Bathroom faucets only get lukewarm water - except when the sprinklers are on!?

Question

I'm having a strange problem in a house I just moved into. It has a brand new water heater and a new two-handle sink faucet in the bathroom. The tub has separate hot and cold handles.

The water coming to either the sink or tub is lukewarm at best. And it takes at least 60 seconds to reach that temperature. And that's with only the hot turned on. I've tried turning off the cold source under the sink and I get the same results.

Interestingly, I've noticed that when the yard sprinklers are on, I get scalding hot water to the bathroom sink and tub. As soon as the sprinklers go off, it's back to lukewarm.

Oh, and the kitchen faucet is fine - it gets very hot.

Any thoughts - I really miss my hot showers.

Answer 1

I had a similar problem years ago and it took me forever to figure it out.

Since you do get hot water, there's nothing wrong with you hot water heater. Obviously you're getting a mixture somewhere in your plumbing system. Another possibility is the check valve is malfunctioning.

Do you have a common connections somewhere? The two that I can think of are a laundry room faucet and a "Y" connector for the washer.

The "Y" connector is used for the cheaper type of washers where there is only one inlet which is connected to both the hot and cold water supply. You adjust temperature by turning on/off the hot or cold water supplies. If both are left on, then when you run cold water somewhere it creates a "low" pressure situation drawing hot water through the "Y" connector and into the cold water pipes.

The other scenario is from a laundry room faucet. These commonly have a threaded end where you can hook a garden hose to it. If you have a garden hose hooked to it and the hose has a shutoff valve, then when you leave the hot and cold water on, it will mix.

Answer 2

That is very strange! Have you checked the water from the sprinklers, to see if it is hot? Sounds like someone got something tied in wrong. Check to see where the water is coming to the sprinklers. There should be a Vacuum breaker assembly, somewhere on the side of the house, with a valve to shut the sprinklers off. Close that valve and see if the water temperature is the same in the bath. You might need to have a local plumber come out and check for a cross connection somewhere. Did the previous owner install his own sprinklers? I would really like to know what you find out! Good luck!