Hot water in Shower only after briefly turning on Kitchen faucet hot

[sspin]

Hi,

I just had some remodeling done, moving a bathroom and leaving an existing bathroom as it was. I also just moved into this house, so don't have a lot of history.
I have a Amtrol indirect fired hot water tank with Gas fired boiler/furnace. The Hot water tank is working as it should. The water is hot.

All hot water in the house is on a single line from the hot water tank. It runs from the tank, to the kitchen faucet, dishwasher, to bathroom #1 to bathroom #2. Bathroom number #1 is still the original plumbing. Bathroom #2's plumbing was moved from 1 side of the house, to the other.
Also, I just replaced the kitchen faucet from a standard single spout moen to a single spout Delta (touch), but plumbing was not changed there.

Now, in the morning, the hot water in bathroom #1 (both shower and sink faucet) is only luke warm.
If I go the kitchen sink, the water is Hot as it should be.
If I turn the Hot water on at the kitchen briefly, the water in bathroom #1 immediately gets HOT too.
Note, the kitchen faucet does not need to stay running Hot for bathroom #1 to get hot. Only turning it on briefly does it.
This scenario is somewhat random, so it is hard to diagnose.

Although I can not confirm, I expect that bathroom #2 will exhibit the same symptoms, but I have not been able to verify yet.

Water pressure is fine everywhere.

Is it possible that there is a vapor lock somewhere and briefly turning on the kitchen faucet clears it?
Thanks a lot

 

[Smooky]

My guess is there is a cross flow of cold into the hot at the new delta kitchen faucet. That faucet is suppose to have check valves installed at the angle stops. If the check valves were omitted then that is probably where the problem is located.

http://www.deltafaucet.com/repairparts/details/rp53468.html