#19 Why does recirc creep occur in DHW systems? (with Cody Mack)

Greg and Dan invite "the dynamo of donut testing" to the series, the one and only Cody Mack.  Recirc creep is something that plumbers no doubt experience.  But, what is recirculation creep, when does it occur, what are the symptoms and - most importantly - what is the solution for your domestic hot water system?   They'll discuss ASSE 1017 and thermostatic mixing valves.  Can an aquastat be installed to fix the problem?  Are certain facilities more at risk?  What is the impact of piping practices?  Can I dig deeper (show me the resources!).  

Don't know Cody?  He serves as an education and training manager in North America for Caleffi.  Cody also is behind-the-camera in the popular series "5 Things You Need to Know" video series.  Feel free to watch. 

Thanks for tuning in!

5 Things You Need to Know About Recirc Creep

https://bit.ly/AboutRecircCreep

Transcript

0:00

[Music]

00:05

welcome to ask a leffy

00:06

the podcast that dives into real life

00:09

problems that plumbing and hvac

00:11

technicians face in the field we're your

00:13

hosts from the calefi tech support team

00:15

i'm greg tubbs and i'm dan ferkus

00:17

welcome

00:18

we look forward to sharing some stories

00:20

from our tech calls and using our

00:21

background and expertise

00:23

to make your days a little easier

00:28

[Music]

00:29

hey there welcome back here we are

00:31

another episode of the ask luffy podcast

00:33

how are we doing dan you're doing good

00:35

yeah welcome back everybody

00:37

what do we got cooking today oh today

00:39

we're excited we got a guest in the

00:40

studio here

00:41

we got cody mack our training and

00:43

education manager

00:44

uh he's the our official whiz kid here

00:47

at cleffy yes oh

00:48

that's a title i don't deserve he is the

00:50

dynamo of donut testing around here

00:54

i am a connoisseur of donuts i will

00:56

agree with that

01:01

no thanks for having me guys no this is

01:02

a lot of fun i i appreciate you guys

01:04

having me on

01:05

yeah we're happy you joined us so

01:08

five things we all need to know that's a

01:10

series that we have out

01:12

yeah you're right greg yeah we started a

01:14

an interesting training initiative

01:16

uh you know as time goes on and people

01:18

are more accustomed to social media

01:20

their attention spans seemingly get

01:21

smaller and smaller

01:23

and uh i'm looking at you greg

01:26

shiny thing but yeah so you know we have

01:30

uh some great initiatives like coffee

01:31

with kalefi which go into

01:33

great detail and a lot of information

01:35

and everything like that and we wanted

01:36

to really narrow it down and hit like

01:38

the

01:38

the high notes and and just be straight

01:40

into the point and everything like that

01:41

and that's where we came up with the

01:43

the five things you need to know and

01:44

again wide range of topics we've got a

01:46

number of them on our youtube channel

01:48

they're on all of our social medias as

01:50

well

01:50

and uh and it's been going really well

01:52

so far yeah good yeah

01:54

it's a down and dirty educational you

01:56

know kind of like us

01:57

it kind of hits the high points hits the

01:59

important the important key factors on

02:01

certain topics

02:02

sure talking to research creep today

02:04

aren't we yeah this is one of my first

02:06

ones that we did

02:07

it was the five things you need to know

02:09

about why research creep occurs and

02:11

and uh research creep is something that

02:13

most plumbers have probably experienced

02:15

although they probably don't even know

02:17

how to actually put a name on it uh or

02:20

how to define it and

02:22

they probably just thought it was a bad

02:23

mixing valve in a lot of cases i know we

02:25

take some calls like that where they

02:26

have certain

02:27

mixing valves certainly we get a lot of

02:28

calls on that yeah for sure

02:30

plenty of them but uh but yeah no it's

02:33

it's a big thing and and uh research

02:34

creep is

02:35

it can affect everybody it can be

02:36

dangerous it's it's a

02:38

it's definitely something that you want

02:40

to address and and uh

02:42

and yeah i think this this particular

02:43

episode was a great one in the fact that

02:45

it hit

02:46

all those real high notes and again we

02:48

do have more in in-depth and more

02:49

detailed stuff

02:50

uh with coffee with colefi as well right

02:52

yeah again topic we get calls on a lot

02:54

and plumbers

02:55

you know a lot of them don't even know

02:57

why it's occurring or what's occurring

02:59

yeah for sure and that's the thing and

03:02

so so you know like what actually is

03:03

research creep

03:04

um you know research creep is a scenario

03:07

that can actually happen

03:09

when you have a recirculation system on

03:11

a domestic hot water supply system or

03:13

domestic hot water distribution system

03:15

and then you've got a mixing valve

03:16

involved as well

03:18

and it's kind of this perfect storm of

03:20

specific things that need to happen in

03:22

order for

03:23

research creep to occur but the idea is

03:27

is that you've got a mixing valve you've

03:28

got a research system and

03:30

the issue with i shouldn't even call it

03:32

an issue but it's something that you

03:33

need to be aware of it's i'll call it a

03:35

limitation

03:36

with a lot of thermostatic mixing valves

03:38

especially is that they don't have the

03:40

ability to completely close off

03:42

one side or the other whether it be hot

03:44

or cold and so the the problem occurs

03:47

and the fact that when you bring your

03:48

research back

03:49

and you tie it back into the you know

03:51

the domestic hot water supply or the

03:52

mexico water source

03:54

if that mixing valve doesn't have the

03:55

ability to completely close off that hot

03:57

side

03:58

uh you could actually be adding more

04:00

heat to the loop than what the loop is

04:01

giving off

04:02

uh in heat loss throughout the building

04:04

and whatnot and so

04:05

when you add more heat to the loop than

04:07

what the loop is giving off

04:08

and there's no demand from the fixtures

04:10

you could actually have that whole

04:11

distribution line and your research line

04:13

creep up

04:14

that's the word creep we talked about to

04:16

whatever the storage tank temperature is

04:18

and that's where

04:19

that's what the real big problem is

04:20

because if you're storing at 150 or 160

04:23

somebody's going to get scalded and

04:24

that's going to occur more at a time

04:26

where you have a low use like maybe the

04:27

middle of the night

04:28

you know 100 or a system that just has

04:32

you know they're dead legs because say

04:34

it's a hotel that's not

04:35

being used occupied yeah and and

04:39

that's the other thing too is is you

04:40

know you talk about symptoms you know

04:42

like

04:42

again i mentioned it before a lot of

04:44

plumbers and guys have probably

04:45

experienced it but they didn't know how

04:47

to really put a a defined name on it

04:49

and and so the kind of the symptoms that

04:51

you're gonna run to like dan said

04:53

you know the fact is is that when you

04:55

have little to no demand from your

04:56

fixtures like an overnight period of

04:58

eight

04:58

nine ten hours or whatever or if it's a

05:00

commercial building unoccupied for 12

05:02

hours at a crack

05:03

um you're going to come in the morning

05:05

and then you know whoever opens up that

05:06

first faucet is going to get some just

05:08

absolutely smoking hot water and then

05:10

the mixing valve and everything's gonna

05:11

work just fine the rest of the day

05:13

and so you you know obviously they think

05:15

well it's not controlling the

05:16

temperature it must be a bad mixing

05:18

valve

05:18

um but in all reality it's it's just

05:21

again

05:22

kind of a thing with assc 1017 is that

05:24

it does not require complete shutoff on

05:26

either side

05:26

in order to uh to pass an assc 1017

05:30

certification so

05:31

right yeah yeah so the first person

05:34

comes on does the

05:35

initial purge maybe get scalded

05:38

and that's where the problem lies yeah

05:39

that's when the call comes in

05:41

yeah exactly and it's especially

05:43

important too you know you get into a

05:45

lot of

05:45

healthcare facilities nursing homes

05:47

elderly care facilities you know

05:49

whatever you want to call them

05:50

um you know those people i mean they get

05:52

scalded

05:53

and it's one thing to get scalded but

05:55

then you have all the complications from

05:57

you know third-degree burns and things

05:59

like that um infections and

06:01

i mean people can literally die without

06:03

getting scalded yeah it becomes a real

06:05

liability issue for sure

06:06

lawsuits ensue yeah nobody nobody wants

06:09

a lawyer coming after him so

06:11

it's it's a big thing we talk about it

06:12

pretty regularly so again research creep

06:15

is something you don't want to happen

06:16

and and there's definitely some ways to

06:18

take care of it um

06:20

you know there there's different piping

06:21

methods and things like that that we

06:22

describe in our technical brochures

06:24

you know i mean you guys could probably

06:26

get calls about it all the time too all

06:27

the time

06:28

yeah good piping practices to help

06:30

prevent that yeah

06:32

yeah so i mean the the one of the

06:33

biggest things that we've run into is

06:34

that if you've got a thermostatic mixing

06:36

valve like that that cannot completely

06:38

close off the hot side or the cold side

06:40

you know basically when when you've got

06:42

no demand and your research is still

06:43

running

06:44

you know a lot of people think like oh

06:45

my gosh i can just put an aqua stat on

06:47

there

06:48

like that would fix everything and and

06:50

really it solves one problem while

06:51

creating

06:52

other problems right you know um and we

06:55

we have this conversation a lot too

06:57

you know the the fact is is that you're

06:59

not meeting a minimum

07:00

exactly yeah so so that aqua stat you

07:03

know if you set it to 120 or whatever

07:05

the case may be you know it's going to

07:06

shut down the research and

07:07

and creeps not going to happen that's

07:09

great but now all of a sudden you've got

07:10

a

07:11

two inch mixing valve that has a minimum

07:12

flow requirement of eight gallons per

07:14

minute

07:14

and you've got no flow going through it

07:16

which is is going to cause a lot of

07:17

issues because when you're not meeting

07:18

minimum flows then that

07:20

that mixing valve is bouncing all over

07:21

the place because it's not getting a

07:23

good read on mixed temperature because

07:24

it's

07:25

it's not getting enough turbulence

07:26

inside the valve body

07:28

makes sense yeah it does yeah it happens

07:31

happens quite a bit

07:32

um so when we see a lot of them pipe

07:35

directly

07:36

the research lines pipe directly back to

07:37

the tank not even pipe back to the

07:39

mixing right

07:40

so you're just oh that's escalating that

07:42

problem yeah you're escalating it

07:43

one you're not meeting your minimum

07:45

flows and two you're pushing that

07:47

elevated hot water up and past that hot

07:49

side of that mixing valve

07:50

yeah in a lot of cases you know if you

07:52

don't have a mixing valve on your

07:53

domestic hot water source whether it be

07:55

a storage tank or whatever the case may

07:56

be

07:57

you know bringing back a research is

07:58

really easy you just tie it back into

08:00

the cold inlet to the domestic hot water

08:02

source some people use a tapping on the

08:03

tank whether it be in the mid

08:05

mid range on the tank or or even at the

08:07

drain at the bottom

08:08

but when you add a mixing valve into the

08:11

scenario that's where things really

08:12

start to get

08:13

um you know a little bit dicey and you

08:15

got to make sure that you're you're

08:16

piping it properly and so

08:18

yeah like dan said when you're you're

08:19

doing that um

08:21

you know in in reality what you need to

08:23

be doing is taking that research and

08:25

splitting it and one

08:26

actually goes to the tank and one goes

08:27

to the mixing valve at the cold inlet

08:29

and it's a little bit hard to describe

08:31

via podcast obviously

08:33

i could probably spend an hour doing

08:34

that but i think a great place to look

08:36

is going to be our technical brochure or

08:38

go to the five things you need to know

08:40

about uh video and and watch it there's

08:42

a good diagram in there yeah we have

08:43

great diagrams

08:44

and i mean we've even sent them off

08:48

many a time to to guys that you know

08:50

while i don't have internet or

08:52

for whatever reason we'll text it to

08:54

them or get it to them one way or

08:55

another yeah just referring back to that

08:57

installation instructions you'll see

08:59

that diagram in there

09:00

um and and you're right you know you

09:02

talk about splitting it back to the

09:03

mixing valve and

09:04

and you need to do that to make up your

09:06

minimum flow rate but you look at

09:08

our smaller valve like our 521 series

09:10

where you have a one gpm minimum flow

09:12

rate

09:12

you know guys can get away with not

09:14

tying back to the mixing valve

09:16

and they'll meet their one gpm minimum

09:18

flow rate and they won't have an issue

09:20

but that's where they really get that

09:21

research creep is because

09:23

you know you're pushing past that hot

09:25

side of that valve right and that valve

09:27

doesn't close off 100

09:28

nope exactly but you know um

09:31

i think the biggest thing to think about

09:33

here is is you know and we've we've

09:35

taken calls like this before too and

09:37

and i i've probably been um i've

09:39

probably done it myself too for that

09:41

matter

09:42

you know you think it's a bad mixing

09:43

valve you replace the mixing valve and

09:45

then all of a sudden

09:46

the new one does the same thing imagine

09:48

that imagine that i know

09:50

so you replace it a second time because

09:51

you know the first it must be a bad

09:53

batch or something like that

09:54

you know of course um you know but but

09:56

don't hesitate to call us because it's

09:58

one of those things where you know

10:00

it might be not be a phenomenon that

10:01

you're familiar with but you explain the

10:03

symptoms and we could you know

10:04

we can put you know pin a tail on that

10:07

donkey pretty quick

10:08

but we've had some where it's been

10:11

multiple phone calls and we're happy to

10:12

take those multiple phone calls because

10:14

we want to help you along the way

10:16

for sure because we're honestly every

10:18

system is different

10:19

like there could be something missing

10:21

there might be something piped in and

10:22

around

10:23

something somewhere where or a check

10:26

valve in the wrong

10:27

in the wrong place or a check valve

10:29

that's stuck you know right

10:32

and we've had it where we've had to walk

10:34

guys through

10:35

multiple phone calls and then we finally

10:38

get it or we don't

10:39

we don't hear anything back right and

10:41

then it kind of peaks our curiosity no

10:42

news is good news greg don't

10:44

yeah i know i know but we try to follow

10:48

up on it as much as we can

10:49

yeah most of the time it's they've got

10:51

it figured out but no that's really the

10:52

advantage to giving

10:54

giving us a call right away because

10:55

think about the time involved

10:57

to go get a different mixing valve to

10:59

switch it out to have it still happen

11:01

again to now run and pick up a third

11:03

mixing valve to change that out your

11:06

your customer loses confidence it's like

11:07

you could call us the first time

11:09

we'll walk you through and ask your

11:12

questions and do the same thing when we

11:13

were in the field oh yeah i tell guys

11:14

all the time if you can't figure it out

11:16

and really

11:17

nail it down as far as what the problem

11:18

is within a half an hour you need to be

11:20

calling something right

11:21

yeah and that is the greatest thing you

11:22

know like when i started doing service

11:23

work

11:24

uh we didn't have company cell phones we

11:25

had cb radios

11:28

and nowadays like everybody yeah

11:30

everybody's got this

11:31

you know the full-blown computer in

11:33

their pocket you know take pictures send

11:35

pictures give us a call

11:36

you know check our website you know

11:37

whatever i mean it was

11:39

it was just revolutionary when we

11:41

started carrying around smartphones that

11:43

how how much easier and how much more

11:44

information i could have

11:45

readily available you know and and so

11:47

there you know

11:48

the idea of going back and call back

11:50

after callback because of something that

11:52

you're unfamiliar with

11:53

you know it really something that can be

11:55

uh mitigated for sure right right right

11:57

we've taken them calls and we're happy

11:58

to oh yeah but

12:00

well we're happy to take them but it's

12:02

kind of a bummer when we hear from the

12:04

guy

12:04

on mixing valve number two or number

12:06

three and

12:08

well this just keeps doing it okay and

12:10

you keep replacing the valve

12:12

yeah well it's got to be the only thing

12:14

and then we're kind of

12:15

reverse engineering things and talking

12:17

them through what's going on

12:19

so again as soon as a problem arise

12:23

arises just give us a call we'd rather

12:26

hear

12:26

pictures we love pictures yeah okay

12:29

they're worth a thousand words

12:30

but uh in our world they're worth a

12:32

million words yeah because

12:34

absolutely you know it's great again

12:36

we've got this little computer in our

12:37

pocket you take the pictures you email

12:38

them over you text them to us

12:40

you know we can say hey wait a second

12:42

you know that's that's not where it's

12:43

supposed to be you need to move that

12:44

checker

12:45

or maybe the checks in backwards or

12:46

whatever you know there's a lot of

12:48

different scenarios but the other cool

12:50

thing with

12:50

with research creep is that you know

12:52

because just because assc 1017 doesn't

12:55

require you to completely shut off the

12:57

hot inlet port doesn't mean you can't

12:59

so so we do have actually some mixing

13:02

valves that

13:02

can completely close off the hot port

13:04

right that will completely

13:06

eliminate racer creep which is really

13:08

awesome and so we've got two different

13:09

models we've got our angle mix which is

13:11

i think a revolutionary

13:13

product um as far as mixing valves

13:16

because the valve body the connections

13:18

are angled so it's not a cross type

13:20

of a valve anymore it's a pretty sweet

13:22

little valve

13:23

yeah it's piping a lot easier makes

13:24

piping so much easier

13:26

yeah it's a great valve yeah we've got

13:28

that available half three-quarter in one

13:30

inch which is going to be great for a

13:31

lot of your small

13:31

residential like commercial type stuff

13:33

but then we've also got our lead geomics

13:35

which our legio mix has been just an

13:37

absolute uh awesome product for us the

13:40

last handful of years

13:41

that is a digital mixing valve and it's

13:43

using actually a three-way ball valve

13:45

assembly so

13:46

being a three-way ball valve it does

13:48

have the ability to completely close off

13:49

bubble tight even

13:50

on the hot or cold which is awesome yeah

13:53

yeah it's been a great product it has

13:55

it's been very popular

13:58

so yeah i mean we like i said we take we

14:00

take a number of calls about it we want

14:02

to make sure everybody stays safe we

14:03

want to make sure that you're

14:04

understanding what's going on and again

14:06

this isn't just a kalefi issue with

14:08

racer creep this is

14:09

every manufacturer of mixing valves so

14:12

if you ever see a mixing valve diagram a

14:13

piping diagram that says that they

14:15

require an aqua stat

14:16

that's probably because they're just

14:18

trying to cover their rearrange yeah you

14:19

know a little cya never hurt anybody i'm

14:22

sure the lawyers added that one but

14:23

sure but with that in mind there are

14:25

means of being able to run

14:27

constant research or constant

14:28

recirculation without running into creep

14:30

uh so definitely you know if you're

14:32

looking for more information let us know

14:33

and the other thing too is in this day

14:35

and age you know putting an aqua stat on

14:38

a recirculation system is a terrible

14:39

idea you know we we read more and more

14:42

about how

14:43

legionella and legionella bacteria and

14:45

legionnaires disease is becoming more

14:47

and more of an issue

14:48

and by turning off that recirculation

14:49

system you are turning that big giant

14:51

distribution system of domestic hot

14:53

water into a giant petri dish

14:55

absolutely and that's what legionella

14:57

bacteria wants it wants that stagnant

14:59

warm water in order to breed and thrive

15:01

and everything else

15:02

and by by keeping that recirculation on

15:05

you're you're lessening the chance of

15:07

legionella bacteria happening

15:09

and so you want to make sure that that

15:11

stuff runs uh pretty much continuously

15:14

but obviously you want to keep your

15:15

occupants safe as well yeah keep your

15:16

temperatures elevated and keep that

15:18

water moving

15:19

yep variable speed pumps have come a

15:21

long way and they're pretty handy in

15:22

these situations yeah i think aqua stats

15:25

initially was done for energy efficiency

15:27

but when you look at the variable speed

15:29

pumps

15:29

you're getting your energy efficiency

15:31

there so you're you get safer

15:33

a safer domestic hot water system if you

15:35

keep that water moving yeah absolutely

15:37

for sure and and yeah you're i think

15:39

you're hitting the nail right on the

15:40

head dan the fact that

15:41

it was done for energy efficiency but

15:43

you know you look at some of these

15:44

variable speed circulators now

15:46

and how much it actually costs to run

15:47

them it's kind of a moot point

15:49

and you know granted it might be code in

15:51

certain areas i know i think it's

15:53

california is one of them that require

15:54

aqua stats

15:55

but in all reality we all know building

15:57

code is centered around

15:59

occupant safety in these buildings and

16:01

and you know

16:02

if we can be energy efficient at the

16:03

same time that's fantastic but i think

16:05

one of these days

16:06

any requirements for aqua stats that are

16:08

going to get thrown out the window right

16:10

well that's great so this is the five

16:12

things you need to know series we're

16:14

gonna have a lot of other topics coming

16:15

up

16:16

uh from cody you can find those on our

16:18

youtube channel

16:19

yep and all the other social medias as

16:21

well linkedin facebook

16:22

instagram i don't know what others

16:25

anywhere what are the snappers these

16:27

days i don't know tweeting

16:29

i don't know anywhere we can put it okay

16:32

yeah but yeah it's everywhere so check

16:33

it out

16:34

uh you know and if you guys have topics

16:36

you want to recommend

16:37

too i mean definitely uh reach out to us

16:39

we uh we we've got a lot of good stuff

16:41

coming down the pipeline but

16:42

we're always interested in making sure

16:44

you guys uh get the information you need

16:46

well great yeah we'll have you back on

16:48

with more cody all right thanks dan

16:49

thanks greg appreciate the time yeah

16:51

happy to have you here

16:52

thank you thank you for tuning in if you

16:55

ever need help

16:56

please feel free to contact our tech

16:58

support team anytime

17:00

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17:04

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