTERIZE A BUILDING
Water heater tank flushout - how to let air into the water tank: Here we explain methods to allow air to flow into the hot water heating tank during a water tank drain procedure. Without this step you may find it difficult to drain down the water heater.
We discuss how to use the pressure/temperature relief valve to let air into the water heater to make draining easier, and we describe how to fix a dripping or leaky pressure relief valve or how to replace the pressure/temperature relief valve if necessary.
Green links show where you are. © Copyright 2014 InspectApedia.com, All Rights Reserved.
The articles at this website will answer most questions about diagnosing and curing noisy domestic water heaters and about the procedure to remove mineral deposits, lime, water scale, silicates, sulfates, aluminates, or silt and sand from a water heater tank.
Warnings Before Starting to Work on a Water Heater
Watch out: draining and flushing out a residential water heater is pretty easy and only a few common hand tools (adjustable wrench) are needed. But it's only easy if nothing goes wrong. A stuck or broken control valve or drain valve, or difficulty finding how to drain water out of a basement-located water heater with no nearby floor drain can all present challenges during the drain operation, and there can be a few surprises when you are putting things back together too: a leaky water heater drain valve or leaky water heater relief valve.
See DRAIN a WATER HEATER TANK This article describes dealing with the more common of these water heater tank draining troubles: defective water heater tank drain valve, water heater cold water-in supply valve won't operate.
Our standard water heater drain procedure for flushing out mud, silt and crud as part of regular heater maintenance is at WATER HEATER FLUSH PROCEDURE. See WATER HEATER DEBRIS FLUSH for a detailed photo guide through draining and cleaning out a water heater that had been sending debris into the building water supply piping.
Watch out: Safety Warnings: don't tackle this water heater cleanout project on a Sunday night when you can't call a plumber or buy a replacement part. Water heaters, their heating source (oil or gas burner or electricity or solar hot water), and particularly their relief valves include critical safety components. Do not modify or remove relief valves, chimney connections, draft hoods, etc. as you may create dangerous conditions.
You'll find that just opening the tank drain doesn't do a thing unless there is a way to get air into the water heater tank as water is running out.
How to Let Air Into the Hot Water Tank to Speed the Tank Draining Process
This article explains using or removing temperature and pressure relief valves on residential water heaters to let air into the hot water tank during draining for cleaning or other purposes. For more details about water heater safety valves see RELIEF VALVES - Water Heaters and for a discussion of temperature and pressure relief valves used as safety devices on heating boilers please see Relief Valves - TP Valves on Boilers.
It is possible to speed the heater draining and also to ease the flushing procedure if you open a hot water tap nearby so that you can let air into the heater as water leaves it
Some plumbers open the water heater pressure/temperature relief valve for this air-in purpose - but there is risk that you'll later be unable to get the valve to shut fully again - debris can clog the valve seat - sometimes we can stop a relief valve from dripping by tapping on the valve lift rod that protrudes through the valve lift lever
Other plumbers simply remove the relief valve entirely - this is the process recommended by some water heater manufactures such as A.O. Smith. Removing the relief valve makes it easy to inspect this critical safety component itself, and it's easy to clean or replace the safety valve at that time.
When replacing the relief valve use an approved teflon tape or pipe sealant and work neatly and with care so that there will be no leaks at this location.
Safety Warning- a damaged, improperly-selected model, or modified pressure/temperature relief valve is dangerous and could lead to a serious BLEVE explosion should the water heater later overheat.
Notice that the manufacturers say to remove the relief valve?
You could just use that test lever on the valve to open it. Manufacturers don't want you messing with that lever because their experience, and ours, is that on occasion the valve will continue to leak after the lever has been moved. That's what happened to us. Below we describe the problem, what repairs we tried, and what finally worked.
The Temperature/Pressure Relief Valve is Leaking on my Water Heater - Now What?
OK so we told you so.
If the TP valve is leaking because the temperature or pressure are too high, it's doing its job.
See RELIEF VALVES - Water Heaters for details about how TP valves work, why they leak, how dangerous leaks or malfunctioning valves may be.
But more likely, even though we told you not to, you tried messing with the test lever, you left it in the "open" position as a quick easy way to let air into the water heater tank. To be honest, we do this too. But we never ever touch that lever unless we are prepared to either leave the water heater shut off entirely OR we are prepared to go buy and install a new TP valve.
Here are some things to try if the TP valve is just dripping:
Tap gently on the rod that protrudes through the test lever and that would be pulled (against an internal spring) when you lift the lever. Sometimes a gentle tap will seat the valve and it'll stop leaking.
Watch out: Tap GENTLY. If you bang on it and damage the valve or seat or internal washer, the leak will get worse.
Lift the valve and flush the valve seat. That's what we tried recently when our TP valve was leaking after draining the water heater discussed at WATER HEATER DEBRIS FLUSH. That heater tank had a lot of floating debris particles and we had the fantasy that we could flush the valve seat and it'd stop leaking. It didn't work.
Watch out: The risk too is that if the internal TP valve washer is in poor shape, you may blow out the washer or part of it when you open and flush the valve, making the leak worse. We lifted, flushed, then tried the tapping trick again. It didn't work. The water heater was cold so we knew this wasn't an overheat or overpressure problem.
Put a bucked under the valve extension tube so we don't flood the floor.
Watch out: But do NOT accept this as a remedy. If you leave the valve leaking it may eventually stop leaking due to build up of mineral deposits from the hot water passing by. Then you have no working TP valve and there is a risk of water heater explosion.
Replace the TP valve with a new unit. That's what we had to do in the system discussed at WATER HEATER DEBRIS FLUSH. The valve dripped on the floor over the weekend until the owner bought a replacement TP valve.
Here are Detailed Steps in How We Replaced a Water Heater Temperature/Pressure Relief Valve
If you \were dealing with water heater scale and lime, after flushing out the water heater tank, the second step in curing water heater noise or insufficient hot water is to remove scale or lime from the water heater tank. If the unit is an electric water heater, you'll also need to remove scale from the electric water heater elements. See WATER HEATER SCALE - De-Liming Procedure for the full article on the detailed procedure for removing lime and water heater scale.
Green link shows where you are in this article series.
Frequently Asked Questions (FAQs)
No FAQs have been posted for this page. Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.
Questions & answers or comments about how to get air into a water heater tank to facilitate draining water out of a water heater and how to stop or repair a leaky water heater pressure temperature relief valve.
Check the FAQs just above, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Search the InspectApedia website
HTML Comment Box is loading comments...
Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.