Doesn't matter which,both #! and #2 are SUPPOSED to turn HOT water off to all fixtures. They look like gate valves and gate valves seldom turn completely off after a few years.

In the bathroom, under the sink should have water shut off for both hot and cold water. Turn them both off. You shouldn’t have to shut off the water to the entire house/condo.

thank you @klem1 and @amateurdeziner. Both water shut off valves under the sink are stuck and I have been struggling to turn them off.

@klem1 I live in a condo, so, do you think the main water supply valve in somewhere in the basement of the building?

@User thank you for your pointer. I will check it out tomorrow - I am guessing somewhere in the basement. I only wish it were somewhere in my unit in case of emergencies :-(

Also @User, is the cold water pipe #1 or #2 in the heater picture?

For what you are doing it doen't matter which is cold or hot but here;s how to find out. Turn any hot faucet in house on and feel the pipes #1 and #2,one will feel cold,the other hot. From where i'm at there's no way I can tell you where main valve is located but if you have a meter key (keys sold at any big box or hardware) you can turn main supply off at meter. If you have an outdoor hydrant,look near it for in ground box containing main valve.

If you're new to plumbing, have a bucket and mop ready or a shop vac that can handle water, and do youyour work whewhen the hardware store is open.

.Good advice Sigrid. The gas line picture make's me think storing family photo albums off site until finished might also be wise.

@klem1 why do you think gas line could pose a problem? can you please explain?

hello folks - here is an update. i went into our basement and can only see a valve but that is for the entire building. I am guessing it is a water valve because there is a sprinkler attached to the pipe? there is a knob and i have no idea what that is for. I can meter on the street but no other traces of valve. Does this mean my condo does not have a supply shutoff?

I have a breakthrough. I was able to locate the water shutoff for my unit. It is the #1 knob in the heater picture. I was able to test it!

"I was able to locate the water shutoff for my unit. It is the #1 knob in the heater picture."

Really? Are you sure? Valve #1 would only affect hot water by controlling the flow of water into or out of the water heater. It wouldn't control cold water.

@wdccruise thank you. yes, I tested it by turning on all the faucets and as soon as I turned the knob to the right, all the faucets had no water. I am going to validate this again tomorrow and let you know. the #1 knob is coming from the wall and it is cold to touch. #2 pipe is coming out of the heater and it is hot to touch.

Why do you think it is not the shutoff?

@wdccruise lesson learned. since i am a newbie i did not realize the picture would make such a big difference. i apologize - here is a picture from different angle. there is a T-pipe near #1 knob.

I was thinking the same thing as klem1. If you can't tell a gas pipe from a water pipe then you have no business touching the plumbing in your condo. I emphasize condo because other people live there, and you could damage or destroy their home along with yours.

@suburbanmd: "If you can't tell a gas pipe from a water pipe then you have no business touching the plumbing in your condo."

She asked for help and figured it out.

I have been told by several folks that as a homeowner it is imperative that one knows the main water shutoff. Isn't that the case?

If you were looking for the shutoff valve for the sake of knowledge, rather than with the intention of doing plumbing work in your condo, your thread wouldn’t make me feel so uneasy. Besides, you might be violating condo rules or local regulations. I suggest that you bring your questions and plans to condo management.

thank you @suburbanmd! absolutely - i adhere to HOA rules and regulations all the time.

@suburbanmd: "you might be violating condo rules or local regulations."

Leave her alone. All she wants to replace a faucet.

You don't even think about touching a shutoff valve under a sink without complete knowledge of where the main shutoff to the building is locaed. My insurance company paid about $20,000.00 in tuition for me to learn this lesson, then dropped me. The new guys raised my rates.

Enablers always think they are helping but in reality they only make it easier for bridge jumpers.