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Thread: Need advice on tankless/PEX system

  1. #1

    Default Need advice on tankless/PEX system

    I am using PEX for the first time. I just bought a tiny house and have pulled out all the old plumbing stuff. I thought maybe I could save space in the kitchen closet by going tankless. The question is, how far away does a tankless water heater have to be from the manifold to be safe. I see in the Manabloc manual that it should be mounted 18" horizontially or 36" vertically, but I was wanting to put the water heater above the manifold instead of below using something like this.
    Eemax series II

    Does the fact that it is above the manifold make a difference in heat stacking? Anybody have any good ideas of how to put both together with minimal space?


    Michael

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    Your link get corrupted...probably because it included a name Terry doesn't want to compete with. You may need to spell it out rather than how you did it.

    If small locations with limited needs and users, a tankless can make sense. They require much more maintenance than a tank, and will be harder to get parts for when it needs them, possibly leaving you without service while they arrive. If you live where the incoming water gets very cold in the winter, make sure you take that into your calculation as to what you need. This could also be a factor if you have a deep well, that water can be quite cold year round once you get the tank emptied.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3

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    Thanks Jim,
    I live in Georgia where it's not so much an issue. In fact I've found myself taking cold showers here in the summer Anyway, I am particularly curious about the distance away a heater needs to be from the manabloc. I can't seem to find any documentation anywhere about mounting a tankless above a manifold. It's seems safe enough, but I would hate to be the unfortunate pioneer that had to replace both my heater and my manifold.

    Again, thanks for your help.

  4. #4

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    Where I live at for any water heaters (tank or tank less) you must have at least 6 inches of copper then a tempering valve and then another 12 inches of copper. As far as I know this is a local code issue and I do think it will spread in a few years. Look into local codes before starting.

    I have seen where a few tank less systems say to use copper for the first 12Ē or you get in to the warranty thing.

    I would think that the best solution for you would to mount your hot and cold manifolds under the unit at about 3.5 feet high. As far as the heater I would mount it about 4 to 5 feet or as the manual wants. As far as how to get your 18 or 36 inches I would get a 4í stick of copper and 5 elbows and the fittings for the manifold and the tank.

    Run the copper out of the heater a few inches and turn down.
    Run down a few inches past the heater and toss on your second elbow to run under the heater.
    Run to the far side of the heater (at least 12 inch run).
    Use 2 more elbows to turn around.
    Run back about 10 inches toss on an elbow and then down to where you want your manifold.

    With mounting the heaters I like to be able to stand and work on them (we have hard water so I work on them a lot). When I install a manifold I like to be able to work on them whale sitting on a 5 gallon bucket. (I hate PEX unless it is part of a heating system so I have not gotten to be the best with it and I end up having to pick up and set down my tools a lot.

    I found in a tight location itís quicker to hit 18Ē before you hit 36Ē. I will tell the talk to the owner about the problems with there tank less system and draw them a layout of the manifold, heater, and the copper pipe before installing or they think Iím high when the look at it.

  5. #5
    Licensed Grump GrumpyPlumber's Avatar
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    Quote Originally Posted by got_nailed
    Where I live at for any water heaters (tank or tank less) you must have at least 6 inches of copper then a tempering valve and then another 12 inches of copper. As far as I know this is a local code issue and I do think it will spread in a few years. Look into local codes before starting.

    For us it's a minimum 24" from any boiler or heater before you can connect PEX or CPVC...DEFINITELY a local code check
    "The biggest regrets we have in life are the chances we never took."

  6. #6

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    Where Iím at they say at least 6 inches off the heater tank less or tank then a tempering valve and another 12 of copper on the outlet. The inlet we have to have 12 of copper butting up to the heater. After you meat this you can use anything you want.

    We have to install tempering valves on everything if you do anything within 3 feet of the hot water heater and bring it up to code as stated above.

    The bad part is trying to tell people that if I ďTĒ off the lines right there itíll be another $150 but if I move down a few feet it will be cheaper. Iím to the point that when I step in to your hose and I look at whatís going on that I will pull out a sheet of paper that has this on it with a copy of the local code and there contact info. I will make them sign it and let them keep a copy.


    I had an issue a few months ago where someone could not get there hot water heater lit and I could see the problem right off. When I said it will be $175 to fix it and explain what I would have to do I was kicked out the door. I did call to see if they would let me to relight the burner with out the tempering valve they said no. I told the husband to meat me down the road at the gas station in 10 min so I could tell him that he was confused about the orientation of the gas valve handle to the way the pipe was run. When he thought it was on it was off. He handed me a 50 and thanked me for my time. He asked me for a few of my cards because I was now his plumber for life. So far I have done 2 small jobs, and an addition. I think I have had about 30 referrals off him but Iím not sure.

    -GrumpyPlumber-
    At one point we had 24 horizontal or 42 vertical of copper before you could use anything but copper. On the inlet of a heater you had to use 12 of copper before you tied in.
    Most of the tank less systems I have seen had 18" horizontally or 36" vertically of copper before you could use plastic.
    I donít think itís worth going into why they want the copper on both sides of a water heater but someone say the word and Iíll get into this.

  7. #7
    Licensed Grump GrumpyPlumber's Avatar
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    Quote Originally Posted by got_nailed
    I had an issue a few months ago where someone could not get there hot water heater lit and I could see the problem right off. When I said it will be $175 to fix it and explain what I would have to do I was kicked out the door. I did call to see if they would let me to relight the burner with out the tempering valve they said no. I told the husband to meat me down the road at the gas station in 10 min so I could tell him that he was confused about the orientation of the gas valve handle to the way the pipe was run. When he thought it was on it was off. He handed me a 50 and thanked me for my time. He asked me for a few of my cards because I was now his plumber for life. So far I have done 2 small jobs, and an addition. I think I have had about 30 referrals off him but Iím not sure.

    -GrumpyPlumber-
    At one point we had 24 horizontal or 42 vertical of copper before you could use anything but copper. On the inlet of a heater you had to use 12 of copper before you tied in.
    Most of the tank less systems I have seen had 18" horizontally or 36" vertically of copper before you could use plastic.
    I donít think itís worth going into why they want the copper on both sides of a water heater but someone say the word and Iíll get into this.
    Nah...the codes are different state by state...what really got my attention was your story.
    When I first went self employed my "better half" couldn't understand why I went to such great lengths to make sure the customers where happy.
    I'd let them berate me, blame me for things that weren't related to plumbing, then tactfully enlighten them after they'd cool off.
    She understands now, I get a majority of my work through referrals..keeps the ad budget waaayyyy down (yellow pages are beaucoup bucks and not very effective these days)
    Your story, I will admit, trumps any of mine....kudo's to you.
    "The biggest regrets we have in life are the chances we never took."

  8. #8

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    I work at a Japanese plant that makes the friction disks for automatic transitions. They build them for every thing form motorcycles to trains. I work night shift working on the computer systems that run all the Japanese machines. I deal with DC up to 90 volts and 120 AC. The good old computers, the relay systems, electronic air valves, and all kinds of other stuff.

    I mostly do new houses, additions, hot water heaters, some well stuff, and some repair work. I have never put any ads in any where and I donít plan on it. The bad part is I donít even own a hand snake. Most of the big stuff I do I come in on Friday night and work through Sunday morning. I can ruff in a 4 bedroom 3 Ĺ bath in a weekend just me and my g/f. During the week I will do about 12 hours of work mostly getting the stuff for my next week end. Most of my work comes off of 3 GCs and I think the main reason the use me is they know I will be there and be gone and done by the time they get back.

    Right now Iím tied up for the next 3 months on the weekends doing ruff ins and a few finish work jobs. The one smart GC I work for has the first and third weekend pre booked till the end of the year. The bad part is I will have know idea what Iím doing till the week before witch put me into having to having my own supply house.

    My g/f dose 90% of my paper work, deals with all of my calls, keeps my orders up to date, and has to do all the inventory on my supply house. When I take a job I order all the finished stuff right then and store it till I need it. She went hay wire last month because I had over 100 grand of stuff in my supply house and only 50 grand in my business account.


    As far as the state to state code changes I donít know to much about but I work in 3 different counties and all the codes are different. I went through all of them and made my own codes that I use that are worse than thereís. So far I have only failed one inspection in 2 years and that was for a PVC line that had been hit with a saw on a Monday and my inspection was on a Tuesday. That was a $2,000 repair because I had to be out ASAP so he could get a second inspection so he could rock the walls.

    I think this thread is now hijacked.

  9. #9
    Licensed Grump GrumpyPlumber's Avatar
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    Quote Originally Posted by got_nailed
    I think this thread is now hijacked.

    Lost me on that...meaning off topic?
    "The biggest regrets we have in life are the chances we never took."

  10. #10

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    Not just off topic but taken over.

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