Plumbing System Controls & Valves
Guide to all types of controls used on plumbing systems
PLUMBING CONTROLS & VALVES
- CONTENTS: Description of common stop valves used on plumbing water supply piping. Drain valves installed on water heaters, water tanks, heating boilers etc. Stop valves installed at plumbing fixtures. Gas and oil piping fuel line stop and control valves & check valves. Links to details about all types of plumbing system valves on supply piping, drain piping, & plumbing fixtures or appliances: check valves, flushometer valves, etc.
Types of Plumbing Valves Used on Water Piping: Globe Valve, Gate Valve, Ball Valve Compared
Thanks to Carson Dunlop Associates, a Toronto Home Inspection Firm and Home Inspection Educator, for permission to use sketches shown in this article.
As Carson Dunlop Associates' illustrations below show, a broken water control valve stem can obstruct or block water flow through the valve. Globe valves (below left) tend to most restrict water flow compared with the gate valve (center) and ball valve (right). But a broken stem on a gate valve can also leave the valve stuck partly or even fully closed (or open), regardless of how you may be able to turn the valve handle.
[Click to enlarge any image]
Also see SHUTOFF VALVE LOCATION, USE for a discussion of how to find, use, & repair building water supply shutoff valves and stop valves.
Drain Valves: boilers, water heaters, water pressure tanks
On heating boilers and steam boilers the drain valve attached on or close to the boiler body is commonly called a boiler drain.
Watch out: Often an unused or rarely-used plumbing valve may be stuck, may have lost an internal washer, and may otherwise fail to close properly if you touch it. We advise against attempting to open or adjust heating equipment drain valves unless you are prepared to shut down the system and install a replacement valve in the event of a leaky valve that can't be shut off.
FLUSHOMETER VALVES for TOILETS URINALS - with adequate water pressure, flow, and volume and proper installation, the flushometer valve eliminates the requirement for a water reservoir tank at toilets and supports urinals in restrooms
Plumbing & Heating Controls Valves, Service Valves, Safety Valves
MIXING / ANTI-SCALD VALVES - found on tankless coils used for making domestic hot water and at other hot water supply systems that produce very hot water; also found installed directly at some plumbing fixtures such as sinks, tubs, and showers.
Watch out: do not touch, open, or otherwise manipulate relief valves on heating equipment unless you are prepared, should the valve leak, to shut down the heater and replace the leaky valve immediately.
Electric Solenoid Operated Gas, Oil, Water Valves used in Buildings
Here we describe electrically operated plumbing valves used for water control of equipment or piping in buildings.
Reader Question: where can I buy a solenoid-operated water shut-off valve?
15 January 2015 Martin said:
... Any ideas where I can purchase solenoid-operated water shut-off valves?
Martin a number of companies provide electrically-operated solenoid-type shutoff valves including valves that can close off a water supply line. The operating pressure range and piping diameters among the various products vary so you’ll want to contact the company’s technical or sales people to discuss your specific needs.
Prices for electric solenoid valves range from under $50. U.S.D. to over $500. U.S.D. depending on the application.
WATER SOFTENERS & CONDITIONERS - Other solenoid operated valves that are integral parts of building mechanical systems such as water softener regeneration cycle or backwash cycle control valves.
Our complete list of types of control valves use in buildings and on building mechanical systems is found at MORE READING.
Other Plumbing System Control Valves
CHECK VALVES, WATER SUPPLY or backflow preventers are used on on water supply piping are used on well piping systems to prevent back-contamination of the public water supply. Note that in many jurisdictions use of a conventional check valve is not a suitable substitute for a backflow preventer..
Reader Question: Installing a pressurized system & Flushometer Valve Toilets & Urinals on a Well & Pump Water Supply System
I have a well system at a marina and would like to install commercial flushometer toilets and urinals. It is old and is currently served by a standard residential system.
I have space above the rest rooms and would like to install a stand alone pressurized system that is fed by the existing residential system, but would provide the gpm and pressure to function the commercial units. Likely to be a total of 3 toilets and two urinals.
Any ideas or plans available? Thanks, Bill
Reply: Be sure that your well water supply system, pressure tank, pressure, and water supply piping diameter & flow rate can support flushometer valves; consider waterless urinal fixtures.
Bill, there is no technical reason why one could not install flushometer type toilets and urinals at a property served by a standard pump and well system, but the cost and trouble may be more than first meets the eye. Where we find flushometer type toilets and urinals installed it's usually at a building served by municipal water supply and employing larger diameter water supply piping than the 1/2" pipe usually found at residential type properties.
That's because flushometer fixtures, relying on both water pressure and total gpm flow rate to work properly, need a higher pressure and total flow rate than most residential systems deliver. You can achieve the necessary pressure and water quantity for the fixtures by adding a water tank and pump at a suitable location, but you might need also to install larger diameter water supply piping to each fixture.
Reader Question: what's the purpose of the inline float valve at the top of an electric water heater? Can I remove it?
What is purpose of & is it necessary ? In- line ball- cock valve in water entry line going into top of electric water heater. Would it be ok to eliminate line containing floating ball ? It sticks & completyely restricts my hot water flow. - Randall Doran
Reply: thermosiphon prevention device?
I'm guessing from your description that you are describing an anti-siphon valve at the top of your water heater. The valve is intended to prevent hot water from circulating up into the building water supply piping by "gravity" (warm or hot water, being less dense than cold water, will naturally rise up out of a hot water tank into cooler water in building piping).
If that's what you've got you could remove the valve but the result might be wasted energy - sending hot water out into building piping (where it will cool off) when no hot water is being drawn at a plumbing fixture.
In general you could eliminate a control valve feeding water into your water heater, but it will make it impossible to turn off "hot" water in the building when service or repair to the heater is needed - you'll instead have to turn off water to the whole building.
Watch out: An improperly installed shutoff valve on a water heater can be very dangerous, risking an explosion. Usually the "hot water tank shutoff valve" is installed only on the cold water pipe coming into the water tank. There should be no shutoff valve installed on the hot water line leaving the water tank.
See WATER HEATER SAFETY
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Thanks to reader - R.S. (anonymous by req.) for discussing hot water loss problems - August 2010
 Sloan Valve Company, 10500 Seymour Ave., Franklin Park IL 60131, Tel: 847-671-4300, website: sloanvalve.com
 Sloane-Regal Installation Instructions for Standard Exposed Closet and Urinal Flushometers, Regal I.I. Code 816312, Models 110/111 through Model 117. 120-122, and 180, 186, 1997, Sloan Valve Company, 10500 Seymour Ave., Franklin Park IL 60131, Tel: 847-671-4300, website: sloanvalve.com
 Sloane Installation Instructions for Exposed Regal® XL Water Closet and Urinal Flushometers, Code 0816312 (newer version of above document), Rev. 1 05/10, Sloan Valve Company, 10500 Seymour Ave., Franklin Park IL 60131, Tel: 800-982-5839, or 888-SLOAN-14 / 888-756-2614, website: sloanevalve.com
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: email@example.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones