Tankless Whole House Hot Waster System

[ChrisA Edwards]

Looks like one, of our two, hot water systems may have finally died.

Both, I believe, are original for when the house was built 22 years ago and are electric units in my crawl space.

So, I think I will take this opportunity to go with whole house instant hot water system.

I now have natural gas, so I think that's the direction I'd like to go.

Also, I think an external unit would be preferable for the annual servicing.

So I'm looking for pro's and con's and recommendations from those of you who may have been down this path.

Thanks.

[Bill Dufour]

external mount may freeze. there is no pilot light to prevent freezing.
Bill D

[Jim Becker]

I had two NG-fired tankless hot water systems in our old house and loved them. There was never a want for hot water and they required a minimum of space. We could have three showers plus the dishwasher going with no issues. (I do not have gas here at the new property...it's in the street, but the cost to bring it in is steep. Not for the install of the line, but for the requirement to convert so many things within 12 months to not have to pay over five grand for the install)

In extremely temperate/tropical climates, external systems are fine. I would not consider outside in your geography at all.

[Steve Jenkins]

Don’t confuse instant with unlimited. Tankless will provide unlimited hot water but before the hot water gets to your faucet it still has to travel the length of the pipes.

[Jack Frederick]

I represented Rinnai in my business for 29 yrs. you get enough of a winter in TN to make me say, avoid .the outside units. The ,freeze. Protection (elec) kicks in around 38*. Do they work, yes, but .a direct .vent interior .will be best for you. Steve is correct. You have to look at your homes lay-out fixture wise. I one unit sufficient? Hmm,in looking at what I’ve written so far I find that topping with my broken hand is an issue. Ip’ll p\m you my .phone number.
PI can cover more territory that .way.

[Malcolm McLeod]

... Also, I think an external unit would be preferable ...

My neighbors have them outside in this area, with zero reported issues (AFAIK).

The (name brand) gas-fired units I have looked at in the recent past all had 2 stage freeze protection: 1- ceramic heaters (elec) turn on when low temps are detected; 2- if the heat exchanger, or other such components, drop below freezing, then the gas heater itself also fires briefly/repeatedly (even with no flow) to hold temps above freezing.

Obviously, if your electric or gas service is unreliable, you are open to serious water heater issues (among other things).

[Scott Clausen]

When I ran the numbers it just didn't add up for me. I have ample room in the basement for a $500.00 gas WH that I replaced myself. When I compared that to tankless they cost more.

[Jerome Stanek]

Looked at one for my son and the savings was not there to change.

[Mike Henderson]

I have two units at my house. Love them. Highly recommended.

Mike

[Jerry Bruette]

Didn't we have a thread here a few months ago about the tankless water heaters failing in Texas last winter during the power outages?

I wouldn't put one outside at all.

I think you'll have to take into account how you're going to power the tankless heater. Will you have to run new electrical or gas service to the unit? Either one could be costly and have a long payback.

[Erik Loza]

Didn't we have a thread here a few months ago about the tankless water heaters failing in Texas last winter during the power outages?..

Yes, I was one of the victims (along with many in my neighborhood). For better or worse, the common method of installation around here is exterior mount. My immediate neighbors have a Rinnai and drained the unit prior to Freezemageddon. Their unit survived just fine. Ours got bricked because I didn't think ahead and do the same. This fall, I'm going to do some winterization steps:

-Fabricate some sort of insulation blanket for the housing and some sort of insulative wrap for the service valves.
-Install one of these: https://safeguardpowersolutions.com/hugo-x1r-350w-pure-sine-wave-battery-backup-for-tankless-water-heaters-room-heaters-direct-vents-furnaces-combi-boilers-and-gas-appliances-compatible-with-rinnai-navien-rheem-noritz-and-more/
-Get a compressed air fitting for the hose barb, so I can fully blow any water out of the heat exchanger.
-Pay f***** attention to the weather and not just "assume" the grid will hold. :rolleyes:

I imagine that the builders do surface mount because it's easier and cheaper than interior but will add that I know a guy whose Rinnai burst INSIDE the attic, because it was around 15 degrees for 3-5 days with no power. All this being said, I love our Rinnai and have no hesitations in recommending them.

Erik

[Jim Braun]

We put in a Rinnai 2 years ago and we are very satisfied. It is not cheap, but we did it to reclaim about 9 soft of floor space in our tiny laundry room. We have the unit with the recirc pump and have it programmed so the water is warm we we get up in the morning and before we go to bed. It needs yearly maintenance where you pump 3 gallons of white vinegar trough the system and clean a filter, very easy if you have the isolation valves.

Make sure you get a good installer, I asked that the heater be place as close to the ceiling as possible so that I could use the reclaimed floor space for a cabinet, etc.
463964

[Jim Becker]

Looked at one for my son and the savings was not there to change.

When I installed them in my previous home, it wasn't for "savings" specifically...it was primarily for constant, un-interrupted hot water. That said, the gas usage was pretty low, anecdotally speaking. We have a 50 gallon electric tank type here at the new property. So far, it's worked fine for just the two of us and since we do not currently have natural gas connected to the house, I don't even have the option of going to a tankless unit. If I had gas, I wouldn't immediately change out the relatively new existing system, but I'd consider it down the road at replacement time.

[Brian Elfert]

The natural gas for my water heater costs me about $3.50 per month. (Does not include the $9.00 service fee.) I would never see payback if I went to a tankless water heater. My water heater was installed in 2014 and is a power vent model.

[Erik Loza]

We never really got the tankless for power savings (gas). The "on-demand" part plus form factor were the attractions. We were doing a major remodel at the time, so it made sense. Our upstairs shower, which is farthest from the unit, takes maybe 30-45 seconds to receive hot water. Not a negative in my book. I wouldn't install on just to have it but as Jim mentions, it's worth considering if there are other reasons.

Erik

[George Yetka]

The only benefits I see is that the unit takes up less space, Costs less to run depending on how often it needs to run, and less likely to build hydrogen sulfide.

You wont get hot water faster except for the first time you turn it on

[Jim Becker]

Up off the floor is another benefit when there's a wet basement involved or a need to install in interior space. An example of the latter is in the addition of our old property...the unit is on the wall in the laundry room and takes up zero floor space.

[Brian Elfert]

Here in Minnesota most houses have basements so finding space for a traditional water heater is not an issue. I wouldn't mind a tankless water heater if it came with a house I bought, but I will probably never buy one unless they become mandated. They cost more than tank water heaters and are very picky about maintenance. I may very well go electric with my next water heater to use up some of my solar power. An electric tankless water heater requires enormous amounts of electricity.

Navien heavily markets their tankless water heaters here, but I've seen tons of videos on Youtube of them failing left and right.

[Jerry Bruette]

Here in Minnesota most houses have basements so finding space for a traditional water heater is not an issue. I wouldn't mind a tankless water heater if it came with a house I bought, but I will probably never buy one unless they become mandated. They cost more than tank water heaters and are very picky about maintenance. I may very well go electric with my next water heater to use up some of my solar power. An electric tankless water heater requires enormous amounts of electricity.

Navien heavily markets their tankless water heaters here, but I've seen tons of videos on Youtube of them failing left and right.

If you have hot water heat you could get a indirect fired water heater. I've had one since 1988 and the only thing I've done to it is adjust the temperature. Don't remember ever running out of hot water either.

[Bruce Wrenn]

In our house, we are on our second 40 gallon propane fired WH. First only lasted 18 years. It was a "top of the line" bought from plumbing supply house. Second (23 years old) was a cheapie from Lowes. As for heat losses, we just spent three days at the beach. Before leaving, I shifted control to pilot, cut off supply line (water,) and relieved pressure at closest spigot. Upon returning today, turned control back on. The WH did NOT fire up, because it hadn't lost enough heat in three days to kick it on. Never have we ever run out of hot water, in the forty one years we have been in our house.

[Bruce McVeety]

I’m retiring and moving up to northern Minnesota to a place with well water. I wanted to upgrade to a propane fired tankless unit to save space but was advised against it because of the difficulty heating cold well water in the winter.

[Ronald Blue]

I’m retiring and moving up to northern Minnesota to a place with well water. I wanted to upgrade to a propane fired tankless unit to save space but was advised against it because of the difficulty heating cold well water in the winter.

I would expect the well water to be 50 something degrees year around. Sounds like the plumber/contractor really doesn't like the tankless heaters. I was just looking at specs on a 9 gpm LP unit. The water output does drop about 1/3 for water at 53 degrees Fahrenheit. So 5.7 gpm instead of 8.5 at 75 degrees. If you really need more flow then a larger unit would be an option. Just an observation here though.

[Jim Becker]

I agree with Ronald. Wells are no problem for heating the water regardless of heater type...the ambient temperature of water out of the ground from down deep is not the same as at ground air temperature. One concern there is with tankless systems in particular, but can also affect other methods, is mineral content in the well water. It's a maintenance issue, but tankless systems are more demanding around dealing with mineral content and regular maintenance to mitigate. There are a lot of plumbers who just don't like tankless, too. Some of that may be profit margin which can sometimes be huge on tank type units.

[Ronald Blue]

Another oddity to me is that the tankless use a smaller temperature rise then tank type. Since the recommended temperature for discharge is 120 it makes no sense to me that tank type are rated for a 90 degree temperature rise in first hour recovery. I'm sure I am somehow missing a crucial piece here. Maybe someone else can educate me on this peculiarity in the data. But comparing the tankless to tank type vs initial cost it looks like the tank type higher initial cost is basically recovered in the first year. $480 for tankless and $690 tank type annual estimated cost of operation.

[Mike Henderson]

Another oddity to me is that the tankless use a smaller temperature rise then tank type. Since the recommended temperature for discharge is 120 it makes no sense to me that tank type are rated for a 90 degree temperature rise in first hour recovery. I'm sure I am somehow missing a crucial piece here. Maybe someone else can educate me on this peculiarity in the data. But comparing the tankless to tank type vs initial cost it looks like the tank type higher initial cost is basically recovered in the first year. $480 for tankless and $690 tank type annual estimated cost of operation.

I noticed that my gas usage went down after I installed the tankless water heaters. I think the reason is that a tank heater has to keep the water hot all the time, while the tankless only heats water when you're using water.

Mike

[BOB OLINGER]

Don’t confuse instant with unlimited. Tankless will provide unlimited hot water but before the hot water gets to your faucet it still has to travel the length of the pipes.

Right on - hot water supply at the using point takes a bit longer with the tankless system, but IMO worth it.

[Jim Becker]

Right on - hot water supply at the using point takes a bit longer with the tankless system, but IMO worth it.


Takes the same amount of time to travel the pipe as from a tank system. :) Unless the system is a recirculating type that always has hot water flowing.

[mike stenson]

Tanked systems always have hot water in the tank, so heat does exchange. It basically makes it feel like it's faster, because the temperature change isn't as abrupt.

We went from years with a tankless to a dual zoned tanked system in this house. When these heaters go, I'll go back to tankless.

[Rod Sheridan]

My only comment is that I went from NG to electric to reduce my carbon consumption, an easy change that doesn't affect my lifestyle.............Rod.

[Alan Lightstone]

We put in a Rinnai in our new home when we remodeled 3 years ago. There is a definite time lag to get hot water (it has to go up 4 floors), then it is continuous.

Our propane usage is so low, the gas company just comes out twice a year to check on us, so operating cost is incredibly low.

Definitely want indoor installation with direct venting.