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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3answers
59 views

Water Heater (Tankless), Furnace, Chimney? What order of work? Different contractors?

PRIORITY 1: I have a 21 (yes 21) year old water heater (go AO Smith!) that I want to replace with a tankless water heater (live in MD). WANT 1: I have a chimney that needs to be lined and a fireplace ...
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2answers
90 views

How to wire a double pole breaker with #6/2 AWG wire?

I'm installing a whole house tankless water heater and I'm a little lost as to wiring this power hungry unit and yes I'm upgrading to 200a service(by electrician). I've done some wiring before but not ...
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2answers
142 views

Tankless hot water smells

We bought a house with a Rinnai RUC98 tankless hot water heater already installed. We didn't notice anything about the water at first except only that when we did laundry, the dried clothes smelled ...
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1answer
131 views

Rinnai tankless on-demand water heater making a high-pitched whistling sound

I have a Rinnai tankless on-demand water heater. The unit is making a high-pitched whistling noise. I have: -Unplugged the unit from the electrical wall socket. -Turned the gas valve to the off ...
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1answer
25 views

No shutoff valve for tankless hot outlet

I just had a tankless water heater installed and I noticed that although it's recommend by the manufacturer, the installer did not add a shutoff to the hot water outlet. Will this cause any problems ...
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0answers
54 views

Trying to replace this leaking heater with a tankless, need help with the piping

Just moved into this house, South Florida, two stories, the heater is leaking and I'm replacing it with a tankless. I'm not sure how to plumb it since now I realized I have more pipes coming and going ...
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3answers
391 views

Replacing conventional: electric hot water heater with tankless

I have a 30 gallon electric conventional hot water heater that started leaking. It is in a cabinet above the washing machine; a tight fit: Since it is such a cramped space, I'm considering a ...
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1answer
86 views

Low flow bathroom appliance doesn't activate tankless heater

I have a whole house tankless water heater installed, and so far it's nice except one problem. I also have a nonelectric hot and cold toilet mounted bidet installed. Since a high pressure jet would ...
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1answer
181 views

Tankless water heater causes magnets (ceiling fans, induction oven) to hum while actively heating water

I replaced a tankless water heater with the same model, but a couple of years newer. (The original was damaged by careless house painters). This is a 13 kw Rheem unit and on its own circuit. Since ...
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2answers
85 views

Install Tankless water heater in the cold line

During cold season almost all the time we need to wait for hot water coming from the water heater to our faucets, showers etc. I want to install tankless water heater in the cold line as a ...
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2answers
76 views

Can I use existing 40 AMP breakers when the item calls for 30 AMP

My tankless water heater stopped working and I purchased a new but slightly smaller one. The description on the website said that it used the same wiring as my last one (3 40 AMP breakers and 8/2 AWG ...
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0answers
33 views

Propane tankless heater before an electric one?

I am renovating a property that I use for a bed and breakfast. I have a fairly well working 30 gallon water heater that is electric. I also have a propane tank that I use for limited heating in my ...
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0answers
83 views

Where is the 2 internal drain valve in Navien 240a tankless water heater (damaged needs replacement)

I have a 3 year old Navien 240a tankless water heater. A lot of water continuously flow through the condensation line even the heat exchanger is not operating. The leak can only be stopped when I ...
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1answer
64 views

Adding a Tankless Hot Water Heater after a 40 Gallon DHW Tank to extend Hot Water Supply

I have a 40 gallon tank supplying hot water to 3 tenants (and sometimes their significant others) in 3 bedroom rental home. The 40 gallon does not provide sufficient hot water, so I would like to hook ...
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2answers
103 views

Can I convert 2 two-pole 60A breakers into 3 two-pole 40A breakers

Considering a new electric tankless water heater. But my 18yr old existing subpanel doesn't match what most new heaters use. Any help on the best way to go about this would be great. TIA UPDATE: ...
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1answer
51 views

New Rheem RTG-84-XLN-1 Error 12

I just installed a new Rheem RTG-84-XNL-1 tankless water heater. The unit has been throwing error code 12 off and on since it was first run. The manual and their tech support only entertain the idea ...
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56 views

How does a recirculation valve used with tankless water heaters work?

I understand that a recirculation valve will push cold water into the cold line from the hot line, until the water reaches a certain temperature in the hot line. But curious how does it do it? What is ...
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2answers
56 views

Is a condensing tankless heater that expels excess water outside also a dehumidifier?

I understand that a condensing tankless water heater will recycle that extra heat and only vent the heat that it cannot use; this is why they have a greater efficiency. But the water that condenses ...
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1answer
54 views

Do these look like good PVC exhaust and intake termination ends for a new tankless gas heater?

I just had a new tankless gas water heater installed, and it seems to be working well. But looking around here, other sites, and my own HVAC system, the terminating ends seem to come out further from ...
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3answers
115 views

Should I keep my 5-year-old electric tank heater as a storage unit if I am about to install a new gas tankless heater?

A plumber recently told me that its perfectly common to keep the old 40 gallon tank water heater in series with a new tankless water heater. The motivation is to decrease the time it takes to get hot ...
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1answer
201 views

Tankless Water Heaters in Series

I am building an addition with a basement underneath. The existing home is on a slab foundation, and the 20 year old tank water heater is in a closet. I was planning to replace this water heater ...
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1answer
65 views

Shower Runs out of hot water after a few minutes but sinks stay hot at the same time

I've just moved into a new house and my shower runs out of hot water after a few minutes. It's heated by a 10 year old Bosch tankless natural gas unit which I believe claims 105k output BTU which ...
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3answers
819 views

How can I mix tank and tankless hot water to feed my bathroom?

We are doing a master bathroom renovation and are considering adding a tankless hot water heater to supply just that bathroom. Our current 50 gallon hot water tank runs out after about 2.5 consecutive ...
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1answer
221 views

Installing hot water recirculating pump on a tankless water heater

I'm trying to see if I can install a hot water recirculating pump on my current setup. My understanding is that the pump sits just before the hot water line that goes into the building, but since ...
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2answers
254 views

Wiring size for 75-foot run from 40 amp breakers to tankless water heater?

I am planning out my future tankless water heater install. What type of wire will I need to use for a long run from my 40 amp breakers? Heater will be 240v and about 50-55 feet from the panel. I'm ...
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3answers
381 views

Point-of-use tankless water heater electrical connection

Can I plug my new eemax SPEX3512 Point-of-use tankless water heater with these Specifications Volts: 120V kW: 3.5kW Amps: 29A Temp Rise F at .5 GPM: 48 Degrees Recommended Wire Size: 10AWG Into a ...
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2answers
182 views

Can I install a subpanel for an electric water heater next to the main panel?

I am replacing my A.O. Smith electric water heater with a Stiebel Eltron tankless water heater. This water heater needs 3 inputs of 40amp 125v. My existing A.O. Smith water heater is next to a gas ...
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0answers
79 views

Can tankless water heaters be mounted to the underside of joists in a crawlspace?

My single-story 1100 sqft home (1 bathroom + laundry + kitchen) currently has a gas 40gal tank water heater. We're looking to renovate and remove the tank water heater. It would be replaced with ...
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1answer
256 views

Rinnai R85 - no water pressure after flush

I have a Rinnai R85 tankless water heater. We recently had an issue with no hot water which was resolved by performing a flush. Since then, upstairs sinks and tubs are fine, but our two kitchen ...
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2answers
72 views

warm water only when we replaced the hot water heater with a tankless heater

We replaced the hot water heater with a tankless version. We now only get warm water from the faucets and showers even though the temperature is set at 140 0F on the heater and the outlet pipe from ...
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1answer
40 views

Changing 240 tankless water heater to 120v tank heater

The wall is wired with 8/3. and the white was not used, capped in the junction box. The breaker box has two-pole 30 amp breakers. I want to change the wire size in the junction box to feed the 18a ...
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1answer
2k views

Installing a tankless water heater next to electric service panel

I am in the process of installing an outdoor natural gas tankless water heater. The issue I'm running into is clearances around the heater. There's a small spot on the back wall of the house where I'd ...
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1answer
2k 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
710 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 ...
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0answers
680 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 ...
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1answer
2k 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 ...
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2answers
1k 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 ...
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2answers
1k 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 ...
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3answers
1k 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 ...
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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 ...
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1answer
102 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 ...
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0answers
540 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 ...
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0answers
105 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, ...
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0answers
45 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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1answer
421 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 ...
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1answer
120 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 ...
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1answer
588 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 ...
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2answers
818 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
30 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 ...
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1answer
89 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 ...