Shower & Irrigation - strange thing

[NikkiPlace]

Dear forum,

I have this strange situation, that has been confusing two plumbers that I was consulting. I hope you can help with advice!

When I start my irrigation system, my master-bedroom shower will make a terrible grinding noise, followed by some water leaking from the shower head (see/hear in the attached video). This will last a few seconds, then fade. Except for that effect, both the shower and the irrigation system seem to work without problem.

More information:

• House water pressure is around 100 PSI.
• The shower is on the upper floor (split-level house). The house has other showers (including on the same floor and in the basement), but the aforementioned effect takes place ONLY in that one specific MBR shower.
• That shower was sometimes leaking (without noise) when toilets were flushed in the house. Plumber was called and replaced the Kohler K-GP876851 Rite-Temp Valve, and it fixed the problem with the flushing. However, a few months later when I started the irrigation system, the problem I mentioned started.
• The plumber said the new problem has nothing to do with the part that he replaced (which I find weird), and suggested it’s because of the high water pressure. He suggested installing a pressure reducer after the meter, taking the water pressure down to around 85 PSI.
• The irrigation system is automated, and has a solenoid master-valve located just below ground level. Its water supply is ¾”, right next to my water meter in the basement, approx 6 ft below ground. It has a Febco 765 Backflow Preventer before the master-valve.
• I called a second plumber who saw the leak/sound effect, said he never saw anything like that and hence preferred not to deal with it.

My questions:

• First and foremost, can I operate the irrigation system safely, or does that sound/leak indicate something bad is going on? (if so what am I risking?)
• What do you think is the root cause of the issue, and then what should be the fix?

I’m completely confused about it and have no idea how to go about it.
Thank you for any advice or direction!
Nikki

 

[Twowaxhack]

Lower your pressure to 80 psi.

 

[Rossando]

Sounds like pressure issues is causing this. First lower pressure then its possible that this shower cartridge is worn and might have to be replaced if the leaking continues. Noise should fade when PRV is installed. Also make sure you have an expansion tank

 

[havasu]

My automated sprinkler valves have warnings that say they MUST me installed above ground level, or their backflow valves will fail. Just something to consider.

 

[NikkiPlace]

Thanks for the replies, @Twowaxhack and @Rossando !
1. Seems like lowering the pressure would be a good idea anyways. The water meter is in the wall in a finished basement (see pic), so installing a PRV + expansion tank will require extra work. So before going into that bigger project I wanted to check if there's something else that could be the reason.
Related question - can the expansion tank be installed someplace else in the house, keeping only the PRV next to the meter?

2. I contacted Kohler with the same question, and they sent me a replacement mixer cap and pressure balancing cartridge kit (GP876851). Is it worth installing that first?

 

[NikkiPlace]

My automated sprinkler valves have warnings that say they MUST me installed above ground level, or their backflow valves will fail. Just something to consider.

Thanks @havasu , I do have a Backflow Preventer, Febco 765, which is installed above ground. Installation was done by a professional irrigation company, I hope they did it right...

 

[Paul Capozzoli]

Thanks @havasu , I do have a Backflow Preventer, Febco 765, which is installed above ground. Installation was done by a professional irrigation company, I hope they did it right...

Should be 12" about highest head per code. My first guess if the presssure is a bit too high as others have mentioned.

 

[Geofd]

the above poster is correct , but you can use something like a watts 909or 009 I always I install a check valve within a foot of the backflow device on the house side, this device can be installed above ground or below your highest heads

 

[NikkiPlace]

@havasu , @Paul Capozzoli , @Geofd -

M Febco 765 Backflow Preventer is ~2ft above ground.
Doesn't it include a check valve? (I'm not an expert, obviously)

 

[Geofd]

I use a separate check valve in front of the backflow, it stops.any turbulence that would cause the backflow to chatter

 

[Geofd]

@havasu , @Paul Capozzoli , @Geofd -

M Febco 765 Backflow Preventer is ~2ft above ground.
Doesn't it include a check valve? (I'm not an expert, obviously)

Yes it does

 

[Paul Capozzoli]

@havasu , @Paul Capozzoli , @Geofd -

M Febco 765 Backflow Preventer is ~2ft above ground.
Doesn't it include a check valve? (I'm not an expert, obviously)

Is that a pex 1/2 supply line? What is your GPM?.

 

[Mitchell-DIY-Guy]

My automated sprinkler valves have warnings that say they MUST me installed above ground level, or their backflow valves will fail. Just something to consider.

How do you install a sprinkler valve above ground level? Mine are, and always have been, buried in a box specifically made for valves.

 

[Mitchell-DIY-Guy]

When I lived in Michigan, the "tap" for the irrigation started in the house, after the 1" water meter on the main before anything else that used water. This 1" copper line then went outside to a similar PVB (pressure vacuum breaker). When the irrigation was running, the water flow was considerably greater than anything that ran in the house, probably greater than running everything at the same time. This extreme high flow caused some noise we'd always hear. I think it may have been vibrations from the water meter that then transmitted through some of the home's piping system.

Here in NC totally different setup. The irrigation has its own meter at the street, and has nothing to do with any piping in the home.

 

[Paul Capozzoli]

When I lived in Michigan, the "tap" for the irrigation started in the house, after the 1" water meter on the main before anything else that used water. This 1" copper line then went outside to a similar PVB (pressure vacuum breaker). When the irrigation was running, the water flow was considerably greater than anything that ran in the house, probably greater than running everything at the same time. This extreme high flow caused some noise we'd always hear. I think it may have been vibrations from the water meter that then transmitted through some of the home's piping system.

Here in NC totally different setup. The irrigation has its own meter at the street, and has nothing to do with any piping in the home.

Nice thing about the dedicated meter is you don't pay the sewage charge which where I live in VA amounts to about 60% of the bill.

 

[Twowaxhack]

Nice thing about the dedicated meter is you don't pay the sewage charge which where I live in VA amounts to about 60% of the bill.

I get the best of both worlds. Great clean city water at 80psi and I have a septic system with sandy soil.

I can get 3” of rain in a couple hours and there’s no standing water 10 minutes after the rain stops.

 

[Mitchell-DIY-Guy]

Nice thing about the dedicated meter is you don't pay the sewage charge which where I live in VA amounts to about 60% of the bill.

Exactly. In Michigan, basically all the towns/cities within a 50 mile radius or so of downtown Detroit used the Detroit water system, and they did not allow a break on irrigation water. Some towns apparently gave their residents a break on their own. Not the town I lived in. So, my subdivision (whose HOA fees were 60% water for irrigation) dug two wells, and we irrigated with well water. That allowed the subdivision to maintain the same annual HOA dues for over 25 years.