Temperature Problems w/ Hansgrohe Faucet

[SAS]

We have a single handled Hasngrohe kitchen faucet. From time to time the water temperature fluctuates significantly. For example, the handle might be set on full hot or full cold but the water will come out mixed. Not only that, but you can feel pulses of hot water when you are running it on cold and vice versa. During one period that this happened I turned off the cold water to the faucet. The hot was then fully hot. So it would seem to be the faucet. I have changed the cartridge once before, but could a bad cartridge cause this behavior? If it's not the cartridge, what else could it be? And if it is the cartridge, why does it only happen occasionally? It's not an inexpensive faucet, but would I better off just replacing it?

 

[Michael Stoecker]

Hello, Please contact Hansgrohe at 800-334-0455 for troubleshooting.

 

[Sponsor]

 

[SAS]

Hello, Please contact Hansgrohe at 800-334-0455 for troubleshooting.

I called them, and while they were very polite, they couldn't offer me much help. They insisted that it couldn't be the faucet or faucet cartridge, and it turns out that they may be correct. Tonight the same problem happened, and warm water was coming out when it was on full cold. I quickly turned off the hot supply valve, but the warm water kept coming. So the faucet can only be the problem if the water is mixing across the cartridge when the water is turned off. The folks at Hansgrohe say that isn't possible. If they are right, I am stumped.

 

[Terry]

You may have a crossover somewhere else. Sometimes that occurs when someone has added a shutoff for a shower head and left the valve open. It could also be a recirc line.

 

[Reach4]

I quickly turned off the hot supply valve, but the warm water kept coming.

Do you mean you closed the valve on the input to the WH?

 

[SAS]

Do you mean you closed the valve on the input to the WH?

No just the stop under the sink for the faucet.

 

[SAS]

You may have a crossover somewhere else. Sometimes that occurs when someone has added a shutoff for a shower head and left the valve open. It could also be a recirc line.

I've looked everywhere I can think of, including the recirculation system. My guess was that the check valve might be failing and allowing the hot to feed back into the cold, but I changed that check valve once already because it was a possible source of the problem and the pipe above the check valve is quite cold. Is there some other way in which the recirculation system could cause this problem?

 

[Reach4]

No just the stop under the sink for the faucet.

OK. Let the warm water flow that way. Then feel the incoming cold pipe. Warm I presume. Go to all of your faucets, and feel the cold supplies. The cold where the crossover is will feel warm. Other colds to the faucets will not feel warm.

 

[SAS]

OK. Let the warm water flow that way. Then feel the incoming cold pipe. Warm I presume. Go to all of your faucets, and feel the cold supplies. The cold where the crossover is will feel warm. Other colds to the faucets will not feel warm.

I've tried that with all but the shower faucets, as those pipes are not easily accessed. The only cold water pipe that I've found that seems to be a bit warmer than you'd expect (although with pvc pipe it's not that easy to tell) is the one for the kitchen sink. So despite what the Hansgrohe folks say, could it be that even when the faucet is off, there is a crossover between hot and cold? How would that happen? How do those cartridges work anyway? In the off position is there any chance that hot and cold can mix inside the faucet body? In fact, how would any fixture allow crossover unless that mixing occurred in the faucet body when the fixture was off?

 

[Reach4]

So despite what the Hansgrohe folks say, could it be that even when the faucet is off, there is a crossover between hot and cold?

With the hot stop valve for the kitchen sink closed, a hypothetical crossover in the kitchen sink faucet unit could not produce warm water; there would be no hot water available to mix with cold.

This is not to say that the kitchen faucet unit does not have a problem also, but there must be a crossover somewhere else anyway. It is the case that even with a problem, it could not make warm water with its hot supply line cut, it seems to me.

Maybe the recirculation system somehow provides the path. Some recirculation systems use the cold pipes to return water. Some have dedicated return paths.

If your various pipes are not accessible to feel, that would make finding the crossover harder.

 

[SAS]

With the hot stop valve for the kitchen sink closed, a hypothetical crossover in the kitchen sink faucet unit could not produce warm water; there would be no hot water available to mix with cold.

This is not to say that the kitchen faucet unit does not have a problem also, but there must be a crossover somewhere else anyway. It is the case that even with a problem, it could not make warm water with its hot supply line cut, it seems to me.

Maybe the recirculation system somehow provides the path. Some recirculation systems use the cold pipes to return water. Some have dedicated return paths.

If your various pipes are not accessible to feel, that would make finding the crossover harder.

Yes, if the hot stop valve had been left closed, the crossover could not have occurred prior to my discovering the cold water had been mixed with hot, but wouldn't this be a theoretical cause:

• Both hot and cold stop valves are open, but kitchen faucet is left off.
• During this period, the hot and cold are able to mix in the faucet body due to a design or (more likely) a failure in the faucet and/or cartridge.
• When I run the cold water from that faucet, the cold supply now has some warm water mixed with it.
• Turning off the hot stop valve doesn't change anything, because the warm water has previously mixed into the cold supply.

I don't think the recirculation system is at fault for three reasons. It does have a dedicated return. The problem only happens at the kitchen sink. I replaced the check valve that would likely be the fault if it were in the recirculation system, and it had no effect.

 

[Reach4]

Turning off the hot stop valve doesn't change anything, because the warm water has previously mixed into the cold supply.

Any previously mixed warm would have been exhausted in under a minute, wouldn't it?

 

[SAS]

Any previously mixed warm would have been exhausted in under a minute, wouldn't it?

Perhaps, but a minute seems like a long time when you're standing at the sink waiting for the water to become cold. Another reason I'm suspicious of the faucet is that upon occasion while running the hot water I have felt occasional streams of cold mix in. What I'm thinking of doing is installing a two handled kitchen faucet to ensure that the hot and cold are indeed separate. The only problem is that my wife wants a faucet with a pull down spray and very few two handled faucets have that.

 

[Reach4]

Perhaps, but a minute seems like a long time when you're standing at the sink waiting for the water to become cold.

I was thinking of testing purposes, and not as a regular work-around.