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Thread: Tankless in an unconditioned NJ attic

  1. #16

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    Quote Originally Posted by Noth Jersey View Post
    Yeah, it seemed like a practical solution to fill a 200 gallon garden tub and to get the tank out of my home theater.

    Yup, I went tankless to help out with my HT layout. My HT layout is more of a multi purpose room, so I added the washer and dryer hidden at the rear of the HT room. I also added a direct vent gas fireplace for heat for that basement room. I did not have enough room for a clean HT layout, the gas fireplace and a tank type water heater, so I went with a tankless water heater B vented via existing chimney.

    No problems with the tankless even with 40 degree incoming water temperature.

  2. #17
    DIY Senior Member Noth Jersey's Avatar
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    You know, I could locate the tank elsewhere, but I'd be putting the unit about 20 feet further from the kitchen and the location of the new master suite. The run from the well pump would also be lengthened about 20 feet. I would have to run the 1" Wirsbo PEX along the rim joist to avoid punching 30 holes round trip in my floor joists. I guess I'd have to run the whole bundle of 1/2" along the rim joist as well. I'm just want to be sure I can supply enough volume for my Kohler River Bath and everything else.

  3. #18
    Master Plumber master plumber mark's Avatar
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    Talking you are in for some trouble

    If your attic is not heated,, it will eventually freeze solid....

    so why not just put
    that tankless heater outside on the back porch so when it
    finally freezes and explodes it wont flood the whole house????

    it might as well be outside ......


    those peopel that give the advice on these things
    will tell you ahything to get you to buy one



    you are on a well, so you got to have a water conditioner

    where are you going to put the water conditioner??

  4. #19
    Master Plumber master plumber mark's Avatar
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    Talking installed into an existing chimmney???

    Quote Originally Posted by Ladiesman271 View Post
    Yup, I went tankless to help out with my HT layout. I did not have enough room for a clean HT layout, the gas fireplace and a tank type water heater, so I went with a tankless water heater B vented via existing chimney.

    No problems with the tankless even with 40 degree incoming water temperature.

    I dont want to tell you what to do, but what I have read
    about all the tankless is that they must have a dedicated chimmney usually run out of the proper SS materials...

    I also was going to install one into my brick and tile chimmney and save me tons of trouble,,,,
    but was told by Takagi that was a very bad no-no...

    I might burn down the house due extremely to high temps...

    did you b-vent completely through an existing old chimmney, or did
    you jsut dump the fumes into an old chimmney



    but you ought to check this out with whoever you bought that from

  5. #20
    DIY Senior Member Noth Jersey's Avatar
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    Quote Originally Posted by master plumber mark View Post
    If your attic is not heated,, it will eventually freeze solid....

    so why not just put
    that tankless heater outside on the back porch so when it
    finally freezes and explodes it wont flood the whole house????

    it might as well be outside ......


    those peopel that give the advice on these things
    will tell you ahything to get you to buy one



    you are on a well, so you got to have a water conditioner

    where are you going to put the water conditioner??
    I really wanted to colocate the heater with the water softener and the blasted flow restricting sediment filter, but they sit in the corner of the house with the main entry door, porch, windows on both walls, and sidewalks below (this is a largely above-grade walk-out basement). If I ran the vent along the rim joist, I'm not sure I could maintain clearance from combustible materials. The twenty-foot run would also require a five-inch drop for condensate drainage.

    So the whole freeze protection to -30 is inaccurate? The advice I got was post-purchase from the Rheem folks. They seemed pretty convinced that it would operate OK in the attic. Macplumb 777 told me about a freeze kit from Paloma, which apparently owns Rheem. I don't like the sound of having the coil freeze solid.
    Last edited by Noth Jersey; 01-21-2009 at 06:26 PM.

  6. #21

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    Quote Originally Posted by Noth Jersey View Post
    You know, I could locate the tank elsewhere, but I'd be putting the unit about 20 feet further from the kitchen and the location of the new master suite. The run from the well pump would also be lengthened about 20 feet. I would have to run the 1" Wirsbo PEX along the rim joist to avoid punching 30 holes round trip in my floor joists. I guess I'd have to run the whole bundle of 1/2" along the rim joist as well. I'm just want to be sure I can supply enough volume for my Kohler River Bath and everything else.

    FWIW, my tankless is about 40 feet from our master bath. In comparision between our old tank setup and our tankless, it takes about 8 seconds longer to get hot water now to get to the shower.... No biggy. You won't have a problem filling that 200 gal tub that's for sure!

    On another note, it would scare the crap out of me to have pipes to tankless in the attic that could freeze. Talk about a making a mess of the house. But maybe they do that up north and don't think twice.
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  7. #22
    Retired Defense Industry Engineer jadnashua's Avatar
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    While the anti-freeze stuff IN the tankless might prevent it from bursting internally, it won't do much of anything to the pipes coming and going from it. And, as noted, if you have a power outage, all bets are off. Keep in mind that all of that combustion air is being pulled through cracks in your house, bringing in outside air (and if it can't get enough, creating CO). This negative pressure will also affect things like a gas stove, dryer, fireplace, etc. This will mean more air you have to heat, killing any savings on the tankless. In the winter, what does it say about gpm flow rates? The things often adjust the flow based on the incoming water temperature. So, to get it warm enough, you might only get 3 gpm, so to fill your 200 gallon tub, would take maybe over an hour. In that time, what is in there is cooling off, so you'd be tempted to start with it much hotter, wasting more energy.

    So, really, what kind of flow rate and outlet temperature can you get with say 40-degree inlet temperature water? Are you willing to wait an hour to fill the tub in the winter? It should go much faster in the summer, but maybe not depending on the depth of the well and the size of the bladder storage tank. The solution, if you stay with tankless is to maybe use two units in series, or get a much bigger unit, which would have even more combustion air makeup problems (unless you go with direct vent). Is your gas line big enough, too? A good 3/4" valve to your tub could draw 14 gallons/minute and fill the tub quickly IF there's enough flow. You sure your pump can keep up and the well produce enough? That's a pretty big tub!
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  8. #23

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    Quote Originally Posted by master plumber mark View Post
    I dont want to tell you what to do, but what I have read
    about all the tankless is that they must have a dedicated chimmney usually run out of the proper SS materials...

    I also was going to install one into my brick and tile chimmney and save me tons of trouble,,,,
    but was told by Takagi that was a very bad no-no...

    I might burn down the house due extremely to high temps...

    did you b-vent completely through an existing old chimmney, or did
    you jsut dump the fumes into an old chimmney



    but you ought to check this out with whoever you bought that from


    Takagi specifies type 3 venting. The Takagi units have fan assisted exhaust. You can't vent those units into a chimney per the gas code book. That so called "high temperature" claim means nothing to me.

    I have an older atmospheric vented ELM Aquastar that only requires a single wall gas vent into a gas vent or chimney. B vent is preferred over single wall in a cold climate (gas code). My unit is 5" B vented to the 8 x 12 (?) clay tile liner of the masonry chimney. This conforms to the 7 X rule.

  9. #24
    Master Plumber master plumber mark's Avatar
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    Talking the clay liner was the problem

    Quote Originally Posted by Ladiesman271 View Post
    Takagi specifies type 3 venting. The Takagi units have fan assisted exhaust. You can't vent those units into a chimney per the gas code book. That so called "high temperature" claim means nothing to me.

    I have an older atmospheric vented ELM Aquastar that only requires a single wall gas vent into a gas vent or chimney. B vent is preferred over single wall in a cold climate (gas code). My unit is 5" B vented to the 8 x 12 (?) clay tile liner of the masonry chimney. This conforms to the 7 X rule.
    that is about what I had palnned, and for me it would
    have been almost a direct dump into the 8x12 tile liner...

    I was told that Takagi frowns on that....becasue it blasts out of the unit almost like a jet engine...


    So if they tell me it might burn my house down,

    I generally take notice..
    I will have to do some more ivestigation....




    This sort of makes me wonder how many people
    have thrown away the instruction manuels and just
    rigged up these things to what loooks like will work..???.

  10. #25

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    Quote Originally Posted by master plumber mark View Post
    that is about what I had palnned, and for me it would
    have been almost a direct dump into the 8x12 tile liner...

    I was told that Takagi frowns on that....becasue it blasts out of the unit almost like a jet engine...


    So if they tell me it might burn my house down,

    I generally take notice..
    I will have to do some more ivestigation....




    This sort of makes me wonder how many people
    have thrown away the instruction manuels and just
    rigged up these things to what loooks like will work..???.


    I think the issue is moisture, not excess heat. You ever hear the story about the exploding tank type water heater? How about the exploding house?

    I have read the 1996 Gas Code Handbook, and what it pretty much says in Section 11 is that fan assisted units can not vent into a masonry chimney. You need to have all old type draft hood units with no fan assist on any unit connected to the vent. There are various tables in that vent section.

    Anyway, the handbook also states:

    Exception: The installation of vents serving listed appliances shall be permitted in accordance with the manufacturer's instructions and the terms of the listing.

    The way I understand the gas code, since the Takagi units (all fan assisted) require the type 3 vent that is what has to be used. That means follow the Takagi instruction manual.

    If my present tankless ever goes bad and is not repairable, there is no current B vent unit around that has a thermostatic water temperature control. I will be forced to do a chimney reline or something else if I need to replace my present unit.

    I still have my 50 year old original hot air furnace that I am looking to replace in the near term. The plumbing inspector said that as long as the water heater drafts properly after the old FHA heater is removed from the shared vent, I only have to conform to the 7 times rule for the water heater.
    Last edited by Ladiesman271; 01-22-2009 at 05:47 AM.

  11. #26
    In the trades Dana's Avatar
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    Yep, the issue with the newer higher efficiency forced-draft units is condensation. With less dilution air they get better controlled higher combustion-efficiency, but less dilution air also means higher CO2 concentration, which lowers the exhaust's dew point. That, combined with the lower exhaust temp due to the higher-efficiency heat exchanger, stack condensation is all but guaranteed (even in side vented units.)

    The older atmospheric drafted units like the E.L.M. never got much above 80% combustion efficiency, whereas the newer ones are all in the mid- or even high 80s. The new ones are in many respects more akin to low-mass modulating boilers than the old-school tankless heaters.

  12. #27

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    I don't think these things are meant to be installed outdoors in a freezing climate. Takagi says that their freeze protection is only good to 5 degrees F. Your going to be running a lot of electricity to keep that thing from freezing all winter long.

  13. #28
    DIY Senior Member Noth Jersey's Avatar
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    Quote Originally Posted by tourne View Post
    I don't think these things are meant to be installed outdoors in a freezing climate. Takagi says that their freeze protection is only good to 5 degrees F. Your going to be running a lot of electricity to keep that thing from freezing all winter long.
    You're right, I think most of the outdoor models still need protection from freezing temperatures. The only basic difference between my indoor model and the outdoor model is the vent. I talked to Rheem and several techs told me that an attic install would be OK as long as my vent is sufficiently long. The inline condensate drain seems like a bad idea, especially if the heater will be in close proximity to the termination. I'm going to do a short offset with an elbow condensate drain to avoid freezing.I'm going to place the pex under tented insulation in the attic. I've also considered putting a small electric heater in a vented enclosure in the attic.

  14. #29
    Retired Defense Industry Engineer jadnashua's Avatar
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    It's my understanding that you don't see a lot of condensation until the efficiency gets a little higher. My boiler (obviously not the same as a tankless), condenses even in the summer when it's 90-degrees out (it's at about 95%). My old boiler was 88%, and there'd sometimes be drips out the exhaust vent (the horizontal section had to have a downward pitch to ensure it didn't fall back into the burner). It was hot enough to ensure it couldn't condense for at least a few feet, and you had to turn from vertical to horizontal before that.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  15. #30
    Master Plumber master plumber mark's Avatar
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    Talking they are menat for florida and arizona

    [quote=Noth Jersey;181255]You're right, I think most of the outdoor models still need protection from freezing temperatures.

    I hope that you dont find out the hard way about these things...

    the outside units that are menat to be put outside are meant for Arizona, and florida.. NOT NEW JERSEY


    I will be going to a meeting with the "expert" on thursday, the owner of the biggest supply house in our state. is having a seminar about plumbing issues
    that we all face today... sells only about 50 Takagi units a month...

    going to see if I can shake him down for a decent Takagi unit... and I am going to talk to them about
    the issue of installing these things directly into the chimmney...

    and I am going to find out wether its condensation or high temperatures that they are worried about...

    .

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