Info and Advice on Tankless Water Heaters

[Turbo1Ton]

I didn't go back and read through all of this, but I will say I have had a Noritz tankless installed since late 2016. I installed a whole house filter/softener, along with sediment filters at the same time. With the exception of a thermal fuse blowing a year and a half ago I have had no issues. I do flush it almost yearly, every time I change my sediment filter elements. The only issue I did have with it was that during the Arctic Freeze event in February 2021, I had issues with it functioning, which I am 100% certain was due to the outside temperatures. I got several fault codes, replaced the corresponding parts, and it didn't correct it. Once the temps warmed up into the 10's and teens, I had no issues with it, even after installing all of the original parts back into it.

Good news is I shouldn't need to buy any more parts for it, as I have a gas manifold, a control board, thermal fuse, and ignition detection rod.

I do not have any issues with a single point of use not flowing enough for the water heater to function. It does take a good long while first thing in the morning to get hot water in my kitchen, which is about 60' or so from the water heater.

--Jeff

 

[JoyfulNoise]

I’m looking at Rinnai right now as that is what my plumber installs. I like what I’m seeing but I want to get their eyeballs on my utility closet to make sure they think it will fit. I’m also going to have to convert an never-used light fixture (assuming it’s for lighting the closet at night when something bad happens at 2am and you need to fiddle around inside a dark utility closet outside in your pajamas … with snakes, scorpions, tarantulas and bats around) into a 120V outlet. No big deal there. Sadly my plumber is booked until next Monday so we’ll be limping along with one heater for a week. I already got a quote back from them on simply replacing my tank heater because they have everything in stock and ready to roll … it’s a decent price and it could all be done this week … but I’m going to see what tankless goes for.

As for rebates, I can get a $300 federal tax rebate for this year. It can be combined with any state or local incentives so that’s my next web search.

 

[reggiehammond]

Have you considered a heat pump hot water heater? They’re quite a bit less expensive upfront and are the equivalent of a 1-speed pump vs a variable speed pump in terms of energy savings.

 

[JoyfulNoise]

Have you considered a heat pump hot water heater? They’re quite a bit less expensive upfront and are the equivalent of a 1-speed pump vs a variable speed pump in terms of energy savings.

There wouldn't be an electrical service in the closet to handle a heat pump nor the ability to add one. Since I already have gas supplied there, and gas is cheap in these parts, I'll stick with that. But thanks for the suggestion.

 

[PoolGate]

TLDR, but I was looking at these a few years ago. Gas doesn't heat fast enough so go electric. If you need more than 1-2 bathrooms going at a time, tankless isn't for you. Overall, a traditional tank water heater is the most efficient appliance in your house. There is no ROI replacing it with a tankless. I think the best place for tankless is a vacation property that is not often visited.

 

[JoyfulNoise]

TLDR, but I was looking at these a few years ago. Gas doesn't heat fast enough so go electric. If you need more than 1-2 bathrooms going at a time, tankless isn't for you. Overall, a traditional tank water heater is the most efficient appliance in your house. There is no ROI replacing it with a tankless. I think the best place for tankless is a vacation property that is not often visited.

Long story short - the dead 50-gal tank heater is in a very cramped exterior-access only utility closet (my home is a split floor plan so 1/2 the utilities are there and 1/2 in the garage). The heater in the closet supplies the master bathroom suite (shower, tub no one uses, 2 sinks), a small half bathroom sink and the kitchen hot water faucet. So about 5 lines in total with the only major use being the shower and kitchen sink (and not at the same time typically). Gas is the only option as there is no electrical service in the closet big enough to supply the amps needed.

Plumber comes out on Monday to give me his thoughts. I appreciate your suggestions.

My main interest is not ROI as gas is cheap here and so is electric so neither is a clear winner. My interest is in simplifying the closet as it was completely under designed - in it sits the HVAC furnace/air handler and a 50-gal tanked water heater. It is a sardine can and difficult to work on the AC equipment. The designer/builder of these homes clearly did not care about serviceability and so a tankless heater can go a long way to cleaning up what is a mess of a utility closet.

 

[cdchris1]

I just had 2 - Navien NPE-240A2 tankless heaters put in last week. I went through 2 Rheem 75gal tanks in under 6 years due to various problems. While I cannot comments on long term, I am very happy with them so far. I was right on the boarder line of the max capacity for one unit. My plumber said that it would maintain temp, but I would see a reduction in flow if we had too many taps open at once. Also, being without hot water many times over the past 6 months, I was happy to go with 2 so i always have a back up. The units talk to each other so they share the load equally. I opened every faucet I have in the house full blast hot and did not see any reduction in temp or flow. These units also have have built in recirculating pumps if you have a line for them. They also sell a thermal valve that you can install under the furthest faucet that utilizes the cold water line as a make shift re-circulation return. There are some concessions to that as opposed to a true return line, so I chose not to install one. I wanted to live with them for a while and see as the valve can easily be DYI'd. So far though, I have not noticed any more delay on getting hot water that I did with the old tank.

 

[Mdragger88]

I’m also going to have to convert an never-used light fixture

Depending upon when your house was built & the code at the time- the light fixture may not be wired with 12 gauge wire so verify that before you go depending on it.

 

[Ahultin]

Depending upon when your house was built & the code at the time- the light fixture may not be wired with 12 gauge wire so verify that before you go depending on it.

The electrical demand for a modern GAS tankless is negligible and a 15amp supply is more than enough (noritz specifies power consumption of @178 watts with "accessories" and rinnai states less than 3 amps )
The, having the plumber ensure the gas line is capable of supplying sufficient flow is much more important and historically the source of many tankless "complaints". Just like installing a 400k btu sometimes requires a meter upgrade, installing a 200k+ btu tankless can need the same

 

[Bperry]

I’d read the gas flu can sometimes need to be upgraded when moving to a tankless unit. Something the plumber will be able to advise.

 

[JoyfulNoise]

I’d read the gas flu can sometimes need to be upgraded when moving to a tankless unit. Something the plumber will be able to advise.

The flue stack is designed to handle a forced air gas heater as well as the atmospheric vent for the current water heater. I believe it is sized pretty large but you are right, the plumber will have to advise on that. They will also have to look at the gas supply line too. Both very valid questions.

 

[wireform]

I had a tankless for close to 12 years and at the time the only vent pipe was a double walled stainless steel with dedicated gaskets and clamps which can be costly. Tankless heaters are usually side wall vented and need the double wall vent pipe.

 

[JoyfulNoise]

I had a tankless for close to 12 years and at the time the only vent pipe was a double walled stainless steel with dedicated gaskets and clamps which can be costly. Tankless heaters are usually side wall vented and need the double wall vent pipe.

Actually there are many different options nowadays. Condensing style tankless heaters (not appropriate for my use case) can actually just use PVC pipe for the vent because the exhaust is very cool. Some models use simple atmospheric venting like a standard tank water heater has. It seems from all I’ve read with posts on other sites going back as far as 15 years that there were lots of issues raised in the early days of tankless that have now been addressed for the most part including units with built in recirculation pumps, etc, etc.

Technology marches onward

 

[wireform]

Correct you are as my high efficiency boiler now vents out with dedicated pvc of sorts.

 

[borjis]

I've got a Rennai that was here when I moved in. It's been a great unit. I'll never go back to a regular water heater. Mine is mounted in the garage wall. The other side of it, is outside...it has an internal fan that blows the exhaust out it's side vent to the outside.

 

[Turbo1Ton]

The flue stack is designed to handle a forced air gas heater as well as the atmospheric vent for the current water heater. I believe it is sized pretty large but you are right, the plumber will have to advise on that. They will also have to look at the gas supply line too. Both very valid questions.

Noritz makes their EZ series that has top water connections and is suitable for use with the existing flue pipes. Designed to basically drop in place of a tank.

Noritz EZ Series

www.ezseries.noritz.com

I haven't looked at Rinnai but I would think they would also have something similar.

--Jeff

 

[Ahultin]

Yep, the rinnai condensing units can be vented in a retrofit application with a pvc tube sent up the existing b vent. Just helped a friend in AZ with one last summer like that. His existing gas supply line was 3/4" and the meter supplied sufficient volume so no upgrade was required (home circa 2004). For the electrical connection we ultimately added an outlet by replacing the single gang box for the door bell transformer which happened to be in the same location with a dual gang box so ignore the precarious extension cord lol

 

[Ahultin]

I had a tankless for close to 12 years and at the time the only vent pipe was a double walled stainless steel with dedicated gaskets and clamps which can be costly. Tankless heaters are usually side wall vented and need the double wall vent pipe.

When we built our home this was also the case, stainless steel vent pipe. Luckily this is no longer the case. Our initial plumber had zero tankless experience and was certain we would hate it so he insisted we plumb for two so twice as much stainless vent pipe . in the end we have never installed the second unit and even when we have a full house it has no issue keeping up.

 

[JoyfulNoise]

Yep, the rinnai condensing units can be vented in a retrofit application with a pvc tube sent up the existing b vent. Just helped a friend in AZ with one last summer like that. His existing gas supply line was 3/4" and the meter supplied sufficient volume so no upgrade was required (home circa 2004). For the electrical connection we ultimately added an outlet by replacing the single gang box for the door bell transformer which happened to be in the same location with a dual gang box so ignore the precarious extension cord lol

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Is that 5 gallon bucket there to catch the condensate from the heater? How often does it fill up? Also, it was my understanding that condensing units are more suited for cold weather climates like the NE rather than warmer areas like Arizona. Was there another reason your friend chose the condensing unit?

 

[Ahultin]

Is that 5 gallon bucket there to catch the condensate from the heater? How often does it fill up? Also, it was my understanding that condensing units are more suited for cold weather climates like the NE rather than warmer areas like Arizona. Was there another reason your friend chose the condensing unit?

yup, the 5 gallon bucket was the temporary solution to the condensate drain until the next time I make it out there to help run it properly. It's been that way since February and he said it has never gotten fuller than about .25"
The condensing units are negligibly more expensive but on average about 10% more efficient. The exhaust of the condensing units is significantly cooler which allows for the use of alternative (typically pvc) vent pipe.
The non condensing units typically produce the condensate as well but in the vent pipe. The condensate formed by both types of units is acidic (hence the need for stainless and a horizontal section with drain so it does not drip back into the unit)