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Thread: Changing to 1/2 pipes

  1. #1
    DIY Member ChuckS's Avatar
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    Default Changing to 1/2 pipes

    As I keep saying, the problem with our new tankless is the time it takes to get hot water. All of the pipes except the last little bit that goes to the facets are 3/4". I am wondering, what will happen if I change everything on the output side of the tankless to 1/2" pipes? What negative effect would that have?

    My logic is there would be less water to clear out the pipes before we get to the hot stuff...

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    Forum Admin, Expert Plumber Terry's Avatar
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    All of the pipes except the last little bit that goes to the facets are 3/4". I am wondering, what will happen if I change everything on the output side of the tankless to 1/2" pipes?
    It will no longer meet plumbing code for one.

    You will be reduced to using only one faucet at a time.
    Everyone in the house will have to take turns using water.

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    DIY Member ChuckS's Avatar
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    Quote Originally Posted by Terry View Post
    It will no longer meet plumbing code for one.

    You will be reduced to using only one faucet at a time.
    Everyone in the house will have to take turns using water.
    Bad idea I guess, I don't want to be against code...

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    Master Plumber nhmaster's Avatar
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    You should ask Greggy. It's probably all your imagination or something you did wrong.

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    Moderator & Master Plumber hj's Avatar
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    Default pipes

    If the tankless replaced a tank type, the time it takes the water to get there should be EXACTLY the same as it was before. Tankless give you more hot water, not faster hot water unless you move the heater closer to the bathroom.

  6. #6
    DIY Member ChuckS's Avatar
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    Quote Originally Posted by hj View Post
    If the tankless replaced a tank type, the time it takes the water to get there should be EXACTLY the same as it was before. Tankless give you more hot water, not faster hot water unless you move the heater closer to the bathroom.
    The tankless was installed about 20' further from where the old tank was. So he ran a 3/4" X 20' line and tied it in where the old tank heater was. So now we have 3/4" X 20' delay on top of the delay from the old tank heater.

    Our kitchen facet flows at exactly 1gpm according to my scientific testing. I timed how long it took to fill an empty 1 gal milk jug and it was exactly 60 seconds.

    I added a recirculation loop which cut the time to hot water from just over a minute down to about 45 seconds. Unfortunately there seems to be a bottleneck in the recirculating loop where the water goes into the input side of the tankless heater. The bottleneck appears to be twofold, 1. the recirculated water has to compete with the city water pressure for a place to go and 2. the tankless heater limits how much water it allows in by it's ability to put up to temp water out.

    What I really need is a tank or bladder that can quickly take the 2 gals of cold water that is sitting in the 35' of 3/4" lines then slowly release it into the input side of the tankless as we use hot water so te tank or bladder will be empty and ready for the next water use.

    Something similar to the lungs in our body that can suck in 2 gals in say 20 secs on the inhale phase then after about 30 seconds of holding the water, exhale slowly but with enough pressure to win the contest against the city water so it can be emptied by feeding the water back through the water heater so the tank is emptied and ready for the next cycle.

    My imagination takes me to an in line expansion tank with a compressor. If the air pressure would quickly drop when you turn on the facet it will allow the 2 gals of water sitting in the lines to enter the expansion tank. Then the compressor can kick on say 1 minute later. As the compressor increases the air pressure in the expansion tank, th expansion tank will begin releasing its content back into the system... I have no idea how to build something like this or what kind of parts to use but this would work great according to my feeble mind...

  7. #7

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    I have no idea how to build something like this or what kind of parts to use but this would work great according to my feeble mind...

    Well gosh. Now we have monkeys so smart that they are doing pluming stuff.
    And now you go ands ask that qestion, and it makes me feel kinda lik a monkeys uncle. I cant figger it out either.
    What do you mean breathe in and out.
    You mean like a scuba diver?
    Do they are breathing water in and out, and it gets warmer?
    So the water get waremer. then then you drink it.,
    But is it good to drink water that has been in a scuba divers lungs?
    Does this seem right?

  8. #8
    Master Plumber nhmaster's Avatar
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    Puttin a re-circ line on a tankless usually voids the warranty.

  9. #9

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    Quote Originally Posted by nhmaster View Post
    Puttin a re-circ line on a tankless usually voids the warranty.

    Not if you follow the directions that are supplied with a lot of tankless heaters. Then again, you have to read the directions first before you can follow them!
    Samuel James Witwicky

  10. #10

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    Quote Originally Posted by ChuckS View Post
    The tankless was installed about 20' further from where the old tank was. So he ran a 3/4" X 20' line and tied it in where the old tank heater was. So now we have 3/4" X 20' delay on top of the delay from the old tank heater.

    Our kitchen facet flows at exactly 1gpm according to my scientific testing. I timed how long it took to fill an empty 1 gal milk jug and it was exactly 60 seconds.

    I added a recirculation loop which cut the time to hot water from just over a minute down to about 45 seconds. Unfortunately there seems to be a bottleneck in the recirculating loop where the water goes into the input side of the tankless heater. The bottleneck appears to be twofold, 1. the recirculated water has to compete with the city water pressure for a place to go and 2. the tankless heater limits how much water it allows in by it's ability to put up to temp water out.

    What I really need is a tank or bladder that can quickly take the 2 gals of cold water that is sitting in the 35' of 3/4" lines then slowly release it into the input side of the tankless as we use hot water so te tank or bladder will be empty and ready for the next water use.

    Something similar to the lungs in our body that can suck in 2 gals in say 20 secs on the inhale phase then after about 30 seconds of holding the water, exhale slowly but with enough pressure to win the contest against the city water so it can be emptied by feeding the water back through the water heater so the tank is emptied and ready for the next cycle.

    My imagination takes me to an in line expansion tank with a compressor. If the air pressure would quickly drop when you turn on the facet it will allow the 2 gals of water sitting in the lines to enter the expansion tank. Then the compressor can kick on say 1 minute later. As the compressor increases the air pressure in the expansion tank, th expansion tank will begin releasing its content back into the system... I have no idea how to build something like this or what kind of parts to use but this would work great according to my feeble mind...



    Do you have a water shortage? If not, why are you spending your time and money on a recirculation system?

    I doubt if your recirculation system is installed the correct way. If the recirculation system was installed the correct way, hot water would be at the tap in a few seconds after you turn on the tap!
    Samuel James Witwicky

  11. #11
    Master Plumber nhmaster's Avatar
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    One more stooge and you guys would have a career in movies.

  12. #12
    DIY Member ChuckS's Avatar
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    Quote Originally Posted by Ladiesman271 View Post
    Do you have a water shortage? If not, why are you spending your time and money on a recirculation system?

    I doubt if your recirculation system is installed the correct way. If the recirculation system was installed the correct way, hot water would be at the tap in a few seconds after you turn on the tap!
    See diagram... http://img153.imageshack.us/img153/7...ulationfv9.jpg

    Mine is not a normal recirculation system that runs on a timer etc...

    I have a flow switch that kicks on the pump as soon as a facet is opened. The aquastat then turns the pump off when the line gets hot. This way the recirculating system only runs when I need hot water instead of paying to heat water when not in use.

    I can also turn a facet on and then off again when I go to the rest room to start the recirculating system and by the time I am done doing my business, I have hot water ready to go.

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    Master Plumber Redwood's Avatar
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    Redwood points the spray in laddy boys face and....
    PPPFFFFSSSSSSSTTTTT


  14. #14
    DIY Member ChuckS's Avatar
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    Quote Originally Posted by nhmaster View Post
    Puttin a re-circ line on a tankless usually voids the warranty.
    This is from my heaters warranty. From my guestimation, I still have the full warranty with the type of loop I installed but would still have 3 years warranty even if my loop doesn't qualify.

    All Applicable Warranties will be limited to three (3) years from the Effective Date if the water heater is installed in a system in which the water is re-circulated, but not if it is an on-demand re-circulation system which utilizes existing hot and cold water lines, or a dedicated return line without the use of a temperature sensor, timer, or a continuously operating pump.

  15. #15
    Master Plumber nhmaster's Avatar
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    and what is the warranty without the loop at all? 3 years goes by real fast.

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