# Hot Water on Demand System



## CompletePlumber (Jan 9, 2013)

Have a customer with an NTI On-demand hot water system. It operates both in-floor heating as well as domestic hot water. 
Problem: They have a Moen Shower system installed with 4 body sprays, shower head and hand spray. 
The NTI is good to produce 4 - 6 gpm. When the customer has the body sprays and shower head running at the same time you're looking at 10 - 12 gpm. The on demand system can't keep up. 
Is there a simple solution?


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## OldSchool (Jan 30, 2010)

CompletePlumber said:


> Have a customer with an NTI On-demand hot water system. It operates both in-floor heating as well as domestic hot water.
> Problem: They have a Moen Shower system installed with 4 body sprays, shower head and hand spray.
> The NTI is good to produce 4 - 6 gpm. When the customer has the body sprays and shower head running at the same time you're looking at 10 - 12 gpm. The on demand system can't keep up.
> Is there a simple solution?


What the manufacture told me was to install a tank along with this piece of crap or throttle the water outlet of the hot on this piece of crap


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## johnlewismcleod (Apr 6, 2012)

His demand far exceeds his supply...no simple fix. 

Supply must be increased.


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## plbgbiz (Aug 27, 2010)

CompletePlumber said:


> ...Is there a simple solution?


Cap off the body sprays and hand shower. Problem solved.


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## OldSchool (Jan 30, 2010)

The problem with the NTI is they use a plate heat exchanger to heat the domestic hot water .. IMO it's under sized ...


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## justme (Jul 4, 2012)

CompletePlumber said:


> Have a customer with an NTI On-demand hot water system. It operates both in-floor heating as well as domestic hot water.
> Problem: They have a Moen Shower system installed with 4 body sprays, shower head and hand spray.
> The NTI is good to produce 4 - 6 gpm. When the customer has the body sprays and shower head running at the same time you're looking at 10 - 12 gpm. The on demand system can't keep up.
> Is there a simple solution?


its going to depend on the incoming temperature of the water and the temperature rise of the heater. One solution would be to turn the heater up to maximum settings and run it through a small holding tank then through a mixing valve.Set mixing valve to a lower temp like 110 that could give you the GPM you are needing to satisfy the customers needs.


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## CompletePlumber (Jan 9, 2013)

They aren't going to be happy.

Thanks!


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## plumberpro (Jan 1, 2013)

or you could do what a supplier said to me once is to install a second tankless to help meet the demand of the body spray shower.

Sent from my iPhone using PlumbingZone


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## Catlin987987 (Nov 12, 2010)

Install a holding tank and a pump, set the holding tank @100F. With a 20-40f temp rise you might get 12gpm. Have the hot outlet to the building right after the tankless.


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