Noisy hot water mixing valve

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Noisy hot water mixing valve

Postposted on Tue Aug 14, 2012 7:06 am

Do we have any plumbing types on TR?

On top of my gas water heater I have a Watts 1170-C thermostatic mixing valve to moderate the hot water temperature down. Unfortunately every time a tap is shut off it makes a "chunk-chink" sound - I suspect it is the mixing piston being driven across by the pressure spike. My water pressure isn't excessive, measured with a cheap gauge from Home Depot at about 75psi, and I've put water hammer arrestors on the washing machine outlets (the worst offender) but everything still causes it to make the noise. I know it is the valve and not just loose pipes because I listened to it carefully whilst my wife turned a tap on and off and also if I shut off the cold supply to the tank and mixing valve then it stops happening.

Is this just the valve going bad and I need to replace it? Or is this to be expected on this valve type? Worth trying a different manufacturer? Am I missing some pressure handling stuff in my plumbing setup to reduce the spikes or balance it across the hot and cold lines feeding in to the valve?
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Re: Noisy hot water mixing valve

Postposted on Wed Aug 15, 2012 6:55 am

I would try over here:
http://www.dslreports.com/forum/homerepair

There seem to be some geeky electricians and plumbers who frequent the forum...
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Re: Noisy hot water mixing valve

Postposted on Wed Aug 15, 2012 8:16 am

notfred wrote: water hammer arrestors


Sorry to thread jack but I never knew this was even such a thing. So my washing machine experiences this hammer/jolt when the hot water is turned on and off or goes from hot to cold. The question I have is where does this device sit? Does it sit between the valve outlet and the hose or do you have to weld it on the pipe itself?
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Re: Noisy hot water mixing valve

Postposted on Wed Aug 15, 2012 9:09 am

http://www.homehardware.ca/en/rec/index ... r+arrestor

Screw this on to the washing machine pipes at the wall, then connect the washing machine hoses to the outlet of this. There are other types that you put on the plumbing as you build the house, see the related products on the above page.
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Re: Noisy hot water mixing valve

Postposted on Wed Aug 15, 2012 9:18 am

why do u need a hot water temp regulator coming off the water heater? why not just turn down the thermostat on the water heater itself?
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Re: Noisy hot water mixing valve

Postposted on Wed Aug 15, 2012 9:25 am

XorCist wrote:why do u need a hot water temp regulator coming off the water heater? why not just turn down the thermostat on the water heater itself?

Many local plumbing codes call for the heater to be kept above 140F to kill off any nasties that might be in the water. Since 140+ is unsafe at the tap, the code also requires a mixing valve to reduce the output to 120F or lower.

I installed my own water heater so I never bothered with the mixing valve.
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Re: Noisy hot water mixing valve

Postposted on Wed Aug 15, 2012 9:29 am

You can make your own "Water hammer" effect remover by simply placing a 'T' somewhere along the pipe that sits upwards with a cap on the end that can hold air, and even better if you can inject air as needed. Commercial ones contain a bladder to prevent the air from dissolving away for low maintenance. The air acts as a shock-absorber. The closer to the "load", the better it will work at eliminating the vibrations.
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Re: Noisy hot water mixing valve

Postposted on Wed Aug 15, 2012 9:37 am

Captain Ned wrote:
XorCist wrote:why do u need a hot water temp regulator coming off the water heater? why not just turn down the thermostat on the water heater itself?

Many local plumbing codes call for the heater to be kept above 140F to kill off any nasties that might be in the water. Since 140+ is unsafe at the tap, the code also requires a mixing valve to reduce the output to 120F or lower.

I installed my own water heater so I never bothered with the mixing valve.


ahh the joys of living in california...good luck getting a water heater to go over 140..LOL so many failsafes its stupid...never knew of a code like that...knowledge is power...

anywho i was doing some googling and found this http://www.plumbersurplus.com/pdf/01741.pdf down on the second page has this
Valve is noisy • Water velocity is too high• Reduce water velocity with pressure regulating valves

so i'd assume ur running 3/4" to it, you could try http://www.homedepot.com/webapp/wcs/sto ... CvBUJZFk6I it outputs at 50psi, so that should help you.
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Re: Noisy hot water mixing valve

Postposted on Wed Aug 15, 2012 10:44 am

notfred:

Put an expansion tank on the cold water supply line. Should fix your problems right quick. An expansion tank will also solve any problems with a weepy/drippy T&P relief valve.
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Re: Noisy hot water mixing valve

Postposted on Wed Aug 15, 2012 11:44 am

liquidsquid - Without a way to inject air e.g. by draining down the system, all the air will be gone in a year or so. The ones I linked to are the commercial variety.

XorCist - The valve noise they are talking about in the PDF is flow noise, usually a whistling noise. I'm getting noise with no flow through the valve. I was looking at just that pressure regulator when I thought my pressure was excessive and the noise was plain water hammer, but 80psi is right on the upper end of the normal range from my reading, so I'm not sure a pressure reducing valve will help.

Captain Ned - I don't have any backflow prevention on the cold water feed that I am aware of so no drips out of the T&P valve. I suppose the expansion tank would just act like a giant water hammer arrestor, sounds like a good idea - thanks!
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Re: Noisy hot water mixing valve

Postposted on Wed Aug 15, 2012 12:16 pm

Captain Ned wrote:
XorCist wrote:why do u need a hot water temp regulator coming off the water heater? why not just turn down the thermostat on the water heater itself?

Many local plumbing codes call for the heater to be kept above 140F to kill off any nasties that might be in the water. Since 140+ is unsafe at the tap, the code also requires a mixing valve to reduce the output to 120F or lower.

I installed my own water heater so I never bothered with the mixing valve.

As a nice bonus, the hot water supply lasts longer because the effective tank volume is the actual volume multiplied by the average mixing ratio. Also, this is the only correct way to set up a water heater when it it is supplying a recirculating heating system in a small apartment or cabin. I once lived in some school-owned apartment housing that used such systems with water heaters that did not use mixing valves and could not be turned above 120-125F without tripping the TPR. That housing was less than 10 years old at the time, too. I think the architectural engineer should have been forced to spend a winter there as punishment.
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Re: Noisy hot water mixing valve

Postposted on Wed Aug 15, 2012 12:46 pm

As someone else said an expansion tank is usually recommended on the cold side of a hot water tank. A mixing valve like you said is to regulate temperature. Code here in Canada is no hotter than 49C. I would adjust your tank so that your hot water temp is 49C or lower and remove the mixing valve(reducing temp will save some energy costs also)

GSW and john woods (same products) will have some info on piping schematics for HWT's
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Re: Noisy hot water mixing valve

Postposted on Wed Aug 15, 2012 12:53 pm

As ludi said a mixing valve virtually increases the tank volume, and it also gives most of the energy savings that a lower tank temperature would. It really is the best of all worlds apart from this clunk-chunk noise it makes if a tap is shut too quickly. I'm going to look in to the expansion tank idea.
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Re: Noisy hot water mixing valve

Postposted on Wed Aug 15, 2012 1:21 pm

notfred wrote:As ludi said a mixing valve virtually increases the tank volume, and it also gives most of the energy savings that a lower tank temperature would.

That's why I love my indirect HW heater. Put it in to replace a direct-fired coil in the boiler which, while always hot, could produce about 2 gal/min of hot water. Now I've got a big 50 gallon tank that gets its heat from a loop run off the boiler (essentially a third zone in my HW heating system). Haven't run out of hot water since.
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