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  1. #14
    Join Date
    Oct 2012
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    95
    Quote Originally Posted by gasguy View Post

    Edit: We are Rinnai dealers and they are top quality units and we've had very few problems in about 10 years of installing them, but they are not the answer to everything. They are also not recommended in areas with 'hard' (high mineral) water. Even with regular flushing/de-scaling they don't like it.

    That's what I've read too about Rinnai. But good that you reaffirm their one drawback - hard water.

  2. #15
    Join Date
    Oct 2012
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    95
    Quote Originally Posted by tedkidd View Post
    Navien will be perfect for you. ...

    From a technological perspective I view Rennai as a typewriter (high quality selectric), Navien as an iPad. I've heard the waiting for water bothers some people enough that they've pulled their Rennai's and gone back to tanks.

    I always insist on the Navien A - buffer tank and pump. I know people who regret not having the ability to turn from "on demand" to "instantaneous," and am grateful the blame doesn't fall on my shoulders.

    Recirc loop should come back from furthest fitting and be completely insulated. We've installed whole house water filters in front of these heaters, might be a good durability upgrade since this looks like it'll be 30 financed.
    @tedkidd - The model the builder & his plumbing folks are recommending is the NPE-240A which has the pump & buffer tank.

    However, we want to install this outside & the plumbing folks don't seem too enthusiastic due to possible cold snaps.
    Alternative is Rinnai but I don't see any cutting edge defroster on Rinnai's either.

    Any feedback on cold weather outside install for the Navien HPE-240A?

  3. #16
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    I had a NR-240A installed in my home this Spring. Looks like the NPW just made a couple small imrpovements, but is basically the same unit. I haven't had any issues, other than minro things, like having to reset the clock after a power outage more than 5 minutes, the recirculation isn't 5+2 day programmable (might be now). IDeally you could even set different water temps based on time of day. We only need 108 for washing hands all day, but like 112F for showering in winter, 110F showering in summer.

    Clean the inlet screen at least once every 3 months. Bugs and dust can plug it off pretty good. The screens on the water were suprisingly clean after 4 months. I guess my minicipal water is pretty good.

    I installed about 200' of recirculation piping with a 3/4" main header and five 1/2" branches and/or loops. I get hot water within 1-2 seconds from my kitchen, and 4-5 seconds from my other bathrooms where I only had access about 4-5' away. The longest is the 1 shower that's about a 6-8 second wait. PReviously that shower could be a nearly 1 minute wait or longer. It's on the 2nd floor, and probably at least 100' from the water heater.

    NOt sure about outdoor installations. I do know the hat instulation on hte buffer tank is not really heavy, so the enclosure stays pretty warm. Howev,er like many combustion appliances now, like my Carrier Infinity furnace, the whtire enclosure is used as an intake air plenum. So outside air gets drawn into the enclosure. The enclosure is metal and not insulated. I suspect that for freeze protection, the unit might cule on periodically to heat piping. Any cold water piping should be heat traced and insulated if you have a likely risk of freezing anyway. The hot water pipe should be insulated. I don't know where you are, or what the freeze risk is at your location. I've always lived in home swiht basements and in cold climates. Anythign outdoors gets insulated and heat traced.

    As long as you don't have a power loss, the circulation pump and buffer tank should prevent freezing. But you still have to consider the cold water piping leading to hte heat exchanger. But as mentioned, that's not a big deal to heat trace and insulate. But Id' run a seperate circuit for the heat tracer and hte water heater.

  4. #17
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,735
    A lot changed on the new unit. Can be piped 3/4, even 1/2 inch if short. 1/2 pvc. Different tank insulation. Different flow sensor and thermistors (they got tired of issues). One burner instead of 3. Better condensate basin. Much easier access. Brain that figures out usage and runs buffer tank accordingly.

    possible cold snaps


    Has freeze protection and outdoor cap accessory, but that's not going to be any magic bullet. If neighbors don't have heaters outdoors, I don't think I'd want this to be the test rat.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  5. #18
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    From the pictures online at least didn't look much different than the NPE. I hate it when I install something and there's a major upgrade 6 months later. No sensor issues...yet. But a little smarter recirculation logic might be nice or at least more settings for temperature swing, or other method to prevent short cycling.

    Do you know if the improved sensor are reverse compatible? So if you have a failure or problem, can you upgrade? I'm guessing not.

    BTW - Because the recirculation loop added some much piping and it stays hot most of the time, I'm not seeing any savings. My gas useage might have even gone up just a little. But instant hot water is well worht it in terms of comfort as well as safety. It's not even possible for our 3-1/2 y/o daughter to burn her hands since it's only 112F. No need to mix in cold water either.

  6. #19
    Join Date
    Oct 2012
    Posts
    95
    Quote Originally Posted by motoguy128 View Post
    ...

    Clean the inlet screen at least once every 3 months. Bugs and dust can plug it off pretty good. The screens on the water were suprisingly clean after 4 months. I guess my minicipal water is pretty good.
    Thanks for the maintenance tip.

    Quote Originally Posted by motoguy128 View Post
    ...
    NOt sure about outdoor installations. I do know that insulation on the buffer tank is not really heavy, so the enclosure stays pretty warm. However like many combustion appliances now, like my Carrier Infinity furnace, the entire enclosure is used as an intake air plenum. So outside air gets drawn into the enclosure. The enclosure is metal and not insulated.
    Do you mean the enclosure is or is not warm since it seems you are saying both above.


    Quote Originally Posted by motoguy128 View Post
    ... I suspect that for freeze protection, the unit might cut on periodically to heat piping. Any cold water piping should be heat traced and insulated if you have a likely risk of freezing anyway. The hot water pipe should be insulated. I don't know where you are, or what the freeze risk is at your location. I've always lived in homes with basements and in cold climates. Anything outdoors gets insulated and heat traced.
    We are in central VA & so the MidAtlantic will get a couple of days/nights below freezing a year & a freeze snap (5+ days) about 2x a decade.

    Quote Originally Posted by motoguy128 View Post
    ...As long as you don't have a power loss, the circulation pump and buffer tank should prevent freezing. But you still have to consider the cold water piping leading to the heat exchanger. But as mentioned, that's not a big deal to heat trace and insulate. But Id' run a seperate circuit for the heat tracer and the water heater.
    We'll be speaking to the plumber & our builder on their plan to insulate the gas & water piping to the tankless.

  7. #20
    Join Date
    Oct 2012
    Posts
    95
    Quote Originally Posted by tedkidd View Post
    ...


    Has freeze protection and outdoor cap accessory, but that's not going to be any magic bullet. If neighbors don't have heaters outdoors, I don't think I'd want this to be the test rat.
    Our builder's 2 recent houses have tankless strap to the outside of the house.
    However, we've had 2 mild winters here the last 2 years.
    So we want to prep for the inevitable luck running out 2x a decade but trying to be fiscally sane about it.

    Plumber points out that outdoor tankless heaters have freeze protection that require electricity (so unit can periodically fire to keep warm), and the warranty does not include freeze damage. (This is true for Rinnai as well, but Navien has traditionally been even more skittish about this.)
    & of course we have to cut through the roof & wall to get vent the air in & out.

    So therefore, if we have an extended cold snap and an extended power outage, we will need to drain the hot water heater.
    Not sure on this last point when that will occur...in the middle of a sub freezing AM???!!

  8. #21
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Drain is pretty easy, but not a lot of fun with if it's 20F outside.

    I know that indoors in my basement the enclosure is a good 15-20F warmer than the indoor temp.

    Looking at the online Manuals, it looks like freeze protection is accomplished by runing the circulation pump when one of hte tmeprature sensor detects it's getting too cold. Probably at around maybe 40F. But it would defnitely require electricity.


    Rather than just drain it, you could also jsut leave a hot water tap running slightly. IT will cycle periodically. At about 0.05gpm, with a 60F temp rise, the unit would cycle on low fire about 10% of the time. So on for maybe 5 seconds and off for almsot a minute. You'll use about $0.50 in natural gas at $1.00/therm every 24 hours doing this. So which is better, going in the cold ot drain the thing... or wasting 50 cents in gas????

  9. #22
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    97-1/2% design temrpatures in VA range form 16-22F. I'm not sure that's a place I'd stick a water heater on an outside wall. In a garage... possibly. Water heaters in garages in central Missouri are common and it's colder there (and much hotter too). A Garage will retain a little bit of heat.

    You don't ahve a little bit of closet space you can spare??? When direct venting, the clearances are pretty minimal. Where is the piping comming into?

  10. #23
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,669
    im not sure on what is better, the company i work for has installed a few hundred rinnai with minimal issues . most are propane fired and a big issue is the quality of water if you have hard water you will need a water softner
    We really need change now

  11. #24
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,735
    I believe mineral precipitate increases with temperature. Navien is probably better for hard water as it runs straight temp rather than hot 140/150 and mix down.

    Moto, I'm not surprised you don't "see" savings. Most people don't spend much on hot water, so "seeing" a fraction of that may require a magnifying glass, particularly if you are looking at monthly.

    You might see it when you look annually. Hope that recirc loop and at least 12" of each branch is well insulated - or there'll not be any savings to see.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  12. #25
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by tedkidd View Post
    I believe mineral precipitate increases with temperature. Navien is probably better for hard water as it runs straight temp rather than hot 140/150 and mix down.

    Moto, I'm not surprised you don't "see" savings. Most people don't spend much on hot water, so "seeing" a fraction of that may require a magnifying glass, particularly if you are looking at monthly.

    You might see it when you look annually. Hope that recirc loop and at least 12" of each branch is well insulated - or there'll not be any savings to see.
    I will never see it annually with heating use mixed in. An average temp difference in jan of just 1f might cost me $30. Only buy adding up summer months. This summer it was a clear step shift from around I thin 8-10 therms to 11-13. But again keeping 200' of pipe warm even withn 1/2" insulation costs money.

    Sent from my SGPT12 using Tapatalk 2

  13. #26
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by tedkidd View Post
    I believe mineral precipitate increases with temperature. Navien is probably better for hard water as it runs straight temp rather than hot 140/150 and mix down.

    .
    I didn't realize other models have a fixed temperature and mix down. That doesn't seem very efficient, but does greatly simplify operation. I would eliminate a need for a flow sensor. You could use a flow switch instead to trigger the unit at a minimum setpoint.

    Mineral deposits is why with the Navien and all tankless units, you want to set the temperature as low as possible to both reduce percipitates as well as maximize flow through the heat exchanger. So if you set it to 120F, then you have to blend in about almost 40% cold water at 50F to achieve a 105F setpoint for a shower. If you set it to 110F, you're blending in only about 10%. I find it also makes shower temperature more stable and easier to control with less guesswork. Also, again, with young children, you elminate the risk of scalding.

    I mounted my controller next to my thermostat in my living room. I suppose I could have also mounted it in my bathroom with a little extra work. Then you could leave it at a lwoer temeprature for handwashing 90% of the time, then raise it when showering if you like really hot showers or soaking tubs.

    For dishes, I find that even 108F is enough to cut grease and I rely on the heating elements in my dishwasher to raise the wash temperature. It seems silly to set the unit at 125F just for a single appliance.

    FOr capacity, I still don't think I've maxed the unit out. When the municipal water cools off in a few months, I may try again and turn on my big fat basically wide open 1/2" pipe soaking tup spigot (you have to love old 1920's fixtures, not of the flow restriction garbage on them ) then open one one or two other faucets and I should be pretty much maxed out on incomming water flow. Then set the temp to maybe 130F and get a thermometer and see if it holds temp. Then maybe cycle on the two furnaces and see if my supply can handle 460k BTU's of gas at one time. Heck, next year I might put in a permenant gas grill, so we'll raise that up to 485-500k. Ahhh nothing like uring up $0.07 of gas a minute. Not so bad. On average ,I'm buring about 3X that amount per minute in gasoline.... about $0.30 or so.

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