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 ...
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 ...
- 27.7k
22
votes
Should I replace two 75-gallon (gas) water heaters in series with a tankless heater?
We live in the Midwest in a large home that was built 20 years ago. At the time, we installed two 75-gallon gas water heaters, and the plumber did this in series, not parallel
That is the correct way ...
16
votes
Should I replace two 75-gallon (gas) water heaters in series with a tankless heater?
Option (0) would appear to be to "address this" by fixing the defective installation, without replacing anything major, since it's very likely an installation problem or a simple part ...
- 202k
12
votes
Accepted
Do tankless water heaters have a maximum temperature limit for the incoming "cold" supply water?
A Rinnai tankless gas water heater does indeed have a temperature sensor and regulates the outgoing hot water temp. based on incoming water temp. So the burner in the Rinnai has the ability (and the ...
- 4,523
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 ...
- 27.9k
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. ...
- 20.9k
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 ...
- 23.1k
9
votes
Accepted
Should I replace two 75-gallon (gas) water heaters in series with a tankless heater?
A completely different cause (unrelated to the water heaters) might be failed anti-scald valves in one or more of various fixtures around the house.
Due to design of such valves, the fixture does not ...
- 202k
8
votes
What kind of putty should be used for sealing rim joist exhaust vent holes?
So the water heater installers had a beaver or squirrel on the crew to gnaw a hole, rather than using hole-saws like competent workers? Ugh.
I'd wrap that tightly in a scrap of plastic (housewrap or ...
- 202k
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 ...
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 ...
- 64.1k
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 ...
- 129k
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 ...
6
votes
Accepted
Shower gradually cools, gets hotter when sink is on. Navien tankless whole house HWH
Problem solved
I deduced that the recirculation pump backflow valve inside the HWH must be broken. The water at the shower cools because it is pulling water from the HWH "hot" side and also ...
- 406
6
votes
Accepted
What kind of putty should be used for sealing rim joist exhaust vent holes?
That kind of putty is called “duct seal” and you can get it pretty much any hardware store, big box hardware stores, electrical supply shops, etc. it will work fine.
- 2,291
6
votes
Is it ok to plug my 240v tankless water heater directly into a 50 amp RV plug instead of putting it on two 30 amp breakers
This is wrong in many ways:
Instructions are based on UL/ETL/etc. determination of the safe way to power and install the device. In particular, when a large power device moves from 1 circuit to 2 ...
6
votes
Tankless water heater help
Sounds like you fell for the hype of tankless.
Most of the marketed "benefits" of a tankless heater are misleading at best.
Instant hot water only happens when it's a point of use heater or ...
- 11.6k
6
votes
What size breaker box am I going to need?
A tanked water heater is superior to tankless in every way other than how much hot water you get at once. A hot water tank is a battery that you can can charge slowly (even overnight at lower rates). ...
- 11.6k
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 ...
5
votes
Accepted
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 ...
- 24.2k
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 ...
- 316
5
votes
Accepted
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 ...
- 739
5
votes
Do tankless water heaters have a maximum temperature limit for the incoming "cold" supply water?
The tankless doesn't have a valve to block flow. So the pre-hot water will roll right through it. It'll add heat if it's under-temperature.
This means the water could be scalding!
Tankless heaters ...
5
votes
Retrofit tankless installation in an apartment building with rooftop solar
Given the described situation, would it make sense to install a high-capacity electric tankless water heater upstream of the 150-gal?
All schemes which place a tankless heater in series with a tanked ...
5
votes
Can I replace a 30 amp double pole breaker w/ 60 double pole breaker for tankless? Breaker is tripping
You will have to replace the wires from the panel to the heater too. A 30 amp breaker probably has #10 AWG connected to it which is only good for 30 amps. Your new heater will require 54 amps which ...
- 78.7k
5
votes
Accepted
Best solution for undersized wire/breaker?
Load Calculations are mandatory
The procedure that must be used is described in NEC Article 220. Dwellings may use the alternate method in 220.82. The electrician will require this anyway. Note ...
5
votes
Tankless gas water heater exhaust pipe
248 Mass. Reg. 5.12 says:
Plastic Piping. The only plastic piping which may be used for venting
appliances shall be CPVC, polypropylene, and other pipes which have
been Product-accepted for that ...
- 10.9k
4
votes
Accepted
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 ...
- 1,593
4
votes
Accepted
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 ...
- 202k
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