Tankless H20 Heaters: Navien vs. Rinnai vs others?

[Ben44]

Looking for some advice on brands below in terms of technology, quality, warranty & service for our new 2900sf 3.5 bathrooms build. Plumbing sub is recommending Navien because the wife likes instant hot & the Navien has the recirculating pump onboard. But at a cost of kwh it appears.

So Navien vs. Rinnai vs others?

[2old2rock]

We install Navien. They work great - for the most part.
Personally, I would not install a tankless, unless your hot water usage will be very high.
I know lots of guys here love tankless, and they can save $'s.
But 1 out of warranty repair will easily wipe out any savings.
We put one in recently, and it locked up when the owner changed his whole house water filter. Just a few tiny grains of debris locked up the flow sensor. Our fault? His fault? Who knows.
If I were building new, I would go with a power vent/40 or 50 gallon tanked water heater with a recirc pump if you want "instant hot water.

[kangaroogod]

Navian with buffer tank and recirc loop. As stated before, unless you have very little or high usage you probably will not get the payback. In many cases it will cost you more to operate especially if you have several females In the household.

[tedkidd]

Navian with buffer tank and recirc loop. As stated before, unless you have very little or high usage you probably will not get the payback. In many cases it will cost you more to operate especially if you have several females In the household.

Navien is about to come out with gen3. Absolutely get an A unit (recirc and buffer tank). You won't regret having it and are likely to regret not having it. Naked tankless tend to get complaints of long wait for hot water.

What are the reasons you are interested in Tankless?

I generally recommend tankless or electric.

Sort of like Prius or Hummer. If you drive 50,000 miles a year, prius. 500 miles - get whatever you like cause mileage doesn't matter.

[Ben44]

Navien is about to come out with gen3. Absolutely get an A unit (recirc and buffer tank). You won't regret having it and are likely to regret not having it. Naked tankless tend to get complaints of long wait for hot water.

What are the reasons you are interested in Tankless?

I generally recommend tankless or electric.

Sort of like Prius or Hummer. If you drive 50,000 miles a year, prius. 500 miles - get whatever you like cause mileage doesn't matter.

I have a wife who loves long hot showers.
We also have a 70" clawfoot tub she luvs to wade in for hours.
She also has a wardrobe change every min. it seems - so lots of laundry.
& She uses all her cooking equipment - so more dishes.

Our builder has always supplied his build with Rinnai but his sub just brought Navien up & referenced some 'new' model coming out.
I suspect he's referencing the gen3 product.

Brief conversation today appears to reference the Navien being able to supply no lag hot water to only 2 points?
Can you expand on that?

[tedkidd]

I have a wife who loves long hot showers.
We also have a 70" clawfoot tub she luvs to wade in for hours.
She also has a wardrobe change every min. it seems - so lots of laundry.
& She uses all her cooking equipment - so more dishes.

Our builder has always supplied his build with Rinnai but his sub just brought Navien up & referenced some 'new' model coming out.
I suspect he's referencing the gen3 product.

Brief conversation today appears to reference the Navien being able to supply no lag hot water to only 2 points?
Can you expand on that?

Navien will be perfect for you. You may want to wire controller to the kitchen.

Many early tankless had undersized gas lines, typically low bid retrofit done by people who thought they could shortcut changing gas lines. They won the bid because proper install was not included. Changing gas line ain't free.

Poorly operating Rennai's masked the problem through use of a mixing valve. Mixing valves and bad gas pressure are both efficiency killers invisible on gas, but on Propane poor volume = soot. If you have propane be extra careful to avoid shortcut contractors.

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.

[Ben44]

Navien will be perfect for you. You may want to wire controller to the kitchen.

Many early tankless had undersized gas lines, typically low bid retrofit done by people who thought they could shortcut changing gas lines. They won the bid because proper install was not included. Changing gas line ain't free.

Poorly operating Rennai's masked the problem through use of a mixing valve. Mixing valves and bad gas pressure are both efficiency killers invisible on gas, but on Propane poor volume = soot. If you have propane be extra careful to avoid shortcut contractors.

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.

Thank you for the info. Some good stuff to chew on with my builder & the subs.
Actually fwd your & SkyHeating 's mssg to my builder already last night & have gotten feedback aligned with the sizing recommendations.

How is the customer service & warranty for Navien?
hard water issues?

[Ben44]

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?

[SkyHeating]

We used to install Navien, we now just install Rinnai. To many recalls on Navien, I have had two parts break on mine, my fathers unit needed a new control board after only a few months. I won't put another one in unless by special request. Maybe gen3 will be better but the first two generations have to many problems. Us and one other company are the only service provides for Navien in my area so we see all sorts of issues.
Also make sure anybody putting in a tankless runs at least a 1" dedicated gas line or a 1.25" or larger whole house gas line. 99% of 3/4" gas lines I see going to tankless units don't supply more than 140k BTUs and many plumbers and even heating guys don't realize a tankless takes more gas line than a standard water heater.

[Ben44]

We used to install Navien, we now just install Rinnai. To many recalls on Navien, I have had two parts break on mine, my fathers unit needed a new control board after only a few months. I won't put another one in unless by special request. Maybe gen3 will be better but the first two generations have to many problems. Us and one other company are the only service provides for Navien in my area so we see all sorts of issues.

Hmm...that's not a good reference for Navien.

Also make sure anybody putting in a tankless runs at least a 1" dedicated gas line or a 1.25" or larger whole house gas line. 99% of 3/4" gas lines I see going to tankless units don't supply more than 140k BTUs and many plumbers and even heating guys don't realize a tankless takes more gas line than a standard water heater.

Good to know & will speak to my builder & his construction manager about this.

[gasguy]

You don't buy a tankless for saving $$, you get it for it's abilities and/or space considerations. If you are going to have a demand for A LOT of continuous hot water (having 5 consecutive showers, then filling a huge spa tub, then running the dishwasher, then doing laundry) or you just don't have a spot to put a storage tank, then it's perfect. Otherwise just get a large-ish storage tank (40-60 gal). If you want 'instant' HW, put in a recirc loop.

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.

[Ben44]

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.

[tedkidd]

Just finished attending the npe webinar. It can use 1/2 gas pipe because it's basically able to pull gas out of the pipe instead of counting on it being supplied. (simplified one stage modulating negative pressure venturi gas valve instead of 3 stage positive pressure set up on nr/np series):

This is a reminder that "Introduction to Navien's NPE, Premium Condensing Tankless Gas Water Heater" will begin in 1 hour on:
Fri, Oct 12, 2012 10:00 AM - 11:00 AM PDT
Add to Calendar

Can learns hot water habits and manage recirc.
Solar and storage delay to sense temp.
100' 1/2 recirc, 500' @3/4

Amazing product!! And HUD/Manufactured Home approved.

[syndicated]

Just finished attending the npe webinar. It can use 1/2 gas pipe because it's basically able to pull gas out of the pipe instead of counting on it being supplied. (simplified one stage modulating negative pressure venturi gas valve instead of 3 stage positive pressure set up on nr/np series):

This is a reminder that "Introduction to Navien's NPE, Premium Condensing Tankless Gas Water Heater" will begin in 1 hour on:
Fri, Oct 12, 2012 10:00 AM - 11:00 AM PDT
Add to Calendar

Can learns hot water habits and manage recirc.
Solar and storage delay to sense temp.
100' 1/2 recirc, 500' @3/4

Amazing product!! And HUD/Manufactured Home approved.

Pull gas out of the line? That's crazy!! So what happens when another appliance needs gas and the pressure drop is too great for it to operate properly?

[tedkidd]

Yes, this means if you do a crappy job of sizing the gas line the other appliances may suffer.

[motoguy128]

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.

[Ben44]

...

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.

...
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.

... 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.

...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.

[tedkidd]

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.

[Ben44]

...


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???!!

[motoguy128]

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?