Questions tagged [tankless]

A tankless water heater directly heats water on demand, instead of maintaining a reservoir of hot water. Use this tag in conjunction with the [water-heater] tag

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votes
9answers
9k views

Prewarming for tankless waterheater

I have a tankless water heater that is just a little bit to small for our new house - the temperature rise isn't quite enough for the winter months. Our basement is big and relatively warm so I struck ...
2
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1answer
80 views

Battery backup system for tankless gas water heater (outdoor install)

I have a Takagi T-K3-SP tankless gas water heater, which is installed outdoors. It still needs electricity though, so when I lose power at home, there's no hot water. The manual states it uses 86W ...
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2answers
74 views

Correcting Navien Tankless Hot Water Heater Installation

A while ago we had a plumber/friend install a Navien tankless water heater. We trusted him and thought everything was just fine as we were getting hot water throughout the house. There is a ...
0
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1answer
50 views

How can I figure out if a Combi Boiler will be adequate for my house?

We recently moved into our new home that currently has a Super Hot MG-100 Hydronic Boiler (installed in 1986, when the house was built). Clearly, it's done its job and in need of a replacement. We had ...
1
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3answers
944 views

tankless water heater before the reg hot water

What if I installed a new tankless water heater before the regular hot water heater, so that the tank water heater is getting filled with hot/warm water vs the 40 degrees water its getting now? Our 80 ...
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2answers
99 views

Why am I getting hum and lights dimming with a new electric tankless water heater?

So, I just installed an electric water heater and I'm getting a light hum from the water heater and the breaker panel. It's also dimming some lights.. unevenly. It seems to be more noticeable when the ...
1
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3answers
908 views

T&P valve draining - expansion tank issues?

I am having issues with my Water Heater. It's a slantfin tankless boiler (TR-30 PT). It's running on a 4 zone setup. I typically only use one of the zones though. We've been in the home for a year and ...
1
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1answer
70 views

What is this “on” cap that's adjacent to my tankless water heater's service valve?

There's a "cap" next to my water heater's service valve that says "on" with an arrow. What is this "cap" and its purpose?
3
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3answers
1k views

Chemical Smell After Tankless Water Heater Install

I recently had a plumbing company install a tankless water heater in my crawlspace. Everything with the install works and looks great, but we are experiencing a very strong chemical smell (like nail-...
1
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0answers
67 views

Why does my tankless water heater turn off when I open the cold side of the faucet?

Just got a new Canon tankless water heater. I was wondering, why does the heater go out when I turn on a cold water knob while the hot water knob is still open. Like, I'll turn on the left/hot water ...
2
votes
2answers
9k views

What could cause my tankless water heater to make a knocking sound?

I recently replaced my water heater with a tankless unit (Rheem). After installation I noticed that whenever I turned on the hot water; or when my central heating unit would turn on, the tankless unit ...
2
votes
1answer
71 views

Can I connect a tankless water heater with 3/4“ connections to my 1/2” plumbing?

I have 1/2" pipes from the water meter throughout the house with two full baths. Every fixture installed is fed by 1/2" line and doesn't have pressure problems. Soon I will need to replace my hot ...
2
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2answers
115 views

Why would turning on/off hot water when the toilet is flushing cause the tankless pressure relief valve to release water?

I noticed the other day that my tankless hot water tank was occasionally spraying water all over the place from the Pressure Relief Valve. The only way I've found that seems to reliably trigger this ...
0
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3answers
93 views

Tankless Hot Water Filling Tub - GPM?

I have a question about how filling a bathtub would work with a tankless system. Due to my panels load/capacity I'm looking at the RHEEM RTEX-11 with a Flow Rate: up to 2.68 GPM. I'm worried about ...
13
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4answers
3k views

Can tankless & conventional water heaters join forces?

Although I have properly maintained my nearly 20-year-old 40-gallon (150-L) Kenmore natural gas-fired water heater, I have been considering replacing it with a natural gas-fired tankless water heater ...
1
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0answers
60 views

Service needed to add a tankless water heater

I am currently building a detached 250 sq feet studio in my backyard. The studio will have a tiny bathroom with a tankless water heater, a baseboard heater, and a few lights, a mini split (ac), of ...
1
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1answer
51 views

I12 eccotemp tankless water heater

I am getting ready to install an Eco temp i12 tankless water heater. From what I have heard there is a possibility of cold air backdrafting through the direct vent and into the water heater, thus ...
1
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0answers
59 views

Why momentary chemical smell after Tankless Hot Water Heater install

Why is my hot water stinky for a few seconds? This is a strong but hard to describe chemical smell like CPVC glue, not rotten eggs and not sewage or gas. I put in a new propane-fired tankless water ...
1
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0answers
50 views

Tankless Hot Water Recirculation

I recently had a Rheem Tankless Water Heater installed. The rtgh-95dvln-2. They installed the pump kit meant for the water heater, the ap17920. However, I do not have a dedicated recirculation line, ...
0
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0answers
10 views

Service valve attachment for a Bosch tankless water heater

Has anyone installed a service valve for a Bosch Greentherm tankless water heater? In-line 3/4" service valves are available on the internet but this unit has built-in valves at the bottom. They ...
0
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0answers
38 views

Tankless hot water system only providing luke-warm water?

I have tankless hot water which has been working well up until this week. A week ago we discovered a leak on the hose from the propane tank, so we replaced the hose, but since then it hasn't seemed ...
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0answers
82 views

Installation of Liquid Propane Gas line to new Takagi Tankless Water Heater

I'm installing a new Takagi Tankless water heater and wanting to make sure I have the line plumbed to the unit correctly. I have the Main line @ 3/4" hard Pipe, 3/4" Ball valve, 3/4" Flex Line, Tee ...
1
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1answer
82 views

Water heater noises when my neighbor's sprinklers are active

Hello I recently (few months ago) installed a tankless water heater following a failure of the old 55gal gas heater. Performance has been fantastic, it actually resolved a number of problems, but I ...
1
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2answers
190 views

How to make a flushometer toilet look nicer?

I'm the new owner of a 3 bed, 2 bath condo in Chicago, built in 1923. It's lovely and old. Both toilets are flushometer style, tankless. They look exactly like a toilet you'd see in a public school (...
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1answer
22 views

Adapter for NTC boiler probe

I just bought a replacement NTC probe for my boiler (bought with specific part number) but once the item arrived I noticed the connector wasn't matching. I think this is due to past maintenance when ...
1
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1answer
68 views

tankless water heater with four lugs

I'm replacing a old tankless with a new one. The old one is wired with 240 on two 60 amp breakers. It had two lug connects along with a ground. The new heater is 4 lugs and requires two 60 amp ...
0
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0answers
49 views

Rinnai tankless water heater service cost

My tank-less water heater stopped working with an error code 11. I had somebody out to take a look at it. relatively quickly we went through the troubleshooting steps and concluded the flame rods/...
0
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2answers
181 views

Is there an electric tankless water heater that takes multiple electric lines as input?

I currently have a 50 gallon water tank in my house and I want to replace it with a tankless system. The primary reason to replace it is space. I recently installed 2 HeatWorks Model 1 units to test ...
13
votes
5answers
889 views

Installed Electric Tankless Water Heater - Internet loss when active

I installed an Ecosmart 27kw tankless water heater yesterday and as far as heating the water goes, everything works perfectly. The issue is when the water heater is running, I lose internet! Specs: ...
2
votes
1answer
316 views

Tankless water heater and shutting off main water supply

I have a tankless water heater, love it! And it's not the issue. I have a very leaky shower. I've been in my house for almost 20 years and for the first 10, I didn't mind the very slow drip since my ...
0
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1answer
58 views

Planning to switch to a tankless water heater

I am planning to convert to a tankless water heater but have a few questions to make sure I am on the correct path. I live in a rowhouse in Philadelphia where natural gas is used for heat and my ...
3
votes
1answer
478 views

Derating 6 current-carrying conductors?

I'm having a hard time understanding 310.15(B)(2)(a). Here's the boat I'm in: I hooking up a tankless water heater that calls for 3 40 amp breakers (it's a 24 kw Ecosmart). So I put in a sub panel in ...
7
votes
2answers
984 views

When do tankless water heaters need to be descaled?

I had a Bosch tankless natural gas water heater that stopped working with C7 and EA error codes and the plumber indicated that the unit had failed due to water getting into the internals like the fan ...
9
votes
4answers
3k views

Want to switch to tankless, but can I use my existing wiring?

The tankless water heaters I am looking at require 8 AWG wire but the existing wiring is 12 AWG. Can I do this without having to rerun new wire?
2
votes
2answers
605 views

Will a 2 PSI natural gas line be sufficient for a tankless water heater?

I'm planning on installing a tankless water heater that maxes at 160K Btu. I only have a 1/2" line from the meter to the furnace(75K) in the same room. The city told me that there is 2lb gas from ...
1
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2answers
2k views

Tankless Water Heater and turning off main water supply

I presume there must be plenty of protections for such a case, but is there any reason to be concerned if I turn off (or my fortrezz value and smartthings turns off) my main water supply and my Rinnai ...
1
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1answer
700 views

Tankless water heater plumbing: neutralized condensate and pressure relief valve

Hello recently my old 50gal gas water heater developed a crack and started leaking. I replaced it with a tank-less gas heater. Everything is good, I installed the proper intake an exhaust with 3in ...
8
votes
4answers
833 views

Can my home's power supply handle this tankless water heater?

So my home was built in 1960 and 15-20 years later another room was added on. There are panel boxes everywhere ha. I have mapped it all out and isolated almost everything. Anything that is ...
1
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4answers
3k views

Buffer tank on input or output of tankless water heater?

As I understand it, in residential systems, tankless water heater are commonly paired with a buffer tank to deal with the "cold sandwich" and finite capacity of tankless heater1. This seems ...
0
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2answers
65 views

Tankless hot water to heat home

I have a 1200 square foot second floor apartment that is presently heated using a forced hot water radiator system. The system is called a Paloma "Paloma Pak" heating system. It is basically a ...
2
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2answers
318 views

16“ center bracket to 24” center framing

I'm installing a tankless water heater (150lbs static load, 10" deep) I only have one option for installation and it is a 2x3 framed wall with 24" centers. The Top bracket is designed to mount on ...
1
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3answers
71 views

Is a tank less water heater a bad choice for a house with low water flow?

We are thinking of replacing our current natural gas tank water heater by a high efficiency tank less heater. However we have a water main issue, the house is from 1930 and the main is partially ...
0
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1answer
101 views

Tankless Water Heater - wasting water

It takes a while for the water to heat going to the tankless water heater and in doing that, a lot of water gets wasted. Is there such a thing as a pre-heat switch that would start the heating ...
0
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1answer
60 views

Tankless water heater venting

Most of the images show 90 degree angles for the venting. Can I run mine at a 45 degree angle like the image below?
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2answers
794 views

help determining amp service to my house

I'm considering installing an electric tankless water heater in my house, but need to know what amp service I currently have. I read that you should look at the amps on the main breaker to the house ...
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0answers
43 views

unique ? about venting tankless water header

I am installing a tankless water heater at the house. My question is unique because I can not find a reference anywhere in the code and the installation manual about where to place my exhaust vent. I ...
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0answers
170 views

Furnace draft inducer switch tripping

I have an older furnace and a brand new natural gas instant water heater that I installed. I only start this way because the furnace had one thing break last year, so I'm not sure if things on it are ...
3
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0answers
454 views

Tankless 240V water heater in detached garage tripping AFCI/GFCI breakers in house

We have two separate buildings, a house and a garage/workshop, about 20 feet apart, sharing the same electrical service. On the service entrance, there's a Siemens whole-house surge protector. The ...
1
vote
1answer
54 views

what is a reasonable amount of condensate water produced by my pump?

I have a Ruud hi-efficiency furnace and also a Ruud tankless hot water system, both with condensate lines running down to the pump. My problem is... the pump runs (intermittently) ALL day long..lol.. ...
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2answers
6k views

I Replaced Pressure Relief Valve on Rinnai water heater (twice!!). New one does not hold ANY pressure

I just finished replacing the pressure relief valve on my Rinnai hot water heater. Everything went well, I turned on the cold input and wham, water just started gushing out of the relief valve. All ...