Water Heaters - Hot line pressure loss to all fixtures

Hi,

I made a mistake and drained my water heater instead of flushing it. The instructions I followed said to attach a hose to the w.h. drain, open a hot fixture somewhere, close the incoming gate valve, and drain away. It wouldn't start draining until I re-opened the gate (supply) valve to the w.h., then once it started flowing out the driveway I shut it again and kept it shut b/c it kept flowing.

Once it stopped I opened all hot fixtures and re-opened the gate (supply), then proceeded to shut each fixture once water started flowing from it. As per the intructions.

I immediately noticed a large decrease in volume from the hot to each fixture. Serious trickle, not even enough for a shower!

Granted, we have old galvanized pipes that are in need of replacing, but why the sudden flow loss? And to each fixture!

I unscrewed the union on the OUT line above the w.h. and opened the gate and had good flow, so if there's a clog it must be downstream but upstream of the Tee from which the two sets of fixtures come from. Tub, bathroom sink to one side, laundry room, kitchen to the other.

It seems to me (newbie) that flow loss this sudden is due to either blockage or pressure loss of some kind.

I can't do much if it's the former, but is my latter theory even true?! If so, solutions?

Any suggestions (other than replacing our aged lines, which will be happening soon)?

TIA,
mark

Did you check the aerators at each fixture? The air and surge of water probably stirred up a bunch of gunk in the pipes.

I did, thanks. While there was gunk in the aerators, that unfortunately isn't the culprit!