We’re rewarding the question askers & reputations are being recalculated! Read more.
25

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 Legionnaires Disease, and it turns out a "warm" water heater is a breeding ground for it and other bacteria. 140°F (60°C) is scalding, and that necessitates the ...


23

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 that was upgraded (DO NOT) then the wire itself would turn into a heater and burn down the house. What I'm saying here is that when too much electricity is ...


10

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 the pressure loss in check. Allow me to share some personal experience based on 11 years of living with a Rinnai instant water heater (R75LS). First of all, ...


9

With a tankless water heater it's all about how many degrees the heater can raise a certain quantity of water. In your situation, you will need a heater to raise the temperature of about 5 gallons per minute (two showers running at once or one shower and another hot water tap running). If you live in the north, and the water out of the tap is be 40 degrees ...


9

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 something not designed for potable water to your plumbing. That's just asking for trouble. The pex idea is interesting. The only reason that I can think that ...


9

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. Even new wiring of the proper size might not be enough because your electric service might not have enough capacity for a central electric tankless WH. What is ...


8

The numbers you need are flow rates and desired temperatures. For example, Home Depot's guide gives the following flow rates: Bathroom Faucet: 0.5 – 1.5 gpm Low Flow Kitchen Faucet: 3.0 – 7.0 gpm Shower: 1.0 – 2.0 gpm Dishwasher: 1.0 – 2.5 gpm Clothes Washer: 1.5 – 3.0 gpm Tankless heaters are rated for how much heat they provide at a given flow. If ...


7

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 bigger unit to supply the whole house and a smaller one at the shower for use during the winter. In either case you're going to get a lot further with this ...


7

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 up one cable and returning on another cable. The heater would work properly, but would kick stupid large amounts of EMF from the two imbalanced cables. Just ...


6

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 exchanger thoroughly and repeat annually depending on mineral content of ground water. (From Bosch 2400E NG user manual) or maybe something like Periodic ...


6

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 open and may be covered with drywall (a.k.a. sheet rock). It this instance the installation of extra studs or cross blocking is not so easy and other methods are ...


6

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 heater is more efficient, this shouldn't be taken for granted. The more efficient unit should be upstream so it carries the heating load. The downstream is ...


5

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 even if it is but the utility didn't provision it well (e.g., they can, as I understand from other questions regarding service-entrance vs. "other" cables for 100A ...


5

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 the tanked heater off when you don't have guests, avoid the standing losses, and take advantage of the higher efficiency of the newer tankless unit.


4

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" tank in this application - cold in the bottom, warmed out the top) or run a long run of large-ish diameter PEX (to minimize pressure drop) around the basement ...


4

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 operation of your tankless water heater. How crucial is this? What it will not do is prevent or replace what is crucial, and that is the maintenance of the ...


4

...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 expensive electrical installation (huge power draw needs huge wiring and often a service upgrade to support something like 3X 40A breakers) that might save 1-3% on ...


4

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 as a service panel utilizing the 6 switch disconnect rule, NEC Article 230.71 (A). The 100A breaker you are referring to appears to be servicing the subpanel. ...


4

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. Pilot through the studs to avoid splitting. You won't need to pilot into the end-grain of the blocks unless they're very hard wood. ...


3

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 Northwest of North America. For everyone else, scale is a fact of life. Certain minerals dissolved in the water, for instance calcium carbonate, have solubilities that ...


3

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 connection. so the valve is closed. you could take that black cover off and add another pipe there and open valve. from your other question your trying to clean it....


3

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 runs to the bathrooms and has plumbing in place. Presumably the old water heater has a fuel supply and venting means, or you might have mentioned that as a ...


3

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 restrict water flow, like, you could get a cup of tea out of it if you're patient. Don't even bother with on-demand unless you are willing to run 240V to the ...


3

Well, to simplify the maze somewhat, you have all the usual loads of an all-electric house. 50A furnace 50A range 30A air conditioning pack 30A dryer Eleven 120V branch circuits, some MWBC, many on 30A breakers (WTH?) Obviously we can oversubscribe this somewhat, e.g. You're not likely to run heater and A/C at the same time. The fine art of panel ...


3

To give this question some perspective, let's consider a chart. This shows how hot your wires will get for a given AWG size and current. If we follow the 12AWG line, which is required to be protected by a 20A breaker, we see that the wire will heat to about 10C above ambient (ie: ~32C in normal room temperature, or 90F for those who refuse to join the ...


3

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 suggest is upgrading your phone line from the box to your modem with something that is better shielded, like Cat6. If you can afford it, going even higher (Cat6a ...


3

Whenever a valve opens and closes, it causes a pressure spike. This is because water is incompressible, so it tends to telegraph pressure spikes a long distance. Water has mass. When you open a valve, the water has to start to move. That causes a local low pressure area which of course is what makes the water move. When you close a valve, a ...


2

I have the same water heater and those knock noises are the flow valve actuators turning on and off...completely normal.


2

I just installed a tankless water heater - Installed Electric Tankless Water Heater - Internet loss when active 27kw is about the minimum you want for a whole house (unless you live in a very hot climate), as others have pointed out this will be 3x40amp 8awg lines. I'd recommend installing something similar and pulling new cables if you are serious about ...


Only top voted, non community-wiki answers of a minimum length are eligible