#17 Installing or Troubleshooting a Mixing Valve. Why not give us a call?

You're ready to install a thermostatic mixing valve.  Interested in pointers to make your install be successful?  OR... you've got a mixing valve installed and it's not working.  Now what?  From the "before" call to the "oh, no!" call, Greg and Dan are here to make you successful with your customer.  They'll dig into how flow is controlled in the valve, what causes temperature creep, and tankless water heaters and their implications with these valves.  Learn about laminar flow, pressure drop, ∆T, pressure ratios and pressure drop.  How about maintenance?  Yes, Greg and Dan discuss calcium and lime build-up, too.  Did you know that you can talk to Greg and Dan real time?  Bottom line, our Ask Caleffi team wants to make YOU look good!  Contact us at (414) 238-2360 ext 3370 OR techsupport.us@caleffi.com.

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Transcript

00:02

[Music]

00:05

welcome to

00:06

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 firkis welcome we look

00:18

forward to sharing some stories from our

00:20

tech calls and using our background and

00:22

expertise to make your days a little

00:28

easier

00:31

hey everybody we're back

00:34

the next episode yeah we are back they

00:37

let us back in they did

00:38

welcome back everybody thanks for tuning

00:41

in

00:41

yeah thanks for the feedback too we've

00:43

been receiving some

00:45

uh feedback on our podcast from some

00:48

tech calls so i appreciate that

00:49

yeah all positive stuff um you know if

00:52

we get some negative we'll be sure to

00:54

share that too

00:55

but uh everything so far it's good

00:58

positive

00:58

yeah that's been fun yeah what have you

01:01

been up to lately

01:03

not a whole lot it's pretty hot here

01:05

yeah it's darn hot

01:06

uh hot and dry we need rain we need rain

01:09

real bad

01:11

i'd like to say i was mowing my lawn but

01:13

it's unfortunately too dry to do that

01:15

i'd like to say i would be out fishing

01:16

instead of mowing my lawn

01:18

well yeah i agree with that too okay

01:21

priorities right obviously your

01:24

priorities are better than mine

01:29

nothing but fun buddy right but fun so

01:31

what are we going to talk about today

01:33

greg

01:33

you know we get a lot of phone calls

01:35

questions

01:36

on mixing valves and i know it's kind of

01:39

a general topic but

01:40

thermostatic mixing valves definitely

01:43

lead themselves to plenty of questions

01:45

from any

01:45

anything on the sizing end you know the

01:48

before call before it's installed to

01:52

oh man this thing's installed it doesn't

01:54

work

01:55

right yeah i know we've talked about

01:57

mixing valves in the past and

01:59

you know the different models we have

02:01

and and sizing and that

02:02

but you know what we haven't spent a lot

02:04

of time on troubleshooting

02:06

no no and i think i mean we can play off

02:09

some of the scenarios like i had a good

02:10

one

02:11

come in this morning uh the guy

02:14

calls me up says yep i want to use your

02:17

520.

02:19

okay cool are you using the tank mixer

02:23

or are you using just the 520 angle mix

02:26

sure no i'm just going to use the the

02:29

angle mix body

02:31

okay the question was

02:34

hey do i need to run balancing vowels

02:38

in the research return and

02:41

realistically in reason he asked that is

02:44

because he read the literature

02:46

right thank you thank you thank you one

02:48

of the few that

02:49

read the literature read the literature

02:51

and said

02:52

this thing's got 100 close off on it

02:54

right and it does

02:56

yeah it absolutely does the cartridge

02:57

will close off 100 percent if it gets

02:59

too hot yeah it's a really quick

03:00

reacting cartridge

03:02

actually uses a similar cartridge to our

03:05

um

03:05

esse 1070 yes balancing valves right

03:09

very quick reacting 100 percent close

03:11

off so yeah

03:13

that you could do that the reason you

03:16

would want to use

03:18

globe valves or a balancing valve globe

03:20

valves are probably better

03:22

absolutely are better because some

03:24

balancing valves are actually a ball

03:26

valve and ball valves

03:28

don't control the best i always say to

03:30

guys you know when you when you think

03:32

about how the flow is controlled

03:34

um a ball valve or a gate valve is kind

03:37

of like sliding your finger over the end

03:39

of a hose

03:40

it'll start to close it off but you know

03:42

it changes the velocity

03:43

where a globe valve as you start to

03:46

close that

03:47

it will maintain a kind of a similar

03:50

velocity

03:50

as you slow the flow down that's a great

03:53

analogy

03:54

it's perfect so back on topic

03:58

yeah love it you don't need necessarily

04:01

to have

04:03

a balancing valve or a globe valve in

04:06

the recirc returns going back

04:10

to the tank and to the cold inlet of the

04:12

mixing valve

04:13

the cold feet of the mixing right

04:16

because of that cartridge being able to

04:17

close off once that

04:19

once that system starts to creep and

04:22

it's because of the

04:24

more because the hot can't close off 100

04:26

right

04:28

it it can't but if the system were to

04:31

start to creep

04:33

what's causing that is the the path of

04:36

least resistance

04:37

right going back into the tank is it

04:39

going to take

04:40

the small line going back into the cold

04:43

feed

04:43

of the mixing valve or is it going to

04:46

take that wide open space

04:47

to the tank oh it's going to drive

04:49

through the tank first i mean there's

04:50

more restriction at that cold side of

04:52

that mixing valve so that pump is going

04:54

to push through the tank

04:55

and you know a product like our 521

04:58

where it can't close off

05:00

the hot 100 percent right it's going to

05:02

drive that elevated tank temperature

05:04

through the hot side of the valve and

05:05

raise your

05:07

raise your hot water temperature to the

05:09

fixtures

05:10

which is what we call creep exactly but

05:12

you're right that 520 won't do that

05:14

no because it that that cartridge is

05:16

going to pinch off close it completely

05:19

and then it's just going to pump water

05:21

through the area where it can flow

05:23

right which will be that cold inlet side

05:26

and continue to do

05:27

what it needs to maintain a nice uh

05:29

mixed

05:30

recirc line yep exactly yeah i had one

05:33

actually uh yesterday it was a good call

05:36

it was

05:36

um a guy with a 521 mixing valve

05:39

okay and he was looking to install that

05:41

with a tankless water heater oh boy

05:43

yeah so um he had not read the

05:46

instructions

05:47

no and it says right in the instructions

05:49

for the 521 really not recommended for

05:51

that installation

05:53

now are they installed that way sure

05:55

there's thousands of them installed that

05:57

way out there

05:58

they're working because there's maybe

06:01

some other things that have been done to

06:02

the system and we'll dive into that

06:04

right yeah but you know if you read the

06:06

instructions on that model it says it's

06:08

designed to be used with a system with

06:10

storage

06:11

so storage means a tank style water

06:14

heater or indirect style water heater

06:15

that's what that 520

06:17

521 model is going to work right

06:19

something with really good laminar flow

06:21

very even keeled right no drops going

06:24

through it

06:25

not like a combi coil or a tankless

06:28

water heater

06:29

where there's a big drop going through

06:32

that coil

06:33

yeah you have a pressure drop and then

06:34

you also have a lot of turbulence in

06:36

that flow and that reacts

06:37

how that cartridge can measure and react

06:40

right it kind of bobbles around

06:42

in there it does so

06:45

after it comes out usually when we see

06:48

problems

06:49

guile have it installed contractor will

06:51

have it installed

06:53

call us and say this thing's not working

06:55

so

06:56

one we want to see the literature on

06:59

that says 27 degree delta

07:01

right delta t yeah but realistically a

07:05

20 degree

07:05

seems to work fine okay if we nailed

07:09

that down you're expecting

07:11

we'll say 125 degrees out of that valve

07:14

you got to produce at least 145 to 150

07:17

degrees a lot of tankless water heaters

07:19

have trouble doing that

07:20

right you know i mean that's really the

07:22

high end you know 140

07:24

you know is really the high end and then

07:26

they start to really drop off in

07:27

efficiency

07:28

right so for efficiency purposes

07:32

that's where they that's where they're

07:33

programmed to be right

07:35

but we get that nailed down that yup we

07:39

have

07:39

a 20 degree delta t feeding it with the

07:43

appropriate temperature

07:44

on the hot side but you have no way of

07:48

knowing

07:48

what the pressure drop is unless you

07:50

install exactly where my mind is pt

07:52

ports right nobody does that i mean when

07:54

i did water heaters

07:56

granted they were basic tank style water

07:58

heaters

07:59

installing pressure ports was not a

08:00

thing well no you're not going to have a

08:02

huge pressure drop across that but you

08:04

look at a tankless coil where

08:06

you've got a lot of btus and a very

08:08

small heat exchanger looking to raise

08:10

the water temperature from

08:13

you know 50 degrees to 120 or 30 or

08:16

or 50 if you're trying to use that

08:19

mixing valve and the snap of a finger

08:20

right i mean you have a pretty high

08:23

pressure drop across that heat exchanger

08:26

right in a case like that

08:29

you're you're going to really probably

08:31

want a balancing valve on the cold side

08:33

of that

08:33

mixing valve so that you can balance

08:36

that pressure differential

08:37

right and that's that's where my mind

08:39

was going is

08:40

when i get a trouble job like this

08:44

talking to the contractor they have it

08:46

all installed

08:47

you know this is the end of the day or

08:50

they've got two other jobs lined up

08:51

behind us they need to get this done

08:54

what can i do to fix this do i got to

08:56

tear this thing out i really don't want

08:58

to tear this thing out because it's

09:00

supposed to be in here

09:01

right what do i do well

09:05

there's got to be a problem with that 2

09:06

1 ratio that two to one pressure rate

09:10

hot to cold or cold to hot sure the

09:12

example of

09:13

hey we're feeding the system coming into

09:16

the house with

09:17

50 pounds of pressure we'll just use

09:18

that as a nice even number

09:20

sure by the time you feed the valve you

09:23

tee off and feed the valve the valve is

09:25

getting 150

09:26

ps or i'm sorry 50 psi

09:30

50 psi all right of cold water pressure

09:33

to it on the cold and left side of the

09:35

mixing valve then you're feeding

09:37

the tankless or combi coil or whatever

09:40

it is yeah you're hitting that pressure

09:41

drop

09:42

yup that's your pressure drop with 50

09:45

you have no way of knowing unless you

09:46

test the pressure coming out which would

09:48

be feeding the hot

09:50

inlet side of that mixing valve but say

09:53

we're down

09:54

you take a measurement and it's 23 20

09:57

psi

09:58

right feeding that hot inside of the

10:01

valve out of your outside your

10:02

differential you're outside your

10:03

differential

10:05

that that cold pressure is going to win

10:07

over the hot right

10:08

and you're never going to you're never

10:09

going to temper water correctly

10:11

yeah exactly another scenario to that

10:14

though is

10:15

you may put it in and it works perfectly

10:18

okay

10:18

it happens to work you know it works

10:20

well and

10:22

six months or a year later now it

10:24

doesn't

10:26

what you know you may have experienced

10:29

that the heat exchanger is starting to

10:31

line up starting to hard water you know

10:33

starting to get to a point where it

10:35

needs to have maintenance done on the

10:36

water heater

10:37

and that your pressure drop is

10:38

increasing and now so you install it you

10:41

walk away you think boy i did it

10:43

okay it's working well and then six

10:45

months down the line you get a little

10:47

lyme or

10:48

calcium buildup in that heat exchanger

10:50

your pressure drop increases you drop

10:52

outside that two to one pressure

10:53

differential and now the valve won't

10:54

work

10:55

right and you know another rabbit hole

10:57

here

10:58

where i hear those calls the most the

11:00

lining up is usually combi coils and oil

11:03

boilers

11:04

yeah because they get so hot they really

11:07

they really cause that issue a lot

11:10

quicker than a gas-fired appliance

11:12

yeah they absolutely do and you know you

11:14

think about that the hotter the water is

11:16

the quicker the minerals are going to

11:17

precipitate out of that water the

11:18

calcium the lime build up

11:20

and where is that going to land it's

11:22

going to land in the small ports of that

11:23

heat exchanger

11:24

absolutely so what would be a better

11:26

valve for that application

11:28

honestly i love that 520 because of that

11:32

the quicker reacting cartridge it's a

11:35

little bit smaller body

11:37

it just works better right and easier to

11:39

pipe

11:40

yeah you look at coming out coming out

11:42

of the bottom of a

11:44

on-demand water heater you've got your

11:46

hot and cold ports well

11:48

you can drop right out of the hot board

11:49

into the into the mixing valve

11:52

come right out of your mixed outlet

11:53

they're in a straight line and then

11:56

the t is already essentially in place to

11:58

come in to your cold side

12:00

beautiful so it takes less space and

12:02

it's easier to pipe

12:04

yeah i 100 agree with that so

12:07

but backing up a little bit here

12:11

we have a problem with that differential

12:13

due to you know on initial install

12:16

let's say we want to balance down that

12:19

cold

12:20

right that's where that cold balancing

12:22

valve comes in

12:23

adding a globe valve to the cold inlet

12:26

just

12:26

to the cold inlet side of the mixing

12:30

valve

12:31

right off the feed just going into the

12:33

mixing valve now

12:35

i understand piping can be tight and we

12:36

get that a lot we get the oh

12:38

man i haven't really i have no room i've

12:40

got room for that

12:41

uh yeah you're gonna have to get

12:43

creative unfortunately if you're

12:45

experiencing that problem right but

12:46

that's

12:47

like that's the troubleshooting solution

12:49

that we can offer

12:50

is look you got to balance down that

12:53

cold

12:54

just the cold feed to the mix valve

12:57

i've had guys maybe not quite understand

13:00

that

13:00

because they ran out of room for piping

13:02

so then they just throw the globe valve

13:04

in

13:05

and not only do they choke down the cold

13:07

flow through the mix valve

13:08

they also do it through the heat

13:09

exchanger then i get a call back an hour

13:11

later

13:12

it's still not working right because you

13:14

don't maintain your differential right

13:16

right so you just choke the pressure off

13:18

to both sides instead of just one

13:20

right so you got to just trim down the

13:23

cold feet of the mixing valve

13:25

only that's all you're doing to change

13:27

that two to one ratio back

13:29

right right what other questions

13:33

ah the other thing again we we kind of

13:37

talk about it anytime we talk about

13:39

mixing valves is

13:40

knowing your minimum flow rates yeah and

13:43

in a smaller system it's not usually a

13:45

problem right no

13:46

and that's where you know like the 520

13:48

or 521

13:50

um you know it's not a problem i mean

13:52

the 521 has a one gallon per minute

13:55

minimum flow rate

13:56

the 520 we have two body sizes we have

13:59

the smaller

14:00

half or three quarter inch model which

14:02

has a 0.5

14:03

uh minimum 1.5 gpm minimum flow rate and

14:06

then we have the larger 3.5 cv body

14:09

which i really like

14:10

yeah um that has a 1 gpm minimum flow

14:13

rate

14:14

but actually has a 16 gpm maximum so

14:17

it's a little higher than the 521 on the

14:19

maximum

14:19

yeah it's that's pretty nice especially

14:22

for larger homes and that's where we

14:23

start to see

14:25

the weird things happen with minimums

14:28

not being met because

14:30

quite frankly if the house has

14:34

inch and a half or inch and a quarter

14:35

piping one can assume that

14:38

we need an inch and a quarter inch and a

14:40

half mixing valve right

14:41

well why wouldn't you go why wouldn't

14:43

you why wouldn't you why wouldn't you

14:45

need that right that's what the pipe

14:46

size is yeah

14:47

but that's where we run into problems so

14:49

when you

14:50

when a guy looks at installing

14:54

an inch and a quarter or an inch and a

14:55

half valve both of those have minimum

14:58

flow requirements

14:59

they usually look at our high flow

15:01

valves right when they're looking at

15:03

some of this bigger stuff

15:04

well we need we need bigger so

15:07

we're going to go to the high flow valve

15:09

and those work well

15:11

those are certainly you know a great fit

15:13

in the marketplace

15:14

they do thermostatic high flows it's a

15:16

big hunk of brass it's a lot of money

15:19

so it's a high flow rate it is a high

15:21

flow rate

15:22

you know that that smaller body that

15:24

inch and a quarter one inch model

15:26

five two three one yeah four point four

15:29

minimum

15:30

5.4 gallons per minute minimum flow

15:33

requirement for that guy to mix properly

15:35

right

15:36

yeah and that's where you know having a

15:38

recirc line is

15:40

a necessity it is that's what's going to

15:42

make up your minimum and it needs to

15:44

that research needs to work anytime

15:46

there's a demand

15:47

on the system sure you know if yeah i i

15:51

always tell guys you'll run the research

15:52

line continuously

15:54

run that pump continuously we have

15:55

variable speed pumps go with that

15:58

right and then you step into the larger

16:01

body

16:02

an inch and a half and a two inch

16:05

that's an 8.8 right 8.8 gallons per

16:08

minute minimum flow requirement

16:10

that's a big resource yeah so usually

16:12

when we're getting calls

16:14

and the valve is hunting it's not

16:16

maintaining

16:17

it's not performing it's usually during

16:19

a low flow application

16:22

without a research line right and

16:25

i hate to say it but retirement homes

16:28

old folks homes

16:30

are the biggest offenders a guy will go

16:33

in there replace another brand of mixing

16:35

valve

16:36

or the building never had one and then

16:39

they got inspected and oh we need to put

16:41

one in right

16:42

they go off pipe size it was never built

16:46

initially years ago with a recirc right

16:49

they throw it

16:50

in maybe it works maybe it doesn't

16:53

we get a call a month or so later hey

16:57

this thing used to work and now it

16:58

doesn't right well you know what i like

17:00

when i get that call

17:02

i don't like when i get the call that

17:04

says

17:05

um we this is what we installed we

17:08

installed one of your 5231s and it

17:10

didn't work

17:10

so we replaced it and then we installed

17:12

another one

17:13

yeah and now this one's not working so

17:16

we're thinking about you know

17:18

do we did we have two bad valves

17:21

no we didn't because and i'm going to

17:24

rant a little bit here

17:25

here he goes i was trying to stop that

17:28

but

17:28

all right go ahead we gotta look at

17:31

these things okay

17:33

or or we never see them because somebody

17:35

just decides we're gonna sit on it but

17:37

then we're gonna call you angrily

17:39

and complain about it not working

17:43

why didn't you call us when you had the

17:45

problem initially right well i shouldn't

17:47

please call us please call us please

17:49

please call us

17:50

you start to see a problem pick up the

17:53

phone and call us man we

17:54

are very happy to take that phone call

17:57

now

17:58

before the problem escalates to you

18:00

getting your hind end chewed by

18:02

the property owner health manager or

18:05

whatever

18:06

and it kind of helps us go through every

18:09

little thing with the system

18:11

right and in the end it'll save you

18:12

money on a job because it will

18:14

you know you're going to buy one put it

18:16

in it's not going to work you're going

18:17

to go buy another one

18:19

and you're going to want to warranty it

18:20

put it in that one's not going to work

18:22

so

18:23

in that case you've now made a couple of

18:25

trips there

18:26

i still haven't corrected your problem

18:28

and now you finally call and we're going

18:30

back

18:31

now we're coming up with a solution and

18:32

you're going back to fix it which is

18:34

further costing you money so right and

18:36

then in the end

18:37

we get this valve back go to test it we

18:40

test it

18:41

and it works right because we put the

18:43

minimum flow to it

18:45

and all is working then i got to deny

18:47

your warranty

18:48

which we don't want to do yeah we don't

18:51

like doing we don't like doing that

18:52

we want to help you out absolutely but

18:54

at the same

18:57

what's fair right well that's where you

19:00

know hey

19:01

and we want you guys to look good yeah

19:02

and we want you know we want everyone to

19:04

be successful

19:05

yeah we want everybody to be successful

19:07

we want you to save face with the

19:08

customer and look good with your

19:10

customer

19:11

right so yeah take the time and call us

19:14

i had a call the other day

19:16

we did a episode early on

19:19

about thermostatic mixing valves and you

19:22

know the different product lines and

19:24

sizing them

19:25

and i actually just had a tech call from

19:26

someone who had listened to that

19:28

really and said you know what i'm gonna

19:31

i wanted to call you because i listened

19:33

to your episode

19:34

about sizing the mixing valves and i

19:37

figured i'd get your help now

19:39

before i get out there and have an issue

19:40

so it was great yeah

19:42

and that's kind of what what triggered

19:44

us to go you know what let's do some

19:45

talk about troubleshooting

19:47

mixing valves you know we appreciate

19:49

that i'd rather have that call up front

19:52

yeah and don't be afraid to reach out to

19:54

us via the tech email

19:56

or you know blog yeah or they ask lefty

19:59

blog

20:00

on our youtube people are constantly

20:02

leaving comments and questions there

20:06

us up we're happy to help that's what

20:07

we're here for if we don't get to you

20:09

right away we're going to apologize

20:11

we'll get to you um we get to everyone

20:14

pretty quick

20:14

yeah i i think we'd go pretty good job

20:16

yeah absolutely

20:18

well i think we covered it pretty well

20:21

yeah i think so

20:22

i'm sure we're forgetting something we

20:24

can circle the wagons and talk

20:26

we'll come back on this i mean this is

20:28

we get this call

20:29

so often we'll be back with more all

20:31

right thanks for tuning in

20:34

thank you for tuning in if you ever need

20:36

help please feel free to contact our

20:38

tech support team

20:39

anytime at techsupport.us

20:43

caleffi.com or call us during our

20:46

business hours

20:47

at 7 30 a.m to 4 30 p.m

20:51

central time at 414-238-2360

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[Music]

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