GAS tankless water heaters

[A1an]

I'm downsizing from a nice three car garage (standard two plus an oversized single) to a relatively small but seemingly standard for houses these days 2 car garage. Unfortunately, this small two car garage has a HUGE gas water heater in it. With space being at a premium in this garage I really want to get this removed as soon as possible so I can get started on getting some custom shelving built up to deal with some other space issues in the garage (will start another thread on that next month).

I saw a thread on electric tankless heaters, but didn't find much on the gas counterpart. Does anyone here have any long term experiences with these heaters? What brands would you gravitate towards or away from?

I'm thinking more along the lines of a big box brand due to availability unless there are some other brands to consider that plumbing companies gravitate towards. Going to also pay for installation since I've never worked with gas before.

Appreciate the help.

 

[MisterMike]

I can only claim experience with one brand, Navien. We had one installed in our house about five years ago and it's worked well, until we had a recent hiccup with a worn flame sensor. The service call and replacement of that part ran about $300.

This heater replaced a giant (80-gallon) electric tank heater and has saved us a huge amount of money. The overall cost was around $3,000, but between high electric costs and low natural gas costs, plus a 30% tax credit, we recouped the cost in around 18-24 months.

With the exception of the issue I noted earlier, it's been completely reliable, but I did shudder at the thought that the thing might be completely belly up when it stopped working. The biggest limitation that I can think of, one that doesn't apply to you, is that when the input temperature of water is low (as it can get here in the Chicago area in winter), an annular valve reduces the water flow to allow sufficient heat rise to meet your preset target temperature. That means that it takes a bit longer for the hot water to reach the faucet and that the output is somewhat decreased . . . noticeable when you're filling a large tub, but otherwise not a biggie.

I've heard good things about Bosch as well.

 

[8man]

Going with Rennai (sp) in the new house with a circulation pump to keep hot water at the faucet - no long run times. Buddy had the same set up and worked well. The builder who is a licensed plumber has put in quite a few and swears he's had no problems.

 

[Voi]

I have the last generation of non-condensing Rinnai. I think we purchased it in 2010 for the tax credit and had it installed in early 2011.

We have well water that is just hard enough to cause us some issues with another appliance but have had no issues with our tank less heater. I'm ashamed to say I've only flushed it with vinegar once but it's working great.

Our house lays out well for one since all three of our bathrooms share a wall and/or floor. The heater sits right behind or below all three bathrooms. Very short runs so the cold water lag isn't much of an issue.

It wouldn't work well if all three showers in our house were running at the same time. But it works great when family is staying with us and we get back home from the lake and eight people or so all need to take showers. Just have to wait for your turn.

We had a power outage for a few days back in 2013 and simply ran an extension cord to an AC adapter in one of our vehicles when we needed to shower. It was great being able to shower after spending hours digging ourselves out of the snow.

We are considering a Bosch propane model for our seasonal cabin.

 

[GDPossehl]

I've got one at home and really appreciate the thought of not keeping 80 gallons hot at all times. It came with the house we bought in November and isn't very old (I forget the install date offhand) so I can't speak to longevity. It does take a while for hot water to get to our kitchen which is across the house, but that's partly due to the way the lines are run. I've been meaning to put a T fitting near the outlet of the HWH and running a PEX line to the kitchen sink. Luckily there is an unfinished ceiling in the basement/crawl space.

 

[MisterMike]

Going with Rennai (sp) in the new house with a circulation pump to keep hot water at the faucet - no long run times. Buddy had the same set up and worked well. The builder who is a licensed plumber has put in quite a few and swears he's had no problems.

I think it's spelled Rinnai. They've got a good reputation. There are others that offer the recirculation option. It's effective, but you do lose some of the energy efficiency advantages of a tankless since you're regularly heating and circulating water through the pipes. My Navien uses a slightly different approach . . . it's got an itsy-bitsy reserve tank (about two liters, I believe) that holds preheated water, kind of a mini version of a tank heater, but enough to save a couple seconds of lag that you otherwise encounter while you wait for the heat exchanger to get up to its operating temperature.

Lou Manfredini, who hosts "Mr. Fix-It" on WGN radio, speaks highly of Rinnai.

 

[A1an]

Thanks for the input so far.

Forgot to ask in my original post....for those that have had them installed, what did you pay for installation?

 

[MisterMike]

Thanks for the input so far.

Forgot to ask in my original post....for those that have had them installed, what did you pay for installation?

It's been a while, but I think our installation was around $1,000. However, it replaced an electric, so there was no venting or air intake in place. It was in a fairly difficult to reach area and they had to drill through the concrete basement wall in two locations to complete the installation, plus run the gas line. There was a gas supply close by, but Illinois requires rigid pipe for gas lines, so that involved a bit of work, too.

 

[Streetbu]

I bought and installed a Bosch propane unit for my house about 7 years ago. No issues so far. Only thing I would recommend is a water pressure regulator if you're not on public water. On a well, as the water pressure varies thru the cycle the flame size chnages and therefore so does the water temp. I have ours set very low. Low enough in fact that when we take a shower, we only use the hot water. Perfect temp all the time. If we need warmer water than that you're probably going to boil a pot on the stove anyways. So why have it turned up so high you have to mix cold water with it to be able to use it. I've taken 45 minute showers followed by my wife and son. Never ran out of hot water! Installation was very simple. Hardest part was finding out it took B vent which no one stocked and had to be ordered so we were without hot water for a few days. I was able to get mine at cost thru my work, and its a smaller unit, so all in I only had $650 total into it including plumbing and venting.

 

[rlitman]

I have ours set very low. Low enough in fact that when we take a shower, we only use the hot water.

I'd be concerned about growing Legionnaire's disease in the plumbing. With water temperatures at the faucet below 120F, you've created a bacterial breeding ground.

Also, you think you're saving money on hot water, but your dishwasher needs to run its electric element a lot more because the water entering it is too cold. It can effect your clothes washer too.

 

[BearsFan315]

I have a Rinnai we put in when we did our addition 5 years ago, LOVE IT !!

Will not go back to a tank. We opted for the external version, so there is NO exhaust piping or such. we did get the freeze kit, JUST in case. Ours has a remote mounted inside our house we can adjust up to 120, and I can flip the switch inside the unit outside and go to 140. we keep it at 120 with the kids around. more than hot enough.

our model is Rinnai RL75eN Natural Gas, it does 7.5 gpm per minute, wash laundry, do dishes, take a shower , and no one knows the difference.

also LOOK at the Minimum Activation Rate , this is the minimum water flow required to activate !! if you are under this flow rate then it does not activate and heat the water. our unit is 0.4 gpm (1.5 lpm). a few other models are higher.

also Rinnai does offer a few solutions for re circulation options for those that can not wait or have LONG runs.

If you mount indoors you have to have a dual pipe for exhaust and cool air intake. that must be vented to the outside.

here is our with the kit installed

 

[BearsFan315]

Oh Yeah... you can buy these from amazon and MOST of our local shops HVAC/ Plumbing deal with these EXCLUSIVELY guys and prefer them over others. go to the link below and find a local dealer.

They have been around for years and quality is TOP NOTCH !!

https://www.rinnai.us/

Yeah they cost more, but look at warranty, craftsmanship, quality, durability and customer satisfaction !!

When I move I am getting a new one at my new place...

 

[davidlee]

I have two Rinnai tankless units and I love them. They have been in for about 4 years with no problems. They replaced one 50 gal gas and one 40 gal electric

 

[ca90ss]

I've installed a fair number of Rinnai and Noritz units and would have no problem recommending either brand. As far as recirculation, you can get point of use pumps that you can mount under your sink and then put them on a motion detector so they only come on whenever you enter the room. If you wanted to add a whole house recirculation pump you'd need to run a return line from the furthest fixture from the water heater back to the water heater which can be a pain.

 

[rsanter]

I have one on my house, and love it
My gas bills are lower and I never run out of hot water

Bob

 

[A1an]

I truly appreciate the information. Seems like Rinnai will be the winner based on what I have seen here and the overall positive reviews online. House is set to close on the 15th so this will be done a few months after we move in. Just need to call around to find some installers that won't price gouge...this also seems to be a common theme with some folks online, however this may be with electric units. Seems replacing a gas tank with a gas tankless is a more straight forward swap for the most part.

 

[Jackfre]

The biggest installation mistake in installing a new tankless, from a tank is inadequate gas line sizing. If you choose to have a unit with the re circulation capability built in it will be the RUR model. It comes with a recirc controller and the cross over valve. Personally I prefer a dedicated 3/4" return line. With our current water situation in the west, recirc is no longer just a matter of convenience. While we have been going energy, energy, energy for decades today it is water, water, water. I guess there is a balance there somewhere.
The other choice is condensing/non-condensing. I chose the 82% unit and I am pleased with it. I can make about 5gpm at a 70* rise. With the condensing unit it would be about 6. What do you need? I've worked with Rinnai for the past 25 yrs. let me know if I can help.

 

[bugnout]

I've have a Takagi T-K1 for 12 years now. Love it. Cost about $1600 installed about 2.5x the cost of a tank. Great investment, I will never go back to a tank.

Minimum flow rate is critical. I live in the midwest so solution for me was to put high flow shower heads and faucets where the flow wasn't enough to kick the tank on. If you can't do that, then make sure the min works for your fixtures.

Had two issues with it. Flame sensor needed to be cleaned and the pressure sensor used to sense if the exhaust fan is running needed adjustment.

 

[Crizzle]

Subscribed.

 

[A1an]

The biggest installation mistake in installing a new tankless, from a tank is inadequate gas line sizing. If you choose to have a unit with the re circulation capability built in it will be the RUR model. It comes with a recirc controller and the cross over valve. Personally I prefer a dedicated 3/4" return line. With our current water situation in the west, recirc is no longer just a matter of convenience. While we have been going energy, energy, energy for decades today it is water, water, water. I guess there is a balance there somewhere.
The other choice is condensing/non-condensing. I chose the 82% unit and I am pleased with it. I can make about 5gpm at a 70* rise. With the condensing unit it would be about 6. What do you need? I've worked with Rinnai for the past 25 yrs. let me know if I can help.

We aren't going to go with the recirc. Is there any standard size for gas lines? House was built in the mid 90s and the water heater was replaced in 2011. Any chance it may already have the right size? If not, is this new sizing run from outside the house? Pardon my stupid questions...never dealt with gas before.

Not sure about condensing versus non-condensing. Still doing a bit of research on that subject but based on my initial findings probably condensing. Going to assume my existing venting would work with that (not in house yet, but I think I recall metal piping as opposed to plastic/pvc). Any suggestions on the choice between the two?

I've have a Takagi T-K1 for 12 years now. Love it. Cost about $1600 installed about 2.5x the cost of a tank. Great investment, I will never go back to a tank.

Minimum flow rate is critical. I live in the midwest so solution for me was to put high flow shower heads and faucets where the flow wasn't enough to kick the tank on. If you can't do that, then make sure the min works for your fixtures.

Had two issues with it. Flame sensor needed to be cleaned and the pressure sensor used to sense if the exhaust fan is running needed adjustment.

Hmmm...certainly going to look into this a little further. We like to use the low flow shower heads for water conservation and because we are cheap.

 

[Charles (in GA)]

A friend of mine had a non-condensing Noritz installed several years ago in her farm house. A tube did pin hole in a bend, but Noritz repllaced it under warranty after she agreed to install a new thru the wall vent. The original thru the roof vent was used by the authorized, factory trained installer and Noritz said that caused the problem (it didn't by any stretch of the imagination).

When she moved to her Grandmothers old house in town, I ended up doing the plumbing for her, and after the factory authorized installer showed up (different person than years earlier) and exclaimed that he had "never seen one of these" (it was a 90% condensing unit) and had practically no tools with him, we sent him packing and I installed it myself, covering every facet of the instructions for any quirks or limitations that might cause future warranty problems.

End result is the unit works wonderfully. The venting is done with solid 3" PVC pipe (you gotta go to a plumbing supplier to get that, big box stores don't have it) (not cellular core ****). It draws outside air for combustion so the only clearance requirements are for maintenance.

Your issue is how far it is to the faucets and showers, and you have to change your mindset about how you use hot water. I turn it on and off frequently (I have a tank heater) and think nothing of it. With an instant unit, you gotta turn it on and let it run till you are finished, so have everything ready at the sink or whatever so you don't have to let it run needlessly.

They make northern and southern versions, southern versions can be installed outside, and can be had with a heating element to keep the unit from freezing in "barely freezing" climates.

Install manual for the model 711DV-LP model I installed

Plan on trashing all of your original venting and probably going thru the wall. Look at the manual I linked to, it is pretty representative of how most of the condensing units install.

Recirc to keep warm water in the pipes, on the Noritz at least, shortens the warranty period dramatically as the heater cycles much more frequently and consumes more gas.

Your tank gas water heater draws much less gas than a tankless unit. Odds are the gas line is not big enough. With the one I installed, new LP plumbing was being installed throughout the house and the LP people were given the specs and told to plan for this water heater in their install.

Charles

 

[A1an]

Inspection was done yesterday. Asked the inspector about the gas line size coming into the garage and he confirmed it is the required 3/4"...so I have that going for me. Closing date is set for less than a month assuming we can talk some sense into the sellers with price and a few other things. They the entire a/c system was replaced within the last few years without the required permits and they have been running it without air filters for god knows how long. Morons.

 

[JonnyMac]

Yep. Rinnai is available in australia and used as the industry standard on new build houses. I have a friend who is a commercial installer who swears by bosch units. Plenty of options with them, i would consider the solar boosted units if they are available as they are extremely efficient.

 

[A1an]

Found out today that there are various energy conservation rebates available for switching out gas appliances. I can get $550 for going to a tankless gas unit. Something worth looking into with your local gas utility.

http://www.getgasfl.com/rebates/teco.aspx

 

[kevinwilly]

I have the same situation- small 2 car garage (about 400 sq ft) and the tank takes up about 8-9 sq ft of that. Very annoying. I always said that when it died that I was going tankless.

That day came about two weeks ago. Bad timing, but i figured what the heck? The only thing left in the house that can be a major expense was that heater and the HVAC unit, which I'm having done in the fall or the spring.

It went out at 10pm on a Sunday. So I start researching. Turns out you need 3/4" gas line because these things are like 140,000 btu (as compared to a tank one that is 35-40,000). I only have 1/2".

I look into it more. I only have 1/2" coming in from my meter... a large chunk of 3/4" black pipe was replaced with 1/2" soft copper at some point. So my furnace also technically only has 1/2" supply, and it's 160,000 btu or something like that. It works fine.

But running 300,000+ btu from 1/2" inlet? Asking for trouble. And as much as I wanted to reclaim the garage space, I don't want to re-plumb all the gas line for my whole house.

I went to lowes. They had a nice 50gal tank with a small dent in it marked down from $650 to $200.

I threw it in the back of my truck and installed it in a couple hours. Grand total with fittings and such was $325. Plus about 4 hours of my labor. Just the tankless unit would have cost me $750 or so, plus significantly more labor. And despite what people say, tankless does NOT save that much money over the new high-efficiency tank units. Maybe $50 a year in our case.

Maybe if it happened at a different time I might have done the work to go tankless, but I've just got too much going on right now to bother and too big of an ego to call a plumber....

 

[JonnyMac]

Cant quite establish from your descriptions but, all australian systems are mounted externally. Now i understand that if you are up in the more northern states that the cold will force these to be installled internally but they are rated for external installation if your climate is suitable. I would say georgia is just fine for external use.

 

[47powerwagon]

I had a bosch,biggest piece of junk I had,i had nothing but problems

 

[dave*99]

I put in a Navien condensing tankless unit is 2013. No problems so far. As stated in other posts, it takes some living adjustments. It takes longer for hot water to appear at the faucet. If you are just washing your hands at the sink, it can be a bit frustrating waiting for the water to get hot. But you adapt.

The plusses are unlimited hot water and no standby losses. My application is a beach house that has an outdoor shower. And 2 indoor showers. It's common to have 6 people cycle through the showers after returning from the beach.

Local utility company provided a $500 rebate. Heater cost about $1200. Installation was part of a major remodel so I don't know the exact cost.

In the winter, the house is seldom used and of course the water heater does not consume energy. I am careful to turn everything off when I leave the house for extended periods. A leak in a hot water pipe will not only flood your house, but steam all of the sheet rock off the studs. And you will get a big gas bill adding insult to injury.

One more thought - I put a hydrant in the garage. Its a valve assembly with a hose bib and 2 valves. It mixes hot and cold and feeds a garden hose. Unlimited hot water in the hose means you can wash things in the winter etc.

 

[cbracer]

I installed a Noritz just a couple months ago for my whole house. Love it. Yes 3/4" pipe for water and gas. A recirculating system is nice with a trunk type distribution but I haven't sprung for that since my distances are short. Use PEX and uponor brand is my favorite.

 

[rodsnratfinks]

Love our Rinnai. No recirculation, but I am considering adding it since the unit is at the far end of the house.

Sent from my SM-G920V using Tapatalk

 

[GDPossehl]

Rather than recirc, I would consider a 4 gal electric heater under the problem sinks. If run in line with the hot water heater it will eliminate any lag and not cause continuous gas consumption.

 

[SteveCh]

I did a lot of checking into a tankless [propane] a few years back. I ended up building my own solar water heater because of what I learned. One thing is that if you are at a lower elevation, no problem. Higher elevations, problem. I spoke with rep's at Bosch, Aquastar, Paloma, and Rennai, and all told me the same thing: higher elevations, their units won't work. Now, I don't recall what those elevations were, let's say it was somewhere above 6000 ft. I am at 8500 ft. and all told me it was a complete no-go. That's ok, I moved on.

Meaning, if anyone is considering one of these units, be sure to check whether they'll work or work sufficiently at your elevation.

Another thing I found is that Rennai, at least at that time a few years ago, in my area, advised me they'd sell only through installers and will not sell to a person doing his own install. Most people won't want to do the install, so no problem; I've build my own home by hand and done all work since day one, thirty yr. ago, plus I'm in an out-of-the-way place contractors don't really care about servicing. This doesn't hurt my feelings or anything, Rennai's policy, I'm simply advising any DIYers out there that Rennai requires professional installation.

Neither of these things will affect most people. All manufacturers other than Rennai had no problem with my doing my own install.

 

[BearsFan315]

Yeah that is odd, as you can buy Rinnai all day on Amazon now, sure they recommend Pro Install, but any handy man that can follow instructions and such should be able to do it. Run Gas Line, Water Lines, Vent, etc...

 

[bmw57isetta]

Put a Rinnai in last Fall. I had heard a few knocks on tankless heaters but we've been very satisfied with ours. Hot water fast and only when you need it.

To put it in context, I'm in Austin, Texas where summers are a clambake and winters are pretty mild for the most part. When it hit 27 degrees outside last winter we had hot water in seconds. External Rinnai at front side of house, master bath at the rear.

I'd recommend or buy another one in a heartbeat.

 

[scissorman]

I bought and installed myself, a Paloma gas tankless water heater that I purchased from HD. I lived in the house for probably 7 years after install and never an issue.

 

[redmondjp]

Rather than recirc, I would consider a 4 gal electric heater under the problem sinks. If run in line with the hot water heater it will eliminate any lag and not cause continuous gas consumption.

I have done this myself - I have been using a Bosch tankless gas water heater for about 15 years now - it will run a shower forever, but forget about so much as opening a sink faucet at the same time.

So in my bathroom and kitchen which are both long runs from the heater, I have a 2.5 gallon (in bathroom vanity feeding both sinks) and a 4 gallon Arston brand electric tank heater under the kitchen sink (really recommend 6.5 gallon here instead).

This setup works well for me.

I am actually planning on going back to a tank, just for the purpose of emergency preparedness (we live in high earthquake zone) to have some potable water on hand. Right now we couldn't live on the 7 gallons in the two toilet tanks for very long!

I had a natural gas tank heater before switching to the tankless (both installed in heated portion of the house), and honestly have seen no difference in my gas bill - any heat 'lost' by the tank heater was that much less heat that the furnace didn't have to put into the house. YMMV if your heater is not in a heated area.

 

[Showkey]

I had a natural gas tank heater before switching to the tankless (both installed in heated portion of the house), and honestly have seen no difference in my gas bill - any heat 'lost' by the tank heater was that much less heat that the furnace didn't have to put into the house. YMMV if your heater is not in a heated area.[/QUOTE

^^^^^^^^^^^
Not the only one to see no reduction in fuel cost. Often goes up with a large family with kids because they shower for ever.
Payback on tankless is often a concern when purchase and install can run $3-4k.
Maintenance on a tankless can be huge concern depending on you water quality.

It is not popular opinion in this thread .......BUT.......do you home work. Tankless are not a perfect nor a good solution in many applications. There are many tankless reports of yearly cleaning of the burner and coils.

My water heating bill is $20-25 a month with a NAT GAS power vent heater that cost $700 with dirt cheap parts and service ( that it never needs). My tank system has a gravity recir system which makes instant hot water at every device. If I saved 30% which seems unlikely on Nat the math still never works. Kinda like spending $$$$$ on motorcycle telling your wife you bought it save money on gas :

Do your home work.........

 

[cbracer]

Yeah I don't think a tankless saves any money in gas bills. It's only advantage is endless supply and size. By putting in a tankless I gathered enough space to add a pantry for my small kitchen so it was well worth it. If size doesn't matter and you don't need endless hot water then a tank type is better.

 

[jnyost]

I installed one in our house a few years ago and have mixed feelings. We installed a Takagi, which was the highest rated at the time. It is definitely nice to have unlimited hot water. We can take 4 showers at a time and still have more than enough.

Pros
- Nearly unlimited hot water.
- Possible money savings.

Cons
- Minimum flow rate can make it hard to get a small stream of hot/warm water or even slightly warm water.
- Trigger delay can mean even more cold water is entering appliances during their fill cycle. It's not just the cold water in the lines that will fill the appliance. There's also a trigger delay, then the blower comes on, then it fires and has to get hot, etc.
- You can find yourself wasting water because you don't have to rush before running out of water. I had a teenage daughter who LOVED hot showers and would stay in one forever. I didn't have to worry about it when we had a tank.

Regardless of the cons, I still love ours. We added an addition to our house and made it very long. Our new master suite is quite a ways away from the heater. I'm thinking of either adding another heater or installing a small tank (~6 gallon) to bridge the gap until the hot water gets there.