Flushing Hot Water Heaters?

[– Colonel –]

I remember my Dad saying that hot water heaters should be flushed annually to remove minerals and prolong their life.

Does anyone know if this is true?

If so, do you just attach a hose to the HW heater, run it to a sink or outside the house, and then open the valve?

If so, how much of the water should you drain out? (Not the whole tank, I hope?)

I guess what's confounding me about this is, why doesn't the HW heater get "flushed" every time you draw hot water out of it?

Thanks for any advice.

Col.

[Bob]

Yes, you should flush them, but this will only get out light sediment, and not things like calcium deposits. Drain the water until it runs clean. If it's one of those cheap plastic drain valves, be prepared to replace it, because sometimes you can't shut them off again.

[Joseph Meehan]

It goes like this. If you have had the heater for 10 years and not flushed it, now is not a good time to start. It should be done every 6 months to a year.

You have the procedure down about right. How much to flush depends. I would suggest at least 10 gallons. In some cases you would want to totally empty the WH. That is you want to empty that amount of water, you don't generally shut off the inlet water supply.

What really works and is needed depends greatly with the local water conditions. Where I am it is not really worth the effort. In some areas I would do it ever few months.

Note: most water heaters have really cheap drain valves. Be ready to replace the one you have, especially if you are going to try this after five years of not doing it.

In some areas it is wise to check the sacrificial anode rod and replace it if it is in bad shape.

Good Luck

[Bob]

[bill allemann]

the heated water normally exits the tank at the top. the drain valve is at the bottom, where the sediment builds up.

[spudnuty]

Well the sediment builds up in the bottom of the tank. Drawing water off the top does not draw the sediment from the bottom. I saw an episode of "Ask This Old House" the other day and they did a project about the same problem. The expert was hesitant to drain the sediment because he said if it had been sitting like that for a long time draining it might cause it to fail sooner. He pumped it out of the house with a electric hose pump. Sure enough the heater failed within 6 months. He then did a cutaway of the heater to show how the sediment builds up inside. Richard

[Art]

Consumer Reports did a report on water heaters and talked about flushing but to me the report was ambiguous as to whether they thought it would actually help. They cut some up to show the mess inside and it looked like rocks which would not be removed by flushing.

[philkryder]

Well soft water might help reduce build up...

I keep a hose on the cheap plastic valve - a very good quality hose, with a nozzle that shuts off AND a ball type end of hose shut off valve.

That gives me 3 shutoffs total in case the water heater valve fails.

I just unwrap a few feet of hose every few weeks and shoot the water into the washing machine or water softner - not wanting to waste it.

by doing it often, there is little time for build up.

my particular heater also has a "swirl" design purported to mix the incoming water and minimze settling and "self clean".

the buildup is supposed to cause increased energy usage (on gas heaters) by reducing conductivity.

[spudnuty]

Well on that show that I saw it was an electric water heater. The lower heating element was completely crusted in that stuff you're talking about. The upper one was the only one doing any heating. Richard

[Sev]

I'll second it about those plastic valves. Decided to flush mine some years back, having read it was a good idea. Had a hell of a time to shut it off again- finally did, though it dripped for a couple of days- cursed myself for bothering with it. Water softener or filter system to prevent stuff getting in there seems like a better idea.

[buffalobill]

[– Colonel –]

Thank you for the info, everyone.

Since the water is pretty soft here, and since I haven't flushed the heater in 3-4 years (and it's not an especially new heater anyway), I think I'll just leave well enough alone and take my chances.

Col.

[Joseph Meehan]

It can help IF you live in an area that has water problems (I would guess most people do) AND IF you start doing it soon enough and IF you do it often enough.

The trick is to flush out the heater BEFORE those rocks form. Before they become rocks they are high concentrations of mineral rich water, then sand then larger. You can flush out the water and the sand, but the rocks are a different matter.

I will add that some areas have material in the water that is a larger problem and likely flushing will not help.

Finally, I make this suggestion. If you replace that cheap plastic valve from the start, you can flush it with little trouble and very little chance of doing any damage. You may add years to the life of your water heater doing that.

Also don't forget to service the anode rod. Again the need for this depends on your water supply.