I know, you’re not my electrician, so noted. I’m hoping for someone passingly familiar with electrical codes. My background is in electronics and I am comfortable working with normal house wiring.
My water heater runs on 240V. That is, there are three wires (not counting ground) supplying this: Line 1, Line 2, Neutral. There is 120V from L1 to Neutral, there is 120V from L2 to Neutral and there is 240V from L1 to L2. So far, this is the way it was dating back to when I bought the house.
I’d like to add one of those recirculating pumps that pushes hot water to the farthest faucet (where there’s a valve that regulates this) and that pump and timer require 120V–at the water heater.
Can I just tap L1 and Neutral at the water heater electrical junction box for this? The power company won’t care about an extra couple amps, but is there anything wrong with going off a line that’s normally–I don’t know–balanced(?) to do so?
I fear I didn’t explain this properly but I hope I’ve made the question clear: Can I effectively add a small load on just one side of the wiring that was run specifically to power my water heater? Electrically I don’t see where it would make a difference but sometimes building codes are strange beasts.
I did this when I installed my central AC unit on our house: I installed a 120 VAC receptacle next to the outdoor condenser unit by tapping into one of the hot lines and neutral. (When I installed the condenser, I also ran a neutral line for the purpose of installing the receptacle.)
Works great! But then someone told me it was not code. If this is true, I’ll need to remove it if I ever sell this place.
The way to do it per code is to install a breaker box at the end of the 240 volt line and tap off the 240 for the AC and the 120 for the receptacle. Otherwise you end up with a 120 volt line with a 15 or 20 amp receptacle and #14 or #12 wire on a 30 amp breaker (which should be #10 wire in most cases).
Same issue for the OP. If there is a short, the wiring and receptacle will catch fire long before the breaker trips.
I installed a box next to the condenser unit. It contains two 30 A fuses and a disconnect switch. I think I installed an inline fuse (15 A or 20 A fuse) when I tapped in to L1 and neutral for the 120 VAC receptacle. I’ll check. If so, would that meet code?
Fuses and breakers are to protect the wiring, not the device (like the pump). The short run from the 240 junction to the pump is a pigtail and does not have to match the power feed. For example, every lamp has a run of 18-22 gauge wring with the plug on the end plugged into a 15 or 20 amp circuit.
The electrical question has been answered, but I’m curious how you’re going to add a recirculating pump to a system that wasn’t installed with one. You’ll need the hot water faucets to be piped in a loop, right? I have that at my house, but it couldn’t be added if it didn’t have it already, because the hot water pipes are under the concrete floor.
There is a special device that hooks to the hot and cold taps at the farthest faucet. Inside that is a temperature-sensitive device that is open when the water on both sides of it are cold. On demand, or on a timer, the recirculating pump sends hot water through the hot water line, to this valve, and then forces it back on the cold water line. It does this until the temperature valve senses that hot water is now available at the faucet. At this point the valve closes, leaving hot water at the hot faucet.
There’s a lengthy writeup here:
The loop is completed by the temperature-sensitive valve at the farthest end from the heater. This goes under the sink at the faucet connections. You could probably do this as you don’t need into-the-concrete access.
Granted, the white and copper (ground) are tied together in the heater junction box. That’s what initially made me think it would be all right to add a circuit onto it.
This is not kosher. Neutral and safety ground should be connected together at exactly one place - the main breaker box. The white should just be capped off with a wire nut.
Note that this would be a subpanel which requires isolated neutral and ground buses. You need to remove the screw which shorts the neutral bar to the panel enclosure and add a separate ground bar. In that subpanel you will need a 20A single pole breaker for the pump and a 30A (or whatever is currently feeding the heater) double pole breaker for the heater. The breaker in the main panel stays as it is.
Not terribly complicated, but not entry-level DIY either.
ETA: A subpanel is subject to the same access requirements as a main panel (unobstructed space in front of the panel), you can’t just stuff it anywhere it will fit.
IIRC, in just about any jurisdiction when you get to installing sub-panels you also get into the realm of “Needs a building permit, a licensed electrician, and a close-out inspection.”
Ahh, the never-ending joys of buying a used house. Granted it’s been that way since (before) we moved in–a decade ago, but it’s always so fun learning what (else) the previous owners screwed up.
In this case, nothing, since the neutral is not carrying current. In a 120V or a 240/120V circuit it would put current on the ground and could energize any metal connected to ground.
Does the pump even need to be at the water heater? Why not put it somewhere along the hot water line that’s more convenient to another electric circuit?
At least for the one I installed a few years & houses ago …
It needs to be on the inlet side of the water heater, but downstream of any other cold-water branches. So the only thing it is pressurizing is the soon-to-be hot water.
Even if you could install the pump on the hot / output side of the HWH, you’d need it upstream of the first branch of the hot distribution lines. Unless you wanted to pressurize only one portion of your hot distribution. Which is not inconceivable, but also not the most likely use case.
In either case, given the typical branching nature of plumbing, the pump generally wants/needs to be physically close to the HWH.
If this is true, I’ll need to remove it if I ever sell this place.