Hot Water is Easier Than It Sounds

 We've been talking/arguing with plumbers. Kevin Holloway sounds great on the phone, but he doesn't want to come all this way from Issaquah. We've been around and around.

He says, go electric.

I had decided to go gas. because electric needs more than 240V x 50-amp = 12kW. A lot more. We have a convenient 50-amp, 240V line right there, but 12kW's the limit.

This afternoon, Mr. Holloway suggests the Rheem RTEX-11 11kW 240V Electric Tankless Water Heater. Amazon sells it for $260. As Mr. Holloway says, "Buy a couple for spares." It serves up to 2.68 GPM, which should be enough for a shower. It's the size of a piece of paper and 3-5/8" thick (8.25" x 12.625").

Looking at the user manual, it must be mounted inside with 12" clear above and below, 6" to each side. That's 20.25" and I'm not sure we have that unless we mount it on the east wall of the closet. It requires no venting.

Greenwood is coming out tomorrow (10/15/20) at 11am, but they already said they want too much and won't consider a cheaper water heater than the upsell they put in their bid. But bid guy doesn't talk to field guy, apparently. I also talked to Fischer Plumbing--they don't bid, they do time and materials. So I could get the Rheem from Amazon and Fischer would put it in.

Trying to understand Rheem's data table. It seems to say that this model, at 2 GPM (a typical shower, I think) can raise the temperature 38 degrees. Is tap water 55 degrees? Then you get a 93-degree shower.

Do we install the tankless unit inline with the old tank? Do we remove the old tank and hope the Rheem keeps up? The User Manual says we might want a Flow Regulator to "prevent the exit temperature from becoming too cool." The manual says if the inlet water temperature is 60-degrees, we want a 1.5 GPM Flow Regulator. The water here is about 59-degrees, as measured by the kitchen thermometer.

I like it as a solution (it costs thousands less), but it's right on the line of working. I like Rheem (that's what I bought for the main tank), and they actually make a smaller one, just 8kW.

If we go this way, we just have to bring the 50-amp wires into the house. That means opening the wall, removing the closet shelf and figuring out what the conduit has to do.

Should be simple enough. If the wires don't reach, we'll need a j-box. Maybe we cover these wires with the j-box and run the new wires back in the house from there. They must be individual wires and in a metal conduit, I think, but that's doable.

Possible deal-breaker: the User Manual calls for 6-ga wire (I don't know what we have, maybe 8-ga) and a 60-amp breaker. That seems odd because the same table says the max amperage draw is 46 amps, so you would think a 50-amp breaker would suffice.