No cold water on sink and bathtub faucet

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Neshco

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Have finished my self my bathroom on the upper floor of my house approximately two months ago.
Have used pipe in pipe system, Wirbo/Uponor q&e connection.
Everything worked just fine until about a 2-3 weeks ago when suddenly stopped run cold water from the bathtub faucet. Have tried to Google the problem and found a lot of situations where trapped air in a pipes can do this. There was recommendation to close a faucet with a hand and open cold water side and then slowly start hot water to fill that air. I tried that without success. Tomorrow tried the same and suddenly water started flowing on cold side too. That worked until an hour ago and then I lost cold water on both bathtub and sink.
Again, i have tried to do the same truck, but it didn't work this time and now I write this post to ask for help/advice.
Pipes are on both sink and bath U shaped from the junction box to the sink and thub and they are of course separate and i don't have idea where that potential air block could be.
Any suggestions, ideas, advice...?
Thank you in advance for help.
 

Terry

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I have sometimes found a small plastic ball in the line, thinking maybe from the heat traps for a water heater.
Air should not have been a problem. Running the faucet lets any air out.
 

Neshco

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Thank you Terry for tips, but I am not sure that it is a case because there is 0 flow there. If there is some kind of dirt, it would at least have some drops of water, but that is not the case. There is literally no a single drop of water. Plus, unlike last time, now I had exactly same problem on a sink. 0 flow cold water.
First time when it happened I have tried to get rid of air like described in video shared and it didn't succeeded first time, but after several tries during the day, it come back while I tried that.
Another thing that is indicative is that both pipes for bath and sink goes from the wall (approximately 90cm height from the floor) where is a junction box down below floor level approximately 30cm down and the again up to the sink and bath forming "U" shape. Both are separate and there is no any junction out of junction box, every pipe goes separately to the sink, bath, shower and toillet. Shower and toillet have horizontal water lines, not U shaped like sink and bath. I am not sure if U shape can form air lock, but it is indicative that only that pipes had that kind of problem.
This morning, water is back on sink, but on a bathtub is still off completely. Guess I can fix it by the system in video after enough water pushing back in cold line, but I am not sure how to permanently fix this, because I don't know where and what to search for.


 

WorthFlorida

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You'll need to open the system by removing the cartridges or stop valves at the faucets to flush the lines.

At the tub/shower valve body remove the cartridge. First shut the water off with the stop valves or stop valves built in the valve body. With the cartridge removed slowly open the cold water stop valve. Any debris should be able to be flushed out. If water flows that is where at least one problem source is. If it doesn't flow then the problem is elsewhere. At the sink, do the same.

Is there one stop valve for all of the fixtures with the problem somewhere in your plumbing? What type of valve? A flat washer type, the washer can break away from the stem and the water pressure keeps it against the valve in the close position. Ball valve type or 1/4 turn will not have this type of problem.

I doubt there is an air block. The water pressure will push out any air. Air block can be had with a closed hydronic heating system (hot water system).

I've had MOEN brand POSI-TEMP cartridges that were manufactured around 2000-2010 where the anti scalding device would jam in one position where no water would come out of the hot.
 
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Jeff H Young

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remove shower cart . turn water on let it blow with hot water off at water heater if water comes out great! at sink remove angle stop let water blow if it comes out your good! just gotta let the debris blow out.
Obviously if water comes out then problem is at angle stop supply line or faucet just gotta work through these simple steps
 

Neshco

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Thank you all for tips, just to clarify few things.
Bathroom and installations are new, just 2 months since we start using it and there was no any other problems with it then this. Sink have stop valves, flat washer type, but bathtub does not. There is a flexi pipe connected directly to the 18mm pipe under bathtub. Bathtub have Grohe Grandera 4 holes faucet. Shower does not have any problem and there is no any valve between hub and shower cartridge. Toilet is also ok. So, problem is only in bathtub and sink (meanwhile sink start work out of nowhere), while bathtub still does not have cold water at all.
I'm going to check if valves are problem at the sink, but what to do with bathtub? There is nothing between distribution hub and bathtub faucet literally, no valves, no nothing and installations are brand new.
Sometime, pressure of the water drop down because we have private water supply for cca 20 households and that is the reason, so probably when it happened (pressure drop down) maybe air bubble is formed and later when pressure increase it is not able to push it out!?
In the basement, where supply line come into the house, I have water softener which work very good and there is no problem with calc and deposits for sure.
If its a air that make the problem (but I don't know if its possible to be formed on U shaped pipe) maybe water pressure booster will help with that!?
And again, I am not sure that debris or anything similar can stop the water so good that there is no any single drop of water out of faucet...
I don't know what to think, really weird things happened there.
 

Jeff H Young

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You're losing me with the air bubble . my only recommendation is above. maybe some other ideas?
 

Reach4

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Sometime, pressure of the water drop down because we have private water supply for cca 20 households and that is the reason, so probably when it happened (pressure drop down) maybe air bubble is formed and later when pressure increase it is not able to push it out!?
No, air will easily be pushed out by pressurized water.
 

WorthFlorida

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You'll need to remove the cartridge at the tub and flush out the valve body. I looked up the model for this Grohe and for the tub shower they read "thermostatic" mixing valve. As I said before, possible the cartridge is jammed with the cold water side closed, doubtful, because you never want to fully close the cold water to prevent scalding. Everyone else here agrees that there is debris inside the cartridge or valve body and no air lock. Removing the cartridge will prove that cold water is getting to the valve body.
Only two months old, the builder's plumber should be trying to solve this. There must be some kind of warranty.
 

Jeff H Young

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You'll need to remove the cartridge at the tub and flush out the valve body. I looked up the model for this Grohe and for the tub shower they read "thermostatic" mixing valve. As I said before, possible the cartridge is jammed with the cold water side closed, doubtful, because you never want to fully close the cold water to prevent scalding. Everyone else here agrees that there is debris inside the cartridge or valve body and no air lock. Removing the cartridge will prove that cold water is getting to the valve body.
Only two months old, the builder's plumber should be trying to solve this. There must be some kind of warranty.
What about his LAV. tried telling him same thing pull guts out shower valve. pull angle stop.
Common issue on a new system or one worked on construction debris gets in pipe . but hope he gives up on the air bubble theory
 

Neshco

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Got you all guys, Ill try flush it with angle stop removed as soon as I get some free time. Meanwhile, got cold water back on a bathtub too.
I hope you are right about this, because, if I am right, that is much bigger problem then debris or angle stop issues.
Thank you for all advices and ideas, I will get back here as soon as I fix that.
 
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