I have a Delta single arm/ball faucet in the kitchen. If you put it in the HOT position, the flow is fine but the water is just tepid. By turning off the water alternately on the hot and cold sides under the sink, it appears they are working the way they are supposed to... getting water from the right pipes... other than the hot water isn't hot. It didn't used to be that way, but it must have happened gradually because it wasn't like it was working one day and suddenly not the next. The hot water is really hot everywhere else in the house. How can it be that the water comes from the hot water pipes under the sink but it isn't hot?? It doesn't make sense to me, so I'm sure there is something going on that only pros understand. Can you help please? I can't afford a plumber right now... :confused:

Two points where the flow can get clogged. Check the stop on the supply line below the sink and more likely, check the cartridge inside the valve for debris.

I have a Delta single arm/ball faucet in the kitchen.
I don't believe you have a cartridge in a "ball type faucet". (see image)
Turn the water off and renove all the parts including the seats and springs.
Now place a pan over the open faucet and turn the hot water stop back on and let it run for awhile. Do yo get hot water now? If so clean around the inlet ports and replace the seats and springs. If you can't get hot water through the open valve click on back and tell me about it. Good luck, Tom

I don't believe you have a cartridge in a "ball type faucet". (see image)
Turn the water off and renove all the parts including the seats and springs.
Now place a pan over the open faucet and turn the hot water stop back on and let it run for awhile. Do yo get hot water now? If so clean around the inlet ports and replace the seats and springs. If you can't get hot water through the open valve click on back and tell me about it. Good luck, Tom

Tom: I tried what you said, and still no hot water. I don't see any kind of cartridge. Mine is just slightly different in style than the image you sent, but essentially the same parts. I'm stumped.

Two points where the flow can get clogged. Check the stop on the supply line below the sink and more likely, check the cartridge inside the valve flor debris.

There isn't any problem with the flow at all. Just the water temp, and only at this particular place in the house. This type of faucet doesn't have a cartridge -- ball type faucet by Delta.

Still stumped.

Tom: I tried what you said, and still no hot water. Did you place a pan over the open faucet and turn the hot water stop back on and let it run for awhile? Do yo get hot water now? If you can't get hot water through the open valve click on back and tell me about it Are you saying that when you had the valve open and turned on the hot water that only luke warm water came out of the hot water supply? If so the problem isn't in your faucet. Any work done on your plumbing lately? Talk to me! Tom

Are you saying that when you had the valve open and turned on the hot water that only luke warm water came out of the hot water supply? If so the problem isn't in your faucet. Any work done on your plumbing lately? Talk to me! Tom

Yes, that's what I'm saying. It started doing this about a month ago. The only thing we had done, and it was back several months before that, was Culligan installing a water filter under the sink. As far as I know it doesn't do anything with the hot water at all. And it was months later that this problem started.

I'm so confused as to how the water can come from the hot water valve but not be hot when there's hot water at other places in the house. (We only have one water heater.) And how it could have worked once just fine and now doesn't.? :(

OK! That helps. We can reassemble the kitchen faucet since it isn't the sourse of the problem. Luke wan water coming out of the hot water supply tells me that you have a cross connection up stream from the kitchen. And where do you find crossconnections? In one handled faucets!! That's where.
Let's try eliminating suspects. I want you to go around to every one handle faucet in the house and close the hot water angle stop. Shut them down including the bathtub/shower. Can you get hot water out of the kitchen faucet now? Stay with me on this and I'll wait on your reply. Tom

OK! That helps. We can reassemble the kitchen faucet since it isn't the sourse of the problem. Luke wan water coming outta the hot water supply tells me that you have a cross connection up stream from the kitchen. and where do you find crossconnections? In one handled faucets!!! That's where.
Let's try eliminating suspects. I want you to go around to every one handle faucet in the house and close the hot water angle stop. Shut em down including the bathtub/shower. Can you get hot water out of the kitchen faucet now? Stay with me on this and I'll wait on your reply. Tom

Uh oh... lost me. How to I "close the hot water angle stop"? I don't even know what a hot water angle stop is... Sorry. I'm a learn-as-I-go person...

IfTX, I may have missed a post or two. Have we had you disconnect the hot supply after the valve below the sink. If not try that an then open that stop valve catching the water in a pan or bucket. It should be hot but the flow/volume may be restricted.

Uh oh...lost me. How to I "close the hot water angle stop"?? I don't even know what a hot water angle stop is... Sorry. I'm a learn-as-I-go person...

And if it's the knob you turn to turn off the hot water under the sink, then where would it be located for the showers? There are three other single-handle faucets in the house, all are in the bathroom showers. Are we talking up in the attic? If so, that may have to wait until the hubby is home... I don't do spider areas or heights too well...

Some showers do not have supply stops while some have them built inisde the mixing valve. Most every sink and toilet has a small valve on the supply pipe under the sink or, on a toilet, under the tank. Turn the valve off and disconnect the line coming out of the valve not going into it. Might wait for your hubby to come home or maybe take some pics under the sink and send them to us.

Do you have a recirc pump on the system?