#8 No pressure... but what's THAT noise?

Why is my pressure reducing valve rattling, hammering.... screaming??

Greg and Dan take a new spin in this episode of the Ask Caleffi podcast series, inviting you into a "customer" technical support call in order to troubleshoot the problem.   They will discuss how a PRV should be sized (based on pipe size?).  Is there a more accurate methodology (hint: a design for flow rate!)?  What about install tips and maintenance?  (another hint:  debris is NOT a friend to PRVs).

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Transcript

00:00

[Music]

00:04

welcome to ask Caleffi

00:06

the podcast that dives into real life

00:08

problems that plumbing and hvac

00:10

technicians face in the field we're your

00:12

hosts from the Caleffi 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

00:29

hey there welcome back to the ask Caleffi

00:31

podcast i'm greg tubbs your host and i

00:33

got

00:34

dan firkus here with me welcome back

00:36

everybody today we're going to talk

00:37

about

00:38

prv yeah what's that sound yeah what is

00:41

that sound

00:42

we get that question on occasion here

00:45

on the tech support line we get a guy

00:48

that calls in

00:49

and or even the customer the homeowner

00:51

or the building owner

00:53

with hey your prv is making noise

00:56

what could that be yeah we'll have home

00:59

quite a few homeowners that call in

01:01

and generally it's after the valve's

01:03

been installed for

01:05

you know a day or two or maybe a week

01:06

and it's making a noise and

01:08

you know they're waiting for their

01:09

contractor to get back out and look at

01:11

it so in the meantime that

01:12

homeowner may call us sure we're going

01:15

to run this one a little different

01:16

we're actually going to kind of play a

01:17

roll call so you can kind of get the

01:19

gist of

01:20

like the type of call we get on a day

01:23

about something like this

01:27

good afternoon tech support this is dan

01:30

hi dan this is jim from steve's plumbing

01:32

hey jim how are you doing today well i'd

01:34

be a lot better if your uh

01:36

pressure reducing valve wasn't rattling

01:38

pipes and making so much noise

01:40

i'm sorry to hear that so um let's just

01:43

talk a little bit about your project you

01:45

know what size

01:46

uh prv do you have in well

01:49

the piping to the house is one inch so

01:52

you know i just put a one inch valve in

01:53

okay

01:54

so you got one inch coming in one inch

01:56

going to the home so

01:57

you know you picked a one inch pressure

01:59

reducing valve

02:00

okay um is this a residential or

02:03

commercial property

02:04

well this is definitely residential uh

02:06

it's a

02:07

a three-bedroom house i think they've

02:09

got three bathrooms

02:10

you know and a handful of other things

02:12

running uh

02:14

just two people living there okay so

02:16

only two occupants

02:17

yeah okay um anything unique about the

02:20

home

02:21

as far as like you know high flow

02:23

showers

02:24

or anything like that no everything's

02:26

pretty standard on the shower side of

02:27

things

02:29

i would say they're probably two gal in

02:30

a minute showers if if if that

02:32

okay have you gone through the home and

02:35

come up with a design flow rate that you

02:37

think you need

02:38

well i really didn't i just went with

02:41

what i saw for piping there

02:42

but i suppose we could probably kind of

02:45

figure that out

02:46

yeah it'd be important to do that you

02:47

know kind of total up what

02:49

what you think your shower flow rates

02:52

are

02:53

lavs dishwasher washing machine

02:56

you know kind of kind of come up with a

02:58

total gpm when you look at sizing that's

03:00

what's really important

03:01

so what you did is pretty common you

03:04

sized it based on pipe size coming in

03:07

and through the home

03:08

sure um but not uncommon our valves are

03:10

pretty high flow

03:12

so it's not uncommon that you'll see a

03:15

pressure reducing valve that's

03:17

you know one or even two pipe diameters

03:19

smaller than

03:20

the incoming piping okay that makes

03:23

sense

03:23

you know when you look at that um one

03:26

inch

03:27

pressure reducing valve for example you

03:29

know

03:30

when we size them you know i talked

03:32

about totaling your total gpm coming

03:34

into the home

03:35

and then what you want to do is take a

03:38

look at the flow characteristic charts

03:40

for our pressure reducing valves oh sure

03:43

and then you want to

03:46

take your flow rate and find that in the

03:49

three to six feet per second window

03:51

on that flow characteristic chart gotcha

03:55

um that's going to be the velocity where

03:57

that valve is the happiest

03:59

okay that makes sense so you know what's

04:02

interesting is

04:03

you select at the one inch valve and

04:05

that one inch valve is rated from 10 to

04:07

19 gallons per minute in that three to

04:10

six

04:10

feet per second window on that flow

04:12

characteristic chart

04:13

and here's what i think you're seeing

04:15

you know 10 gallons

04:16

per minute is a pretty high flow rate

04:19

that valve will perform down to one

04:21

feet per second okay so when you look at

04:24

the flow characteristic chart and you

04:25

get down to one foot per second that

04:28

valve will

04:29

is looking deliver 3.25 gpm

04:33

okay so three and a quarter gallon per

04:34

minute so you go to a lab

04:36

sink or you might be one to one and a

04:39

half gpm you're never meeting what that

04:41

valve can handle on a minimum

04:43

that makes total sense so

04:46

i think what you'll find is that you

04:48

know going back

04:50

evaluating the home finding out what

04:53

the typical flow rates are and then

04:56

choosing a valve that

04:58

that will fit that window is what's

04:59

going to work better so you may find

05:01

that the half or even three quarter

05:02

might be a better fit there

05:04

sure so this is

05:07

the typical phone call we get about a

05:10

noisy prv

05:12

or vibrations happening from a prv

05:15

yeah if i could count the amount of

05:16

times i've had this exact conversation

05:19

in real life

05:19

it's it happens a lot yeah so oversizing

05:23

is

05:24

usually the biggest trouble um yeah well

05:26

and you know what you'll find

05:28

is that valve's going to be noisy it's

05:31

going to be

05:31

it's a lot of vibration and shuttering

05:33

and clunking or water hammering sound

05:37

because it's always working at the

05:38

minimum right so

05:40

you know in a home where you can hear

05:43

the valve

05:44

you're gonna notice it if it's located

05:46

in a mechanical room or out in the

05:47

garage or

05:49

or even outside in some applications

05:52

they're outside or in a basement

05:54

you know you may not or the the

05:56

homeowner may not hear that sound

05:58

so that valve will work okay

06:03

but it's going to wear the seat out on

06:04

that valve certainly will

06:07

so going through and really looking at

06:10

the sizing chart

06:11

i mean we have pretty good documentation

06:13

on how to size a valve properly

06:16

right so that's that's a pretty big deal

06:20

yeah so that i mean number number one

06:23

most

06:23

important thing is know your flow rate

06:26

know your flow requirement

06:27

absolutely not do not focus on pipe size

06:30

well and then the same thing can go for

06:33

undersizing

06:34

a valve i mean on occasion we get that

06:36

too we do

06:37

you know too much pressure drop it's

06:39

going to cause a lot of screaming of the

06:41

valve

06:42

yeah cavitation yep and usually we see

06:45

that in much larger systems where

06:47

they're stepping the pressure down

06:48

way too much too soon too right

06:52

yeah typically you'll want to be within

06:53

that two to one pressure ratio but

06:56

you know never exceeding three to one

06:58

right

06:59

it'll operate at three to one but it's

07:02

highly recommended to stick closer to

07:03

that two to one

07:04

what else i mean we talk about two-stage

07:07

pressure reduction

07:08

that's that's another big one you know

07:10

yeah if you uh

07:12

depending on your area you have you know

07:14

you can have some really elevated

07:16

water pressure coming into your

07:18

buildings especially a lot of like like

07:20

mountain areas

07:21

you know that when you're working at

07:22

higher elevations you tend to build a

07:24

lot of pressure

07:25

sure or if you're working on a high-rise

07:29

rise you know they've got booster pumps

07:31

in there and you're looking at

07:33

an incoming of of 150 you know 90 to 150

07:36

psi

07:37

pressure if you're trying to knock it

07:38

down to 60 psi

07:41

at 150 that's not quite gonna do it

07:44

right

07:45

yeah you're really pushing that valve

07:47

yeah it's it's pushing it

07:49

um that's where you know two-stage a

07:51

two-stage installation is gonna be

07:54

a good application you know if you have

07:56

a building that's

07:57

you know 150 psi and you want to take it

08:00

down

08:00

to 50 you know you might take one prv

08:04

your first prv

08:06

and set it to 90.

08:09

right so you're knocking it from 150 to

08:11

90

08:12

and then your second one will take it

08:13

from 90 down to the 50 psi

08:15

which is perfect then you don't have to

08:17

worry about valve streaming and

08:20

wearing things out as fast right right

08:22

quieter application

08:24

certainly and i think another thing that

08:27

you know

08:27

is going to cause maybe an undersized

08:29

condition

08:31

is a dirty prv this thing

08:34

this is what gets me the most is

08:38

we get the phone call it's either not

08:41

closing off

08:42

or the pressure is really reduced you

08:44

know what's going on with this is this

08:46

valve bad

08:47

right or it's building pressure yeah or

08:50

you have that valve where

08:52

you know you're stepping it from 90 to

08:53

50 and then

08:56

um over time it's creeping back up to

08:58

maybe 70 80 or up to that 90 pounds

09:01

because it's it's continuing to over

09:03

pressurize

09:04

right and so then we'll get these back

09:06

as returns

09:08

and we go pull them out of the box

09:12

we look right inside them and you can

09:13

see debris chunks of paint

09:16

uh copper following the one we just got

09:18

back i've never seen so much magnetite

09:20

oh geez that one was really bad yeah and

09:23

then pieces of

09:24

thread tape in it right so yeah chunks

09:27

of copper chunks of solder thread tape

09:30

you name it we found it in debris and

09:32

even the smallest chunk of copper in

09:34

that

09:35

in that seat will cause it to over

09:37

pressurize

09:38

right it doesn't take much it doesn't

09:40

and if you look at the ceiling

09:42

area of that cartridge it's real fine on

09:44

the bottom and you just take

09:46

one little piece of copper fouling in

09:47

there to to wedge it

09:49

right and then it'll it'll basically

09:51

it'll it'll mimic a system without a

09:54

thermal expansion tank right the

09:56

pressure will slowly build

09:58

and all of a sudden you're popping

10:00

relief valves you know what's nice about

10:02

ours is that we do have a

10:04

mesh screen filter on them and it's a

10:06

360 degree filter so

10:08

you know our cartridge goes in on an

10:10

angle it has a real big

10:11

you know body to it and it has

10:14

a screen mesh filter that covers

10:18

360 degrees of the opening so you know

10:21

it

10:21

you've got good flow through it in good

10:23

filtration

10:25

right but even the tiniest pieces of

10:27

debris this isn't a filter

10:29

it's not designed no no but it's

10:31

designed to protect the cartridge from

10:33

larger pieces of debris

10:34

yeah absolutely so but what's nice with

10:37

ours is that you know it

10:39

talk about maintenance so you know

10:42

you install this on a project you walk

10:44

away and then you know maybe the

10:46

municipality comes in and they change

10:48

something or they flush their hydrants

10:50

and they not

10:51

create a lot of velocity in the pipes

10:53

and not debris shot

10:54

or you're in doing service on the water

10:57

heater

10:57

and you know you're recharging the

10:59

system and you know velocity goes up and

11:01

you knock some debris loose and now your

11:03

pressure reducing valve

11:04

is over pressurizing ours you can easily

11:07

pull that cartridge out

11:08

clean it out put it back in and you know

11:10

a wrench to break it loose and then

11:12

you're spinning it out by hand right

11:14

yeah and you pull it apart and you

11:15

notice that hey yeah there is debris

11:18

so you're going to want to wash that

11:19

thing out and hopefully you have some

11:22

a way to wash it off or wipe it out with

11:24

a rag but then what we're going to

11:26

even recommend going further is all

11:28

right if you got that much stuff

11:29

built up in the body and on the

11:31

cartridge maybe what you're going to

11:33

want to do is

11:34

if you can slide a bucket underneath

11:36

this thing and open the main up

11:38

and slowly yeah and just allow

11:41

that debris to kind of carry up and out

11:43

right it's always good to flush it

11:45

before you put it back in so you don't

11:46

get more debris

11:47

and honestly if if you can make it

11:49

practice and not everybody can

11:51

you know every job is different but if

11:53

you can make it a good solid practice

11:56

before installing a new prv have a

11:58

bucket handy

11:59

purge the main you know purge a few

12:01

gallons off you might be surprised how

12:03

much debris comes

12:04

out of it right yeah that debris is

12:06

there so if you can purge it off you

12:08

know it's not going to get stuck in that

12:09

valve right

12:10

then you go through with installing your

12:12

valve you know whether it's press

12:14

npt or sweat and make the install and

12:17

then

12:18

pressurize the system and just go

12:20

through and check it all out again

12:21

right yeah we do have you know all of

12:24

our valves our union connection

12:26

so we do have you know jumper nipples

12:28

that you can put in there

12:30

um if you wanted to sweat it in place

12:32

put it in place

12:33

put a jumper nipple in flush that mane

12:36

purge it off real well or even during

12:38

construction put that jumper nipple in

12:40

until you know the system's been flushed

12:43

and clean

12:43

and then pull it out and then install

12:45

the body right yeah

12:47

so i think what we could take away from

12:48

this i think the biggest

12:50

nugget of information take time and find

12:53

out

12:54

figure out what the gpm demand is for

12:56

each application that's really going to

12:58

save you a lot of headaches

12:59

that's what's really important know know

13:02

your system requirements and then select

13:05

the valve that's going to fit that

13:07

so tune in next week for episode nine

13:09

and i think we're going to talk

13:11

yeah we're going to talk about

13:12

troubleshooting your zone relay box

13:15

that sounds good that's a big topic i'm

13:17

looking forward to that

13:19

yeah i mean you might even get a little

13:20

bit of education on how to use your

13:22

tools a little better

13:23

yeah so well we'll look forward to that

13:25

we'll talk we'll see you next week

13:26

see you next week thank you for tuning

13:29

in

13:30

if you ever need help please feel free

13:32

to contact our tech support team

13:34

anytime at techsupport.us

13:38

caleffi.com or call us during our

13:40

business hours

13:42

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

13:45

central time at 414-238-2360