Hot water not so hot

I am having a bathroom remodeled. The house is 10 years old, pex lines and has Delta valves. The bathroom being remodeled is in the front of the house. The contractor replaced the valve in the shower. However, he hasn't yet put the cartridge in it. He says he only wants to do it once, after the walls are tiled, to protect the o-rings. The problem is the hot water in the rest of the house, except the laundry room, is now tepid. I measured the laundry room at 129-130F. Every place else is 101-103F. I am thinking that without the cartridge water can mix in the empty valve body, and depending upon the deltaPs of the various lines I end up with cold water mixing into the hot leg. Is that realistic, or am I hallucinating?

no you are correct to assume that

Did he not put any service valves on for the new diverter

I fail to see how the water can be turned on with out the cartridge in place.
unless the valve has stops on the hot and cold, but, these would not let the water mix

I am confused as to what you are talking about

If the cartridge is not in it and the test "plug" is still in it, the water will cycle through and mix.

SHEPLMBR said:

If the cartridge is not in it and the test "plug" is still in it, the water will cycle through and mix.

Click to expand...

never seen a ''test plug'' in a shower valve

guess i learn somthing new
throw me a picture up if you have one

frodo said:

never seen a ''test plug'' in a shower valve

guessi learn somthing new
throw me a picture up if you have one

Click to expand...

Delta use to have a few different tub/shower valves. When I was doing new work (track homes), we would put in the standard. Then when someone bought it we would end up tearing out drywall to change the valve because the wanted a certain trim that only fit the 1700 series and not the 1400 series. Now it's one valve body and the cartridge comes with the trim...Figures they would change it after I retired out of the field.

Sheplmbr is correct. When u install the valve body without the cartridge it creates a cross connection. The hot and cold water mix to create barely warm water. It's even more noticeable now since its winter and the incoming water is colder.
That test plug system only works on new construction where most new homes dont have utilities yet so the plumber fills the system on the cold side to check for leaks and since there is no water heater at the time of test the cold water flows from the cold side into the hot side thru the shower valve body to test the hit pipes.

Long story short.... install the 14 or 17 series cartridge and it will fix it.