Last week I told you what to do when your plumber says "you already have that."

Here is the correction I owe you. Most of you do not have any of it. No return line, and not even the cheap crossover valve. The far bathroom runs cold for ninety seconds and everybody treats that as how houses work.

It is not how houses work. It is a line item nobody put on the plan.

Ninety seconds does not sound like much until you multiply it by every shower, every face wash, every time somebody rinses a dish at the far sink.

That water is not free. You paid for it, you are paying to heat the next batch behind it, and in most towns you are paying a sewer charge on it going down the drain. On a well and septic it is your pump and your field.

Then there is the part nobody puts a number on, which is that you will notice it every single day for as long as you live there.

Not dishonesty. A plan that does not call out a return line gets bid without one, and the plumber is not going to volunteer a line item that makes his number higher than the guy bidding against him. Your plan says water heater, he prices a water heater.

The only thing that changes it is asking before he roughs in.

This is the real objection and it deserves a straight answer, because the fear is not made up.

It comes from the old version of this. A pump running twenty four hours a day, keeping a loop of water hot whether anybody is home or not. That does cost money, in pump power and in heat bleeding out of the pipe all day long.

Nobody has to install it that way, and you should not let anyone install it that way for you.

Put it on a schedule. Most pumps have a timer. Set it to run in the windows you actually use hot water, morning and evening, and it is off the rest of the day. You are paying for a couple of hours, not twenty four.

Or make it on demand. A button at the far bathroom, or a motion sensor under the vanity. You walk in, you push it, the pump runs for a minute and shuts off. This is the version I would put in my own house.

Insulate the loop. Pipe insulation on the hot line is cheap and it is the difference between a loop that holds heat and one that dumps it into your crawlspace. It is also close to impossible to add later.

Do those three and the operating cost stops being a number you would ever notice.

A lot of tankless units now come with a recirculation pump built into the unit, with a scheduler, and some of them have a learning mode that maps when you actually use hot water.

Here is the part almost nobody tells you.

The built in pump does not create the loop. It still needs somewhere to push the water back to. Either a dedicated return line, or a crossover valve at the far fixture.

So when your builder says the tankless has recirculation built in, that is true, and it is not the whole answer. The follow up is what it is pushing back through. If nobody ran a return line, that pump is working through a crossover valve and you are right back to lukewarm cold water.

Not every house needs a loop.

A small tankless under the far sink. A point of use unit in the cabinet that gives one fixture near instant hot water. Good for a powder room or a guest bath way off the main run. The catch is electrical. Those units need their own circuit, sometimes a serious one, and that circuit has to be on the plan before drywall or you are fishing wire through finished walls.

Two water heaters instead of one. On a bigger house, split the load so no fixture is a marathon from a heater. It costs another unit, plus gas and venting if it is gas. The pre drywall decision is the gas line and the vent path, and both are cheap to rough in and expensive to add.

Every one of these closes at a different moment.

The return line closes at plumbing rough in. The circuit for a point of use unit closes at electrical rough in. The gas line and vent for a second heater close at framing.

None of them are hard. All of them are close to impossible once the walls are closed, which is the only reason I keep writing to you about this stuff.

Dedicated return line

Now, at rough in: about $200 and some pipe while the walls are open.

After drywall: opening finished walls to run it, plus patching and paint.

Pipe insulation on the hot line: cheap now, effectively not addable later.

Circuit for a point of use unit: a couple hundred at rough in if somebody knows where it is going.

"Is there a dedicated hot water return line on this plan, or are we relying on a crossover valve?"

And if the answer involves a tankless with a built in pump, the follow up that will make your plumber stop and look at you:

"What is that pump pushing back through?"

One more thing. If you know somebody who is breaking ground right now or has a framer on site, forward this to them. Their window on this closes in a few weeks and nobody on that job is going to bring it up.

That is it for this week.

If something in here does not match what you are being told on your own job, hit reply and tell me what they said. Those are the ones that turn into the next issue.

Jon | Built With This

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