# Whistling / Noisy Pressure valve on water main



## danielrg (Aug 26, 2011)

I have a pressure valve on the main water line coming into the house, just before the cutoff valve.

I'm finishing my basement, and this valve will be in the wall (with access panel) of our new family room.

When someone flushes the master bed toilet, during part of the filling process, the pressure valve on the house inlet whistles so loud it hurts my ears, for about 5-10 seconds while the toilet is filling. I think it has to do with the flow rate, and some particular flow rate just kicks off the whistling.

This was fine when the basement was unoccupied, but now that it will be I'd like to fix it.

Any ideas? Do I need a new valve? Should I just try adjusting it a little and see if it goes away?

Thanks in advance!


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## jmon (Nov 5, 2012)

danielrg said:


> I have a pressure valve on the main water line coming into the house, just before the cutoff valve.
> 
> I'm finishing my basement, and this valve will be in the wall (with access panel) of our new family room.
> 
> ...


Pinpointing noises like this are often difficult, but the first thing I would do is replace the fill valve on the toilet. It's the most likely culprit and a fairly easy repair. I would try that first before you adjust, rebuild or replace the prv valve.

One thing to try is to turn the water off to each toilet, one at a time, and check if the noise stops. If the noise stops when you shut off a particular toilet then change the fill valve in that toilet tank.

There are of course other possible causes. You could have a faulty pressure reducing valve (as you have already stated) on the water main or a faulty back flow preventer or and outside faucet with a back flow preventer that has minimal flow.


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## danielrg (Aug 26, 2011)

Thanks jmon. You've given me some great things to check into. I'll start with the toilets and go on from there.


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## danielrg (Aug 26, 2011)

*My PRV IS broken I'm pretty sure*

So I bought a pressure meter, the kind you put on your hose faucet. My wife was taking a shower. It measured 44 PSI.

When she stopped her shower, it went up to 95 PSI.

Huh. 

So I turned on a faucet. It dropped to about 55/60. Another faucet and it dropped to 30.

My guess is that the PRV is really leaky. When everything's off, the municipal pressure leaks in, taking it up to 95 PSI.

When something is on, since it is set pretty low (from me trying to fix it I turned it very much CCW), it slows the flow all the way down to its low setting.

When I set it for higher (very much clockwise) the pressure didn't drop as much when the faucets were on, though they still almost immediately dropped to 70 if there was much of any flow.

My diagnosis - leaky PRV, and I need a new one. Does that sound right?


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## jmon (Nov 5, 2012)

danielrg said:


> My diagnosis - leaky PRV, and I need a new one. Does that sound right?


I agree with your diagnosis daniel. That would be the next logical step. 

Your water pressure readings confirmed it. Depending on how it's plumbed it may be an easy swap out. If you need more help, please post some pics of it when you get a chance so we can better assist you. Thanks.


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## danielrg (Aug 26, 2011)

I have a 3/4" Watts N35B. It is discontinued, but repair kits are available.

It looks to have threaded connectors on the top and bottom, so swapping it out could be a 10 minute operation - if I can find a compatible model.

I don't want to do a repair unless I can't get one that will screw into it's place. I'd rather repair than sweat copper pipes, but I'd rather screw a new one on than repair it.

From the pictures, the Watts N45B or N55B look compatible, they seem to have threaded connectors on both sides too. I sent an email to Watts asking if I could swap out for one of those.

Anyone here know for sure if N45B or N55B can swap out with an N35B?


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## jmon (Nov 5, 2012)

danielrg said:


> I have a 3/4" Watts N35B. It is discontinued, but repair kits are available.
> 
> It looks to have threaded connectors on the top and bottom, so swapping it out could be a 10 minute operation - if I can find a compatible model.
> 
> ...


I don't know for sure, need a picture to see what you actually got there. As long as they have the same connections on both ends and pressure rating as your current n35b, they should work. 

Are both ends union? Sometimes in older houses one end is threaded and the other is union. Just make sure you get the right one so you can swap them out easily. Got a picture?

Don't forget the tape and pipe dope for the threaded side if you have one. None needed if both ends are union.


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## danielrg (Aug 26, 2011)

It's called "Double Union Solder" - the Watts representative I talked to said the N55BDUS should be able to replace the N35BDUS at the unions.

Same ratings otherwise.

Local plumbing supply house says they have them in stock. So I'll try one tomorrow and see how it goes!

Thanks again.


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## jmon (Nov 5, 2012)

danielrg said:


> It's called "Double Union Solder" - the Watts representative I talked to said the N55BDUS should be able to replace the N35BDUS at the unions.
> 
> Same ratings otherwise.
> 
> ...


Your welcome Daniel. Hope everything works out for you.:thumbsup:


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## MTN REMODEL LLC (Sep 11, 2010)

Great advice from everyone.... as to solving the PRV pressure problem....

but has *ANYONE ever heard of a whistling noise* from a PRV valve..


.... just plain curiosity:wink:


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## ben's plumbing (Oct 6, 2011)

MTN REMODEL LLC said:


> Great advice from everyone.... as to solving the PRV pressure problem....
> 
> but has *ANYONE ever heard of a whistling noise* from a PRV valve..
> 
> ...


 yep all the time we get calls for prv whistling. hammering..to name a few...ben sr


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## MTN REMODEL LLC (Sep 11, 2010)

ben's plumbing said:


> yep all the time we get calls for prv whistling. hammering..to name a few...ben sr


Hammering, stuttering, shuddering yes.... but there is no air vent in that valve... where does whistling come from Ben..."???


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## jmon (Nov 5, 2012)

MTN REMODEL LLC said:


> Hammering, stuttering, shuddering yes.... but there is no air vent in that valve... where does whistling come from Ben..."???


Good question mtn remodel. I really don't know the answer, but I would take a guess it comes from debris stuck to it, by increasing the pressure and thus reducing the restriction, it could go away temporarily.

You could try to either clean the PRV inlet or better yet just replace the whole thing with a new one. Wichever is easiest for homeowner.


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## ben's plumbing (Oct 6, 2011)

MTN REMODEL LLC said:


> Hammering, stuttering, shuddering yes.... but there is no air vent in that valve... where does whistling come from Ben..."???


 really my guess would be from the pressure on the high side of the valve as the valve is trying to hold back the pressure ...it makes a very high pitch sound ...ben sr


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## TheEplumber (Jul 20, 2010)

MTN REMODEL LLC said:


> Great advice from everyone.... as to solving the PRV pressure problem....
> 
> but has *ANYONE ever heard of a whistling noise* from a PRV valve..
> 
> ...


Have you never heard a squealing flushometer on a urinal or toilet?


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## MTN REMODEL LLC (Sep 11, 2010)

TheEplumber said:


> Have you never heard a squealing flushometer on a urinal or toilet?


E... Yuup... plenty.... just never heard a whisling from a PRV.... but my experience as a GC is limited in plumbing... and I've probably had to replace only maybe 5-6 in my life....

but I'll recognize that symptom now in the future if I encounter it... Thanks

Best 

Peter


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## Ghostmaker (Mar 2, 2013)

Make sure you adjust your water pressure to about 65 pounds static after your install. They come at 40 pounds usually.


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## MTN REMODEL LLC (Sep 11, 2010)

Ghostmaker said:


> Make sure you adjust your water pressure to about 65 pounds static after your install. They come at 40 pounds usually.


Ghost... Ya know what I can never remember... is which direction the screw goes for more/less pressure.... guess I don't adjust them that often or regularily....

Best


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## danielrg (Aug 26, 2011)

MTN REMODEL LLC said:


> Great advice from everyone.... as to solving the PRV pressure problem....
> 
> but has *ANYONE ever heard of a whistling noise* from a PRV valve..
> 
> ...


Yeah, that was my original post. Mine was whistling super loud when my toilet was filling. Eventually it turned into replacing it when I tested the pressure to see if it was bad.


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## danielrg (Aug 26, 2011)

jmon said:


> Good question mtn remodel. I really don't know the answer, but I would take a guess it comes from debris stuck to it, by increasing the pressure and thus reducing the restriction, it could go away temporarily.
> 
> You could try to either clean the PRV inlet or better yet just replace the whole thing with a new one. Wichever is easiest for homeowner.


So I replaced my valve today. The old one had a rock against the strainer on the inlet side, maybe 1/4" in diameter. So I wouldn't be surprised if dirt that at some point got into the city's line might've come through and junked up or got stuck somewhere in my valve, possibly the cause of its failure. I guess water can whistle just like air given the right circumstances, anything to cause a vibration in the audible range.


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## MTN REMODEL LLC (Sep 11, 2010)

jmon said:


> *Pinpointing noises like this are often difficult, but the first thing I would do is replace the fill valve on the toilet. It's the most likely culprit and a fairly easy repair. I would try that first before you adjust, rebuild or replace the prv valve.*
> 
> One thing to try is to turn the water off to each toilet, one at a time, and check if the noise stops. If the noise stops when you shut off a particular toilet then change the fill valve in that toilet tank.
> 
> There are of course other possible causes. You could have a faulty pressure reducing valve (as you have already stated) on the water main or a faulty back flow preventer or and outside faucet with a back flow preventer that has minimal flow.


Quote Dan "Yeah, that was my original post. Mine was whistling super loud when my toilet was filling. Eventually it turned into replacing it when I tested the pressure to see if it was bad. "


Dan... yes, I guess I thought there was a question as to what was whistling.


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## danielrg (Aug 26, 2011)

danielrg said:


> It's called "Double Union Solder" - the Watts representative I talked to said the N55BDUS should be able to replace the N35BDUS at the unions.
> 
> Same ratings otherwise.
> 
> ...


So I promised I'd report back. I went to the local supply house, took the faulty Watts N35B 3/4" valve with me.

They had both the N45B and N55B valves in stock (among others) - it was clear that either one would fit the union joints, and they both were factory set to 50 PSI with a range from 25 to 75 PSI. N55B was all metal, N45B had some plastic part on it. Asked the guy at the shop which he recommended. He just shrugged his shoulders and said, "They both work. We sell a lot of both of them."

I went with the N55B for $70. The model they had was just the threaded side of union on one side, and full union joint with solder joint on other. I wanted to replace the o-rings in the union joints too - since only one side had both sides of the union there was only one o-ring. He just took another out of a box and handed me the o ring from that one too. Very nice.

The union joints were a piece of cake. One side is flat copper, the other side is flanged slightly with a groove for the o-ring. No paste, no thread tape. Took 2 minutes to get the old off, 2 minutes to get the new on, and no leaks or anything. I took a fine file to both the flat copper sides and a brillo to clean them shiny again.

Water pressure tested at 45 PSI. I turned it up a little, to around 50 PSI. We'll leave it there and see how it goes for a couple weeks.

Oh - and last but not least, no whistle when the toilet fills!


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## danielrg (Aug 26, 2011)

MTN REMODEL LLC said:


> Ghost... Ya know what I can never remember... is which direction the screw goes for more/less pressure.... guess I don't adjust them that often or regularily....
> 
> Best


On my model (N55B), it was clockwise (CW) for more pressure
counterclockwise (CCW) for less pressure.


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## danielrg (Aug 26, 2011)

MTN REMODEL LLC said:


> Quote Dan "Yeah, that was my original post. Mine was whistling super loud when my toilet was filling. Eventually it turned into replacing it when I tested the pressure to see if it was bad. "
> 
> 
> Dan... yes, I guess I thought there was a question as to what was whistling.


I didn't do anything about the toilet, even though that was the advice on the first thing to try. I had other suspicions about the pressure because a while ago the manifold started leaking, and I had to really crank down the joint to get it to stop, and the joint by my water expansion tank was leaking a little too. Seemed like pressure gauge to double check was the easiest first step. The rest followed.


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## danielrg (Aug 26, 2011)

Thanks everyone for all your great help and advice. I hope this is a useful thread to searchers in the future. Particularly to know what replacements work with the N35B - I searched all over the internet and nothing said. I had to call the Watts rep. Now at least the compatibility is recorded here - if Google ever ventures to find it!


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## danielrg (Aug 26, 2011)

MTN REMODEL LLC said:


> Quote Dan "Yeah, that was my original post. Mine was whistling super loud when my toilet was filling. Eventually it turned into replacing it when I tested the pressure to see if it was bad. "
> 
> 
> Dan... yes, I guess I thought there was a question as to what was whistling.


Oh, I get it now. I never realized that nuance in ''jmon's" first post. I always read it as "pinpointing the _cause_ of whistling" - and I read it as that I guess because it was so clearly coming from the PRV. I knew the noise was the PRV, I could stand next to it and I'd have to plug my ears. Anywhere else in the house (including by the toilet or along other pipes) I could hear it coming from over by the PRV.

So I think not only was the _cause_ of the whistling the PRV, but the whistling itself was also _coming from_ the PRV.

When I think about it, I suppose it's also possible that the toilet valve's idiosyncrasies _coupled_ with the failing PRV also caused the noise too, but as to where it was coming from I had no question.

I'm glad you brought it up I really hadn't thought about it that way.


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## Ghostmaker (Mar 2, 2013)

The only reason I said 65 lbs pressure is that is the design pressure of most fixtures for optimum working order.


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## danielrg (Aug 26, 2011)

Ghostmaker said:


> The only reason I said 65 lbs pressure is that is the design pressure of most fixtures for optimum working order.


I did notice that the handle on our kitchen sink faucet, which lifts up, will "drift" downward at anything under about 55 and eventually turn off. Sounds like that might be related to the 65 PSI optimum pressure. We turned it up a little past 55 and it stopped drifting downward. Thanks for the tip.


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