AIr being sucked in from shower

[Confused-1]

Hello all. This is a issue I'm having in a single story house. The water pipes recently started knocking and after searching around, I found this going on. I don't use this shower so I never noticed it earlier but after turning off the valve, air starts getting sucked in for a few seconds then stops. I replaced this valve several years ago so I don't know if it's related somehow. After first turning it on, it burbs out a little bit of air. The water pressure seems a little low in this shower as if there's some kind of restriction somewhere. The issue only seems to be in this shower. Any info on what's going on would be appreciated!


Here is the video of it. Sorry about the formatting.

 

[Plumber69]

So when you divert it to shower it start sucking air back?? or even when run tub it sucks air back? is it on top floor?. Are you on some sort if pressure pump system

 

[Sponsor]

 

[Plumber69]

So when you divert it to shower it start sucking air back?? or even when run tub it sucks air back? is it on top floor?. Are you on some sort if pressure pump system

I've never seen this before. Would really like to know wtf is going on

 

[LLigetfa]

There is a siphon created due to the hand shower being lower than the tub spout. It has nothing to do with pipes knocking.

 

[Confused-1]

So when you divert it to shower it start sucking air back?? or even when run tub it sucks air back? is it on top floor?. Are you on some sort if pressure pump system

It's a single story house. When I divert it to the shower, it runs with low pressure. There is no suction at the tub spout until I turn the shower off as LL described. If I run the tub only, it does not do it. This is on city water with no pumps.

There is a siphon created due to the hand shower being lower than the tub spout. It has nothing to do with pipes knocking.

Yes, you're right. I tested it with the hand above the tub spout and it didn't suck air back in. Would installing an air arrestor at the hot water tank help with the knocking issue? Or is that just a bandaid to something more serious going on? The knocking isn't consistent but anytime it does happen, it sounds like its close to where that bathroom is. The hot water tank is on the other side of the wall about 10' away or so.

 

[Bannerman]

The tub spout suction issue was as explained by LL.

It sounds as though there is normal flow to the tub spout, but reduced flow to the handheld shower head. In a process of elimination, remove the shower hose from the upper shower arm and test the flow rate from the shower arm itself. If the flow rate from the shower arm returns to normal, the flow restriction will be either in the shower hose or the handheld part.

Reinstall the hose only with the handheld part removed and retest the flow through the hose alone.

I suspect there is a flow restrictor washer within the handheld part that maybe too restrictive. You could either remove the restrictor, replace it with a less restrictive washer, or enlarge the hole through the current restrictor using a drill bit.

Since the water hammer issue recently started, what in the house has changed? New washing machine, new dishwasher, new faucet etc? Water hammer is often a result of a sudden stoppage of flow. A washing machine and DW use solenoid operated valves to control water flow so they are either Off or On and so do not turn off flow gradually.

Another reason for water hammer is too much pressure. Has your water pressure recently changed? Is there a pressure regulator installed that maybe malfunctioning?

Are there loose pipes that may be moving and hitting floor joists or other components when water is turned on or shut off?

Are there any water hammer arrestors installed anywhere? Often, site made arrestors were installed which consisted of a length of vertical pipe which was capped at the top to trap air to act as a cushion when water from below would compress the air. Over time, that air will dissipate into the water, leaving no air remaining to act as a cushion. Periodically shutting off the main water valve and opening faucets throughout the home will allow water in the pipes to drain so air can reenter those arresters. The arrestors now sold commercially are equipped with a piston or diaphragm to separate air from water, eliminating the need to periodically replace the air.

 

[LLigetfa]

Hammer arrestors are most efficient if installed at the end of a line on whatever line is creating the water hammer. You need to track down the source of the water hammer. It can be caused by fast closing solenoid valves such as on washing machines or ice makers but it can also be caused by a loose washer in a valve. Having very high pressure on city water and/or a bad or no expansion tank is something to look for. If you have a closed system and no expansion tank, there is a good place to start. The expansion tank installed on the cold feed to the water heater, while not intended as a hammer arrestor, does help absorb water hammer.

 

[Jeff H Young]

the sucking air isnt really a problem as someone pointed out . do you need help with a water hammer ? cant see where you brought that up. if so describe in detail. I never put hammer arrestors on unless Im fixing a problem or inspector makes me Its code on ice makers and dish washer, washing machine. a well pumbed and strapped house usually dont have a hammer. And the times Ive been on call for a real bad water hammer the arrestor never fixed it in fact it made another noise that could be heard just not as loud. but its a real hassel when a new house has it and we gotta fix it because the cost is on the plumber.

 

[Confused-1]

Wow thanks for all the info guys! I'll need to read through it all once I get home and will respond back with any additional info