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#12 How do I choose the "RIGHT" mixing valve for my POD app?
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Your customer's domestic water system is not delivering heat correctly. What do you do? You listen into this episode of the Ask Caleffi podcast! Greg and Dan discuss ASSE 1017 Point-of-Distribution valves (not to be confused with ASSE1070!) and how to size them. They stress the importance of understanding a thermostatic mixing valve's minimum and maximum flow rate thresholds when combined with pressure drop.
Greg and Dan discuss what types of products will complement existing systems that do not have recirculation loops such as a "high/low" valve assembly or an electronic mixing valve. Their goal is to help you determine how to apply the proper valve for the circumstance at hand.
Want to hear YOUR QUESTION on Ask Caleffi? Take this quick 4 question survey for your chance to hear your question in a future episode.
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[Music]
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welcome to
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ask Caleffi the podcast that dives into
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real life problems that plumbing and
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hvac technicians face in the field
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we're your hosts from the Caleffi tech
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support team i'm greg tubbs
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and i'm dan firkus welcome we look
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forward to sharing some stories from our
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tech calls
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and using our background and expertise
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to make your days a little easier
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hey there welcome back here we are
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episode 12.
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yeah welcome back everybody thanks for
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coming back so today we're going to talk
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about
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choosing the correct mixing valve for
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point of distribution
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right at the water heater absolutely
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that's a big topic we get a lot of
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questions on how to select that
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we certainly do and you know a lot of it
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is
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looking at what the assc standards are
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right
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right the sse 1017 standards for point
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of
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distribution right and if you kind of
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want to be able to
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tell them apart if you're kind of a
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newbie at this
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asse 1017 1017 comes before
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10.70 yes it does numerically it comes
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before 1070
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it also in the system the plumbing
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system it comes before
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the 1070 valve in the system as well
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because yeah you're right 1070 is going
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to be at the point of use
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you got it we get the question a lot
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about
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having the right size mixing valve and
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it's really not them
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asking question directly we got to kind
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of get it out of them
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you know they'll call us and say yep you
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know i've got a valve of yours and i'm
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thinking
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installing or it's already installed and
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it
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doesn't seem to be delivering hot water
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correctly it's hunting
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right right so we usually have to kind
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of pry it out of them hey
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what size piping you're dealing with
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there and what is the realistic
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worst case scenario flow rate you need
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to deal with right exactly you know what
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flow rate what are the flow requirements
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you know i mean i
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hey isn't it true greg you just select
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the mixing belt based on what pipe size
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is coming out of the water heater
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isn't that the way it goes don't you do
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it no don't do it geez
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that's how it gets done it is more often
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than not unfortunately yeah i mean if
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it's a guy in the field that needs to do
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a replacement because he's pulled up on
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the job
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he's discovered that the valve is either
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lime scaled up and beyond repair
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and it's time to replace it so what are
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we going to do what's what's the thing
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to do
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well it's two inch pipe must need a two
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inch valve i'm gonna go over to the
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parts store and i'm gonna get
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a two inch valve absolutely and then
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they get it installed and the thing
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doesn't work quite right
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then you find out well the building
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doesn't have
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recirc you know and maybe i should back
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up a little bit here and say
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a two inch valve for all practical
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purposes if we're talking about like our
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five two one
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right that guy's got an 8.8
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yeah gallons per minute minimum flow
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requirement
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yeah well and that's what you know so we
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we joked about selecting it based on
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pipe size and certainly don't much to go
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that route unfortunately it happens
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enough but greg's right you know minimum
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every mixing valve out there whether
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it's point of use or point of
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distribution
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we're going to talk a point of
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distribution now
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has a minimum and maximum flow
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requirement and you have to work within
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that minimum and maximum flow
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requirement or have a way to make up the
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minimum flow requirement you got it
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biggest offenders as far as like systems
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are concerned
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its existing apartment buildings where
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let's be honest
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the building owner doesn't want to put
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more into it than what what they have to
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right so if they don't have research and
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we both know almost not everyone don't
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yeah
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yeah not everyone's going to and far
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more won't
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right so right right off the bat your
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your back's kind up against the wall or
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an old folks home tomb that's another
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one that we see a lot of it's existing
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and
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everything's buried so i have no way of
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really making up that
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minimum it's very difficult yeah yeah so
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you want to um
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make sure as you're selecting it that
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you you know what the minimum flow
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requirement of the
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of the product you're selecting is uh
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also know
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that you're working within the design
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specifications of that valve so
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cluffy rates all of their product out to
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their maximum flow rates out to a 20 psi
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pressure drop
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right so you know you'd look at our two
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inch mix
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cal uh that unit is going to be
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8.8 gallons per minute minimum and
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70 gallons per minute maximum at a 20
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psi
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pressure drop so that's the other thing
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to keep in mind your if
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if you need 70 gallons per minute great
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that'll do it it'll get you 70 gallons
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per minute but you're gonna have a 20
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psi pressure drop so keep that in mind
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if your system pressure is only
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50 psi and you need 70 gallons per
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minute
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and once you achieve that 70 gallons per
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minute your building pressure drops to
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30 psi and that becomes unacceptable
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well then we maybe need to look at a
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different product right
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right something like the legio mix with
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a bigger flow
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and we'll we'll get down that that
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rabbit hole eventually
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right so but yeah like you're getting
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back to it
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if you're not hitting the minimum we get
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that question too
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what am i supposed to do what can i do
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well at that point it's almost too
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little too late
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the building owner's not going to want
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to put a research in
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well sometimes you just can't i mean did
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you think about trying to get a research
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into an existing building with
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you know risers and dead legs and you
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know i try to eliminate
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that legs in the system right and that's
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darn near impossible right
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so you could look at you know high low
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mixing valves as options
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yeah high lows are probably going to be
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your best option
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really for a job like that and again
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you're a big chunk
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of change but if you look at the cost of
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something like one of those
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high flow just the high flow alone is
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pretty big money that's a big hunk of
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brass it is but look at what it's going
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to take and cost to add a
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research line a lot of labor and a lot
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of parts
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and it might not even be done right when
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you're finished right right
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so a high low let's talk about the high
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low a little bit
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yeah so the high low is going to have
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two mixing valves it's going to have
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you know a low flow valve which has a
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low minimum
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and a lower maximum flow rate for
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example like our 521
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mixed cal is one gallon per minute
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minimum flow rate
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it'll go out to about a 14 gpm maximum
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flow rate
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and then you also put in one of the
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higher flow mixing valves that's going
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to have you know like a 4.4 gallon per
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minute
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to or even 8.8 gallon per minute to 70.
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depending on what your range needs to be
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right but yeah you're right on the money
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and then
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we had a pressure reducing valve in
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there a prv is kind of a balancer
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right so once once the system starts to
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give more draw it will allow flow
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through that high flow yeah you kind of
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set the prv for the
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like the fallout pressure of the mixing
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valve right so if you know that
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the smaller mixing valve is one gallon
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per minute minimum 14 gallon per minute
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max
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at a 20 psi pressure drop and you know
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that
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your minimum flow rate is 8.8 gallons
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per minute on your high flow
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then you look at your flow
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characteristic chart and you set that
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pressure reducing valve so that when
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that smaller mixing valve
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reaches eight or nine gallons per minute
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you it's going to now open up the larger
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mixing valve
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right that's exactly it that allows you
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kind of to use the smaller mixing valve
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to meet the minimum flow requirement of
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the bigger mixing valve
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and then the bigger mixing valve takes
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over from there perfect
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well and from there we have electronic
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mixing valves we sure do
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yeah we have the legion mix which is a
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great valve
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uh big flow numbers out of it yeah huge
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flow numbers and the benefit to that is
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you know it's a three-way ball valve
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so with three bay three-way ball valve
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you get really high flow numbers at a
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at a lower pressure drop lower pressure
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drop and a smaller valve body
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right yeah that's the that's really the
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key so you know we talked about
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that two inch thermostatic mixing valve
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with the 8.8 gallon per minute minimum
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and 70 gallon per minute maximum boy
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craig what our one inch legio mix give
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you
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94 gallons a minute at a 20 psi drop
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wow so that's quite a bit higher than a
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two inch
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right thermostatic so you're carrying
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in two inch pipe and you're going to
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reduce right at the valve
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right at the valve and go down to one
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inch and people kind of
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they sort of freak out about that yeah
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we see our electronic mixing valves
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really commonly piped even one to two
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pipe sizes smaller than the connection
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type
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and actually that's larger i should say
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sure
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it's okay though because you're dropping
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uh velocity
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in a bigger pipe right right you don't
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have to worry about wearing wearing that
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copper out yeah but what's the biggest
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benefit of jumping up to the electronic
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i really love the fact that it has its
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own
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cleaning function it self cleans
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yeah yeah absolutely it does that
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anti-clog
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function but even bigger than that is
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minimum flow requirements i mean we we
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talked so much about minimum flow
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requirements with those thermostatic
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valves
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that one-inch legio mix electronic 94
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gallons per minute at a 20 psi
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pressure drop but now your minimum flow
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requirement is 3.1 gallons per minute
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right
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so if you have a research that's
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nominally sized right around three
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gallons a minute
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and someone just opens a small faucet
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it's going to work
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absolutely is and then
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you step down to an even smaller valve
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say you can get away with stepping down
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with a smaller valve even though you
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have
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two inch piping to the building but you
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suddenly do the math and go
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we only need 30 gallons a minute through
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this right
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well and i think that's the big thing is
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doing the math
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because you know you don't know if
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the plumber or installer before you
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sized it based on pipe size or actually
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building requirements so
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you know going back and understanding
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the actual use of the building
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you may find out that you know you can
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step down and valve size it's going to
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work perform better your
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pressure drops might be a little less
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it's just going to be more adequate
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right but in a perfect world
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if there is such a thing a properly
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sized research
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all done up installed with you know
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balancing and everything to meet the
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minimum
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i mean that's that's where a system is
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going to work at it's
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that's ideal yeah that it's just ideal
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it certainly is but we
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we know that a lot of this stuff is
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going in as a replacement yeah for
11:00
something old and antiquated or too
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expensive to
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repair right so well and understanding
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what's in there from a flow requirement
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i mean if you have an
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old you know mixing valve in place and
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it's not a cluffy mixing valve and
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you're unsure
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with selecting our you know what product
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of ours to select give us a call
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you know greg or i'll help you
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cross-reference it and pick the right
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right product match up yeah and that you
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know
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we really take pride in being able to
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take your guys's phone calls and emails
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and trying to help you solve your
11:34
problems and help you get the right
11:36
product before you even start the job
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yeah i mean there's nothing worse than
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getting out there with a product and we
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we get those phone calls all the time
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too
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where it's too late somebody told them
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to use it or they just decided well i'm
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going to use this size because that's
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what's here
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right and now we're kind of you're
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holding the bag
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oh you get one of two things either it
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doesn't perform
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it doesn't perform for you either it's
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undersized or oversized because it's a
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different flow requirement than what you
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have
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or you select a product that you could
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have that
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is oversized and the cost the upfront
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cost cost
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you know the building owner more or
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creates an objection on the price side
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and you could have you could have
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dropped down to a
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properly sized more properly sized one
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at a better more affordable cost
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absolutely you know do a little bit of
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scouting up front yeah absolutely scout
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it out and
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and really take the time before you just
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go throwing a valve in
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well the biggest thing greg and i want
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for you is that
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whatever you put in is going to work
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right
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yeah it's going to perform for you we
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know all our products perform well
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right but they got to be applied right
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and that's our job is to help you
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apply it right absolutely well i think
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that was a pretty good episode
12:53
what do you want to talk about next week
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i don't know greg what do you want to
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talk about
12:57
[Laughter]
12:59
i think for sure we're talking about
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water quality and
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we are going to have a guest on next
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week oh i think mark's going to join us
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next week
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that is correct well see you next week
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thank you for tuning in if you ever need
13:14
help please feel free to contact our
13:16
tech support team
13:17
anytime at tech support
13:21
caleffi.com or call us during our
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business hours
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at 7 30 a.m to 4 30 p.m
13:28
central time at 414-238-233
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