25 votes

Can tankless & conventional water heaters join forces?

I see a couple problems there. First, having a tanked heater operate at less than 140°F (60°C) is problematic. The reason is our science has advanced on the Legionella bacteria which causes ...
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23 votes

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

If a heater requires 8 AWG wire, it's because it requires more electricity than a smaller wire is capable of safely delivering. If you used the 12 AWG wire, first the 20A breaker would trip, but if ...
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  • 26.6k
11 votes
Accepted

Can tankless & conventional water heaters join forces?

Your gas pipe plan seems reasonable -- 1" pipe carries a lot of CFH of gas. We'd have to know the pipe length involved to be sure, but it's likely that covering most of the distance with 1" will keep ...
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  • 19.5k
10 votes
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Prewarming for tankless waterheater

The typical way to pre-warm water is to install a standard tank water heater before the tankless, but leave it turned off. Using an automotive radiator is a terrible idea. You don't want to connect ...
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  • 18.8k
9 votes

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

You cannot use an electric tankless water heater in place of an electric tank without a significant upgrade in wiring and most probably adding new breakers to make a total of two or three breakers. ...
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  • 19.6k
9 votes

Can/should I change GFI outlet to standard outlet

Maybe others will chime in, but I don't understand why the instructions would recommend against using a GFCI outlet other than for reducing the possibility of nuisance trips. Perhaps they are ...
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8 votes

Prewarming for tankless waterheater

You could add a smaller tank-less heater in front. Some of them are even rated to be plugged into an outlet so you won't have to do additional electrical work. In Europe I've seen it done with a ...
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7 votes

Installed Electric Tankless Water Heater - Internet loss when active

First, make sure that your three supply cables are paired properly. The unit has 3 heaters internally. There are several ways cables could be crossed that would result in power from 1 heater coming ...
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6 votes
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When do tankless water heaters need to be descaled?

The manual will say something like Flushing the heat exchanger with a descaling solution if mineral build up is evident. Scale build up will shorten the life of the water heater, descale heat ...
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6 votes

16" center bracket to 24" center framing

The other answer given so far describes a solution where the tankless water heater is being installed in an area where the studs are open and not covered. There are instances where the studs are not ...
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  • 61.1k
6 votes

Can tankless & conventional water heaters join forces?

You can run water heaters in series. There's no problem there, typically. Consult the installation manual to be sure. Your main concern is probably efficiency. While it stands to reason that your new ...
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  • 104k
6 votes

Can/should I change GFI outlet to standard outlet

TL;DR Safe answer = Hardwire There are a few different pieces here: GFCI affects stuff That is, IMHO, almost entirely mythical. GFCI is, as I understand it, a basically passive system unless/until it ...
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5 votes

Installed Electric Tankless Water Heater - Internet loss when active

Long shot...if I'm wrong I'll delete. 112 Amps is a HUGE draw. As you probably know, many houses have a total 100 Amp (sometimes less) service. If your service drop isn't significantly larger, or ...
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5 votes

Can tankless & conventional water heaters join forces?

I would use the new tankless heater for the rooms you use most often and the existing tanked heater for guest rooms. It's more plumbing work but it gives you the best of both worlds. You can switch ...
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5 votes
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How to connect flex NMC to Rinnai tankless

OK, so I called the support line, and to my (pleasant!) surprise, they were willing to talk to me, a mere homeowner. Running the power cord up through the grommet is intended. But the gentleman also ...
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4 votes
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How crucial is a filter for your tankless water heater?

This will extend the life of the tankless. It will indeed extend the life of the water heater, because the filter will capture and trap any debris or particles that would otherwise interfere with the ...
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4 votes

Prewarming for tankless waterheater

Do NOT use an automotive radiator - it's not meant for nor suitable for potable water use. If you have a "relatively warm basement" you can either use a plain, uninsulated pressure tank (a "tempering"...
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  • 133k
4 votes
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Electric Water Heaters: Tank vs Tankless (Instant On) Energy Usage?

...in a modern tanked heater with modern levels of insulation, and people actually using hot water from time to time, standby losses are microscopic .vs. use. So a tankless electric is a very ...
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  • 133k
4 votes

tankless water heater before the reg hot water

If your 80 gallon tank turns cold at an unacceptable rate, either you have a broken hot water heater (like, a broken siphon tube), or you really, really like high water flow. For instance a lo-flo 1....
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4 votes
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help determining amp service to my house

A lot of what I am about to answer is personal opinion so there may be quite a bit of comment on this answer. It appears that you have a 200A service being fed to a Zinsco Panel which is being used ...
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4 votes
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16" center bracket to 24" center framing

I would fit two 2x6 (or larger) blocks crossways between your studs at the two mounting locations. Put three 3" construction (not black drywall) screws through the studs into each end of the blocks. ...
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  • 104k
4 votes
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Installed Electric Tankless Water Heater - Internet loss when active

Something you might want to consider here is that your phone line inside the house is probably something crappy and unshielded. Cat3, for instance, offers virtually no shielding at all. What I would ...
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  • 19.7k
4 votes
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Is a condensing tankless heater that expels excess water outside also a dehumidifier?

The condensate from natural gas burning comes mainly from the burning. Methane is the primary component of gas, and it is chemically CH4. When burned, you have: ... a problem, because MathJax does not ...
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  • 947
4 votes
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Replacing conventional: electric hot water heater with tankless

TLDR: Replace house's electric 100A resistance strip-heat "furnace" AND 40A its air conditioning with a 30A wide-range heat pump that does not require emergency heat. Enjoy lower electric ...
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4 votes

How to connect 113A tankless water heater 125 feet from main panel?

Just say no. I know it isn't the question you asked, but in my opinion this is an absurd use of resources. You are taking more than half the capacity of your home electric service and sending it to ...
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3 votes

When do tankless water heaters need to be descaled?

Scale will always occur except in extremely unusual circumstances that only cover 10% of the human population who obtains extremely low-calcium water in extremely wet regions like the Pacific ...
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3 votes
Accepted

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

i need a side pic but as of right now i think that valve is closed. so if this is the case it is a valve to open or close the T pipe. im guessing the black screw cap is there just to cover another ...
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  • 166
3 votes

Should I replace my conventional interior water heater with an exterior tankless model?

Your salesman is evidently an idiot. Perhaps you want to do more shopping and find a vendor with smarter people working for them. You already have the space. The space is well-located for short pipe ...
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  • 133k
3 votes

Tankless point of use water heater that only heats when inlet is cold

TLDR: they all do that, it's a safety feature to avoid scalding. It takes a lot of power to make heat. You won't get much heat out of a 120V on-demand heater unless you really, really, really ...
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