We are unable to get hot water at the bathroom sink even when surrounding fixtures (shower, spare bathroom) run as hot as we like. This is the set-up under the sink and I suspect it was modified for a handicapped resident. Please help me figure out what needs to happen next to warm up the water.
Identify loop under bathroom sink
- Thread starter lambchop
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Plumber69
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hot water runs cold or no water comes out in hot position?
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Hot water runs cool - lukewarm compared to cold water position
Can you turn off the cold water stop valve under the lavatory? If you do that, how is the hot water flow?
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cold water off, hot water runs cool and I can feel the water running thru that loop
While feeling around down there, the cold should have no water running in it, because the stop valve is off. I guess as another test for an unlikely condition is to turn off both stop valves, and make sure water does not come out of the faucet.
One possibility is that the hot from the wall is supplied through a thermostatic mixing valve. If that valve was adjusted too cool or had failed, that could explain the symptoms.
If you don't have a basement, I don't know where I would look for such a valve. I would presume close to the lavatory. Maybe behind an access cover? I am not a plumber.
I have no insight on what that loop is. Your topside photo made one theory go away.
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With both valves off, no water runs thru faucet.
There is no access cover under sink.
Two showers in same room - one has adjustable thermostatic control on wall and other does not.
No basement - this is a high-rise condo. Water heater is located in laundry room separate from bathroom.
I meant access panel in a wall. Is there a utility closet nearby? Is that laundry room nearby? Look for a gadget with 3 ports.
There is no access panel in the wall under the sink, over the sink or in the adjoining cabinet. The other side of the bathroom wall is the dining room.
I see no gadget with 3 ports - only the hot and cold lines and this loop with a gadget on it.
I suspect this loopy thing is controlling the hot water and if so, would like to know how to disable/bypass it.
So what is that thing? Not sure. One idea is that it is a check valve that allows hot to flow to cold when the hot pressure is high enough with respect to the cold, or it could be a thermostaticly limited bypass. That would be part of a hot water recirculation system.
Note that no gadget under the sink (other than a water heater) will raise the water temperature to more than you get with the cold stop valve closed. If water comes out, it is coming via the hot stop valve.
Whatever makes your hot cool is before the hot stop valve.
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