Air in Cold water line and BROWN water?...

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Diggfinder

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I have a tenant in an old building that has been having an issue for the last few weeks, most of the building is copper. It's the only tenant with this problem so far, also the tenant is on the main floor of the building and the other tenants on the same floor haven't reported this issue....The tenant has been at this building for over 20 yrs and only recently has this been happening. The tenant comes in during the morning and leaves for the night after evening time.

When they use the cold water sometimes air and water comes out of the tap and spits out brown water, after a few minutes of the water running it turns clear again. This will happen randomly several times during the day. I checked with the city and no work has been done on the main lines and we are the only building on the street to have this complaint.

Why would air be in the cold water line? With the hot water line the tenant says is not problem, but I heard that air from the hot water tank can go into the cold feed line and move inside the system could this be causing the problem. Also, the building is on a radiator heating system but there is a check valve (one way valve) for the cold feed line for the heating system so I don't think that is causing the problem.

I would assume air is getting into the system and disrupting the lines causing the brown water sediment problem....any suggestions I should try besides redoing the entire main supply line?....:confused:
 
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Jadnashua

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Have the valve from the cold supply to the boiler makeup water checked. It should be more than a simple check valve.

If there's any (short is all it takes) galvanized piping anywhere in his unit, it will get some rust once it starts to go. With some water supplies, it's possible to get some gas in the line when the sacrificial anode reacts. With inactivity during the day, it would be more common to get some air in the upper units, not the one on the first floor, but it's not particularly common. you could have a failing expansion tank putting air into the pipes.
 

LLigetfa

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With the hot water line the tenant says is not problem, but I heard that air from the hot water tank can go into the cold feed line and move inside the system could this be causing the problem.
The cold supply into the HWT normally is directed to the bottom of the tank with a dip tube so air accumulation in the HWT usually cannot backup into the cold supply. Dip tubes have been known to disentegrate sometimes though so there is a slight possibility.

I would suspect that the air is coming into the building from the city main unless the building has an air injection type of iron filter.
 

Diggfinder

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Have the valve from the cold supply to the boiler makeup water checked. It should be more than a simple check valve.

If there's any (short is all it takes) galvanized piping anywhere in his unit, it will get some rust once it starts to go. With some water supplies, it's possible to get some gas in the line when the sacrificial anode reacts. With inactivity during the day, it would be more common to get some air in the upper units, not the one on the first floor, but it's not particularly common. you could have a failing expansion tank putting air into the pipes.

The valve and pressure is correct for the heating system. Not sure about the expansion tank for the heating system, that expansion tank is on the top floor of the building and the hot water boilers and hot water tank is in the basement, how would the air get into the cold line from that expansion tank if its failing?
 

Diggfinder

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The cold supply into the HWT normally is directed to the bottom of the tank with a dip tube so air accumulation in the HWT usually cannot backup into the cold supply. Dip tubes have been known to disentegrate sometimes though so there is a slight possibility.

I would suspect that the air is coming into the building from the city main unless the building has an air injection type of iron filter.

There's no dip tube, as that building has a small RBI boiler that heats water that goes into a reserve storage tank with a connection to a circulating pump that feeds the building. I checked with the city and they confirmed no work was being done, but they did mention that water trucks could illegally be using the fire hydrant but I doubt it as no other buildings on the street are complaining.
 

Jadnashua

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A boiler heating system has an expansion tank, and that wouldn't affect the potable water, but you may also have one on the cold water supply. That could.

Is the brown water restricted to one fixture, or is it everwhere? If say in the tub or shower only, that's one thing. If it's everywhere, that's another. the system probably has a hot water recirculation system. A leaking bearing on the circulation pump can inject some air, but in a pressurized system, it's more common for it just to leak water rather than inject air.
 

Diggfinder

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A boiler heating system has an expansion tank, and that wouldn't affect the potable water, but you may also have one on the cold water supply. That could.

Is the brown water restricted to one fixture, or is it everwhere? If say in the tub or shower only, that's one thing. If it's everywhere, that's another. the system probably has a hot water recirculation system. A leaking bearing on the circulation pump can inject some air, but in a pressurized system, it's more common for it just to leak water rather than inject air.

I don't think it has an expansion tank for the cold water...unless its hidden but never seen it before is there a way to tell. The tenant says it's not just one fixture it's all the taps including the washroom tub.
 

Jadnashua

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If it's everywhere, then it's more likely to be in the supply line, rather than maybe a steel nipple at a fixture. All it would take is one galvanized pipe somewhere verses a brass one to make a difference. That wouldn't account for air in the lines, though. I'm out of thoughts, hopefully a pro with more experience has some ideas.

You may not need an expansion tank on the cold water, so there may not be one. If one is there, it could be anywhere from the inlet to the supply to the WH. Since, if you do have one and they do eventually fail, and they have air in them, a little could leak out. But, eventually, the thing would fill up with water - it could rust, but wouldn't be able to add any more air since it only has a limited supply. Think of a balloon inside of a steel tank. WHen the balloon (bladder) fails, it will release the air it has and let water get to the steel which can rust.
 
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