[M_Six]

There seems to be a good deal of support for this theory. But it sucks that it's so hard to check on some items. The HW circ pump I just had installed has the same part number as the one on Amazon, but there is a different PC: number. I have no way to find out what the PC: means. Could be a different lot number or something. On the manufacturer's site, the same pump (visually anyway) has a totally different part number. And they don't list a price. You have to fill out a form to get a quote. I mean WTF? If there is a difference in build quality, then make it easier to be certain you're getting what you pay for.