Hot water in half the house

[Mickey400z]

Hey guys!
I had my plumber install lines from a water heater to 2 sheds. The shed on the left has a utility sink. The one on the right has a shower and sink. He put a shutoff valve on the line going to the right shed before it enters the shed so we could use the sink in the left while the shower was being finished. When I turn the valve on to the right shed, the left shed has lukewarm water at best. I turned off all cold water valves at the fixtures to make sure there wasn't an issue with the lines. Water comes out at all fixtures (temperature is dependent on the shutoff valve at the WH. Any ideas?

 

[Mickey400z]

 

[Diehard]

What exactly do you mean by this?... "temperature is dependent on the shutoff valve at the WH"

I assume the hot water drops down that red line and splits right and left to the 2 sheds, by way of that tee.

Approximately how long are the hot water lines from the water heater to the point of use, in each shed?

 

[Mickey400z]

Thanks for the reply!

If I turn the water on to the shed on the right it has hot water and the other shed has lukewarm water. If I turn it off, there is hot water to the one on the left.

It's 16' linear from water heater to last fixture in both sheds, so I would call it 30' +/- after going up into the ceiling then back down to the fixtures.

 

[Diehard]

How about when you use just the sink on the right side. Not the shower. Does that have the same affect on the left shed?
I don't believe it should make a difference in this case but those thermostatic/pressure balance shower valves have been know to impact water temperature elsewhere on the system. But as I say I can't see how it could result in what you're experiencing.

 

[Mickey400z]

It doesn't matter if I run the sink or shower on the right side, just turning the valve on to put hot water to the right side at all (with none of the fixtures running) causes the left side to go luke warm.

I will try and run the fixtures at the same time on both sheds to see what happens.

 

[Diehard]

Oh wow!
I assume you were closing and opening the HW valve to the right shed.
Try shutting off that cold water valve feeding the right side shed and leaving the hot water valve open.

I'm thinking maybe with that right side HW valve open the cold water may be pushing back through that shower valve and running back through the open HW line.

 

[Diehard]

If shutting the cold water solved your not-so-hot water to the left shed, you may have a bad shower valve or mixing valve in the right shed.

A simple fix other than trouble shooting the mixing valves, would be to add a swing check valve in the hot water line feeding into the shower shed.

 

[Nukedaddy]

As Diehard indicated a quick fix may be some check valves if no visible cross connection can be seen. Something that is true, however, is that many of the shower mixing valves made in China have the mixing valve placed UPSTREAM of the shut off / volume control and a diverted valve follows the shut off / volume control. So, if the mixing valve design does not prevent reverse flow, the cross connect is there, and is always “on” because the shut off / volume control is downstream.
Additionally, some off these offshore valves have combination check valve AND flow restrictions in their inlets. Removing them to increase flow to American tastes will cause the cross connect as well.