#32 What are the top 5 hydronic expansion tank questions? (with Cody Mack)

An expansion tank is a very simple hydronic system component, yet it can cause complex troubleshooting woes.  Improper charge expectations, waterlogging and sizing can all play a role.  How can you determine if the expansion tank is the culprit for nuisance relief valve discharges? 

In this episode, Cody Mack tells you how to whisper to an expansion tank in this service-focused conversation between three former field techs.  Should you trust a factory precharge?  How do you avoid "bear-hugging" an expansion tank to relieve an over-pressurization?  The guys cover the ways to put your best foot forward with a new expansion tank, relating to proper acceptance volumes and when multiple non-ASME vessels may be an option.  They also point out a few tips and tricks they have picked up to determine if the existing expansion tank needs some help.  Caleffi components like air separators and steady boiler fill valves are part of the equation, too.    

Thanks for joining us today.

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Transcript

0:04
welcome to ask a caleffi  the podcast that
0:07
dives into real life problems that
0:09
plumbing and hvac technicians face in
0:12
the field we're your hosts from the
0:13
caleffi tech support team i'm greg tubbs
0:16
and i'm dan ferkus welcome we look
0:18
forward to sharing some stories from our
0:20
tech calls and using our background and
0:22
expertise to make your days a little
0:24
easier
0:25
[Music]
0:29
hey there welcome back to the ask luffy
0:31
podcast how are we doing dan i'm doing
0:33
good today greg how are you doing oh
0:35
can't complain we get to lean on a guest
0:37
today yeah i'm excited the famous the
0:40
ever so famous very famous cody mac cody
0:43
mack
0:48
thank you guys glad to be here yeah
0:50
welcome back thank you thank you yeah
0:52
it's good to be here again we're gonna
0:54
talk another series of five things you
0:56
need to know today
0:58
absolutely yeah if you don't know
0:59
already cody is
1:01
heading up our
1:02
five things you need to know video
1:04
series um on are you available on our
1:07
youtube channel that's right and today
1:09
we're going to talk about expansion
1:10
tanks and hydronic systems
1:12
yeah so uh you don't need expansion
1:14
tanks so we can just get this going to
1:16
the bar right
1:17
we've seen that before haven't we
1:21
they're totally over where's the
1:22
expansion tank in this system well
1:25
we hid it away somewhere in the basement
1:27
right right
1:28
yeah no the the expansion takes i mean
1:31
it's kind of a commonly overlooked thing
1:32
it's it's part of every closed-loop
1:34
hydraulic system i mean the fact is that
1:37
you know you uh you heat up water
1:39
especially in a closed system like that
1:41
it's it's going to basically build
1:43
pressure and that excess pressure that
1:45
uh it needs to go somewhere it needs to
1:46
expand somewhere and you've got your
1:47
expansion tanks for that and so yeah
1:49
that's not what the pressure
1:50
what the relief valve is for cody you
1:53
guys do make a very good point um as
1:55
long as you have a nice uh cleffy
1:57
branded bucket underneath the uh
1:58
pressure relief i mean then then we're
2:00
in business but okay fair enough
2:04
i know we've all been on that oh yeah
2:06
bucket underneath the pressure relief
2:07
valve the menards 2000 yeah exactly or
2:10
the homer the homer bucket the home
2:11
remember
2:13
yeah
2:14
but uh but yeah so we did a five things
2:16
you need to know about expansion tanks
2:17
and hydronic systems and yeah we can
2:19
kind of touch base on on one of those i
2:21
mean first of which and i mean it kind
2:22
of goes without saying is that sizing is
2:25
something that you need to be really
2:26
cognizant of uh when you when you look
2:28
at sizing and expansion tank it's it's
2:30
based on a couple of things one uh
2:33
the the amount of fluid the volume of
2:35
fluid in the system and not only that
2:37
how how much temperature variants you're
2:40
going to have you know does it go from
2:41
70 to 180 or is it a solar thermal
2:44
system that goes from negative 40 to 350
2:47
degrees i mean that can really big
2:49
difference yeah big big difference and
2:51
so when you look at sizing these guys i
2:53
i would highly recommend i mean a lot of
2:55
the expansion tank manufacturers have a
2:57
sizing guide
2:58
right on their website but we do also
3:00
have
3:01
some of those equations and stuff like
3:03
that on how to figure that out i think
3:04
it was in one of our solar thermal
3:06
hydronics journals that that has the
3:08
equation for sizing expansion tanks and
3:11
and it was more for solar thermal
3:12
because again the expansion tanks
3:13
typically need to be quite a bit larger
3:15
but right but with that in mind it'll
3:17
work for hydronic systems as well or
3:19
boiler type systems
3:20
right well yeah you're right solar
3:22
thermal is going to see a larger
3:23
temperature difference so big swings
3:25
bigger swing bigger expansion rate yep
3:28
yeah very big swings and you need to
3:31
you know obviously you need to account
3:32
for that so uh the other big thing that
3:34
i touched on and the five things you
3:36
need to know is is checking the
3:37
pre-charge um i almost laugh at the idea
3:40
that every expansion tank's preset from
3:42
the factory at 12 psi right that doesn't
3:45
happen anywhere from eight to twenty
3:47
yeah right get your pressure gauge out
3:49
and take a look and and and you'll see
3:51
most of the time they are not at 12 psi
3:54
and the big problem there is is you know
3:56
say for example you set your static fill
3:58
pressure at 12 psi your expansion tank's
4:00
supposed to be at 12 psi but it's not
4:01
maybe it's at 8 psi and what you've
4:04
actually done there is you've lost some
4:06
of the volume in the expansion tank
4:07
already because the 12 psi is basically
4:10
pushing down on the 8 psi and instead of
4:13
you know the full acceptance volume of
4:15
the expansion tank you might only have
4:16
two thirds left and in most cases that's
4:18
not a problem but uh if if your
4:20
expansion tank sizing was uh a little
4:22
borderline or a little flyby
4:26
uh you know that could be a problem with
4:28
that uh pressure relief valve popping
4:30
off there yeah and that's something
4:31
you're always going to want to check
4:32
before you install it when there is no
4:34
pressure on the on the system or no
4:36
water in the tank correct and and that
4:38
that was another thing i brought up is
4:40
as far as how to make maintenance easy
4:42
in there because you know if you ever
4:43
think or you're questioning whether or
4:45
not the expansion tank is still good the
4:47
fact is is that you you need to be able
4:49
to check it and you can always put a
4:50
pressure gauge on the air side of it but
4:52
what you need to realize is when you're
4:54
checking the expansion tank pressure you
4:56
need to basically relieve all pressure
4:58
off the water side of the expansion tank
5:00
right and so by having an isolation
5:02
valve that's one thing and i used to
5:03
deal with this a lot when i was in the
5:04
field i'm sure you guys did too
5:06
everybody was so keen to give you an
5:08
isolation valve but no way to drain off
5:10
pressure on the right side exactly and
5:12
uh my favorite is uh bear hugging an
5:14
ex-troll 60 and having to spin it around
5:17
while it's full of water and take a nice
5:19
bath and so you know there's several
5:21
manufacturers out there of like these
5:22
all-in-one type valves where it's
5:23
isolation and as a drain and all that
5:25
other fun stuff but you could easily do
5:26
it with just like a regular isolation
5:28
valve and a boiler drain too so
5:31
right yeah you're right something you
5:32
never have is a way to drop that
5:34
pressure
5:35
yeah that's very very good drill a hole
5:38
in it and let the pressure out if it's
5:40
water logged anyways but
5:42
yeah it's it's one of those things where
5:43
yeah like i said that my favorite was
5:45
those extra 60s that were you know the
5:47
size of a couple watermelons put
5:48
together and and uh yeah they're yeah
5:50
that thing will bury a five gallon pail
5:52
real easily oh yeah yeah especially if
5:54
it's waterlogged yeah and it had to be
5:56
our most common
5:57
call you know for a water leak from the
5:59
boiler was it it boiled down to it's a
6:03
bad expansion tank for sure yeah tons of
6:06
it and and uh you know when you talk
6:08
about expansion tanks i i would say that
6:09
they're a good barometer for how good a
6:12
water quality you have in those systems
6:14
too because typically your expansion
6:16
tank uh in a hydronic system and it's
6:18
not like it needs to be anything but but
6:20
it's it's it's steel and then you've
6:22
literally got the water touching the
6:23
steel and you've got a lot of ferrous
6:25
components in in most of your hydronic
6:27
systems whether it be cast iron volutes
6:28
on on pumps or
6:30
steel heat exchangers or whatever but
6:32
the fact is is that the steel in your
6:34
expansion tank is basically the thinnest
6:36
point and it's going to be the most
6:37
susceptible to corrosion and things like
6:39
that and so so when if you are
6:42
constantly going back to a job year
6:43
after year because they're pinholing the
6:45
expansion tank and it's leaking all over
6:46
the place it's not because the expansion
6:48
takes a piece of junk it's because your
6:50
water quality is clearly less than
6:52
desirable water quality and too much
6:54
oxygen in the system yeah you're not
6:56
mitigating that oxygen out yeah and i've
6:59
seen that too especially with those uh
7:01
systems with a non o2 barrier pex tubing
7:03
or rubber tube type systems and things
7:05
like that where yeah i mean there's
7:07
literally no way to get the air out
7:09
because it's just going to keep on you
7:10
know the air is going to ingress into
7:12
the system or get into that system and
7:14
at that point
7:15
you know you need to look into a
7:16
plumbing type expansion tank which will
7:18
be lined which means it'll protect it
7:20
against the oxygen right in that system
7:22
a little bit more expensive but
7:23
obviously it's going to save your bacon
7:26
certainly will
7:27
yeah the the last thing that i mentioned
7:29
or one of the other things that i
7:30
mentioned in here too was uh was support
7:33
uh i mentioned an xtrol60 uh you water
7:36
log that sucker and you have it hanging
7:38
off of a half inch copper pipe uh that
7:40
half inch copper pipe is gonna do
7:41
something's gotta give yeah i think
7:43
we've all seen that where you have the
7:44
expansion tank just hanging off a half
7:46
inch copper pipe just hanging in the
7:48
middle of the air it's like boy you
7:50
start adding weight to that water and
7:52
especially get it water logged and
7:54
it's not going to hold up no it's
7:56
definitely i mean there's a number of
7:58
different brackets out there that kind
7:59
of like a belly band that goes around
8:01
the expansion tank there's ones that
8:02
hold the expansion tank like a bracket
8:04
uh as it connects to the threaded
8:06
connection at the top and everything
8:08
like that there's a lot of different
8:09
ways out there now i remember when i was
8:10
in the field we were fighting with uh
8:12
plumber strap and zip ties and all this
8:14
stuff and stuff sure
8:15
and or you know relying on the piping in
8:18
the system to to uh to hang an expansion
8:20
tank yeah you've seen that a ton it
8:22
comes right off the bottom
8:23
of an air separator with the fill and
8:26
it's just hanging there right above the
8:27
boiler
8:28
yeah you're going to have to add some
8:30
piping unfortunately
8:32
do a little more work and strap it to
8:34
the wall with
8:35
with some sort of bracketry right
8:37
yeah and and to kind of you know stray
8:40
off topic here a little bit uh one thing
8:41
that i've been really excited about uh
8:43
and not that there's a lot of exciting
8:45
things about expansion tanks
8:47
but uh you know i didn't really have a
8:50
lot to choose from when i was in the
8:51
field i mean it was always amtrol and
8:53
and things like that but there's a lot
8:54
of other manufacturers out there that
8:56
are making the i would call them like
8:57
the pancake type expansion tanks and or
9:00
the square type ones that are out there
9:02
too and uh you know they're a lot
9:04
slimmer uh heck uh some of the boiler
9:06
manufacturers are what's going to say
9:07
that thanks right right there
9:09
there's a handful of manufacturers you
9:11
see them right in there yeah which is
9:13
awesome you know i mean it's uh
9:15
especially the square ones that i've
9:16
seen they've even got mounting tabs
9:18
right on them so you can mount them
9:19
right up to a boiler board or whatever
9:21
the case may be now you know we
9:22
mentioned sizing earlier you know those
9:24
those boilers that come with an
9:25
expansion tank in the boiler you know
9:27
for your average copper fin tube type
9:30
system that expansion tank's probably
9:31
going to be enough but if you put that
9:33
boiler into an old gravity conversion
9:35
system that has three inch black iron
9:37
pipes larger pipe more volume way more
9:40
volume yeah i mean the sizing is is not
9:42
going to be there and don't hesitate to
9:44
uh to basically add more expansion tanks
9:47
and and that that's another thing to
9:49
bring up too is i mean you get into your
9:50
larger expansion tanks a lot of times
9:52
you have to look into asme certified
9:54
pressure vessels which can be
9:56
expensive and uh and so and not only
9:59
that they're they take up a lot of space
10:01
too and i've seen it where instead of
10:03
doing one large expansion tank and doing
10:05
multiple uh to to cover your bases sure
10:08
multiple number 30s or something like
10:10
that yeah or 60s or something to avoid
10:12
that asme certification if you don't
10:13
absolutely need it
10:15
that that might be something to save you
10:17
money or
10:18
or save you on space because you just
10:20
can't fit a big giant floor mounted tank
10:22
somewhere or something like that
10:24
well that's something you're correct if
10:25
the boiler has the expansion tank built
10:27
into it you can factor the size of that
10:29
expansion tank in your sizing and add
10:32
accordingly you don't need to
10:34
isolate that and add a separate
10:35
expansion tank size for the entire
10:37
system yep yeah for sure i mean you can
10:40
you can always rip it out if you want to
10:41
but it's already there kind of thing you
10:43
know why why rip it out of there but uh
10:45
but yeah like i said there's a lot of
10:46
different types of expansion tanks out
10:48
of there out there now like i said the
10:49
square pancake type ones the the the
10:51
circle pancake ones and obviously your
10:53
traditional barrel type expansion tanks
10:55
so so definitely check those out i mean
10:57
and it just makes life a lot easier if
11:00
you can find the right tank to fit in
11:01
the right spot and whether it be you
11:03
know multiple tanks and parallel or
11:05
whatever the case may be so
11:07
that was a great topic to cover because
11:08
i mean we're we're in the throes of
11:10
heating season right now and
11:12
people are out changing tanks right well
11:14
and expansion tanks aren't a product
11:16
that we manufacture here at collaborate
11:18
but certainly a component that goes into
11:20
your system like our product
11:22
you know i i would say one of the
11:23
biggest things we get probably in you
11:25
guys probably realize it already we get
11:27
calls about is uh
11:29
your guys's pressure reducing valve your
11:31
boiler fill valve it's it keeps
11:33
overfilling i was almost going to go
11:35
there as a scenario
11:36
as a look into a problem call go ahead
11:40
let's go down this rabbit let's do it so
11:42
so we get the call and it's like oh you
11:43
know it keeps over feeding and it keeps
11:45
popping the pressure relief valve and
11:47
it's you know nine times out of ten it's
11:49
not our pressure reducing valve or the
11:50
boiler fill because it's doing what it's
11:52
supposed to do it's replenishing water
11:54
as it's getting lost through
11:56
you know what it whatever whether it be
11:57
a blow down or a pressure relief valve
11:59
popping off but if that expansion tank
12:01
has failed you know uh
12:03
if that pressure reducing valve the
12:05
boiler fill valve it might at a cold
12:07
static pressure
12:09
have that system set at 12 or 15 bsi but
12:12
then from there as you start warming
12:13
everything up and heating it up from you
12:15
know again 65 degrees or 60 degrees all
12:17
the way up to 180 again that expansion
12:19
has to go somewhere and if that
12:20
expansion tank is has failed
12:22
that's one of the biggest things so if
12:24
you
12:25
and i this is how i always help people
12:26
out with that particular scenarios if
12:28
you think it's a bad pressure relief
12:30
valve just isolate the thing shut off
12:32
the fill to the system and then you know
12:34
make sure to cool it down get it to a
12:36
static fill pressure that you want 12 or
12:38
15 psi um and then and then shut it down
12:42
so that way it literally can't add any
12:43
more fluid to the system and then
12:45
obviously if your pressure relief valve
12:47
is still going off
12:48
chances are your expansion tanks your
12:50
expansion yeah and we get that call
12:52
quite a bit and that's the advice that
12:53
we give and
12:55
um it's going to tell you right away if
12:56
it's an expansion tank problem certainly
12:59
will yeah i know a lot of guys that i
13:00
used to work with uh they used to be
13:02
able to whisper to the expansion tanks
13:04
and and not only whisper but they would
13:06
they would tap on it you know they would
13:07
do the tapping on the expansion i don't
13:09
i was never very good at that i i you
13:12
tap on them and it's like is it air is
13:13
it water in there i can't really tell
13:15
the difference and my wife says that i
13:17
have selective hearing as it is but you
13:18
think i'd be able to select to hear
13:20
whether it's full of water or air but uh
13:22
but with that in mind like those um
13:24
those uh
13:25
different types of maintenance valves to
13:27
be able to isolate and drain it is going
13:29
to be a huge time saver and a huge mess
13:32
saver for that kind of stuff very big
13:34
saver yeah but uh but yeah so that was
13:36
that was one of the five things you need
13:38
to know you know and that we did on
13:39
expansion tanks and we've got obviously
13:41
a number of other topics and but uh but
13:43
i thank you guys for having me in today
13:45
and i'm glad we were able to talk about
13:47
it yeah thanks for joining us thank you
13:49
anyone else that wants to find out more
13:50
about it you can certainly look at our
13:52
youtube channel yeah check it out
13:54
thank you for tuning in if you ever need
13:57
help please feel free to contact our
13:59
tech support team anytime at
14:01
techsupport.us
14:04
caleppe.com
14:05
or call us during our business hours
14:08
at 7 30 a.m to 4 30 pm
14:11
central time
14:13
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238
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[Music]