Answer: Hot water issue throughout the house, not just the tub. Two controls on the main tub, and one control on the other bathtubs. No, the plumber did not work on the water heater per se, but it’s possible that one of the valves that he replaced fed the thing. No flash heating device.
DH did a test where he tested the water coming out of the heater at the bottom, and said it was hot. Also said that there was this sediment that was not lime, looked more like plastic. He assumed it was the dip tube. He also did some research online about dip tubes, and found that even though this house was built in ’99, the water heater was made in ’96. Apparently there was some sort of dip tube class action suit at the time, and he’s assuming that it was a part of it, although that expired in 2000. 😛
After much discussion regarding cost of repair for someone else to do this, or even the labour just to pull the puppy apart, deductible for home warranty and basically the headache of it all, he went to Home Depot today and purchased a new 50 gallon heater.
He finished installing it about an hour ago, so we’ll see if this solves the problem. Crossing my fingers, since a home with small children can’t operate without hot water!
Thank you for your input on this, I think that it put us on the right track towards a reason and ergo, a solution to this problem. I’ll let you know if it works! Thanks again!