Long one - Need the "hammer" and tank(less) experts please

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Haeffnkr

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Hello,
I have been searching for an hour now and still have a few questions.

I have a 4 year old Ranch house, I have over the last 2 months or so developed an increasing water hammer problem with mainly the toilets, but a mild hammer with the ice makers. I have made it better but it is not fixed.

I have 60' ranch, water comes in one end and my tankless heater is on the opposite end, vented out the wall, with a few bends to the main line.
There is a Pressure Reducing Valve on the line where the water comes in the house.
Pressure is at 59 pounds, tried to move the pressure down some and the hammer does not go away.
Pressure is at 52 pounds when the toilet runs, then when the toilet stops I can see guage go flucuate a little and then it rests on 59 again. It does not go over 59 when it spikes.
Pressure went to 56 when icemaker fills.

I have 3/4 main lines with 1/2 feeder lines to the fixtures. No arrestors or air chambers were installed with the house.
I have a aquastar tankless heater with a hot water return loop, loop has a 4 gallon electric heater and a pump in line, a CHECK valve is also on the leg of the loop so the loop water does not back feed into the main heater.
I have screwed all the lines tight to the rafters, nothing is loose.
I have tried to drain the system and all, this seems to help for a day, then it is back to normal.
The hammer stopped when I shut off the supply to the main water heater?
The hammer seems to be coming from the water heater...sometimes....but that might be a coinsidense and not the problem....

Last week, in a feable attempt to fix my problem, I put on 2 water arrestors on the hot and cold lines of the washing machine, since it was easy to screw on and 2 arrestors on the main water line, one on each end of the house, which was a mistake I guess. It helped the hammer some but it is not fixed.

I have NO expansion tanks on the system. I have seen the pressure up to 80, I assume that it could be caused by thermal expansion, on my closed system, as I just read about on this site, but I dont think this is the source of the hammer since I can recreate the hammer repeatedly when the pressure is at 59.

So...how do I fix this mess?

Does the Pressure Reducing valve seem to be working as expected, should the pressure stay constant regardless if a fixture is on? Can this valve cause hammering?
I assume I should add some arrestors closer to the toilets and maybe replace the tank fill valves with quiet ones?
I have since read about arrestors in more detail and the opinion is to put the arrestor as close to the problem valve as possible, is that the opinion of this board?
What about an expansion tank? I assume I need one, but for a tankless heater? Is it important to mount the tee on a Horizontal line and the have the tank above it? (my space is somewhat limited under the floor...) I assume this will help my hammering problem some also?

Sorry for all the questions.
thanks for all your help.
Kevin
e-mail - haeffkr at charter dot net
 

Peanut9199

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It could also be air in the pipes.
Does it bang when filling the toilet or bang after it shuts off.
Banging while filling air, banging when shuting off hammer.
The arrestor should be at source on hot and cold lines.
 

Haeffnkr

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Sorry forgot to mention it only hammers when filling and shutting off.

So the arrestors on the main line or probably not doing anything? or could they be helping some....at least the hammering quieted some after I put them on.

thanks Kevin
 

Master Plumber Mark

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try the expansion tank....

I have heard that some tankless
heaters can cause a water hammer in the system.
i dont think that the aquastar is a hig hend unit...


either way..

what you ought to try is install a thermal exp tank
somewhere up stream of the tankless heater and see what
that accomplishes...





perhaps you ought to crank down that prv valve
to 60 psi and see what hapens....



if that dont work, just dont turn off your
faucest so quickly...
 

Haeffnkr

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OK I can try to put in an expansion tank.
Does it need to be mounted above the main line, upside down so to speak?

The pressure is at 59 now, so I can not go down to 60?

Any other ideas?
 

Jadnashua

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An expansion tank is ideally installed on the cold inlet to the water heater. With a tankless, that normally isn't a problem, but even with that small 4-gallon tank you do have, once water is heated, since the pipes don't like to expand much, the pressure rises - probably stressing the hoses in the house (not good).

It doesn't really matter which way is up, but when it fails, it will fill with water, so it is less messy if you have it hanging (and well supported) rather than sitting upside down so when you do unscrew it, it dumps all of the water all over.

If you check out www.watts.com or one of the other manufacturers of these things, you can review their installation and sizing info. Some toilet fill valves can make some weird noises...
 

gerhard

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tankless and expansion tank

I have a tankless (Takagi) with an indirect radiant heating system, in which a circulation pump takes water off of the HW heater, pumps it through a heat exchanger, and back to the hot water heater. The designer of the system speced an expansion tank before the pump, but after the hot wter heater in the line. He was quite clear that I could expect hammer if I didn't put this in; your return loop may be a potential cause of your problem, and I think you do need the expansion tank.
 

King3244

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I had the same problem and it turned out to be a faulty prv. I still don't believe it but it stopped the water hammer. I also have a tank less water heater and never had a water hammer until I switched over to tank less.
 

Haeffnkr

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thanks for all the replies, really appreciate it.

I will research some expansion tanks and see about getting them installed.
I have also looked at the Korky fill valves, will try to get some of those going.
I have FluidMasters in my 3 toilets now.

What about my PRV?
Is it normal that the pressure drops while water is running?
How can I tell if this valve is good (without a shotgun approach and replacing it....)?

I dont see how the HW heater/loop can cause this problem, but apparently it is or is adding to it, since I proved it...but why?

thanks Kevin
 

Jadnashua

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You may have adequate pressure, but your volume may not be able to keep up, thus the drop in pressure when something is running. This is especially likely if you have galvanized supply lines. These pipes rust from the inside, and gradually, they can close off the pipe. In the meantime, the static pressure will be fine until you try to get any flow out of them. Think trying to put out a fire with a straw - you can have great pressure, but the flow is lousy.
 

Haeffnkr

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I have all new construction in my new subdivision.
I have 3/4 copper going through the wall and either plastic or copper going to the meter, I forgot which, but I saw it go in, no galvanized. The meter is only about 25 ' from the wall.
I have about 100 pounds last time I checked the meter pressure.

Anyway.........
I replaced the PRV today. It is a watts model, exact swap out from my existing Watts PRV. This model stated it had a built in thermal regulator and would not let the pressure build up over 10 pounds of the set pressure. All I know is that it apprears to work and is quieter than the original.
I also added 2 expansion tanks a Watts 5 and 12, the 12 went on the cold side shortly before the tankless heater and the 5 went on the other side of the tankless water heater and before the loop pump, as gerhard stated.

When I put the new PRV valve in it stated it was set at 50 from the factory, but my gauge read 40, so I dont know which is right, anyway cranked it up to 60 per my gauge and it all seem to be working well.
Basically NO Hammer, I can hear just a very slight THUD if I listen for it.
Time will tell in a day or two once all the air pockets are out but I would call it a success so far, lots quieter than it was.
I can stand next to the PRV and watch the gauge when the toilet shuts off. The gauge does not bounce/spike like it did before the changes. So something I changed is buffering the system I guess. The new PRV is a lot quieter too. The gauge/PRV does not drop 8-10 psi when the toilet is running with the new valve, only about 4 with the new setup.
So I guess the expansion tanks and the PRV was needed?

I am still going to swap out some of the toilet fill valves with the Korky ones, but ********* did not have them, I will have to try Lowes.
They did have this new QuietFill valve by FluidMaster, anyone tried it?
It said it was quieter and stopped hammer.

thanks for all the help so far.
Kevin
 
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