Our water heater (30 gal State gas tank, '04 edition) is quite overdue for a flush at bare minimum. I was planning on doing a pressure flush with the hot side closed off, the gas valve set to "pilot", and the cold side left fully open; however, the tank sits below the level of the main drain (as does the rest of the furnace room floor) -- the only gravity drain available for it is via a sump (with the obligatory sump pump).

Is it OK to flush a water heater into a sump pump, or is the risk of clogging the pump with sediment and possibly wrecking it too great? Should I try to route the drain hose "uphill" to the one window in the room and then out the window onto the lawn? Should I route the hose into something that can "catch" the sediment and then drain that container to the sump?

  • I don't see an issue with using the sump as long as you're catching the sediment first. I'd probably knock together a simple barrel filter out of a drywall bucket and call it good. – Comintern Nov 5 '16 at 14:08
  • The issue that I'd worry about is pumping hot water with the sump pump. Sump pumps are pretty resilient with dirty water, they are made to pump storm water. The two specific issues that may cause a problem depending on the pump itself: seals may may soften or melt, and the motor itself may stop due to thermal protection. On the other hand cooling the tank first, doesn't that "set" the sediment at the bottom of the tank? – Tyson Nov 5 '16 at 14:09
  • @Tyson -- the idea is to use the pressure from the cold water supply to push the sediment out. – ThreePhaseEel Nov 5 '16 at 19:26
  • @ThreePhaseEel right, but cooling the tank completely I think before starting causes the sediment to contract and become a more solid mass. Even tho your supply water is cold overall hot is better. – Tyson Nov 5 '16 at 20:05
  • @Tyson -- so close the tank in and flush it while it's still firing? – ThreePhaseEel Nov 5 '16 at 20:17

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