Watts Recirculation Pump and Water Hammer issue

[lowlight21]

I'd recommend that you recheck all incoming and outgoing lines from the sensor valve. Also check to confirm that your valves to the faucet are fully opened.

Thanks. I did check all that last night, and realized that if I closed the cold faucet valve 60-70% that the water hammer stopped, and also quickly realized this morning that a mostly closed cold valve won’t allow water to recirculate.

 

[lowlight21]

Thanks. I did check all that last night, and realized that if I closed the cold faucet valve 60-70% that the water hammer stopped, and also quickly realized this morning that a mostly closed cold valve won’t allow water to recirculate.

Also, as a clarification to my first post, I’m getting water hammer at the sensor valve when any other faucet/valve is opened in my house. If I turn off the valves to the sensor valve, it removes the sensor valve from the system and I no longer have any water hammer (but don’t have a functioning recirc loop).

 

[Twowaxhack]

There are check valves in the bypass valves that are bouncing when water stops abruptly. You could try water hammer arrestors as close to each faucet or appliance causing the hammer or reduce the flow of water to the fixtures/appliance or simply turn the fixture off slowly.

Is it possible you have a bad bypass valve ? Sure.

 

[lowlight21]

There are check valves in the bypass valves that are bouncing when water stops abruptly. You could try water hammer arrestors as close to each faucet or appliance causing the hammer or reduce the flow of water to the fixtures/appliance or simply turn the fixture off slowly.

Is it possible you have a bad bypass valve ? Sure.

Thanks. I have been trying to tell if the hammering is coming from inside the sensor valve or from the copper line supplying water to the faucet. In the meantime, I think I'll try some arrestors to see if that makes any difference.

 

[Drip]

Also, as a clarification to my first post, I’m getting water hammer at the sensor valve when any other faucet/valve is opened in my house. If I turn off the valves to the sensor valve, it removes the sensor valve from the system and I no longer have any water hammer (but don’t have a functioning recirc loop).

I just got a new Doohickie (sensor valve) to try. It will be interesting to see if this solves the problem. I'll post what I find. Before it arrived, I tried swapping the arrestors to see if one of them might be defective. I moved the cold to hot and vice versa. It didn't make a difference.

Lowlight21, there is a small check valve that is built into the cold side of the sensor valve. Watts recommends removing this if you are experiencing a water hammer problem. Here is what it looks like:

 

[lowlight21]

I just got a new Doohickie (sensor valve) to try. It will be interesting to see if this solves the problem. I'll post what I find. Before it arrived, I tried swapping the arrestors to see if one of them might be defective. I moved the cold to hot and vice versa. It didn't make a difference.

Lowlight21, there is a small check valve that is built into the cold side of the sensor valve. Watts recommends removing this if you are experiencing a water hammer problem. Here is what it looks like:

View attachment 45347View attachment 45349View attachment 45350

I will absolutely try this. Did you have any luck with this recommendation from Watts?

 

[Drip]

Unfortunately, it didn't make a difference for me. However, your hammer is different than mine. I get it when shutting off the hot water at the kitchen sink and only when the pump is running. Yours is basically the exact opposite. The fact that isolating the sensor valve in your case removes the hammer makes me think there is a good chance removing the check valve will work.

A few days ago, a plumber was working at my neighbors house. I ran this problem by him. The fact that I hear the hammer in an area far from the sink in question and the water heater made him think it might be happening at a manifold somewhere in a distant wall. Not sure what to make of that.

My plan going forward is to install the new Doohickie with the check valve in place and see what happens. If the problem is still there, I will remove the check valve and see what happens. I'll report back when it's done.

 

[lowlight21]

Unfortunately, it didn't make a difference for me. However, your hammer is different than mine. I get it when shutting off the hot water at the kitchen sink and only when the pump is running. Yours is basically the exact opposite. The fact that isolating the sensor valve in your case removes the hammer makes me think there is a good chance removing the check valve will work.

A few days ago, a plumber was working at my neighbors house. I ran this problem by him. The fact that I hear the hammer in an area far from the sink in question and the water heater made him think it might be happening at a manifold somewhere in a distant wall. Not sure what to make of that.

My plan going forward is to install the new Doohickie with the check valve in place and see what happens. If the problem is still there, I will remove the check valve and see what happens. I'll report back when it's done.

Thanks for the detailed update. I will try removing this check valve tonight and report back. Do both of those small plastic pieces (as shown in your photo) come out for this recommendation?

 

[lowlight21]

Thanks for the detailed update. I will try removing this check valve tonight and report back. Do both of those small plastic pieces (as shown in your photo) come out for this recommendation?

Okay, I just removed this check valve per @Drip recommendation. This seems to have resolved my water hammer issue completely, which I hope to confirm over the next 12-24 hours with scheduled use of the recirculating pump. Great stuff. Thanks for passing on this recommendation from Watts. The next obvious question - what purpose exactly does that check valve serve if it can just be removed??

 

[GReynolds929]

With the check valve removed you now have an opportunity for crossover to occur which will mess with water temperatures.

 

[lowlight21]

With the check valve removed you now have an opportunity for crossover to occur which will mess with water temperatures.

Okay, so the check valve prevents cold water from traveling to the hot side of the valve? Trying to deduce if the crossover would challenge water temperatures only on the faucet where the sensor valve is installed, or the whole plumbing loop.

 

[GReynolds929]

Correct. It could be isolated to just the one fixture, or it can affect the whole system.

 

[Drip]

Here is the blurb from the PremierH2O (Watts) website:



I have had this mini check valve removed for quite some time and it hasn't really affected temperatures at all. The recirc pump works as expected, minus the hammer problem.

However, I never noticed the bit about "system pressure over 60 psi". I just glossed over that part. Mine hovers around 70 psi which most say is normal. I wonder if lowering the pressure at my regulator might help.

 

[lowlight21]

Here is the blurb from the PremierH2O (Watts) website:

View attachment 45351

I have had this mini check valve removed for quite some time and it hasn't really affected temperatures at all. The recirc pump works as expected, minus the hammer problem.

However, I never noticed the bit about "system pressure over 60 psi". I just glossed over that part. Mine hovers around 70 psi which most say is normal. I wonder if lowering the pressure at my regulator might help.

I found that too, and it would seem weird to me for the manufacturer to suggest a resolution that could impact overall household water temperatures. I'm also wondering if an external check valve installed near the sensor valve could address any risk of crossover (and hopefully not reintroduce water hammer).

 

[MrInfoPhilly]

Better off running a hot water return line if possible back to the water heaters. Essentially the pump is trying to force water to go the direction it does not naturally want to flow.

 

[lowlight21]

Better off running a hot water return line if possible back to the water heaters. Essentially the pump is trying to force water to go the direction it does not naturally want to flow.

I would love to but it's all existing build and plumbing and there's no viable way for me to run a dedicated return line without opening up lots of walls and floors.

 

[GReynolds929]

If the recirculation pump is set to run constantly it most likely won't be a problem, but if the pump is off then when a faucet is opened water from the unused side can migrate over to the side with less pressure.

 

[Drip]

I finally installed the new sensor valve (Doohickie) and much to my dismay, it made no difference at all. I tried it with and without the small check valve in place. I also tried repositioning the water hammer arrestors before and after the doohickie and the problem remains. I don't think the actual problem is that a pipe is loose because this only happens when the recirc pump is on. If I never used the pump again, the hammering would disappear forever. Even if I could do the nearly impossible task of locating where the sound is originating from and managed to really secure that pipe, would I actually solve the problem? It seems like the hammer condition would still be present and eventually the pipe would work its way loose again or crack or worse.

I honestly don't understand why the water hammer arrestors aren't having any effect on the problem. This makes no sense. I am using small arrestors for compression fittings under the sink. Could it be that these are too small and aren't capable of absorbing the shock in this situation? Would it be a good idea to move them? Where? Should I try to rig one up at the recirc pump with 3/4" fittings? I don't think anyone makes a T style arrestor for 3/4" pipes.

I came across a blurb on a plumber's website today which said the following:
"A phenomenon called water hammer, which creates a hammering sound when the vertical riser connected to a faucet fails to work as designed".

As far as I can tell a riser is a pipe that takes water from on floor to another. In my case the faucet is on an island in the kitchen and I really don't know where the pipes go from downstairs to upstairs. Since the hammer sound appears to be coming from somewhere distant from the kitchen sink, it may have something to do with this riser, but I have no idea what could be going on there to cause a problem. How do risers fail and cause a water hammer? Might this have something to do with venting? Yes, I'm grasping at straws here.

Thanks for reading. I'm open to any and all ideas and suggestions. Thanks

 

[havasu]

Have you drained down your system, allowing water to exit and air to enter the arrestors? I had water hammer once and draining down my water line, then purging the air out of the water heater did the trick. I also used this time to flush out the water heater.

 

[Drip]

How thoroughly should the system be drained? All water completely removed from the whole house or just the circuit in question? I have emptied the water heater once since I installed the arrestors. This is when I checked the anode rod and removed scale from the bottom of the heater. I don't know if this would be considered draining down the system. Can you tell me exactly what you recommend?