Water Hammer After Powers MM430 Instal

BigRob

Hello, I installed a MM430 to temper the water stored in a Triangle Tube Smart 80 gallon tank. The previous tank and tempering valve did not have any noticeable noise. I don't have a sense of the magnitude of the water hammer, but it's not opening any emergency pressure release valves, at least. The expansion tank on the cold input is pressurized correctly. Then the cold splits and feeds two check valves. Check1 for the tank and Check2 for the input to the MM430. The MM430 has the "checkstops" too, in addition to Check1 and Check2. My impression was that the checkstops are just isolation valves. Although, it seems they might be check valves, too. I can't tell from the documentation. The water hammer sound is a "ping" type sound. It's unclear if the sound is water hammer or the MM430 valve body slamming around, if that is a possibility. I'm pretty sure the water hammer wasn't a problem before, so I don't think there is anything special about our fixtures. The building is a 12 unit condo building with toilets and washing machines, although like I said, I would have heard something if it was there. I spent a lot of time tuning the system. Any help is greatly appreciated. I think I'm making a fundamental mistake. For what it's worth, the water hammer seems like it's more pronounced on the cold side piping.

hot_rod

most mixers

are available with or without the check tailpieces. Sounds like you may have redundant checks? You may be able to remover the checks in the new valve.



Check the building pressure. might need to add a water hammer arrestor at the valve.

BigRob

Building Pressure & Expansion Tank

Thanks for the feedback, hot rod.  I checked the pressure and it's at 45psi.  I did some more exploring and I noticed the expansion tank is a light in terms of weight.  The expansion tank is upside down (nipple down) and elevated over the DHW tank.  The pipe to the expansion tank is about 4 feet long and there is no way to vent the air from the pipe.  Does anyone know if this setup could cause or contribute to the water hammer I am experiencing? 

JUGHNE

Expansion tank

I have seen a case where the exp tank was isolated from what it was supposed to "sense/feel" by a check valve installed in the wrong place.  Is the tank for the hot expansion of the heated water or for cold water "air cushion"?

BigRob

Expansion Tank

Great comment, Jugne.  The expansion tank I believe is for the DHW tank expansion.  It must be because there is not a second tank for that.  From my memory, the expansion tank connection is followed by a check valve, then followed by the cold water inlet of the DHW tank.  So, it seems the expansion tank is behind a check valve. 



During experimentation, I closed the expansion tank isolation valve and did notice a rise in the DHW pressure to about 50psi as the boiler fired, which was abnormal.  Usually, the pressue gauge on the outlet of the MM430 is around 45psi unless there is a ping, then it dances around a little.  There hasn't been any emergency pressure valve opening or anything like that, so maybe the pressure is leaking back through the closed ball check valves to the expansion tank and causing the "pinging" sounds.  I did notice the vibration/shock during the pinging sounds seemed stronger on the cold water supply side, for what that is worth.



What are your thoughts?

hot_rod

good point

the tank connection needs to be downstream of the checks. The tank should act as a hammer arrestor to some degree.



I don't think tank mounting position is critical, best to check their website.

BigRob

Update

So, I checked the piping of the expansion tank and it's connected between the cold water input check valve and DHW tank, so this seems to be ok.  My memory is not what it used to be, that and there was a little optimism rolled in. 



I experimented with the system a bit last night.  There are hose fittings at various locations:



1. on the expansion tank pipe T near the DHW cold inlet

2. on the recirculation return port on the DHW tank

3. on the DHW hot output/MM430 hot input



I hooked up a hose to all three hose fittings and opened the valves quickly, slowly, etc.  I was able to create a "hammer" situation at all three locations.  Even when I closed the valve at a rate I would consider slow, the water hammer would occur.  It seems like I just need a water hammer damper?  What is messing with me is I'm sure the previous mix valve/tank did not have this problem.  It almost seems like the valve actuator in the MM430 is slamming around like there isn't enough preload on a spring or something - pure speculation here.  I've attached some photos.  Hopefully somebody can spot something fundamentally wrong.  Thanks for all your comments.

hot_rod

is that a recirc pump

on the DHW? Try the same procedure with that unplugged.

BigRob

Yes, it is

Yes, it is.  I'll try it with the pump unplugged and report back.

BigRob

Results

I tried unplugging the DHW recirculation pump and there was no effect. I was able to narrow down the most probable location of the noise during the water hammer. It seem to be coming from where the building supply supplies the check valves for the MM430 and DHW indirect tank. The supply flows to a T, then to the two check valves. It seems like the water slams into the T. Also, upstream from the T is another check valve. The upstream check valve is a swing type, so I'm going to remove internal valve and see what happens. I'm going to also install some hammer arrestors on a could drain nipples and see if that does anything.

Mark Eatherton

Can you isolate the expansion tank?

I have had situations whereby the expansion tank could create a hammer condition because of its location in relation to the check valves, and it only happened when a valve was closing. If you close the valve slowly, no problem. If you manually close a valve quickly, it will hammer. If you have a fast acting solenoid valve, like a dishwasher, it HAMMERS really hard.



What is your normal water pressure, and what is the tank aired up to?



I agree with the others, the less checks, the better. Maybe ONE where the cold comes in, but get rid of the others at the mixer. They are not really necessary.



ME

Steamfitter66

Its not piped correctly.

Go here...http://media.wattswater.com/S-P-MM-Hilo.pdf

And I think your expansion tank and spring checks are the cause. you only need 1 check but it needs to be piped according to the instructions depending on continuous or controlled recirc.

BigRob

Update

Thanks for all your input. I was able to remove the two checks from the MM430 check-stops, although I wasn't able to remove the two ball check valves and the single swing check before the ball checks. Removing the poppets from the checkstops had no effect. I was hoping to remove the swing valve from the swing check, but I couldn't finagle the pin out.



While I had the checkstops open, I cleaned the strainers and there was some good all on them. It looked like orange algae or like solder flux. Is that possible? I should have taken a picture. I was really surprised to see it there. I would expect water flow and heat to clean it off. I cleaned it and there was no effect on the water hammer situation. Has anyone seen something like this before?



I can recreate the water hammer by rapidly cycling sink fixtures in some locations, so I will just try a water hammer arrestor. It's just really odd there is now water hammer when there wasn't before. I will just have to accept it and try an arrester.

BigRob

Thanks

Hi, thanks for the link. I don't see a difference between any of the diagrams except for the aquastat. What am I missing?

Weezbo

Air in a swing check ,...

might be giving you the "ping" ,

did you loosen the swing enough to let out some water > @ the retainer < for the flapper ?

that might help .

Oh do not just let water out of it once tap it with a rubber mallet and give it another go .. maybe two ..



William.



i have one other thought how good it is me no savey , buh ,..

gate off the line to the expansion tank ,

then drain the line , hook up a purge pump and add like 60 psi water pressure to the tank line ,

,

maybe loosen the bonnet so it weeps some water ,

close the purge and slowly open the ball valve with some sink or something open on the hot water ...



i think it is air hung up someplace in the fittings ..

BigRob

I removed the..

pin cap and water was coming out, so I suspect there is no air in the swing check. Thanks for the suggestion. I bought a NPT hammer arrester and will try it on one of the fill nipples near the mixer outlet when it arrives next week.

BigRob

Guys

What size expansion tank would you use for my setup? The water tank is 80 gallons and the boiler is a Lochinvar KB286. There is a hot water recirculation loop that has 4 branches and an estimated total length of 300ft, at lets say an average pipe diameter of 1 inch.

BigRob

Air

The mixing valve is literally the top of the entire hot water system (boiler room on the roof), so now I'm wondering if air is collecting right above the mixing valve and if that would have any strange effects.

Weezbo

i saw that too.

and the drag is finding a jet vent that size....

BigRob

Mixing Valve Noise w/Video & Audio

Here is a video montage of the noise the mixing valve makes. It's almost like the valve is slamming shut repeatedly:



http://youtu.be/O_mjz_9pARw

RobG

Low Flow Bypass?

Rob, did it work before? You may need a low flow bypass to handle the smaller loads untill the larger tempering valve needs to kick in.



Rob

BigRob

Thanks

Hi Rob, the mixer you see now was a replacement for an older unit that never had any noise or water hammer problems. The valve you see here has always made those noises. What I call the "water hammer" seems to be contained to the valve and cold supply.



The mixing operation is working fine, it's just the banging/water hammer that is the issue.

Eric_32

deleted

BigRob

Update

Hello all, I called the factory and they told me where the model number was located. It was on top of the valve and it was hard to see with the valve mounted so high. The tempering valve is a LHMM434-1 and Powers recommends the LHMM431-1.



I came up with 113 fixture units for our building. 7 units have 2 full baths with tubs w/overhead showers. Five units have 2.5 baths with tubs w/overhead showers. All 12 units have dishwashers and laundry. 113 fixtures units is around 33-38gpm based on some stuff I found online. Using the powers web tool with the apartment/multifamily option and adding 12 laundry units I get 29gpm.



Powers says when a valve is oversized the actuator can go bad in about 6 months to a year. It seems that is the case.



I'm considering putting two Honeywell AMX102-UT-1LF's in parallel. Thoughts? Should I reverse return them or stage them?

SWEI

When a valve is oversized the actuator can go bad in about 6 months to a year

Really?  I guess we better not specify them for summer camps...

BigRob

Gravity

Ok, I did not take into account gravity during my above calculations, although I am a little unsure about how a recirculation line come into play. The tempering valve is on the third floor roof and the pressure at the valve is 45psig. The residences are on levels 3, 2, and 1.



So, I think I need to add pressure.



+5psi x 2 for two floors = 55psi



-2psi for 100ft of horizontal friction = 53psi



I'm a little confused about what to do next. A Powers presentation subtracts 20psi as the minimum design pressure, although in their example, the residences are above the valve.



At 53psi the MM434 would put out ~150gpm

At 63psi, ~169gpm

At 33psi, ~118gpm



How do I handle this?

BigRob

OK

I think I need to subtract the 20psi for the min design pressure at the "last fixture."



I'm still not sure how a recirculation line comes into play.