Jump to content
CBR1100XX.org Forum
Sign in to follow this  
Zero Knievel

Water Heater Question

Recommended Posts

We’re putting in an on demand gas water heater.  We will keep the existing electric tank heater in place but install cutoffs for the inflow and outflow.

 

Is it best to leave the tank full and maybe drain/fill once in a while or drain and leave empty?  I’m concerned that empty will promote tank oxidation.

Share this post


Link to post
Share on other sites

I'm curious why you're leaving the tank unit, and even doing extra work to leave it.

 

If you must leave it: shut off and lock out the breaker (or electrically disconnect entirely), then drain it, refilling with a good quality Bourbon as an antifreeze/preservative.

  • Like 1

Share this post


Link to post
Share on other sites

You had me up until the bourbon bit.

 

We’re keeping it because it works and just in case the new heater fails it can serve as a backup.

Share this post


Link to post
Share on other sites

Empty, it will go away in no time.  Leave it full and flush quarterly or semi-annually?  I'm guessing.  No doubt someone here has actual experience with such things.  

Share this post


Link to post
Share on other sites

No matter what you do, eventually it is going to start leaking, whether it's used or not.  The fact that it will sit stagnant for extended periods will just accelerate that concept, as the water is not being replaced with new water frequently.  If it's in an open area, it's wasted space.  If it's in its own closet, they probably will not install the tankless system in the same area as that is a disaster waiting to happen (a sealed container next to a heat source = boom.)

Share this post


Link to post
Share on other sites

Well, we’re keeping it in place because we’d have to move stuff to pull it out.  So...keep it full and cycle out the water every now and then.

Share this post


Link to post
Share on other sites

Could you leave the power off to the tank but run the water through it to the new heater?  I was thinking with a couple of ball valves, it should be possible and that way the water is always fresh.

  • Like 1

Share this post


Link to post
Share on other sites

No.  Otherwise, conceivably, the hot water will convection back to a tank full of cold water.  Even with a one way valve, the heater won’t draw on the hot water line.

 

That is a thought...have them tap into the hot water line to feed the other heater so water always circulates trough the tank.

Share this post


Link to post
Share on other sites

Complicating a ham sandwich.  Pull out the tank.  That is what you should be doing.

 

If you do something as ridiculous as keeping it as a back up...well, that's not smart.

 

 

Share this post


Link to post
Share on other sites
2 hours ago, Aunt Zero said:

No.  Otherwise, conceivably, the hot water will convection back to a tank full of cold water.  Even with a one way valve, the heater won’t draw on the hot water line.

 

Please, please, please tell me you don't believe there are two lines running to your house.  Also, please tell me you understand that the heater doesn't "draw" from anything, it's pressure from the water company or well.  Please tell me how in the BLUE FUCK that it makes a difference if your tankless system gets it's water inlet from the now non-heated tank or from the cold line running from the street, and how that can POSSIBLY affect the temperature of the water coming out of the faucet or shower.

 

Please tell me you didn't just post that.

I'm usually just sitting back and saying to myself "Zero gonna Zero" but that has GOT to be top 10 dumbest shit I've ever seen you type.

  • Upvote 1

Share this post


Link to post
Share on other sites

Good Lord one can’t think aloud around here.  I know how water flows.

 

I’ll install a bypass on the outflow line of the tank.  Run it back into the cold line.  Any draw will pull from both sources...ensuring water doesn’t stagnate in the tank.

Share this post


Link to post
Share on other sites
2 hours ago, Aunt Zero said:

Any draw will pull from both sources...ensuring water doesn’t stagnate in the tank.

 

 

There is no "draw", and I seriously doubt you'll avoid a stagnant tank if there's a more direct way for the water to flow unless you start playing games with restrictors on the lines. Kill power/gas to the tank and run it all through there if you're set on this idiocy.

  • Like 1

Share this post


Link to post
Share on other sites
3 hours ago, Aunt Zero said:

Good Lord one can’t think aloud around here.  I know how water flows.

 

I’ll install a bypass on the outflow line of the tank.  Run it back into the cold line.  Any draw will pull from both sources...ensuring water doesn’t stagnate in the tank.

 

Hook up a flux capacitor and run your anal dildo off the “draw” from the steam. 

 

Jesus - you’re stupid. 

Share this post


Link to post
Share on other sites

Just don't do it. You're planning a redundant hot water source that will only cause you grief. What's the worst that will happen if your new water heater goes tits up? A few cold showers. What's the worst that WILL happen when your old tank leaks or blows up? A flood, possibly no water at all, and sooner or later that old tank is going to have to come out. Pay a little now, or a lot later. 

Up here home owners /business insurance won't cover any water damage caused by an electric  tank over 10 years old. 

Share this post


Link to post
Share on other sites
2 hours ago, JoWhee said:

Pay a little now, or a lot later.

Maybe the best answer?

Share this post


Link to post
Share on other sites

I agree that the old heater is a liability, a weak link in the system.  And as Tim said, path of least resistance - there's no way to "branch" the inlet water off in such a way that you can ensure any kind of real circulation in the old tank.  I don't see an issue putting it in-line before the new heater, and regarding your concern about heat loss, they make heat traps to prevent soak backwards to the old tank (well, they make them for a different reason, but you can use it for that)... not sure that would affect an instant system, doesn't it have to sense flow AND low temp before it kicks on?  

 

I understand your redundancy theory, but it really is far more logical to at least remove it from the system if not from the space it's in.  If I HAD to leave it for some reason, AND keep it operational-ready, I'd shut off both the inlet and outlet, connect a hose to the drain, and manually flush it once a month by opening the drain and inlet - use the hose to water the plants or a tree or something.  That won't stop the elements from corroding/deteriorating, so it may not work if you ever power it back up anyways. 

 

But I agree with the consensus - there's little advantage in keeping it available, and some potential downside.  You're introducing complexity and an additional failure point to the water system, and possibly an additional preventive maintenance schedule to your calendar.  

Share this post


Link to post
Share on other sites

I don’t see a failure point issue.  I’m doing the plumbing, not someone else.  To pull the tank I’d have to pull the water softener.  It’s less work now to keep it in the circuit.  It’s in the basement, garage side.  A leak will harm nothing.  In such an event, removing it then would be worth the extra work.  Likewise, if the water softener needs replacement, I could pull the tank at that time.

 

For now, we’d have a redundant heater available.  Once we see the new heater is reliable and it’s pointless to have two heaters, I can plan on the work to pull the tank and rework the plumbing.

 

This more of a “right now” job.  Since leaving the tank empty will ensure failure, I’d like to prolong its life...unless there’s a way to pull/disconnect the tank and vent it so it’s dry inside and won’t deteriorate from non use compared to just draining it.

Share this post


Link to post
Share on other sites
45 minutes ago, Aunt Zero said:

I don’t see a failure point issue.  I’m doing the plumbing, not someone else.  

 

The first failure point is where you decided to overthink this.  I hope the second sentence isn't the second failrure point.  Best of luck.

Share this post


Link to post
Share on other sites
5 hours ago, IcePrick said:

 

The first failure point is where you decided to overthink this.  I hope the second sentence isn't the second failrure point.  Best of luck.

 

Watch your fucking use of the word THIS.  Because it ain't THIS....it's EVERYTHING.

  • Like 1

Share this post


Link to post
Share on other sites
20 hours ago, Aunt Zero said:

I don’t see a failure point issue.  I’m doing the plumbing, not someone else.  

 

Add "Master Plumber" to your ever growing list of expertize. I was going to try and re-explain why this is a bad idea, but I'll let you learn it the hard way. 

Share this post


Link to post
Share on other sites

I scrolled straight to the end after about 6 posts.

 

Kill the power, flush it out and empty it leaving the drain valve open, bypass the water lines.  Some surface rust may form from sitting empty, like any piece of metal sitting around, but it won't rust out like it will if left full of water.

 

Hope your tankless works for you, mine kinda sucks and so did my parents'.

Share this post


Link to post
Share on other sites

Curiosity fucking got to me so I went back to read.

On 6/7/2018 at 7:13 AM, Aunt Zero said:

I don’t see a failure point issue.  I’m doing the plumbing, not someone else.

Worst case scen

 

On 6/7/2018 at 7:13 AM, Aunt Zero said:

A leak will harm nothing.

Worst case scen

  • Like 1

Share this post


Link to post
Share on other sites

I see you finally got it installed: 

 

 

Share this post


Link to post
Share on other sites
On 6/6/2018 at 3:57 PM, Aunt Zero said:

No.  Otherwise, conceivably, the hot water will convection back to a tank full of cold water.  ...

 

That wouldn't hurt anything and I doubt there would be much in any event.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×