# Need help on new install



## 100 Watt (Aug 11, 2011)

First off, I'm a plumber but have little experience with boilers. Ordinarily I would pass on this job - but he's a friend and I'm trying to help him out (translation = I'm not making any $ on this). He has a new barn with living quarters in one end. He has already looped Pex underslab for heating two zones. And yes it was installed properly. He is wanting a Navien Combi 240. He also wants to hang an air handler (100k btu) in the other end of the building about 50' away. The air handler won't get much use. Only when he's working out there. The living quarters (1000 sq ft) are for guests. Obviously the combi unit would do his dhw as well. I've looked at the Navien install guides but dont see one for radiant floor heat and an air handler. Any suggestions on how to pipe it? Thanks.


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## beanburner (Apr 30, 2012)

100 Watt said:


> First off, I'm a plumber but have little experience with boilers. Ordinarily I would pass on this job - but he's a friend and I'm trying to help him out (translation = I'm not making any $ on this). He has a new barn with living quarters in one end. He has already looped Pex underslab for heating two zones. And yes it was installed properly. He is wanting a Navien Combi 240. He also wants to hang an air handler (100k btu) in the other end of the building about 50' away. The air handler won't get much use. Only when he's working out there. The living quarters (1000 sq ft) are for guests. Obviously the combi unit would do his dhw as well. I've looked at the Navien install guides but dont see one for radiant floor heat and an air handler. Any suggestions on how to pipe it? call Metropolitan Industries in Romeoville ,Illinois 60446 (815-886-9200) explain to them the set up you have,the company goes way above help its clients


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## rjbphd (Feb 5, 2010)

100 Watt said:


> First off, I'm a plumber but have little experience with boilers. Ordinarily I would pass on this job - but he's a friend and I'm trying to help him out (translation = I'm not making any $ on this). He has a new barn with living quarters in one end. He has already looped Pex underslab for heating two zones. And yes it was installed properly. He is wanting a Navien Combi 240. He also wants to hang an air handler (100k btu) in the other end of the building about 50' away. The air handler won't get much use. Only when he's working out there. The living quarters (1000 sq ft) are for guests. Obviously the combi unit would do his dhw as well. I've looked at the Navien install guides but dont see one for radiant floor heat and an air handler. Any suggestions on how to pipe it? Thanks.


 If navien 240 means 240,000 btu... sounds WAY oversized... and what make you think the pex tubings was installed properly if he wanted to save money?? I've seen more screwed up radiant heating jobs installation than the boiler itself.


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## Catlin987987 (Nov 12, 2010)

rjbphd said:


> If navien 240 means 240,000 btu... sounds WAY oversized... and what make you think the pex tubings was installed properly if he wanted to save money?? I've seen more screwed up radiant heating jobs installation than the boiler itself.


Its only 199MBH, If anything I am guessing it would be working pretty hard. I seen a calculation of how you can only get 60-80MBH out of the heater


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## rjbphd (Feb 5, 2010)

Catlin987987 said:


> Its only 199MBH, If anything I am guessing it would be working pretty hard. I seen a calculation of how you can only get 60-80MBH out of the heater


I've done a 1000 sq ft radiant floor heat with too many windows using 40,000 btu water heater which also used as dhw.


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## Catlin987987 (Nov 12, 2010)

rjbphd said:


> I've done a 1000 sq ft radiant floor heat with too many windows using 40,000 btu water heater which also used as dhw.


The navian can modulate down to 20MBH.


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## Plumbworker (Oct 23, 2008)

there should be a diagram in the instruction manual on how to pipe multi temp systems....


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## bct p&h (Jan 19, 2013)

Plumbworker said:


> there should be a diagram in the instruction manual on how to pipe multi temp systems....


It's on page 23 of the install manual that can be downloaded from their website


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## Plumbworker (Oct 23, 2008)

bct p&h said:


> It's on page 23 of the install manual that can be downloaded from their website


yeah thats what i thought they make it soo easy for the installers nowadays.. just follow their diagram..

i get guys calling me all the time with questions the first thing i ask them is "did you read the manual?..." 99% the response i get is "no?" lol... everything you need to know is in that damn manual.. hell im sure it even walks you through sizing the gas piping..


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## bct p&h (Jan 19, 2013)

Plumbworker said:


> yeah thats what i thought they make it soo easy for the installers nowadays.. just follow their diagram..
> 
> i get guys calling me all the time with questions the first thing i ask them is "did you read the manual?..." 99% the response i get is "no?" lol... everything you need to know is in that damn manual.. hell im sure it even walks you through sizing the gas piping..


They do have a gas sizing chart in the install book Haha
Naviens are pretty straight forward and the book is fairly easy to read but you can tell it was translated from Korean to English with some of the wording.
If you go to the homeowner section of their website it will even help you size the domestic side of the heater by putting in how many people live in the house, number of bathrooms, if there are any roman tubs and body sprays in the house.
With the internal pump you can pipe it pretty much anyway you want as long as you have a primary loop and it will work. Closely spaced tees work, pulling feeds off the top of the primary and returns off the bottom work, you can do a primary loop off of the branches of two tees close to the boiler and dead end supply and returns off of the runs of the tees too.
I've put in about 75 of them and fixed countless others that were piped incorrectly by other people. Once you understand them they are a pretty nice unit especially for the money.


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## plbgbiz (Aug 27, 2010)

I just wish they would take the shell game tactics out of their marketing. 

I think their "it only needs 1/2" pipe" scam is a new low for tankless marketers.


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## bct p&h (Jan 19, 2013)

plbgbiz said:


> I just wish they would take the shell game tactics out of their marketing.
> 
> I think their "it only needs 1/2" pipe" scam is a new low for tankless marketers.


I talked with the local rep about that and he said you can run it in ½" for x number of feet because it will suck the gas out of the line. So if it's close to another running appliance it could actually suck it dry and shut the other appliance off which could start sucking air into the line? No thanks. Every tank less I have put in has gotten 1" except 3 that I can think of that I could only get ¾" to but were close enough to the meter that the sizing worked out. I have a bad feeling I'm going to be changing out a lot of undersized gas pipe to these new water heaters they're saying will work on ½".


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## shakeyglenn68 (Dec 29, 2010)

bct p&h said:


> I talked with the local rep about that and he said you can run it in ½" for x number of feet because it will suck the gas out of the line. So if it's close to another running appliance it could actually suck it dry and shut the other appliance off which could start sucking air into the line? No thanks. Every tank less I have put in has gotten 1" except 3 that I can think of that I could only get ¾" to but were close enough to the meter that the sizing worked out. I have a bad feeling I'm going to be changing out a lot of undersized gas pipe to these new water heaters they're saying will work on ½".


Installed 4 units on 1", 2 where over 110' runs the reg on manifold is rated for 8-10mbh (manifold has 9 legs 4x1", 5x1/2") suck lines is an understatement! when 3 units come on it shuts off the stove. Thank God I convinced them to run the pool heater & out door fire pit seperate lines for another meter! The total btuh call on home without pool heater & firepit is 6millionbtu


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