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Ask Caleffi
#3 Are corrosion and noise signs of air in a hydronic system?
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Episode 3 picks up where Episode 2 left off, to explain Air Separators. There is more to know about a separator, which has an air vent on top. Where the separator should be installed in the hydronic system, how it works, and how to select the right size for each job is discussed.
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[Music]
welcome to
00:05
ask Caleffi the podcast that dives into
00:08
real life problems that plumbing and
00:10
hvac technicians face in the field
00:12
we're your hosts from the Caleffi tech
00:14
support team i'm greg tubbs
00:16
and i'm dan ferkus welcome we look
00:18
forward to sharing some stories from our
00:20
tech calls
00:21
and using our background and expertise
00:22
to make your days a little easier
00:31
hey there here we are episode three
00:33
gonna talk about some
00:34
air separators today how you doing i'm
00:37
doing good yeah welcome back
00:38
everybody thanks for tuning in so
00:41
the question is why do hydronic systems
00:44
need
00:45
air separators well you know i mean air
00:48
is
00:49
it's important to get air out of a
00:50
closed loop system i mean
00:52
the reduction of air is going to
00:55
eliminate the ability for corrosion to
00:58
to grow in the system yeah eliminate
01:00
corrosion
01:01
provide better heat transfer less noise
01:04
less noise right
01:05
yeah so it all it's all relative come to
01:08
comfort yeah
01:09
yeah so we last week we talked about air
01:12
vents greg
01:12
what's a major difference between a
01:14
separator and an air vent
01:16
that's a good question because they're
01:17
commonly
01:19
the terminology is misused a lot i feel
01:22
it is we'll get somebody to call us in
01:24
and says yeah
01:25
i got an air vent or i had a guy calling
01:28
an air vent an air separator a lot
01:30
right and then i had to kind of reel
01:31
them in say look
01:33
this is the difference between the two
01:35
but to kind of
01:36
add to that you can't confuse the two
01:40
you just they're they're they're
01:41
different they they do the same thing
01:43
where
01:44
they they remove air from the system
01:45
right yeah exactly i mean
01:47
air removal whether it's an air vent or
01:49
air separator air removal
01:51
is why they're in the system you know
01:53
but we talked about the air vents last
01:55
week being located at a high point in
01:57
the system
01:58
to remove air that migrates into them
02:00
right you know an air separator is a
02:01
different device that's an
02:03
inline device that it's a pass-through
02:05
device
02:06
right so an air vent it has a single
02:10
connection on the bottom
02:11
at the bottom of the canister at the
02:12
bottom of the body and it allows air to
02:16
come up through the float assembly and
02:18
go out
02:19
the vent right where the vent cap is
02:21
yeah and i mean the air separator is
02:23
going to have that
02:24
similar feature built onto the top of it
02:27
right but now it's installed in line
02:30
and it's a pass-through unit right it's
02:33
a pass-through device with two
02:34
connection points so
02:36
with the added air vent so you've got
02:41
a larger body with an inlet and an
02:44
outlet
02:45
with a coalescing mesh inside that
02:48
captures and trained air the little
02:50
entrained air bubbles cling to
02:52
the coalescing mesh they rise up in the
02:55
barrel
02:55
and go through the air vent right yeah
02:58
they're vented to atmosphere
03:00
exactly you kind of hit it right there
03:02
with the larger body
03:04
what we find is that you know our air
03:06
vent bodies can be three to four times
03:08
bigger than the pipe connection size
03:10
coming to them
03:11
and that's so you get an instant
03:12
velocity drop right
03:14
i mean that wider body will reduce
03:16
velocity
03:18
up to about 10 to 1 ratio right yeah and
03:21
that really allows that
03:22
coalescing mesh to knock those micro
03:24
bubbles loose from the water
03:26
so we have this coalescing mesh and
03:29
everybody does things a little different
03:31
any idea what ours is made out of yeah
03:33
we have a glass reinforced
03:35
mesh in our smaller brass units and then
03:37
we have a stainless steel mesh in our
03:39
larger units
03:40
our larger steel units right that glass
03:42
reinforced nylon
03:44
is in all of our brass units yeah so
03:47
and some of our larger our larger ones
03:49
do have the stainless steel
03:51
they get kind of confused you know we
03:53
always get guys that they call in they
03:55
want a two-inch model
03:57
it's really important to know flow rates
03:58
isn't it that's
04:00
that yeah you you hit it right there
04:01
because we have a two inch model
04:03
you know what we have a bunch of two
04:05
inch models
04:06
um that size crosses over between flow
04:10
rates
04:10
right yeah i mean we have a brass two
04:13
inch model
04:14
you know which is rated for lower flow
04:16
rates up to about 37 gallons per minute
04:19
but then we have a two inch connection
04:21
on a steel model
04:22
uh that has the larger body with the
04:24
stainless steel mesh that's rated to 60
04:26
gallons per minute yeah
04:28
and that is a common i don't know how
04:30
many times we get that it seems
04:32
heating season i bet i get that question
04:34
twice a week you know it's interesting
04:36
though is that
04:37
i usually get the question and it's
04:39
misapplied
04:40
because again guys are you know
04:42
designing their piping and sizing their
04:44
piping
04:45
and so they're picking and selecting
04:47
components to go in that
04:48
based on pipe size always on pipe size
04:51
that's a common mistake guys make
04:53
yeah and you really when you're looking
04:55
at sizing
04:56
you know anything a dirt an air
04:58
separator dirt separator hydraulic
05:00
separator
05:01
you really need to know the flow rate of
05:02
your system yeah and it applies to
05:04
plumbing stuff too
05:05
i mean we're going to beat this like a
05:07
dead horse but
05:08
it it applies in plumbing with mixing
05:11
valves a lot
05:12
we see it all the time and like you said
05:15
with all these separators right
05:17
knowing your flow rate is really going
05:19
to save you a lot in time
05:21
and money well and
05:24
even bigger than that this the product
05:26
is going to work for you you're going to
05:27
get the best performance out of it
05:30
you got it i mean you take a two-inch
05:32
brass model and i know we kind of picked
05:33
that and that's because that's the point
05:35
where they kind of
05:36
you can cross over from brass to steel
05:38
and you take
05:39
a you know a two inch model rated at 37
05:42
gpm
05:43
and you know you have a boiler or a
05:47
system that's
05:48
40 48 gpm
05:52
yeah you have to you have to step to
05:53
that bigger side yeah if you don't it's
05:55
just not going to perform well for you
05:57
no you're going to have a pressure drop
05:58
in that which is no good
06:00
yeah so when somebody picks out
06:03
the right product we have to talk to
06:06
them about
06:06
installation yeah i mean it
06:10
you know being a pass-through device i
06:13
mean does it always have to be on a
06:14
horizontal pipe craig
06:16
we have options to install
06:20
in a vertical pipe but they we only go
06:23
so far and flow rate with those
06:25
yeah those you know being on a vertical
06:28
pipe
06:29
you know you're not passing directly
06:31
through the coalescing mesh in the body
06:33
it's kind of like a side discharge so
06:35
we'll bypass the water off to the side
06:37
through a coalescing mesh
06:39
and then back into the vertical pipe and
06:42
because of that
06:43
you know the body's a little smaller the
06:45
coalescing mesh is a little smaller it
06:47
still
06:47
does a great job of removing air but
06:49
they're only good out to about 10
06:51
gallons per minute
06:53
yeah so having one that's in line in
06:56
in the main loop you know a larger one
06:59
that's
06:59
dedicated for the entire flow rate of
07:01
the system
07:03
is imperative right right yeah typically
07:06
you'll have that on your
07:07
on your hot side of the boiler you want
07:09
to have that on the supply side coming
07:11
out of the boiler and suction side of
07:13
the pump
07:13
right so we wanted high temperature the
07:15
highest temperature
07:16
and the lowest pressure and that's going
07:18
to be the best for removing air out of
07:20
the system
07:21
right right yeah they'll they'll perform
07:24
well for you they're a multi-pass device
07:26
so they will get the majority of the air
07:28
out in the first pass
07:31
but being multi-pass you know it the
07:33
next couple passes after that
07:35
it will continue to remove air and and
07:38
actually any time the system's running
07:40
it's gonna if there's micro bubbles in
07:42
there it's going to remove that
07:44
right and that's always a confusion with
07:47
people too is
07:48
they they get these and they they don't
07:50
realize they are a multi-pass
07:52
and it can also be confused and and
07:54
misapplied in other
07:57
plumbing applications particular right a
07:58
lot yeah we get that question a lot
08:01
about an air separator for plumbing
08:03
and you know they're they're great for
08:05
air removal they're
08:06
more for a closed system so you're not
08:08
going to put that into a plumbing
08:10
application right there they're not low
08:12
lead brass they're not designed to be in
08:14
what's called an open system right right
08:17
so putting those in great you know i
08:20
often see the the fill and expansion
08:23
tank hung below them
08:26
yeah so fill an expansion tank this is
08:29
always a hot topic
08:30
isn't it we seem to get that where
08:32
should that be where should i go
08:33
where can i put it in in this spot well
08:37
we always are going to tell you i mean
08:38
this is best practice
08:40
you want your expansion tank installed
08:43
in a point of no pressure change
08:45
so you want you don't want to be pumping
08:48
right at it
08:48
right you don't yeah i mean it actually
08:51
won't perform well for you if it won't
08:53
perform at all
08:54
you'll lose pressure right you're
08:55
actually going to pump into it you're
08:56
going to pre-load the bladder
08:58
and then you just lost all your room for
09:00
expansion right then you're going to
09:01
have problems with
09:03
with pressure relief valves dripping
09:06
yeah you will um so yeah it's not
09:08
uncommon because you want your air
09:10
separator at the point of no pressure
09:13
to put the expansion tank and fill valve
09:15
in below it is really common
09:17
um and we see that a lot on our brass
09:19
applications but when you get to the
09:21
larger steel models
09:22
you're going to see a drain at the
09:24
bottom of those but is that
09:26
is that where you're going to want to
09:27
pipe that expansion tank typically not
09:29
um even though it's sold as an
09:32
air separator you're looking at a larger
09:35
barrel device
09:36
that has a void at the bottom where the
09:39
potential for debris to build up
09:42
if you have a dirty system it could
09:44
happen right
09:45
so we would hate to see someone put that
09:47
on there they want that as a purge point
09:49
you don't need to purge
09:51
most of the time it's for purging debris
09:53
um
09:54
some guys will use it even to purge a
09:57
little air off if
09:58
the system is you know completely empty
10:00
but honestly
10:01
those larger units they're not using
10:03
that that
10:04
purge air we have a skimmer valve that's
10:06
actually
10:07
probably about a third of the way down
10:09
from the top right and that's going to
10:10
be
10:11
your purge point for removing air right
10:13
right yeah and i mean
10:14
if you tie your expansion tank in down
10:16
below that because it is such a larger
10:18
barrel and you have the coalescing mesh
10:20
in there
10:21
you know as it removes air it is going
10:23
to knock debris loose from the water
10:25
like a dirt separator i mean
10:27
and that will fall to the bottom so if
10:29
you pipe your expansion tank in there
10:31
you run the risk of getting dirt and
10:32
debris in your expansion tank yeah you
10:34
get dirt and debris in your expansion
10:36
tank that's also going to again
10:38
preload the bladder and then you just
10:39
lost room for
10:41
right for expansion yeah you sure did
10:44
what other application do you see these
10:46
used in that doesn't get talked about
10:48
very often
10:49
chilled water filled water yeah we do
10:52
actually we do see those in chilled
10:53
water
10:54
yeah i mean we don't get a ton of
10:56
questions about it but
10:57
not a big deal it it's something you
11:01
gotta
11:01
think a little bit more about but you're
11:04
gonna go
11:05
and install this thing right on the
11:08
inlet side going into the chiller
11:10
most of the time right so yeah the hot
11:12
side of the chiller
11:13
essentially where you know you look at a
11:15
boiler you're putting it on the supply
11:16
line coming out of the boiler where the
11:18
water temperature is the hottest
11:20
with the chiller you're going to reverse
11:21
that and you're going to have it on
11:23
you know the inlet side coming into the
11:25
chiller where that water is the warmest
11:27
yep the most oxygenated water from from
11:30
getting heated up
11:30
after all the all the cool or all the
11:34
yeah all the cold is absorbed out of
11:36
right out of the water out of the
11:37
chilled water
11:39
yeah so yeah i mean chilled water you
11:42
know we're rated for
11:43
use between 32 and 250 degrees
11:46
fahrenheit
11:47
so you know we're gonna cover either a
11:49
chilled or hot water application
11:51
excellent so
11:55
we kind of touched on sizing a bit with
11:57
that but
11:58
i think we could brush up on a little
12:00
more so whenever sizing one of these
12:04
no matter what it is if it's again a
12:06
dirt separator air separator
12:08
hydraulic separator mixing valve
12:11
whatever it is
12:12
we always want to base that off of the
12:15
the gpm
12:16
flow rate right and that's total gpm i
12:18
mean you might have a multiple boiler
12:20
application where
12:22
you'll say you have a hydraulic
12:23
separator and you have a you know a
12:24
header coming off of that
12:26
and all and you have two or three
12:27
boilers tied into that
12:29
um you know you might have you know
12:32
three 200
12:33
000 b2 boilers you know so you're
12:35
looking at 600 000 btus well
12:38
on an individual application you're
12:40
probably at a 20 degree delta t you're
12:42
going to be
12:43
20 gpm per boiler sure but when you're
12:46
sizing that separator
12:48
if you're putting it in the header pipe
12:50
you're going to need to figure for that
12:52
total total load or 60 gallons per
12:54
minute
12:55
yeah that makes sense so you know you
12:58
figure it out
12:59
and or if you're going off of what a lot
13:02
of guys are doing going off of the
13:04
piping that exists
13:06
that kind of can bite you i mean it can
13:08
take you out of contention for getting a
13:10
job
13:11
right because you know you're bidding a
13:14
product that's
13:14
much larger than maybe what you need or
13:17
smaller
13:18
or that might get you in trouble on a
13:19
job because you look at a lot of these
13:21
boilers
13:22
and i mean you you can have a
13:25
you know a 200 000 btu boiler coming out
13:28
in one inch
13:29
coming out of the boiler right and that
13:32
doesn't mean you're going to pipe one
13:33
inch to it that just means what it's at
13:35
what's leaving that heat exchanger at
13:37
exactly
13:38
there's also other types i guess that
13:41
that are out there on the market and we
13:43
have to we end up cross referencing a
13:46
few different types and
13:47
the biggest one is the tangential yeah
13:50
yeah those are very
13:51
uh high velocity yeah unit
13:54
you're typically running at higher
13:56
velocities to make a tangential work
13:58
right it's not a straight pass-through
14:00
device your inlet and outlet are
14:01
typically
14:02
you know coming in at different levels
14:04
of the air separator
14:05
and it's designed to run as a high
14:08
velocity
14:09
or at a higher velocity right you're
14:11
looking at eight to ten feet per second
14:13
on something like that versus a standard
14:15
is right around four to
14:17
say four to six right right yeah and
14:20
with our bodies being so much
14:22
larger we're creating that instant
14:24
velocity drop so we don't have a
14:26
pressure drop through ours
14:27
right right at four feet per second
14:29
eight feet per second we're still
14:31
looking in
14:32
pretty good shape right so when you're
14:34
looking at servicing ours pretty easy to
14:36
service
14:37
i think they're pretty easy to service i
14:39
mean there's not much to it
14:41
we offer models with service check
14:43
valves like for instance on the brass
14:45
ones on the 551 series
14:48
they come with check valves so if you
14:50
have to you know take something apart
14:53
you have that ability to just take it
14:55
apart kind of on the fly
14:57
and that'll that'll allow that that
15:00
check valve will close
15:01
right now not to say that you can't run
15:04
into problems with if there's debris in
15:06
that check valve then it can cause a
15:08
leak
15:08
right so in a perfect world check valves
15:10
work excellent
15:12
yeah yeah they do and honestly they're
15:14
great to have
15:15
but if you want to go one step further
15:17
in your install throw a ball valve in
15:19
there
15:20
absolutely isolation so that you can get
15:22
in and clean it out if you need to i
15:24
mean with all of our air vents
15:27
they're designed to be serviceable you
15:28
can remove the cap and float
15:30
clean the pin out if you have an issue
15:33
there
15:34
you can remove the vent assembly and
15:35
clean that out we actually have a
15:37
replacement vent assembly so you're not
15:39
you're not limited to having to replace
15:41
the whole unit we sell replacement cap
15:43
and floats
15:44
so that you can again you're not you're
15:46
not
15:47
you're not getting into a position where
15:49
you know you have to just replace the
15:51
whole unit
15:52
exactly and that's what's nice about
15:54
them is
15:55
they are very serviceable i mean our all
15:58
brass ones
15:59
from from the one inch on up to you know
16:02
the two inch
16:03
in the 551 series you can actually
16:06
remove
16:07
the entire just the vent vent cap and
16:10
and float you can take the entire vent
16:13
off and actually access the coalescing
16:15
mesh
16:15
you can pull that coalescing mesh right
16:17
out and clean it yes
16:19
and just kind of inspect the body and
16:22
you can reassemble the whole thing
16:23
and you're back in business again yeah
16:26
it was interesting with that you look at
16:27
our
16:29
smaller coalescing meshes the glass
16:31
reinforced coalescing mesh
16:34
the edges are really sharp on that unit
16:37
if you ever pull it out and you notice
16:38
that
16:39
yeah and that that sharpness is there to
16:41
attract
16:42
the the micro bubbles they like small
16:45
sharp edges
16:46
right in the fluid they they slow down
16:48
and they they catch everything that's
16:49
sharp
16:50
right yep it'll allow that to rise up
16:52
and out of the body
16:53
bigger models the flange models the
16:55
steel body models
16:57
you got a very serviceable air vent
17:00
again
17:00
where you can get a cover and float or
17:02
pull it apart and clean it you can pull
17:04
the vent out
17:06
we do not offer replacement mesh for
17:09
those
17:10
it's very rare that one goes bad i mean
17:13
you have to have a lot of
17:14
problems with fluid quality
17:17
and usually that would be debris build
17:19
up as well and
17:20
it usually is you know the probably the
17:23
one advantage with that larger steel
17:24
body is that
17:25
you know it has that big drain poured at
17:27
the bottom so you can flush it off
17:29
you could actually pull the air vent
17:31
assembly off the top open the drain
17:33
valve and flush that coalescing mesh out
17:35
if
17:35
you had a really dirty system and you
17:37
needed to clean that you certainly could
17:39
the only thing you're not going to be
17:41
able to fish out without taking the
17:42
whole unit out of the piping
17:44
shop rags no no we've had phone calls
17:47
about those believe it or not the
17:49
mechanic had
17:50
you know the welder had left a shop rag
17:52
in there and and
17:54
it's they have a major differential
17:56
going across it they're not moving much
17:58
water
17:59
it's too water's hot going in but
18:01
nothing not much going out yeah you're
18:03
creating a big pressure drop
18:05
which you shouldn't you wouldn't
18:06
normally see right
18:08
we've covered some service we've covered
18:10
uh sizing and
18:12
installation how these things work how
18:15
big of a unit do we make
18:17
all the way up to a 12 inch unit it's
18:19
pretty impressive you look at our 12
18:21
inch unit that thing is rated for
18:25
3530 gpm
18:27
that's a lot that's a big flow rate
18:30
that's huge
18:30
think of 30 35 130 gallons per minute of
18:34
flow
18:35
and that thing sits on its own feet i
18:37
mean it's a
18:38
big hunk of steel yeah it is yeah what 8
18:41
through 12 inch are all on legs
18:43
they are on legs you know one thing to
18:45
talk about is our smaller steel models
18:48
you know probably i think it's the two
18:50
through the six inch all have those eye
18:52
hooks on the top
18:53
they do and we get that question hey can
18:55
i hang
18:56
this unit off of those right can i put a
18:58
cable in or something and hang off that
19:01
eye hook
19:02
they're fine for being able to lift into
19:04
place
19:05
but you got to remember once they're
19:07
lifted into place
19:08
and the system is filled with however
19:10
many gallons of water these take
19:12
i mean we've got the chart here you're
19:15
looking at an additional
19:17
eight pounds per gallon right yeah i
19:20
mean they'll
19:20
they have you know pretty good internal
19:22
capacity so
19:24
that's going to add a lot of weight to
19:25
that system right
19:27
you know the unit itself uh we'll say a
19:30
two inch
19:31
just dry weight is 34 pounds but
19:34
it can hold it can hold up to two
19:36
gallons of water in it
19:38
so you added some weight to that right
19:41
yeah so you're gonna add some additional
19:42
weight so
19:43
no you're not going to want to hang off
19:45
of those eye hooks they're there
19:46
for fabrication as a big part of it
19:49
fabrication and painting and then
19:51
also you know getting them hoisted into
19:53
place they're handy for that but
19:55
beyond that that's not a mounting point
19:58
no
19:58
not not a mounting point at all so if
20:00
you got to build the trapeze to hold
20:02
your
20:03
your piping in place when you're putting
20:05
the flanges in or whatever it is
20:07
anything but right clevis hooks and
20:10
threaded rod or something yep
20:11
you got it don't don't use those hooks
20:14
on those eyelid hooks on top of the the
20:16
separator to hang it
20:17
well you know i think that's it on on
20:18
air separators greg
20:20
i think we covered the serviceability
20:22
the install the
20:23
the sizing that sounds about right i
20:25
think we've got everything covered with
20:27
these
20:27
yeah so what do you want to come back
20:29
and talk about next week
20:31
next week we're going to talk about dirt
20:33
separation magnetic and
20:34
and dirt separation i think that's a
20:37
great topic you know we hit air vents
20:38
and air removal we'll come back with
20:40
dirt separation and magnetic next week
20:42
sounds good all right see you next week
20:45
see you next week
20:47
thank you for tuning in if you ever need
20:49
help
20:50
please feel free to contact our tech
20:51
support team anytime
20:53
at tech support us caleffi.com
20:58
or call us during our business hours at
21:00
7
21:01
30 a.m to 4 30 p.m central time
21:05
at 414-238-2360
21:18
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