Water Heater questions

Because it is a good idea if done properly. Sounds like they don't want you to in this case.

This is probably the reason they don't want you to change the valves. I have no idea how well this works.

Vacuum. Put a straw in a glass of water. Put your finger over the end and lift it out. Same thing with the heater. If air is not allowed in, the water cannot get out.

You can open the relief valve to make it drain quicker IF you are draining one you are going to replace. I would advise you NOT to open the relief valve on one that you are just draining (for clean-out). I have seen too many of them that do not seat (or seal) properly once this has been done and then you end up with an annoying drip.

Why doesn't opening hot water faucets prevent/releive the vacuum?

Ken

I agree with both statements, but I ask you the same question -- why doesn't opening hot water faucets also work?

Ken

That'll work too....

But that's the reason for question 3 -- it didn't work

Ken

The hot water faucets are the bottom of the straw, You need to open the top. You can open ten faucets, but they are all fed from the same line coming out of the tank and no way to get air back into it.

Even if you relieve the partial vacuum that will form in the water heater tank the dip tube probably doesn't reach completely to the bottom of the tank, so it wouldn't siphon all the water out either.

Never thought of a water heater overhead in the attic. Usually they have to be pumped out from the basement around here.

They have a lot of water heaters in attics here. Even with emergency pans under them, if they leak, often the ceiling will come down. It depends on how bad the leak is. Then they usually get moved to a garage or laundry room.

The self cleaning water heaters like the "Sand Blaster" have a curved dip tube that swirls the water in the bottom of the tank when you draw hot water. The sediment comes back out the faucets as disolved solids. This way you don't have to drain the tank. It would be very hard to change the curved dip tube but the anode rod should not be a problem if there is enough clearance above the tank.

Stretch

First thought was BS!

Assuming the hose was hooked direct to the WH outlet, opening a hot water faucet in the system should have drained the tank. There is enough pressure in a column of water pushing down to suck the water out of the pipes to let water in.

And then I thought about it. Assuming a tank in the attic (3rd floor) that is 4ft high you only have a 4ft (about) column of water trying to suck a 20 ft column of water out of the pipes.

Then another thought. Why wouldn't the water drain out of the faucet on the first floor?? The hose connection provides for air back into the tank.

I think I'll quit, my head hurts.

Harry K

Depending on the layout of your piping, it might or might not. The pipes are full of water. If there are valleys in the piping, the gravity drain can't suck them back up to the heater. Since yours is in the attic, the plumber thought this was likely. Mine is in the basement where it is more likely to work but still not assured.

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But probably not if the water heater is above the faucet, i.e., in the attic.

Harry, the piping in the house isn't necessarily arranged to be pitched uniformly to either end. It could easily run up and down such that there are low point or entire runs filled with water even if each end is drained.

Some houses, the opening both ends thing could work, most it would not, as some additional energy would be needed to blow or suck the standing water out of the low areas.

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THAT should not happen. If you need to run pipe such that there's a low loop in it, there should be a drain of some kind at the bottom of it.

there's

Did you ever consider a tankless water heater? They are not alot ($ up front) more than a good tank style heater but alot less maintenance as well as a heck of alot cheeper to run. No tank draining, No TPR valve, No tank to rot out, No anode to change. All around a better deal. In europe Tank style heaters are considered antque. almost all houses there are built new with tankless heaters. Just something to think about.

I'd wager it happens more often than you seem to think. I'd say the average house is just not piped such that being able to gravity drain the pipes is a controlling consideration. And after the pipes are roughed in, the walls are sheetrocked and the pipes are covered; no drain points. Maybe a small house intended to be "seasonal" is set up so the pipes can be easily drained, but the average house is never expected to freeze inside.

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Sorry, I didn't mean to indicate that it DIDN'T happen, just that when it does, it's wrong. If there's a low loop that you need to get water out of, the correct solution is to cut a segment out, and install a shutoff with a waste-cap.