How to Test Air-Volume Controls (AVCs) on Water Tanks - is the AVC Working?
How do we know if the AVC is working?
Our photo (left, courtesy of reader Doug Mehak
) illustrates still another type of air volume control. The red arrow at the left of the photo points to the AVC and the right arrow points to the tubing connection on the water pump, in this case a one-line jet pump.
In our photos above and at left, most AVC controls that use a pressure sensing tube connected between the AVC and the water pump.
You will see a small diameter tube which connects the air volume control valve
to a fitting (usually) on the water pump itself so that the valve can respond to the cycling on and off of the water pump (and changes in water pressure).
If the air volume control valve is working properly, it uses the pressure changes caused by the cycling on and off of the water pump to automatically add air to the water tank when it's needed. Makeup air is needed in these water tanks because over time the air charge in the tank is absorbed into the tank's water.
The most common versions of air volume controls, illustrated at the top of This article , look like a disk of about three inches in diameter, as we show in the photographs here. A copper or plastic tube that extends
from the AVC to a fitting on the water pump itself, as we showed on the photograph above. Look at the fitting screwed into the side of the water tank about 2/3 of the way up
from the tank bottom and on the right side of the water tank in the photograph above.
If the air charge in your water pressure tank is not being maintained, either there is a leak in the tank or the AVC is not working. Usually the case is the latter.
Also illustrated earlier in this article, a second common version of air volume control valve is shaped like a small rectangular steel box with fittings shown in our two photographs above.
You also can see the small object connected to the side of the water tank near the top right side
of the tank in this photograph at left.
There is no copper tube connected to this AVC.
Here is a close-up photograph of this more rectangular type of air volume control.
Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.
Ask a Question or Search InspectApedia
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, 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.
 U.S. Gauge Special Application Gauges: Type 300L and 310WJ Air Volume Controls, product description, 2002, Ametek® Inc, U.S. Gauge, 820 Pennsylvania Blvd., Feasterville PA 19053, USA, Tel: 215-355-6900 www.ametekusg.com Customer Service: 863-534-1504, web search 03/23/2011, original source: http://www.jlwinstruments.com/PDF_files/D17_MODEL300-310.PDF Sadly this URL now reroutes to a dead end
 AMTEK, 900 Clymer Avenue 8600 Somerset Drive
Sellersville, PA 18960 U.S.A. or Customer Service at AMTEK, Largo, FL 33773 U.S.A.Sales/Technical Support: 215-257-6531, Customer Service: 727-536-7831, Website: www.amtekusg.com, Email US Gauge at email@example.com.
 flosource.com/ provides links to some US Gauge air volume control products installation and adjustment
Rasmussen Well Drilling, Inc., 1793 Hwy 61, Two Harbors MN. Jeremy Rasmussen provides third generation well drilling and plumbing services on the North Shore of Lake Superior. Photos by DJF. Tel 218-834-3387. Email: firstname.lastname@example.org
We serve the north Shore – Lake, Cook, St. Louis, Carlton and Pine counties, including Duluth, Grand Marais, Clouqet, Carlton, Finland, Isabella, Silver Bay, Grand Portage, Saginaw, and everywhere in Northeastern Minnesota.
 Dill Air Controls Products, 1500 Williamsboro St., PO Box 159, Oxford, NC 27565, Tel: (919) 692‐2300, Website: http://dillaircontrols.com
Smart Tank, Installation Instructions, Flexcon Industries, 300 Pond St., Randolph MA 02368, www.flexconind.com, Tel: 800-527-0030 - web search 07/24/2010, original source: http://www.flexconind.com/pdf/st_install.pdf [Copy on file as /water/Smart_Tank_Flexcon.pdf ] -
Typical Shallow Well One Line Jet Pump Installation, Grove Electric, G&G Electric & Plumbing, 1900 NE 78th St., Suite 101, Vancouver WA 98665 www.grovelectric.com - web search -7/15/2010 original source: http://www.groverelectric.com/howto/38_Typical%20Jet%20Pump%20Installation.pdf, [Copy on file as /water/Jet_Pump_Grove_Elect_Jet_Pumps.pdf ] -
Typical Deep Well Two Line Jet Pump Installation, Grove Electric, G&G Electric & Plumbing, 1900 NE 78th St., Suite 101, Vancouver WA 98665 www.grovelectric.com - web search -7/15/2010 original source: http://www.groverelectric.com/howto/38_Typical%20Jet%20Pump%20Installation.pdf, [Copy on file as /water/Jet_Pump_Grove_Elect.pdf ] - Cooperative Extension, School of Forest Resources, web search 07/24/2010, original source: http://pubs.cas.psu.edu/FreePubs/pdfs/XH0002.pdf
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