Greenish sludgy stuff in water heater tank

hj said:

quote; Tankless water heaters are the way to go. At least they provide unlimited amounts of clean hot water.

The "stuff" on the bottom of water heaters is caused by heating it, so where do you suppose the "stuff" from a tankless heater ends up?

Click to expand...

No anode rod, so no metal accumulation. There is no concentrated mess of goop stored in a tankless heat exchanger. An 8 year old tank type water heater has 8 years of accumulated gook stored in the tank.

Whatever "crap" runs through a tankless water heater is no different than what runs though the cold water tap.

Ladiesman271 said:

Tankless standby temperatures are room temperature. Old and stagnant water is 100% flushed out of the heater every time it is used. After the water heating cycle, a tankless will also heat the water in the heater above 140 degrees.

Click to expand...

A tankless will only heat the water above the 140º if you set it that high. And yes old stagnant water is flushed out when it is used. but what do you think is growing in that old stagnant water? Oh did you read my post https://terrylove.com/forums/showpost.php?p=210728&postcount=20 .

Ladiesman271 said:

You guys should update your thinking. Two people taking a shower at the same time is not a good thing to do. You should also use a lower flow shower head than your use!

Click to expand...

But this goes back to a code issue about suppling enough hot water through out the whole home. The following is what the Plumbing code requires here in Illinois, and I bet it is not much different in other states.

Section 890.1210 Design of a Building Water Distribution System

SewerRatz said:

A tankless will only heat the water above the 140º if you set it that high.

Click to expand...

Hint on peak water temperature in the heat exchanger. What is the coolant temperature in your truck's engine after you turn off the engine?

SewerRatz said:

And yes old stagnant water is flushed out when it is used. but what do you think is growing in that old stagnant water? Oh did you read my post https://terrylove.com/forums/showpost.php?p=210728&postcount=20 .

Click to expand...

What is growing in your household cold water pipes? Same water temperature!

In addition with each use of hot water in a tankless system, by the time hot water gets to the point of use in a private home all of the "stagnant" water has been flushed from the heater and the hot water distribution pipes.

If you use 1/2 of the water in a tank heater you don't have hot water anymore. You do end up with a 1/2 a tank of "old" water mixed with some "new" water. Water in the hot water distribution pipes is never flushed but is just replaced with water stored in the hot water tank.

Commercial buildings like a hospital are hardly comparable to a home hot water system.

SewerRatz said:

But this goes back to a code issue about suppling enough hot water through out the whole home. The following is what the Plumbing code requires here in Illinois, and I bet it is not much different in other states.

Section 890.1210 Design of a Building Water Distribution System

a) Design and Installation. The design and installation of the hot and cold water building distribution systems shall provide a volume of water at the required rates and pressures to ensure the safe, efficient and satisfactory operation of fixtures, fittings, appliances and other connected devices during periods of peak use. No distribution pipe or pipes shall be installed or permitted outside of a building or in an exterior wall unless provisions are made to protect such pipe from freezing, including but not limited to wrap-on insulation or heat tape tracer line or wire.​

Click to expand...

We had that discusion before. What is the legal definition of "peak use"? The prior answer was it all depends!

I think that adequate for the intended use is the term that is used in codes in my area.


.

Ladiesman271 said:

Hint on peak water temperature in the heat exchanger. What is the coolant temperature in your truck's engine after you turn off the engine?

Click to expand...

It will be the same temperature it was before I turned it off. On a Tankless system though the fan runs long after the burner shuts down to help cool the heat exchanger faster when the water stops flowing.

What is growing in your household cold water pipes? Same water temperature!

Click to expand...

Not really. You are starting from a hot water going to warm which is more an ideal growing temperature than cold water.

In addition with each use of hot water in a tankless system, by the time hot water gets to the point of use in a private home all of the "stagnant" water has been flushed from the heater and the hot water distribution pipes. If you use 1/2 of the water in a tank heater you don't have hot water anymore.

Click to expand...

If you keep the tank hot enough like in the Bradford White model GX-2-25S6BN Which stores the water at 180º and distributes it at the set temperature of 120º Yes it may be a small 25 gallon tank but it can provide 155 gallons of hot water in the first hour. Its big brother GX-1-55S6BN which is a 55 gallon tank can give you 200 gallons of hot water in the first hour.

Commercial buildings like a hospital are hardly comparable to a home hot water system.

Click to expand...

Well you are right and you are wrong. Yes a home will not have as long of a distance from the tankless units to the fixtures. But things still can grow in the lines after the tankless system. Also if you think about it lots of people only set their tankless to 115º to 120º which is the ideal temperatures for things to grow in it. Please do not be under a false sense of security that you or your family can not get sick just because you got rid of the tank.

We had that discusion before. What is the legal definition of "peak use"? The prior answer was it all depends!

Click to expand...

Peak use is all the fixtures turned on at once. If you do not believe me call your local plumbing inspector and ask them what they consider as peak flow per the code.

Oh and the minimum water pressure at all the fixtures during this peak flow is to be at least 8 p.s.i. per the code again. When you open more hot water taps in the home and if the tankless system is undersized it will restrict the flow rate so it can still deliver hot water. I have seen installs where when people opened 3 hot water taps I be lucky to see a trickle come out of the fixtures.

SewerRatz said:

It will be the same temperature it was before I turned it off. On a Tankless system though the fan runs long after the burner shuts down to help cool the heat exchanger faster when the water stops flowing.

Click to expand...

Any documantation of your theory? The water temperature will rise after the water flow stops!

SewerRatz said:

Not really. You are starting from a hot water going to warm which is more an ideal growing temperature than cold water.

Click to expand...

A tankless water heater does not store hot water. Cold and hot water pipes will equalize at room temperature, so they are both the same temperature when not in use. A tank water heater never cools down.

SewerRatz said:

If you keep the tank hot enough like in the Bradford White model GX-2-25S6BN Which stores the water at 180º and distributes it at the set temperature of 120º Yes it may be a small 25 gallon tank but it can provide 155 gallons of hot water in the first hour. Its big brother GX-1-55S6BN which is a 55 gallon tank can give you 200 gallons of hot water in the first hour.

Click to expand...

Don't you need a 3/4 inch gas feed for those? I would have to install a new vent also. You know, that looks to be as expensive as a tankless installation!

You also forgot about all the crap that settles in that a tank water heater. 180 degree water storage temperature makes things much worse. That temperature setting conflicts with this recommendation: "** Excessive lime scale formations can also be reduced by setting the water heater temperature control at the lowest possible temperature which will provide satisfactory hot water service. The usage of water softening equipment greatly reduces the hardness of the water. However, this equipment does not always remove all of the hardness (lime). For this reason it is recommended that a regular schedule for deliming be maintained."


http://www.hotwater.com/lit/training/4800r9.pdf


"The amount of calcium and magnesium carbonate (lime)
released from water is in direct proportion to water
temperature and usage, see chart. The higher the water
temperature or water usage, the more lime deposits are
dropped out of the water."

SewerRatz said:

Well you are right and you are wrong. Yes a home will not have as long of a distance from the tankless units to the fixtures. But things still can grow in the lines after the tankless system. Also if you think about it lots of people only set their tankless to 115º to 120º which is the ideal temperatures for things to grow in it. Please do not be under a false sense of security that you or your family can not get sick just because you got rid of the tank.

Click to expand...

Tankless heaters do not store water at 120 degrees. The water temperature in a tankless is room temperature the vast majority of the time. Hardly the "ideal" temperature for things to grow in. Same temperature as the hot and cold water pipes.

SewerRatz said:

Peak use is all the fixtures turned on at once. If you do not believe me call your local plumbing inspector and ask them what they consider as peak flow per the code.

Oh and the minimum water pressure at all the fixtures during this peak flow is to be at least 8 p.s.i. per the code again. When you open more hot water taps in the home and if the tankless system is undersized it will restrict the flow rate so it can still deliver hot water. I have seen installs where when people opened 3 hot water taps I be lucky to see a trickle come out of the fixtures.

Click to expand...

Adequate for the intended use if the general wording of the various codes here.

Ladiesman271 said:

Tankless heaters do not store water at 120 degrees. The water temperature in a tankless is room temperature the vast majority of the time. Hardly the "ideal" temperature for things to grow in. Same temperature as the hot and cold water pipes.

Click to expand...

Legionella will reproduce at temperatures between 68ºF and 122ºF and will grow rapidly between temperatures of 85ºF and 110ºF.

Ladiesman271 said:

Adequate for the intended use if the general wording of the various codes here.

Click to expand...

Where is here? I would like to read up on yor plumbing code for your city. Maybe even talk to the local plumbing inspector.