Hot Water, Almost

Two days ago I finished the plumbing a flash water heater that I built. It's been really cold, and rained all day yesterday. I thought two days would be good to make sure the glue cured thoroughly. This morning I rigged up the electrical part and gave it a test. The pump ran fine and there didn't seem to be any leaks, so I got some wood and lit a fire. Right away I could tell it worked quite well. The infra-red thermometer registered about a 16 degree differential on input and output, but I'm not sure what the effective flow rate was. One problem I soon noticed was that the pump input, which is connected to the water tank cold inlet, was drawing the warm water off the top of the tank. I kind of assumed that they had a pipe extending down into the tank so that the incoming cold water wouldn't mix with the hot. Apparently that was a bad assumption. I originally planned on the pump intake being connected to the drain on the bottom of the tank, but after flushing several pounds of scale out, including gravel sized pieces, I became concerned that the scale would end up either damaging the pump or plugging up the 1/4" tubing in the flash heater section.
Everything seemed to be going fine and I was just sitting on the porch enjoying the momentary feeling of accomplishment when all of a sudden one of the pipes burst. I quickly shut the water off, and assessed the situation. With the flow shut off, temperatures rose in the flash heater and the next thing I knew, the flexible hose connected to the copper blew off: so much for faucet lines. Steam and smoke was all bluring together and the feeling of accomplishment quickly changed to disappointment. Now I'm going to have to use a galvanized or copper line, which means spending more money. At least a certain proof of concept with the flash heater was accomplished. The next step may well be moving to the other side of the house and going ahead with connections to the house tank. That way at least I'll be able to easily use the water once it's heated. The down side is that I'm still a long way from being able to take a hot shower.