Running out of hot water

[armen]

Would appreciate any guidance.

I have two year old navien nhb 150 and a superstor 60 gallon indirect set up as priority zone. After filling a tub run out of hot water. The tub is way smaller than even the indirect. Do I need a mixing valve ? Thank you

 

[John Gayewski]

Not sure if everything working? Is this something that just started? 150kbtu should be able to almost keep up with water heating demands even with a heat exchanger. What's your tank temp set at?

 

[Sponsor]

 

[WorthFlorida]

...... Do I need a mixing valve ? Thank you

A mixing valve is used to lower the temperature of the water.

 

[armen]

Not sure if everything working? Is this something that just started? 150kbtu should be able to almost keep up with water heating demands even with a heat exchanger. What's your tank temp set at?

Thanks John. Take a look at the picture, looks like the aqua stat is 130.

 

[Sylvan]

A mixing valve is used to lower the temperature of the water.

Actually it is used to "temper the water" ;-)

 

[John Gayewski]

Isn't that your tank internal temp? An aquastat would normally be externally set on the piping to tell the temp of water running to the heat exchanger. If it have an internal tank thermostat and it's set at 130 you should have 60 gal of 13 0 degree water. You shouldn't run out. How many people live and shower here?

 

[JohnCT]

A mixing valve is used to lower the temperature of the water.

Some people add a mixing valve and raise the temperature of their stored hot water.

John

 

[Sylvan]

Some people add a mixing valve and raise the temperature of their stored hot water.

John

If the water in a storage tank is 150 deg to kill any type of water borne bacteria how can a tempering (mixing) valve increase the temperature?

This is like saying decreasing the size of a pipe creates more pressure and forgetting it just increases velocity

 

[JohnCT]

If the water in a storage tank is 150 deg to kill any type of water borne bacteria how can a tempering (mixing) valve increase the temperature?

This is like saying decreasing the size of a pipe creates more pressure and forgetting it just increases velocity

My understanding (I haven't done it) is that if you raise the temperature of your stored water from 140F (say) to 170F, you can then mix the output of the 170F stored water with cold water to drop back down to the desired 140F (or 150F) to use less of the stored water and therefore increasing the capacity of the hot water tank virtually.

Rereading my answer you responded to, I think I see the confusion -

"Some people add a mixing valve and raise the temperature of their stored hot water."

I should have added " in order to increase the capacity of the system", otherwise it might come across as "some people add a mixing valve to raise the temperature of their stored water, which is not what I meant.

John

 

[Sylvan]

My understanding (I haven't done it) is that if you raise the temperature of your stored water from 140F (say) to 170F, you can then mix the output of the 170F stored water with cold water to drop back down to the desired 140F (or 150F) to use less of the stored water and therefore increasing the capacity of the hot water tank virtually.

Rereading my answer you responded to, I think I see the confusion -

"Some people add a mixing valve and raise the temperature of their stored hot water."

I should have added " in order to increase the capacity of the system", otherwise it might come across as "some people add a mixing valve to raise the temperature of their stored water, which is not what I meant.

John

John,
Increasing the water temperature will kill bacteria and even prevent running out of HW in most cases BUT a mixing valve such as a Holby is NOT an anti scald device.

We have been using these mixing valves to insure we have a constant temperature + 2 deg or - 2 deg These are not cheap but after testifying in court about scalding I figured one lawsuit cost run in the millions so in the long run we try to protect our clients and ourselves. I am sure there are other cheaper ones available

https://www.supplyhouse.com/Caleffi-600094A-2-Male-NPT-LEGIOMIX-Electronic-Mixing-Valve?utm_source=google_ad&utm_medium=Shopping_withoutdata&utm_campaign=Shopping_Without_PLTV_data&gad_source=1&gclid=CjwKCAiA_tuuBhAUEiwAvxkgTnMMhVgVfLt5Nju2QuQq1ZwGm_atZmsBETLWxvh6ZKDDhSVW7tcHYBoC80gQAvD_BwE