Hot water out of single-lever kitchen faucet

[gnwjr]

I have a single-lever faucet that is giving me issues. In order to get hot water, the lever has to be in the full hot position, nothing in the middle. Anything prior to the full hot stop is cold, no lukewarm, nothing but cold water.

The system is connected to a Rinnai tankless and is less than two years old on a new construction system.

Any ideas on what is going on and hot to repair?

 

[frodo]

your shower valve scald guard needs adjusting.

take the handle off. should be an adjustment behind it,,pull out and rotate

put back and ck

 

[gnwjr]

Frodo,

Thanks for the reply. Does it make any difference that it is a kitchen sink faucet and not a shower mixing valve?

Here is a picture:

Glen

 

[phishfood]

Has it always done this, or is it just occurring recently?

If it has just started occurring, I would suspect a flow issue with the faucet. I would start by cleaning the areator on the faucet to make sure that you are getting sufficient volume through the faucet to trigger the Rinnai.

 

[gnwjr]

Yes, it has always done this.

In addition, there is plenty of hot water, very hot water, (once the lines are cleaned out of cold water from the Rinnai to the manifold to the faucet) and pressure to the faucet. While at the hot water stop on the faucet, the water is maximum hot, then as soon as you come off of the hot water stop, it becomes cold.

Could this still be a flow trigger issue? I would think the hot water would continue to flow for a bit until the cold water started to flow out of the shutdown Rinnai. As it is, it is immediate cold water after coming off the stop.

 

[Caduceus]

Just taking a stab at this, no promises, okay.
When the kitchen faucet is turned on to cold and moved towards middle to mix, there may not be enough demand for the flow switch to actuate and turn on the tankless unit.
Once you have the faucet open fully, then the tankless detects flow and heats the water.
To rule out this possibility, try opening the hot side of a faucet that has separate handles for the hot and cold. Feel the water to see if it's hot.
If it is hot, leave it running and go to the kitchen faucet and see if it starts mixing from cold to warm, warmer to hot.
Let us know what you find.
Edit: I see phish just said the same thing. Sorry.

 

[phishfood]

Yes, it has always done this.

In addition, there is plenty of hot water, very hot water, (once the lines are cleaned out of cold water from the Rinnai to the manifold to the faucet) and pressure to the faucet. While at the hot water stop on the faucet, the water is maximum hot, then as soon as you come off of the hot water stop, it becomes cold.

Could this still be a flow trigger issue? I would think the hot water would continue to flow for a bit until the cold water started to flow out of the shutdown Rinnai. As it is, it is immediate cold water after coming off the stop.

From that description, I tend to think that it is a problem with the faucet itself. The hot water in the pipe between the Rinnai and the faucet will not automatically get cold just because the faucet is adjusted from it's hottest setting, so if the faucet were operating properly, you should still have a brief period of hot water.