Kitchen Sink in Commercial Space - No Cold water

[Stromlid]

The kitchen sink in our office produces only warm water when the faucet is angled to cold. You can run the tap for 5 minutes or more and the water stays warm. We've been in this office for 3 years with no problems until this started about 2 weeks ago.

It's a single handle faucet. The sink has its own water heater, an A.O. Smith Del-10. The building engineer came to take a look at the problem. He initially thought the cold water cartridge in the faucet needed to be replaced. Then he said they determined the hot water heater was constantly running/heating which was affecting the cold water. He thinks that a thermostat on our hot water heater has stopped working.

Does this sound like a reasonable assumption of the problem? Or could it be something else?

 

[voletl]

Check the cartridge

 

[Stromlid]

How can I test if it's the cartridge?

 

[voletl]

Under the sink shut off the cold water. Then turn on the faucet put it to cold if you still have warm water coming out the hot water is crossing over through the cartridge

 

[Stromlid]

I think our building engineer must have shut something else off. If I turn off the cold water nothing comes out of the faucet at all (I confirmed the hot water knob was on under the sink). Is there a shutoff somewhere on the water heater too?

 

[Stromlid]

Never mind, I found the water shut off on the water heater and turned it back on. It didn't matter though because the same thing happened. If I turn the cold water off under the sink and turn on the faucet to cold, nothing comes out of the faucet at all.

 

[newton4mark]

Never mind, I found the water shut off on the water heater and turned it back on. It didn't matter though because the same thing happened. If I turn the cold water off under the sink and turn on the faucet to cold, nothing comes out of the faucet at all.

Sounds like a bad mixing valve

They put them in comercial settings to prevent scalds

It is either in a wall behind an access panel or in the ceiling

If it has a bypass turn it off and see if that solves the issue

 

[Stromlid]

Sounds like a bad mixing valve

They put them in comercial settings to prevent scalds

It is either in a wall behind an access panel or in the ceiling

If it has a bypass turn it off and see if that solves the issue

It doesn't have a bypass valve. I can't get into the wall or ceiling.

I'm starting to wonder if the water heater is actually the problem. Right now the water heater is shut off entirely (because they were concerned about pressure due to evidence the pressure relief valve had opened) and we still aren't getting particularly cold water. I'd say it's cool at best. Not nearly as cold as it used to be.

Edited to clarify: It's definitely not the water heater that's the problem, since our cold water right now is warm again. Our water heater is shut off and the hot water knob is shut off under the sink.

If it's a bad mixing valve, how costly is that to fix? The building won't let us do any repairs ourselves so we'll need to hire a plumber.

 

[newton4mark]

Depends on how accesible it is

If they can bypass it and it is easy to find, they may just charge a trip charge 75-125 dollars depending on the place you call to
Come out

If it has to be repaired or replaced it could be 500 or more depending on the parts and labor

I am no expert so that is a guess... plumbing is costly sometimes
Get a couple of quotes and find an honest plumber

I am not a plumber but have run into this many times in the restaurant business
Code requires these valves to be installed to prevent kids from getting scalded in the bathrooms

Is the faucet a single handle or is it 2 espérate handles?

If it's one it may just be the cartridge

Faucets are cheap
I would recommend a double handle faucet with a separate line to hot and cold

Also is this the only sink with the problem or is all sinks having the issue?