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Thread: Navien Tankless Water Heater Comments and questions

  1. #106
    In the trades Dana's Avatar
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    Quote Originally Posted by FRANKHE View Post
    I am new to this forum. I have a question regarding tankless efficiency. Dana posted a chart on 12-09-10 regarding condensing efficiency. It showed that if the return water temp was too high heater efficiency was greatly reduced. I realize the actual transfer of heat through the heat exchanger is decreased because of the smaller delta t. If concentric venting were used wouldn't the exhaust temp approach the air intake temp? Would the overall efficiency be higher? Thanks
    The short answer is no.

    A concentric vent raises the temp of the incoming air, raising the temperature of that 2000F+ flametip exhaust ever so slightly, which results in a very microsopic DROP in raw combustion efficiency, since to get the heat into the water the stack temp needs to be low enough at the water/exhaust heat exchanger to condense, transfering that heat to the water, not the incoming combustion air. Condensation in the flue doesn't buy you any further efficiency, since that heat isn't transferred to the water.

    But if the vent is long, pre-heating the cold combustion air in winter with the outgoing flue exhuast may make a very small difference in the space-heating load.

  2. #107
    DIY Junior Member ionltd's Avatar
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    Quote Originally Posted by Dana View Post
    A normal startup sequence on a modern tankless takes no more than 2-6 seconds:

    seconds 0-1: Flow is detected.

    seconds 1-2: the blower starts purging the flue of any potential unburnt fuel

    seconds 2-3: The gas & igniters come on

    seconds 3-6: flame it detected and the gas & combustion air flow are modulated to produce the programmed output temperature.

    The exact timing varies with model and manufacturer, but I've never seen it take longer than 6 seconds (which seems interminably long compared to faster units.)

    The time to get the hot water to your sink is a function of pipe diameter and flow, but it should take no more than 6 seconds longer for the hot water to reach the tap than when a tank type heater was installed in the same location. If it's taking 150 seconds where it used to take 10 with a tank heater, it's having SERIOUS startup problems. The rumble & vibe may in fact be a series if micro-explosions as it's trying to ignite a too-lean mixture or flucutating mixture due to gas pressure/regulation issues. The operational gas pressure, combustion mixture & combustion efficiency is something a competent boiler-tech would verify with manometers & combustion analysers before calling the installation complete.

    Gas pressure & too narrow gas line pipe diameter issues are possible culprits, but I'm not a certifiied tech, haven't seen the installation, and don't feel it's safe or sane to web-diagnose this one. I can say with a high degree of certainty base on your info that these installers are not competent to diagnose or fix this problem, and that something is terribly wrong with either the unit (less likely, since it's new) or the installation (highly likely, since the installers deemed these eggregious symptoms "normal".)

    Many HE front loaders fill with short bursts of hot water, but as long as the bursts of flow are long enough to establish ignition on the tankless some hot water should be reaching the washer. If it's taking several 10s of seconds to establish ignition you're probably not getting much (if any) hot water to the washer. As a short term fix many HE washers have high-heat "sterilize" or "steam" cycle which super-heats the water electrically in the washer. But you really need to have the tankless problems properly diagnosed, and the entire installation inspected by a competent party. Document what has transpired so far, including the where/when/what of the conversations you've had with the installers- you may need to go after them legally to recoup the cost of fixing their likely-botched job.

    Call Navien America, see if they can't find a certified installer in your area to come deal with this. Don't wait. The Illinois sales reps might be able to help you find a factory certified installer (and need to know about the screwup installers):

    Metropolitan Industries
    Tel : 815-886-9200
    Fax : 815-866-6277
    http://metropolitanind.com

    Download their diagnostic manual and familiarize yourself with as much of it as you can absorb so you can get more out of the conversation with the techs.
    Thanks Dana for all your help

    I printed out your response to my post about the 2 1/2 minute time for the hot water to reach the kitchen sink faucet for my husband to read. (he's not computer literate) When we finally got the plumber to get here to check out the situation, after 2 missed appointments, and at first he still seemed to think that 2 1/2 minutes was fine. Until my husband decided to show him the print out of what you 'd said...lol

    Then all of a sudden he agreed that 2 1/2 minutes WAS too long. I said I was glad he believed me. He said he'd always believed me, he just didn't know I'd timed it...HUH? That means you didn't believe me.

    So he came back 3 days later when we were out of town (we told him we wouldn't be home but he forgot) to work on it. We got home late last night and found the water pressure had been cranked WAY up from our well pump. The noise is still there, of course he says the noise is normal anyway, and the hot water take a little over 2 minutes instead of 2 1/2.

    Also waiting for us was our bill from him. The amount he charged us or the water heater was pretty close to what he quoted us, but ht had charged us 22 hours labor (2 young guys at 11 hours each) for the installation. I don't have a clue if the guys were licensed plumbers or not, but I'd be surprised if they were. They were full of uncertainty throughout the install, and made 10 trips up and down the stairs every hour. They even had to drive back to their shop (23 miles away) to get different parts because the vent the boss had sent with them wouldn't work. Then they left after 10 hours and had mistakenly shut the system off when they left and had to turn around and drive back to our house. We were charged for both young guys time to drive back and forth both times to correct their screw ups.

    They didn't have to repipe our house. This was the first Navian they had ever installed and the boss wasn't there, but he had never installed one either.

    The boss had quoted us 6 hours labor each for 2 guys. The charge was $70 per guy per hour.

    How many hours is "normal" to install a Navian tankless heater, because I think we got screwed AND it's still not right

  3. #108
    In the trades Dana's Avatar
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    Installation time is all over the place- highly dependent on much plumbing & re-routing is required to place it where it needs to be for adequate gas supply and code-compliant venting etc. It's far more complicated than a simple tank-swap. A 2-8 hour day for a couple of competent installers would be in the reasonable range, neither the low nor the high. A full man-week would be on the high side for a competent installer in most situations. "They didn't have to repipe our house. This was the first Navian they had ever installed ..." tells me they're trying to get YOU to pay for their education at full-retail rates.

    But the fact is, the job's not done.

    The noise is not normal and probably IS dangerous, and 2 minutes is ridiculously long to wait. The unit is not properly installed, and needs to be fixed. Don't pay the bill until it's done. Photograph the installation and any changes that are made in the process of fixing it (whether you let these clowns keep at it, or hire an experienced pro.) Keep notes with dates & times, who was there, what they did/said. Then it comes time to negotiate the bill you'll have the documentation.

    How long and what is the diameter of the gas line? (Is it propane? Natural gas?) Did they monitor the fuel pressures on start-up and at high-fire? Did they test the combustion-efficiency at low & high fire, and document it on a card or label?

    How many feet away is the tap that it still takes 2 minutes for? How many gallons (test it with a bucket- try to be accurate) does it take before hot water arrives?

    What was, and what is the new water pressure on the system? It sounds like they just reduced it from 150 to 125 seconds by increasing the flow rate with high water pressure rather than fixing the startup time/ignition problems. There IS a minimum operational water pressure for tankless units, but it's pretty low for most- 25psi would be plenty for any of them. Navien specifies 15-150psi as an operational water pressure range.

    Contact Navien with that information. They don't need installers like these handling their goods.

  4. #109
    DIY Junior Member ionltd's Avatar
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    Dana
    Thanks again for all your help.

    The new water pressure is a little over 60 psi. We think it was around 30 before. It's really blasting out of the faucet now. We've lived here 25 years and I've never seen so much water pressure.

    I'm going to do the gallons used check this afternoon and redo the time check as well.

    The unit is in the basement right below the sink in question, so I guess that would be 10-12 feet away, but going up.

    I have no idea if the monitored or checked the fuel pressure in any of the circumstances you mentioned. He just showed up unannounced again when we were out of town and he has not contacted us with anything but a bill for 22 hours labor.

    I do realize there are many variations in time necessary to install a tankless water heater and that it is much more complicated than a tank heater, and everything I've read says an experienced licensed plumber should be able to do a simpler install like ours (the only extra pipe was pvc for the exhaust) in 8 hours or less. That's why when we got the bill for 22 hours at $70 an hour for 2 less than experienced kids, it was like adding insult to injury. They were up and down the stairs 100 times with different pipe lengths for the exhaust alone.

    I'm going to do the tests you suggested and get back to you. Then I'll probably call Navian

    Thanks again

  5. #110
    In the trades Dana's Avatar
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    It typically takes a lot fatter gas-line to serve a tankless, and the further it is from the gas meter, the fatter it needs to be. Many tank heaters are fine with half-inch gas lines over some distance, but no Navien is. If you have 15' of half-inch fuel line between the water heater and the meter it'll NEVER work right. If you have 30' of 3/4" gas line it MIGHT work, as long as that's the only burner (no tees off to furnaces/boilers/stoves). Many/most installations call for 1" gas line to have any margin, which is WAY more than standard tank heaters ever need.

    There could also be capacity & pressure regulation issues at the meter, etc. but this is what any idiot who drives a truck with "Heating & Plumbing" correctly spelled on the side of the truck SHOULD know, and be able to diagnose when there are issues. It has more in common with installing a wall-hung modulating/condensing heating system boiler than with installing a tank heater (which Dumb & Dumber probably could have handled, but I dunno... that would be assuming facts not in evidence.) My suspicion is that the gas piping is under-sized and the fuel pressure isn't constant or correct, even when it manages to start up, but that's a testable thesis, one that any competent installer would have checked- and RE-checked with it behaving as it is.

    If the sink is 12' over and 10' above the water heater you should be getting hot water in under 10 seconds (maybe under 5 at full blast) if the unit is installed correctly & working properly, assuming the plumbing is relaively direct.

    Do not pay that bill. They've given you nothing like 22 hours of professional service, the thing isn't installed right and is barely working. They've proven themselves incapable of being able to fix it (on your dime OR theirs), and don't deserve another bite at the apple here. Call Navien. Some other tankless vendors (notably Takagi) have telephone-tech who can talk the average homeowner/installer through a full diaganosis- hopefully Navien has someone who can walk you through the simple stuff to rule things out and zero in on it. (Did you look at that downloadable diagnostic manual?) With that information, hiring a heating contractor who installs condensing boilers to finish the job shouldn't be too outrageous. Anything you pay the second contractor should come directly off the amount originally quoted, but you may have to settle for taking it off their hose-job of an inflated bill if they choose to fight it in court.

  6. #111
    DIY Junior Member ionltd's Avatar
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    OK
    From what you've told me so far, I think you're going to get a good laugh out of this.

    The fuel is propane and the gas line comes into the basement on a 1/2 inch hose that T's off into 3 directions.... one line goes to the furnace (still 1/2" line) and another goes to our dryer, and the third 1/2" line goes to about 1 ft above the tankless heater where it has an adapter which changes it to a 1 inch hose going into the water heater. With the few physics classes I took in undergrad, taking something through a small tube, splitting it 3 ways then expanding the flow space x 2 is really going to reduce the pressure.

    It takes right at 3 gallons of water run at full blast to get hot water....it starts to feel warm after the 2nd gallon.

    So them turning up the water pressure up is pretty much a make shift minor help that didn't even touch the real problem

    I need to make a list of the things I need to discuss with the plumber. Could you help me with it?

    1. Was I charged for the time the boys drove back to the shop to get different parts the hadn't brought because the boss told them incorrect information?
    2. Were the boys licensed plumbers deserving of $70 per hour each?
    3. What happened that made the quote for 12 hours turn into 22 hours of labor?
    4. Did he check the gas pressure (how do I word this?)
    I'm sure there's a lot more

    I doubt if we'd be much help working on this ourselves...we're screwed

    thanks Dana
    Last edited by ionltd; 03-24-2010 at 06:55 PM.

  7. #112
    DIY Junior Member ionltd's Avatar
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    BTW
    We haven't received a call explaining what he found wrong and/or fixed. He also said he was bringing out "a company man" to check things out. My friend was here when we were out of town house sitting for us. She said only one person and one vehicle was ever here

  8. #113
    Nuclear Engineer nukeman's Avatar
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    I'm not a pro, but that 1/2" line is not going to cut it. This is one reason why installing a tankless is expensive: the usual 1/2" gas line is too small and needs to run back to where it can tie into 3/4" or better (and just expanding the 1/2" line to adapt to the fitting on the tankless is not going to do it). This may mean running a new line all the way to the meter depending on how the house it setup.

    I would fight to get it fixed, but it seems like these guys do not know what they are doing. Even if they do fix it, I would only pay for the quoted 12hr as it seems like most of the additional hours were their fault (inexperience, forgetting things, etc.).

    Edit: Check the manual and use the information there to help form your questions. Check the plate on the unit and make sure they didn't install a NG unit while you are using Propane. It also clearly states that the gas line is not to be less than 3/4" and also should be the first appliance connected after the meter. Good luck.

    http://www.navienamerica.com/PDS/ftp...210_240(A).pdf
    Last edited by nukeman; 03-25-2010 at 06:57 AM.

  9. #114
    In the trades Dana's Avatar
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    Quote Originally Posted by ionltd View Post
    OK
    From what you've told me so far, I think you're going to get a good laugh out of this.

    The fuel is propane and the gas line comes into the basement on a 1/2 inch hose that T's off into 3 directions.... one line goes to the furnace (still 1/2" line) and another goes to our dryer, and the third 1/2" line goes to about 1 ft above the tankless heater where it has an adapter which changes it to a 1 inch hose going into the water heater. With the few physics classes I took in undergrad, taking something through a small tube, splitting it 3 ways then expanding the flow space x 2 is really going to reduce the pressure.

    It takes right at 3 gallons of water run at full blast to get hot water....it starts to feel warm after the 2nd gallon.

    So them turning up the water pressure up is pretty much a make shift minor help that didn't even touch the real problem

    I need to make a list of the things I need to discuss with the plumber. Could you help me with it?

    1. Was I charged for the time the boys drove back to the shop to get different parts the hadn't brought because the boss told them incorrect information?
    2. Were the boys licensed plumbers deserving of $70 per hour each?
    3. What happened that made the quote for 12 hours turn into 22 hours of labor?
    4. Did he check the gas pressure (how do I word this?)
    I'm sure there's a lot more

    I doubt if we'd be much help working on this ourselves...we're screwed

    thanks Dana
    From a cold start, with 20 feet of plumbing between the tap and the tankless you should be seeing hot water before the first gallon drawn. If it's 50 feet of plumbing it should be before the second gallon.

    It doesn't matter how much time the guys spent on it- if they didn't do the job right the first OR the second time, you shouldn't have to pay more than the quote. YOU didn't screw it up- THEY did. On successive draws you might experience intermittent dips in temp related to the startup delay, but no more than 5-6 seconds of "cold water sandwich" between the leftover warm stuff that was left in the pipe from the previous draw and the full-on hot.

    If you choose to continue dealing with them, ask them if they monitored the gas pressure during startup, at low flow, then during transitions to high flow on the hot water, or when the furnace is firing during a draw, or if the furnace is starting up during a hot water draw. (How many BTU is the furnace rated for? The dryer is about 22-25,000BTU/hour, but the furnace is likely to be over 60,000BTU, and the Navien is 180-199,000BTU/hr. With propane piping you only get about 10' of half-inch before it drops below the BTU rating of bigger Naviens by themselves (without any other load on that line) or ~15' for the smaller whole house units. I'm sure the recommended minimum is 3/4", which gives you about 40-50' before it craps out on capacity for a tankless on it's own. But if there are other loads Teed off from it, they also have to be properly factored in. Startup pressure glitches often require derating the lengths from the standard pipe capacity charts, which is why you MEASURE the pressures rather than assume.

    Then ask them for the results of the combustion-analysis test to prove that it's actually burning correctly. (Which it probably isn't, and they surely didn't perform the test.) The job isn't done until they've completed a combustion analysis (which requires special equipment, and a trained operator.) If they can't do it, they shouldn't be in this biz, but tell them they're on the hook for paying for getting it done right by a third party.

    Odds are near-certainty that you'l have to upgrade the fuel lines to fatter stuff before it'll work correctly, and that SHOULD HAVE been included in the quote.

    nukeman's comment is something I hadn't even considered, ( maybe I should have, considering the quality of the services rendered) but needs to be verified: If this is a unit set up for natural gas it'll NEVER work correctly on propane. It should say somewhere on the unit, maybe where the fuel line hooks up, maybe on an internal or external rating plate, but if it says if it has no mention of propane anywhere write down the model and serial # and call Navien right away.

    Seriously- were it me I wouldn't let these guys in the house for yet a 3rd shot of burning the place to the ground. If they can show up with a certified Navien tech for a walk through, maybe... Talk to the Navien distributor, give them the full scoop, and get a recommendation for someone ELSE to commission the thing properly. Then negotiate the bill with Dumb & Dumber after the fact. Document EVERYTHING.

  10. #115
    Nuclear Engineer nukeman's Avatar
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    The link that I gave you will show you where to look for the plate on the unit. They also mention that is cannot be converted in the field from one fuel to another. Based on what you have told us so far, I would not be surprised if they did drop in a NG unit.

    I agree with everything that Dana posted above. It sounds like these guys have never installed any tankless before and do not know what they are doing. Sounds like they didn't test anything and they tell you the problems are normal (maybe normal for their installs..lol) in hopes that you will drop it and just live with it the way it is.

    Good luck.

  11. #116
    DIY Junior Member ionltd's Avatar
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    One last question

    What is the going hourly rate range for an apprentice plumber? We're in the midwest and our town is 1700 people and the town the plumber is from is 19,000

    We were charged 22 hours (11 hour each) for 2 apprentice plumbers at $60 to install

    I talked to Navien and they said it was insane. The plumber said it was actually more like 13 hours but he only charged us 11 hours each.

    this has been a nightmare

  12. #117
    DIY Senior Member zl700's Avatar
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    A quoted price is a contract, anyone that would agree to be billed an unknown amount When the install is completed will probably have this happen, difficult to argue now.

    A manufacturer would make a labor and wage opinion site unseen? I have a tough time believing that.

  13. #118
    DIY Junior Member ionltd's Avatar
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    I can't remember ever being told I was a liar before...ever, and I'm 56 yo. I'm sure you'll have a "tough time" believing that as well.

    I spoke for an hour and with the tech at Navien. I answered THEIR questions about what was installed which was the tankles unit, the gas line connection, the exhaust going outide, and small amount of pipe. He asked if the repiped the entire house, which they didn't. He asked if they installed recirculating pipe and told me where to look to see if they did. They did not. He then told me that it should take 7 hours per apprentice in the WORST CASE scenario, but more like 4-5 hours for each of 2 people.

    And since the plumber said it would take HIM (not 2 apprentices) 6 hours to to the install, I thought the Navien tech was generous.

    We THOUGHT we were getting the licensed plumber when we made the agreement with him. And we DID ask about the time frame.

    How on earth would we have known to ask if he was BSing us and was sending someone besides himself to do an installation that they had never done before??

  14. #119
    Nuclear Engineer nukeman's Avatar
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    Did you get a chance to check the plate to see the model and what type of fuel it is setup for? Have you had someone else come to check it out/fix it? Have you had the original guy back out to try to fix it?

    I wouldn't be too worried about the number of hours at this point. The install is not complete until the thing is working correctly. At that point, I would only pay the original quoted hours. If he wants to fight it, you have the installation manual to back up your position and prove that it was a bad install. The manual is your best defense (except for testimony from a Navien tech). Asking another installer why the install is wrong is helpful, but the manual carries the most weight. I say this because different installers may have a different way of doing things and some do it a certain way because they think it is better. However, the manual is gospel as far as the install is concerned. If they didn't follow the clearly marked instructions/warnings, you have proof that it is a bad install.

    It sounds like you are holding all of the cards here. They have no wiggle room. If you already paid them for the whole thing, I would request for a refund for the labor (assuming they used the right unit) and then get someone who knows what they are doing to install. If they don't agree, then take 'em to Small Claims and get your money back that way. Take pictures of the install and show how it doesn't meet the req. in the manual. We also know they didn't do any testing as the 1/2" wouldn't support the gas flow to get the proper WC readings, not to mention the other problems with the unit. Ask them if they checked the WC and ask what the reading was. If you had some email exchanges with Navien about the problems with the install, that would be icing on the cake.

  15. #120
    DIY Senior Member zl700's Avatar
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    At first it was $70 and hour, now its $60 an hour. What was the total bill for the install (install correct or yet to still be corrected) And did you or they supply the heater, still no mention of heater cost.

    How much for the install?

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