# Running a tankless into old water heater



## PlumberJoeOk (Nov 18, 2013)

Customer wants me to run a tankless water heater into a 75 gallon water heater with a recirc on the water heater ... I told him it was over kill ... Anyone ever done this ? He has a 6 bathroom and doesn't want the hot water to ever run out


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## rjbphd (Feb 5, 2010)

PlumberJoeOk said:


> Customer wants me to run a tankless water heater into a 75 gallon water heater with a recirc on the water heater ... I told him it was over kill ... Anyone ever done this ? He has a 6 bathroom and doesn't want the hot water to ever run out


Done it before.. using the heater as a storage tank.. must be piped correctly to get full benifit ..


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## 422 plumber (Jul 31, 2008)

Be a good way to avoid any cold water slugs. Your customer wants to spend more money and you are trying to talk him out of it? You must be buried in work, to turn more down.


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## PlumberJoeOk (Nov 18, 2013)

422 plumber said:


> Be a good way to avoid any cold water slugs. Your customer wants to spend more money and you are trying to talk him out of it? You must be buried in work, to turn more down.


Not trying to talk him out if if just letting him know it's not needed. Some of us are actually honest with customers and don't try to just take their money unnecessarily


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## Hoosier Plumber (Nov 28, 2013)

422 plumber said:


> Be a good way to avoid any cold water slugs. Your customer wants to spend more money and you are trying to talk him out of it? You must be buried in work, to turn more down.


Was thinking the same thing. 



PlumberJoeOk said:


> Not trying to talk him out if if just letting him know it's not needed. Some of us are actually honest with customers and don't try to just take their money unnecessarily


This type of thinking can be the difference between a good year and a great year. 

I'd rather have someone present my options and give me the choice than to make the choice for me. 

Right now I am considering putting a tankless in my home, and while its not needed I am considering using my old tank as a storage unit. I suppose that makes me dishonest with myself. :laughing:


Another thought you might not have considered. What if the unit fails and needs serviced. 75 gallons of hot water at the least will allow the customer minimal usage until service can be performed.


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## 422 plumber (Jul 31, 2008)

PlumberJoeOk said:


> Not trying to talk him out if if just letting him know it's not needed. Some of us are actually honest with customers and don't try to just take their money unnecessarily


That's a great way to fool yourself, thinking you are being honest, when actually you are being dishonest. You are being dishonest by thinking you know what's best for your customers. You can't read their minds. To run a recirc, you need a tank anyway. I used to run them into a 6 gallon heater, because it was the cheapest tank I could find. Thinking about it, I could have used their existing 40 or 50 gallon tank and saved the customer money, and myself a possible injury by hauling the old tank up the stairs. Being a tight azz doesn't make you honest, just tight, bro.


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## wookie (Dec 16, 2008)

The couple of ariston 6 gallon that I've used with a tankless install the customers were'nt real happy with the rise in electric costs. A recirc was installed also with system. A timer was put on the ariston also.

I don't have exact figures but it was significant enough that the customer brought it up.

The eternal sounds good on paper, I've installed one so far at customers request. With plenty of caution from me. Thank goodness ! It went kaput the day I was leaving for Texas at Thanksgiving. Customer was down for a week before replacement unit arrived. Factory rep did the reinstall.


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## PlumberJoeOk (Nov 18, 2013)

422 plumber said:


> That's a great way to fool yourself, thinking you are being honest, when actually you are being dishonest. You are being dishonest by thinking you know what's best for your customers. You can't read their minds. To run a recirc, you need a tank anyway. I used to run them into a 6 gallon heater, because it was the cheapest tank I could find. Thinking about it, I could have used their existing 40 or 50 gallon tank and saved the customer money, and myself a possible injury by hauling the old tank up the stairs. Being a tight azz doesn't make you honest, just tight, bro.


Appearently u don't know that you can run a recirc off the tankless ... But there is a reason the customer calls a plumber out, because they don't know how to do it... So if you get an idiot customer who wants you to hook up all this stuff he doesn't need then he finds out from his huge energy bills that he shouldn't have done it , he is going to assume that the plumber should have known not to do it ... So next time a customer calls you and says "I think I need a new water heater ' and you go out and see that it's just a flex hose leaking you might as well screw the guy and charge him for a new water heater since that's what he called in for , after that you can tell him his toilet needs replaced because it keeps running


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## ROCKSTARPLUMBER (Dec 14, 2008)

PlumberJoeOk said:


> Customer wants me to run a tankless water heater into a 75 gallon water heater with a recirc on the water heater ... I told him it was over kill ... Anyone ever done this ? He has a 6 bathroom and doesn't want the hot water to ever run out


:laughing: Did you explain to this customer how a tankless water heater works?


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## Leach713 (Nov 1, 2013)

PlumberJoeOk said:


> Customer wants me to run a tankless water heater into a 75 gallon water heater with a recirc on the water heater ... I told him it was over kill ... Anyone ever done this ? He has a 6 bathroom and doesn't want the hot water to ever run out


Install 2 tankless 
One tankless feeds one side of the house and vice versa


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## Leach713 (Nov 1, 2013)

Or go with one of these 
http://www.rinnai.us/hybrid-tank-tankless-water-heater/how-it-works


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## 422 plumber (Jul 31, 2008)

PlumberJoeOk said:


> Appearently u don't know that you can run a recirc off the tankless ... But there is a reason the customer calls a plumber out, because they don't know how to do it... So if you get an idiot customer who wants you to hook up all this stuff he doesn't need then he finds out from his huge energy bills that he shouldn't have done it , he is going to assume that the plumber should have known not to do it ... So next time a customer calls you and says "I think I need a new water heater ' and you go out and see that it's just a flex hose leaking you might as well screw the guy and charge him for a new water heater since that's what he called in for , after that you can tell him his toilet needs replaced because it keeps running


Joe, stop with the attitude. I am trying to help. I do very little residential anymore. No need to accuse me of being dishonest. It seems like you are unsure of this, nothing wrong with that. I call other plumbers from job sites and ask questions and pick their brains all the time. Call an tankless rep in your area, and have them design it for you. When I last installed a tankless, which was 2007, you needed a tank if you wanted a recirc. All I have installed is Noritz, so it seems like times have changed. I am saying that if the customer wants to make use of his existing tank, use it! Nothing wrong with making customers happy. I have put in backup pumps, changed sump pumps to ejector pumps, put in ball valves on risers that have angle stops on them right above the floor. You could say they don't need it, if the customer requests it and wants it, does that make me dishonest? I don't think so. It's called peace of mind.


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## MTDUNN (Oct 9, 2011)

I have to agree with Jeff. If you think it's gonna cost the customer more on energy bills, tell him. But if he wants a holding tank, and if it works, and it will, then let him have what he wants.


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## ZL700 (Dec 8, 2009)

*It's these types of installs that give plumbers and tankless a black eye*

Feeding a tank downstream from a tankless (series) results in misguided expectations.

If the tank is fed by a tankless, the flow rate through the tankless is dictated by the size, efficiency and temp rise. Let's say for example the tankless is capable of 5 GPM at a 70 degree rise, then the tank can only be replenished with that flow rate. 

Thus at this point it doesn't matter if the tank is 75 or 750 gallons, the flow rate to the fixtures is still only 5 GPM. And that tank will need to be reheated due to standby loss so, that tank just becomes a complete energy waster. 

Now you could follow proper piping diagrams (as RJ stated) adding a tank to tankless which involves a tank aquastat, external circulator between the tankless and tank and redoing how the cold water enters, but you will still end up with a significant drop in tankless operating efficiency, reduced tankless outputs (tankless manufactures limit the allowed pumped flow rate), dealing with tank heat loss, current consumption of circulator.


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## plumbing ninja (Jan 15, 2012)

MTDUNN said:


> I have to agree with Jeff. If you think it's gonna cost the customer more on energy bills, tell him. But if he wants a holding tank, and if it works, and it will, then let him have what he wants.


 If your customer can afford to own a house with 6 bathrooms, they can afford to pay the energy bill? If you have a houseful full of females there will never be enough hot water and they'll never clean out the trap when it clogs with their hair?


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## MTDUNN (Oct 9, 2011)

Is that a question? Lol


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## mightypipe (Dec 22, 2012)

PlumberJoeOk said:


> Appearently u don't know that you can run a recirc off the tankless ... But there is a reason the customer calls a plumber out, because they don't know how to do it... So if you get an idiot customer who wants you to hook up all this stuff he doesn't need then he finds out from his huge energy bills that he shouldn't have done it , he is going to assume that the plumber should have known not to do it ... So next time a customer calls you and says "I think I need a new water heater ' and you go out and see that it's just a flex hose leaking you might as well screw the guy and charge him for a new water heater since that's what he called in for , after that you can tell him his toilet needs replaced because it keeps running


If his water heater is old enough to have a flex line pop a leak, it is probably old enough to be beyond its useful life, regardless of whether or not the tank is leaking yet. It is probably also inefficient, and if the customer agrees, should be replaced, to avoid the flood and damage to the house which is right around the corner.

Same with his 14 year old crane piece of shiot toilet with the 3.5 gallon tank and water transfer problem, that you say only needs a flapper.

You are doing yourself and your customers a disservice with your 'honesty'.


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## mightypipe (Dec 22, 2012)

Oh yeah... Size him up a proper water heating system and give him what he really needs... Don't hack in some junk.


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## 422 plumber (Jul 31, 2008)

I was figuring on using the existing tank as a storage/recirc tank, not as a heater. Once you quit heating water in tanks, their life span goes up.

Sent from my iPhone using PlumbingZone


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## PlumberJoeOk (Nov 18, 2013)




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## PlumberJoeOk (Nov 18, 2013)

The PEX line coming in from the left is the hot water from the tankless water heater. This guy wanted me to hook the tankless into the tank and the recirc... Any body see anything wrong with doing that?


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## rjbphd (Feb 5, 2010)

PlumberJoeOk said:


> The PEX line coming in from the left is the hot water from the tankless water heater. This guy wanted me to hook the tankless into the tank and the recirc... Any body see anything wrong with doing that?


What the flying fook is that??? Is that domisitc water heater????


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## PlumberJoeOk (Nov 18, 2013)

rjbphd said:


> What the flying fook is that??? Is that domisitc water heater????


Yup. That's what I showed up and saw multiple things that needs changed but it out in bfe with no inspections .... I have a backflow on the outlet of the tankless...


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## MTDUNN (Oct 9, 2011)

I didn't know Salvador Dali dabbled in plumbing


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## rjbphd (Feb 5, 2010)

PlumberJoeOk said:


> Yup. That's what I showed up and saw multiple things that needs changed but it out in bfe with no inspections .... I have a backflow on the outlet of the tankless...


 There's ton of things wrong about it! No exp tank, wrong and way frrickin oversized pump on it, etc etc etc... . You touched it and its your liabitly.. I have walked away from those kind of hackery jobs due to... they'll listen to a better saleman in hack dept.. and get fully paid for it AND then disagree on how much they have to pay to get it corrected..


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## PlumberJoeOk (Nov 18, 2013)

rjbphd said:


> There's ton of things wrong about it! No exp tank, wrong and way frrickin oversized pump on it, etc etc etc... . You touched it and its your liabitly.. I have walked away from those kind of hackery jobs due to... they'll listen to a better saleman in hack dept.. and get fully paid for it AND then disagree on how much they have to pay to get it corrected..


Well the only good thing is I had him sign in invoice that I am not responsible for ANY thing other than the PEX lines and the tankless ...


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## rjbphd (Feb 5, 2010)

PlumberJoeOk said:


> Well the only good thing is I had him sign in invoice that I am not responsible for ANY thing other than the PEX lines and the tankless ...


Did you stamp the humpday Geico logo on it?


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## s.ford (Mar 19, 2014)

Or u could just put 2 tankless in and the pump and aqua stat and use the tank heater for target practice cause u will have all the hot water u can use


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