And now for a devil's advocate response to Dave: It seems that Chris 7 has been doing a pretty good job of estimating the 4 million gallons of water with citations. Tri has said that the FDNY firefighters knew from thermal images where the hot spots were and tried to concentrate their water there. He also said that with fires deep under the rubble, they couldn't focus the water right onto the fires. Even so, they could pour water into the general vicinity for hours and days. C7 I'm not sure what the point is with all this... if you add up all the floors on fire in all three buildings, it came to some 40-50 acres of floor space (my rough guess). Buried deep down where firefighters couldn't get to it. Seems like a whole lot of fire to put out, standard or thermitic either way.
Once the burning debris from those 40-50 acres was in the rubble pile, it could transmit heat to the debris from the remaining floors too. And, as Tri pointed out, there's no way of knowing where the water went when they put it on the rubble pile. A figure of 4 million gallons of water that "percolated through the debris in the first 10 days and collected at the bottom of the Bathtub" is a good starting point, but once all that water had collected at the bottom of the Bathtub it wasn't doing much to put the fires out.
But another important point to look at is this: Christopher7 isn't trying to pretend that the rubble pile wasn't hot. He's trying to claim that burning rubble wasn't the source of that heat. So, in effect, he's claiming that there was something else that was generating all that heat, and his implication is that the something else was thermite. So he's arguing that, because the fires couldn't have burned for weeks and generated enormous amounts of heat despite the water poured on them, then thermite must have burned for the same amount of time and generated the same amount of heat. How much thermite is he talking about? I wouldn't know how to put a number to it, and I'm sure Christopher7 will do anything to avoid doing so; but if the water poured on the rubble pile wasn't enough to remove the heat generated by the thermite, then the amount of thermite present must have been enough to heat four million gallons of water to boiling point and then convert it to steam.
I'd quite like someone to check my arithmetic here. 4,000,000 gallons is about 16,000,000 litres, or 16,000 tonnes of water. Boiling that much water requires 2260 joules per gram, and heating requires 4.2 joules per gram per degree centigrade, so a grand total of about 90,000 gigajoules is needed to heat it from 20 to 100ºC and then boil it. Thermite has an energy density of about 4kJ per gram, or 4GJ per tonne, so over 20,000 tonnes of thermite would be needed to boil off all the water. That's rather a lot of thermite to be left over after the collapse, it seems to me. But I may have misplaced a decimal point there, so someone please check.
But, Christopher7 may say, the thermite doesn't need to have boiled off all that water. Well, I don't think you can stop a thermite reaction by pouring water on it, unlike a fire, so either there was enough thermite to boil it all off
and continue heating the rubble pile [1], or not all the water got to the thermite to remove heat from it. But then, by the same token, we can say that not all the water got to the fire either.
Bottom line: For the heat source to have been thermite, there has to have been more thermite - a lot more - in the rubble pile than all other combustibles that were present in two 110 storey buildings. That's way beyond ridiculous.
And, of course, the thermite had to react slowly, to keep generating heat for months. And that's just plain impossible. You can make a fire burn slowly by restricting the oxygen supply - in fact, that's what happened in the rubble pile - but thermite contains its own oxygen. Once it starts reacting, it won't stop, and it's finished in seconds.
Christopher7's objections are ragged enough when he's just trying to pick holes in the generally accepted account of 9/11. When you look at what he's trying to suggest as an alternative explanation, though, it's not just ragged; it's all the way into the territory of insanity.
Dave
[1] By the way, that was 20,000 tons of thermite
just to deal with the water poured on the rubble pile. I haven't left any to heat the rubble; you'll have to add that to the total amount of thermite that had to be there. At this stage, I'm almost hoping I have made a mathematical error, because things are just getting ridiculous.