7/28/2019 Expansion Tanks 101_ the Facts and Myths
1/3
4/11/13 Expansion Tanks 101: the facts and myths | Hydronics
content from Contractor Mag azine
contractormag.com/hydronics/cm_column_75
Mar. 1, 2000
TweetTweet
Expansion Tanks 101: the facts and myths
Mark Eatherton | Contractor
On some commercial jobs, and extremely large residential jobs,
you may run into a computerized system
called Expan-Flex. This is a microprocessor-controlled expansion
tank that changes the system fill
pressures and the diaphragm charge pressures to compensate for
expansion and contraction. Although it
works quite well, it has too many moving parts for my taste. Air
compressor, solenoid valves, computer,
On some commercial jobs, and extremely large residential jobs,
you may run into a
computerized system called Expan-Flex. This is a
microprocessor-controlled expansion
tank that changes the system fill pressures and the diaphragm
charge pressures to
compensate for expansion and contraction. Although it works
quitewell, it has too many
moving parts for my taste. Air compressor, solenoid valves,
computer, etc.
Ive also seen non-captive tanks that were charged with nitrogen.
This particular
arrangement was on a high-rise system that provided heating and
cooling from the same
loop. The expansion tank had to compensate not only for big
expansion factors, but also
big contraction factors. The tank of nitrogen has to be replaced
on occasion.
Here are some other often-overlooked facts and myths about
bladder-type expansion
tanks. Contrary to popular belief, the bladders do get stuck and
dont allow for proper
operation. Rare, but nonetheless it happens.
The factory always sets the air pressure to exactly 12 psi.
Wrong. The factory sometimes
over- or under-shoots its target. Always check the air pressure
prior to installation with a
tire gauge and adjust if necessary.
Do you know what A.S.M.E. stands for? A Substantial Monetary
Exchange.
You can check the air pressure of the diaphragm with the tank on
line and normal fill
pressure. Wrong. The water-side pressure must be at 0 psi in
order to get an accurate read
of the air pressure on the diaphragm.
Tanks never lose their air charge. Wrong. Tanks do lose their
charge, either through the
Schrader valve, external leak in the tank or through the
diaphragm.
Captive air tanks never get waterlogged. Wrong. If youve either
lost the air charge or the
diaphragm, the tank w ill be waterlogged. Be careful. Treat
every expansion tank as if it
were a loaded expansion tank. Ive smashed more knuckles than I
can tell you from
unanticipated weight gains of supposedly empty expansion tanks.
(Ouch!)
Expansion tanks cant have their air charge raised above a
certain point. True. I f the tank
is only rated for 30 psi, it shouldnt be pressurized to more
than 30 psi. If you need more
than 30 psi, then you need an A.S.M.E.-rated tank. Do you know w
hat A.S.M.E. stands
for? A Substantial Monetary Exchange.
Blogs and Opinions
hat are your economic indicators
aying?
y R obert Ma der
osted 2 w eeks ago
n A s I See It
Copper thieves
y C anda ce Roulo
osted 9 w eeks ago
n Sustaina bly Speaking
Solar Thermal & The Shirley MacLaine
Complex
y John Mesenbri nk
osted 7 weeks ago
n From the Mechanical Underground
CONTRACTOR STORE
HOME > HYDRONICS > EXPANSION TANKS 101: THE FACTS AN D
MYTHS
SHARESHARE Recommend 0
Cl assi fi eds Su bscr ibe Di gi ta l Issu e Ba ck Issu es Newsl
et t er s Con ta ct Us A dv er ti se RSS Sh op
Plum bing Piping Hydronics Radiant Green Bath/Kitchen T
echnology T ools T rucks
Management
REGISTER LOG IN
http://contractormag.com/author/mark-eathertonhttp://contractormag.com/managementhttp://contractormag.com/plumbinghttp://contractormag.com/pipinghttp://contractormag.com/hydronicshttp://contractormag.com/radianthttp://contractormag.com/greenhttp://contractormag.com/bathkitchenhttp://contractormag.com/technologyhttp://contractormag.com/toolshttp://contractormag.com/truckshttp://contractormag.com/plumbinghttp://contractormag.com/pipinghttp://contractormag.com/hydronicshttp://contractormag.com/radianthttp://contractormag.com/greenhttp://contractormag.com/bathkitchenhttp://contractormag.com/technologyhttp://contractormag.com/toolshttp://contractormag.com/truckshttp://contractormag.com/http://contractormag.com/penton_ur/nojs/user/register/%25stephttp://contractormag.com/green-mechanical-contractorhttp://contractormag.com/radiant-livinghttp://www.contractingbusiness.com/http://hpac.com/http://www.comfortechshow.com/http://contractormag.com/blog/what-are-your-economic-indicators-sayinghttp://contractormag.com/penton_ur/nojs/loginhttp://contractormag.com/penton_ur/nojs/user/register/%25stephttp://contractormag.com/http://contractormag.com/managementhttp://contractormag.com/truckshttp://contractormag.com/toolshttp://contractormag.com/technologyhttp://contractormag.com/bathkitchenhttp://contractormag.com/greenhttp://contractormag.com/radianthttp://contractormag.com/hydronicshttp://contractormag.com/pipinghttp://contractormag.com/plumbinghttp://contractormag.com/cataloghttp://contractormag.com/rss.xmlhttp://contractormag.com/advertisehttp://contractormag.com/contact-ushttp://contractormag.com/newsletters/signuphttp://contractormag.com/magazine-issues/contractor-0http://contractormag.com/past-digital-editionshttps://pen-sub.halldata.com/TOlandhttp://contractormag.com/classifiedshttp://www.comfortechshow.com/http://hpac.com/http://www.contractingbusiness.com/http://contractormag.com/radiant-livinghttp://contractormag.com/green-mechanical-contractorhttp://contractormag.com/hydronicshttp://contractormag.com/http://contractormag.com/blog/mechanical-undergroundhttp://contractormag.com/blogger/john-mesenbrink-0http://contractormag.com/blog/solar-thermal-shirley-maclaine-complexhttp://contractormag.com/blog/sustainably-speakinghttp://contractormag.com/blogger/candace-roulohttp://contractormag.com/blog/copper-thieveshttp://contractormag.com/blog/i-see-ithttp://contractormag.com/blogger/robert-maderhttp://contractormag.com/blog/what-are-your-economic-indicators-sayinghttp://contractormag.com/author/mark-eathertonhttps://twitter.com/intent/tweet?original_referer=http%3A%2F%2Fcontractormag.com%2Fhydronics%2Fcm_column_75&text=Expansion%20Tanks%20101%3A%20the%20facts%20and%20myths&tw_p=tweetbutton&url=http%3A%2F%2Fcontractormag.com%2Fhydronics%2Fcm_column_75&via=contractormaghttp://contractormag.com/forward?path=node%2F2712
