(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 8 of 8

Thread: Tankless water heat lag to closest faucet

  1. #1
    DIY Junior Member Kevin Wang's Avatar
    Join Date
    Jan 2014
    Location
    Texas
    Posts
    1

    Default Tankless water heat lag to closest faucet

    I just bought a brand new home with a tankless water heater. My problem: it takes minutes to receive warm water to my kitchen sink which is the closest faucet to my garage-tankless heater. The water never reaches the hotness of my shower upstairs, which receives hot water within a minute. Seller adjusted the hot/cold valves under the kitchen sink but it still takes forever to reach warm temperature. Sometimes, it never gets warm.

    I have not washed hands in warm water in any bathroom faucets either (don't have it on longer than 30 seconds to see if it ever warms up).

    I'm not sure if this is what I should expect with a tankless water heater, or if I need to complain to my homebuilder given I have a 1-year warranty on everything. Any tips by you experts out there on how to troubleshoot this further to determine if there is a defect in my plumbing or if this is working "as intended"? Should I feel the pipes coming out of my water heater and time how long before it gets hot? Thanks for any help.

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,374

    Default

    Whenever the WH is located a long ways from the point of use, it takes time to purge the lines of the room temperature water there, unless it was run recently and some is still warm. The alternative is to recirculate the water like is done in large buildings. But, with many tankless systems, it can either void or significantly shorten the warranty on the unit.

    The tankless systems also have a minimum flow before they'll turn on, so it may never be enough if you have the faucet set to what normally would have been warm. Once they turn on, they may stay on until the flow stops, but getting an initial warm may be tougher.

    There are a few recent threads on similar issues...check this forum and read a few.

    But, once you do get hot somewhere, it should be about the same temp.

    The only other thing I can think of, and it normally isn't an issue with new faucets, is if one of them is defective, and is effectively creating a cross-over - this would dilute the hot, potentially considerably. Do you have anything like, say on the washing machine that connects cold with the hot? Try shutting the valves to the washing machine off and see if it makes any difference. It shouldn't, but it won't hurt to try.

    It may help to also know the brand and model of the tankless unit.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    DIY Senior Member Smooky's Avatar
    Join Date
    Apr 2011
    Location
    NC
    Posts
    479

    Default

    There may be a mixing valve/tempering valve that needs to be adjusted. If the faucet aerator is clogged it takes longer to purge the cold water out of the pipes. Maybe a different type of aerator would help. I think I would open both valves under the sink, all the way.

  4. #4
    Forum Admin, Expert Plumber Terry's Avatar
    Join Date
    Aug 2004
    Location
    Bothell, Washington
    Posts
    14,191
    Blog Entries
    1

    Default

    Most tankless water heaters come preset for 120 degrees.
    In the shower, that seems like plenty of heat. Washing hands or doing dishes, that feels colder.
    An easy fix may be to reset the tankless up to 140. I have used them both ways, one home at 120 and the other at 140.
    Regardless, it does take more time to get heated water with tankless unless you have a recirc line to keep the line warm to the faucet.

  5. #5
    DIY Junior Member TheLex's Avatar
    Join Date
    Jan 2014
    Location
    Northern California Sierra Foothills
    Posts
    23

    Default

    Quote Originally Posted by Terry View Post
    Most tankless water heaters come preset for 120 degrees.
    In the shower, that seems like plenty of heat. Washing hands or doing dishes, that feels colder.
    An easy fix may be to reset the tankless up to 140. I have used them both ways, one home at 120 and the other at 140.
    Regardless, it does take more time to get heated water with tankless unless you have a recirc line to keep the line warm to the faucet.
    Terry, but from what I've read once you hook up a recirc line, the warranty on the typical tankless heat exchanger drops from 15 to 3 yrs. That's quite a dramatic drop in warranty period. Is that something to be concerned about? Do the manufacturers know that with a recirc line the heat exchanger is going to fail sooner?

  6. #6
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,374

    Default

    The unit will fire more often. You sometimes also see that sort of warranty change when something is used in a commercial situation verses a residential one.

    Tankless systems, at least most of them, are not designed for continuous operation like a boiler used for heating. With a recirculation system, they would run much more frequently, and that can take a toll.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  7. #7
    DIY Junior Member TheLex's Avatar
    Join Date
    Jan 2014
    Location
    Northern California Sierra Foothills
    Posts
    23

    Default

    Quote Originally Posted by jadnashua View Post
    The unit will fire more often. You sometimes also see that sort of warranty change when something is used in a commercial situation verses a residential one.

    Tankless systems, at least most of them, are not designed for continuous operation like a boiler used for heating. With a recirculation system, they would run much more frequently, and that can take a toll.

    Oh I understand that. But the manufacturer will also state that HEATED recirculated water also shortens the warranty. IOW, if I run a separate electric heater to maintain a reserve tank and that tanked water gets recirculated to eliminate the cold water sandwich effect, the manufacturer also shortens the warranty for that application. This despite the fact that it's the small electric heater that is maintaining the recirculated water temp, not the main boiler on the the big tankless unit.

  8. #8
    DIY Member Soapm's Avatar
    Join Date
    Dec 2013
    Location
    Aurora, CO
    Posts
    47

    Default

    Quote Originally Posted by Kevin Wang View Post
    I just bought a brand new home with a tankless water heater. My problem: it takes minutes to receive warm water to my kitchen sink which is the closest faucet to my garage-tankless heater.
    Did you follow the pipes to see if it's piped as the closest or does the piping take some strange route?

    Quote Originally Posted by Kevin Wang View Post
    The water never reaches the hotness of my shower upstairs, which receives hot water within a minute. Seller adjusted the hot/cold valves under the kitchen sink but it still takes forever to reach warm temperature. Sometimes, it never gets warm..
    What kind of facet is this? Is it a one knob job? Never reaching complete "hot" temp sounds like it's mixing with cold. I wonder if you're not getting full hot water and it's constantly mixing predominately cold. I don't know how the pro's would check but I would take the hot line off below the sink and see if you get the same results there shooting the water into a bucket or via a short hose into the drain.

Similar Threads

  1. Hydronic air handler: tankless water heater or heat pump
    By RichardFore in forum HVAC Heating & Cooling
    Replies: 2
    Last Post: 08-12-2013, 11:31 AM
  2. Does running Furnace cause Tankless Water Heater to not heat water ???
    By cody21 in forum Tankless Water Heater Forum
    Replies: 4
    Last Post: 12-10-2012, 08:43 AM
  3. Tankless WH Radiant Floor Heat
    By cpmarks in forum Boiler Forum
    Replies: 6
    Last Post: 03-28-2012, 12:54 PM
  4. tankless baseboard heat booster??
    By mlease in forum Tankless Water Heater Forum
    Replies: 1
    Last Post: 01-26-2009, 05:46 PM
  5. tankless water heater for radiant heat
    By pmayer in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 9
    Last Post: 09-10-2006, 05:38 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •