Descale Tankless Water Heater after 5+ years?

JeffKeryk

JeffKeryk

Joined
Jan 9, 2010
Messages
23,964
Location
Los Gatos, CA
Installed a Noritz tankless 5+ years ago; annual flushes are recommended. One plumber(?) told me I could damage it by descaling it now.
Vinegar or solution?
Your thoughts?

Spoiler alert.... I am gonna do it regardless.
 
Shouldn't jinx myself. Yet here it is..................
We installed a Rheem high efficiency 30 ? maybe 40 gal natural gas heater in garage over 18 years ago. The guy who did the home warranty work at the time said "yeah, those Rheem do last a while. You can expect 7-8 years out of it if you follow instructions and you flush and properly drain it! Right. So I drained and flushed it out the very first year. Did the same for the next 2-3 years. I would say now, that heater is still working just fine and I have not flushed it out in over 7-8 years. Keep telling the wife..... "that heater is gonna die soon, But then it keeps just going and going and going etc...... I have started to price the tankless Nat gas set ups for when the old gal (heater NOT wife) passes on. Maybe due to only the two of us here the demand is not so high as in most homes?
 
Every 2 years I drag mine outside. Pull and inspect the anode, pull the drain, and hot water elements and tip it on its side and dump out all the scale. It sux but it's better than buying a new hot water heater. If I let them go more than 2 years the bottom element gets covered with scale.
A tankless lasted me 3 years, went right back to a tank water heater.
 
Last edited:
depends on your water quality . i used to di it every 2 years for a few years , but do it every 5 years now because in a my area we have good water with little minerals in it . still going strong after 18 years

i jsut get 3 gallons of vinegar, and dump into a 5 gallon bucket. my pump is a portable sump pump and hose are old washing machine ones. hook up the in and out and throw the pump into the bucket and let it recirc for an hour. vinegar should turn green/blue by the reaction to the copper tank.

i think the only issue you might have is if you dislodge some big chunks it might clog something . but i have seen vids of the inside of them and the passages are pretty big. So just do it is my rec
 
Most plumbing supply places will sell a product for safe flushing. It is designed to get the scale and not eat up other components. I recommend going that route.
 
CarLuver said:
depends on your water quality . i used to di it every 2 years for a few years , but do it every 5 years now because in a my area we have good water with little minerals in it . still going strong after 18 years

i jsut get 3 gallons of vinegar, and dump into a 5 gallon bucket. my pump is a portable sump pump and hose are old washing machine ones. hook up the in and out and throw the pump into the bucket and let it recirc for an hour. vinegar should turn green/blue by the reaction to the copper tank.

i think the only issue you might have is if you dislodge some big chunks it might clog something . but i have seen vids of the inside of them and the passages are pretty big. So just do it is my rec
Click to expand...

20 years on old water heater and it was never drained or cleaned.

I am aware it’s recommended to drain and clean.

New water heater was installed about 5 years ago.
 
oil pan 4 said:
Every 2 years I drag mine outside. Pull and inspect the anode, pull the drain, and hot water elements and tip it on its side and dump out all the scale. It six but it's better than buying a new hot water heater. If I let them go more than 2 years the bottom element gets covered with scale.
A tankless lasted me 3 years, went right back to a tank water heater.
Click to expand...
Thanks for the warning. Electric or nat gas tankless? For the past ten years in this area the local home builders (they will build a house top of another if allowed! ok-Joking-maybe not) But I have seen them build homes so close I do believe two guys/neighbors could hold a conversation from one house to the next thru windows as each is sitting on their thrones. This is how close these folks build homes. Anyway , the speed at which they manage to throw up new neighborhoods really makes one ponder the planning and quality. So, when one passes and looks over all these new homes they keep throwing up so very fast, one of the first things I noticed was that every home has the tankless water heater system mounted on the outside walls near the garages.
 
I use Calci-Free, bought pump and hoses off Amazon, sump pumps. 5 gallon bucket from Lowe’s. It’s easy, simple, fast process.
Vinegar not strong enough for neglected system.
 
SammyChevelleTypeS3 said:
Thanks for the warning. Electric or nat gas tankless? For the past ten years in this area the local home builders (they will build a house top of another if allowed! ok-Joking-maybe not) But I have seen them build homes so close I do believe two guys/neighbors could hold a conversation from one house to the next thru windows as each is sitting on their thrones. This is how close these folks build homes. Anyway , the speed at which they manage to throw up new neighborhoods really makes one ponder the planning and quality. So, when one passes and looks over all these new homes they keep throwing up so very fast, one of the first things I noticed was that every home has the tankless water heater system mounted on the outside walls near the garages.
Click to expand...
Twas naturalgas.
 
@JeffKeryk
Do you have a water softener or are you too cheap? :ROFLMAO:

Hard water is the killer of a tankless.

But since you are going to do it anyway......what do you intend to use. Most use a solution of white vinegar and distilled water, or just vinegar.

Pump through the ports in the isolation valves for an hour, clean the screens and hope for the best.

Very few are knowledgeable enough, (nor would I trust most) to repair a tankless' heat exchanger as they are very complicated. Rinnai for example, I went to a certification class for them to work on them......I realized in the class that I would never attempt such a repair, to much liability.

So, do what you will, the wort thing that can happen is it leaks and you get a new one to start off 2025 with a bang.

When that happens, go with a Rinnai.
 
JeffKeryk said:
Installed a Noritz tankless 5+ years ago; annual flushes are recommended. One plumber(?) told me I could damage it by descaling it now.
Vinegar or solution?
Your thoughts?

Spoiler alert.... I am gonna do it regardless.
Click to expand...
Do it

It doesn’t make sense to me what the plumber told you. If the water heater was that bad and descaling it would damage it well then there wouldn’t be much life left in it anyway correct?

In the meantime, you’ll be restoring the condition of the pipe and heat exchanger close to when it was new, saving energy by restoring whatever loss in efficiency because of scale buildup in the exchanger
 
I live in the mountains not too far from the OP and every 1-2 years we flush our tankless heater with straight white vinegar with 5% acidity. I just use a bucket with a medium sized aquarium pump with tubing and the appropriate fitting to tap into the water heater inlet and a hose to drain back into the bucket. Pretty easy once you get going. These tankless heaters are fussy about water quality and I think Navien really recommends anyone on well water to install some kind of pre-filter even if it's only for sediment.
 
single guy only use in NE Pa, my small wall mounted 220V stiebel Eltron went 10 years no upkeep, bought another one $200, install samo about an hour for me $00, works for me!! its fed from my oil furnace which is OFF in the summer but assists the tankless otherwise. went tankless because i was burning coal before prices went $$ as only one fuel on one chimney is safe.
 
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