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Navien tankless heater wasting gas

I built a new home in the northwest about 4 years ago, and had a Navien NPE 210A tankless heater (LPG)installed on a loop system, the house is 3000 ft main floor with 2500 sq ft basement, total 4.5 bathrooms. I know when the heater fires up, as the exhaust is right by the back door by the garage. It kicks on constantly, about once every 20 - 30 minutes (minimum), day and night, summer and winter. I filled my propane tank 6 months ago ($500++) and this has been the hottest spring and summer in decades here. The LP gas is used for the water heater and kitchen stove/oven) and furnace. Essentially the gas was used for the water heater and a fraction for the stove, the furnace was never turned on. The LPG tank is now almost completely empty, so im guessing I paid about $400 to heat water continuously all summer! Its me and my wife, spending far more on gas than if it were a tank heater. Is there a way to adjust the cycling on the heater, is it set up wrong, how can I fix this? If it means waiting a few minutes for hot water, I dont mind, because the reality is even with this thing cycling all day and night I still have to wait at least two minutes for hot water in the bath and shower and sink, so what is the point. I think I made an expensive mistake going with a looped system, can it be changed? Or is this heater malfunctioning? The estimated annual cost on the sticker to run it is $192, I'm certain its closer to $700-$800, which is ridiculous. My propane tank should not be empty. And yes, I have had the LP piping system checked for leaks, no gas leaks, just a water heater that is constantly heating water, needed or not. Its not what I call "on-demand". Thanks,

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 11,996
    So this navien only heats DHW? Sounds like something is wrong.

    Post some pictures of the install. What are you using for heat?
  • Larry Weingarten
    Larry Weingarten Member Posts: 2,546
    Hi, By loop system, do you mean that there is a pump, recirculating the domestic hot water? If so, how is that pump controlled?

    Yours, Larry
    mattmia2
  • mattmia2
    mattmia2 Member Posts: 5,517
    And if it is a dhw recirculation loop, is all the piping well insulated?
  • RobertH
    RobertH Member Posts: 3
    Ed, Pictures of the install wont give you much, other than pipes going in and out and into the drywall. I have a propane furnace for heat. Larry, The pump for the loop system is internal and part of the tankless water heater, controlled by the Navien HWH. The idea is to have hot water in all parts of the house at all times. Sounds great, if I had ten people living here. Keeping water hot in the loop so I can have warm water to wash my hands in the bathroom, or take a shower with immediate hot water for two people is extravagant at the very least, not what I asked for. And in the summer, seeing that tankless firing up every half hour is depressing, and expensive. BTW, my plumber claimed to be a genius, has been in business locally for years, but being a swimming pool contractor for 30 years in southern california, I was anything but impressed with his "knowledge" . I only went along with his suggestions because I was new to freezing winters and pressurized well systems. As it is now, he put the pressure tank not inline with the plumbing, but as an aside, so I have to change 3 valves and unplug the HWH to run sprinklers outside, he did me no favors. Now Im convinced he hooked this system up wrong, what does he care, he doesnt live here. Not the way I did business for decades.
  • Steamhead
    Steamhead Member Posts: 15,331
    @RobertH , where are you located? We may know someone who can help..............
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • mattmia2
    mattmia2 Member Posts: 5,517
    If the recirc control is part of the tankless then whoever installed it almost certainly didn't set it up. usually there is some strategy to run it on a timer so it only runs certain times of day or a certain time after a demand or has a button to start it. you could just turn it off altogether as well.

    It is absolutely essential that the piping is well insulated if it is set up for continuous recirculation, the piping essentially becomes a storage tank. If it isn't insulated it will radiate that heat from the piping.
    Ironman
  • kcopp
    kcopp Member Posts: 3,990
    The simple "fix" is to turn it off unless you will need the hot water. there should be a setting in there to allow it to work as a true demand heater and not have it maintain temp...

  • RobertH
    RobertH Member Posts: 3
    edited September 2021
    Steamhead; I live in Medical Lake, Washington,
  • Steamhead
    Steamhead Member Posts: 15,331
    That's right outside Spokane- anyone out there?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Larry Weingarten
    Larry Weingarten Member Posts: 2,546
    Hi @RobertH , It looks like you can play with settings to fix this. Starting on page 65 of the Installation and Operation Manual, it gives you info on how to set up the heater. Here's a link: https://www.navieninc.com/products/npe-210a/downloads

    It was interesting to find statements like the following in the literature... When activated, the ComfortFlow mode results in higher energy usage... NaviLink makes it easy to communicate with your Navien systems anywhere internet service is accessible. The NaviLink module attaches easily to any new or existing* Navien NPE Series tankless water heaters. Once installed, simply download the free app on your smartphone or tablet. Then you will be able to turn your unit on or off, change the water temperature, monitor system status and even activate the recirculation system on your NPE-A tankless water heater with an installed HotButton™ kit.

    Yours, Larry
  • JUGHNE
    JUGHNE Member Posts: 9,760
    I have a gravity recir system that is constantly flowing a small amount of hot water thru maybe a total of 100' of copper, it is marginally insulated and I have noticed little increase in gas consumption. I know it is not free but when I weigh in the pump and controls etc I feel good about it.

    You could have a cross connection between HW and CW that allows a warm mix of water to flush WC's etc. You may not notice this happening as letting the cold run say to get a cold drink it overcomes the mixing.

    This happens in many institutions where the mop sink has the HW and CW both turned on and there is a stop on the faucet discharge which allows the hot to cross into the cold lines.

    I realize you probably do not have a mop sink but this is the simplest explanation I can conjure up. This can happen in a shower valve just as easily. FWIW