Comments on: Faster Hot Water Can Change Your Life

By: Jay

Jay — Sun, 19 Mar 2023 15:48:35 +0000

Great article.
I found it by searching for the benefits of switching to PEX on a long run of copper to a distant bathroom. I was not thinking of a volume change, as the water pressure to the shower is just acceptable as is.
My thought was simply to reduce the heat dissipation through all that copper. Any idea of the relative contribution of less thermally conductive pipe vs reduced volume to the improvement in hot water delivery?

By: CHARLES BUELL

CHARLES BUELL — Wed, 22 Feb 2023 12:51:50 +0000

At 60 psi, through 1/2″ pipe (a little less because it is PEX) you would waste 28 gallons in two minutes. My timer controlled thermosiphon recirc loop on the other hand is hot after pushing out only a cup of water.

By: Mark Walker

Mark Walker — Wed, 22 Feb 2023 00:06:39 +0000

In reply to Paul Szymkiewicz. It only takes two minutes for the hot water to reach all the faucets, but I gave it a small fudge factor. I also insulted all the pipes (pex), so the water is still comfortably warm 30-45 minutes later.

By: Paul Szymkiewicz

Paul Szymkiewicz — Mon, 20 Feb 2023 21:03:20 +0000

In reply to Mark Walker. Mark, that sounds like an interesting solution. Just wondering, why 4 minutes?

By: Mark Walker

Mark Walker — Mon, 20 Feb 2023 20:35:46 +0000

I see I’m late to this blog post but I’ll comment anyway.
I’m on a septic and didn’t want to add more water to it than I have to, so I had a recirculation loop installed during construction. The Grundfos pump can be controlled by the dip switches in 15 minute increments (good luck with that.)
I bought a 4-pack of wifi smart outlets for $20. The pump is set to always on and plugged into one smart outlet. The other three outlets are in the kitchen and two bathrooms. Each outlet has a manual on/off button and at the click of any of those buttons, the automation triggers the pump to turn on for 4 minutes. The triggering outlet automation turns itself back on 2 seconds after the pump outlet is turned on. This confirms that the wifi actually worked.
The pump can also be triggered from our phones and Alexa/Siri/OKG, but clicking the little button is easier.

By: Paul Szymkiewicz

Paul Szymkiewicz — Sun, 01 Jan 2023 16:19:20 +0000

In reply to Charles Buell Inspections Inc.

Charles, let me quote Martin Holladay who called a thermosiphon loop an “energy nose bleed.”

No method (recirc loops, reduced diameters, etc) is free of energy losses, but I would put the thermosiphon in the “worst” category, and for some scenarios, even worse than not modifying anything at all. You mention a timed shut-off valve, trying to understand: what happens when the valve is off and someone calls for hot water?

By: Charles Buell Inspections Inc

Charles Buell Inspections Inc — Sat, 31 Dec 2022 13:51:13 +0000

Hi Allison, I have a thermosiphon loop on my water heater to take care of the one distant kitchen. The only power is a timer for an automatic shut-off to control back siphoning and that it not circulate all the time.
Charlie

By: Caralee Jackson

Caralee Jackson — Fri, 14 Oct 2022 02:52:06 +0000

Google suggested your wind washing post after I was researching spray foam insulation which was excellent, led me to this one and now I plan to go back through your entire blog. I own a 1940’s, gut remodel, 2 flat (because in Chicago it’s easier to strip an old house down to the studs than get permits for a new one!). The 1st floor/basement arr is duplexed for unit 1 with the second floor as unit 2 with bedrooms on either end and in the middle of a 20’x60′, east-facing, brick building. Compared to a lot of nightmare homes I’ve seen they did a lot right, but had some obvious misses (like no insulation except IN CHICAGO except in the small gap between the ceiling and the flat roof upstairs) that I would never have accepted if I done the renovation myself. Needless to say I have… “issues” keeping the east and west bedrooms anywhere near the same temperature as the middle. I recently implemented a partial fix to a hot water issue upstairs where the tankless water heater is in a closet on the far west end and the master bath on the far east. The hot water wasn’t triggering from low pressure and my quick fix was to flush the water heater. It seems simple, but I hadn’t every had a tankless before and didn’t realize how often I should flush it or how much it would help! I want to do a lot more so I’m pretty excited to read through your blog as I prepare for winter and the -30f temps predicted by the farmers almanac. If you’re open to questions from an undereducated engineer with a business degree I would love to pick your brain on a myriad of topics.
Thanks in advance for all the info I’m about to absorb!

By: John Weil

John Weil — Thu, 29 Sep 2022 22:16:14 +0000

Thanks Allison,

Makes sense. Guess that also means no more warm drinking water from the tap, and no using hot water in the pasta pot to speed things up.

–John

By: Allison Bailes

Allison Bailes — Thu, 29 Sep 2022 18:48:04 +0000

In reply to John Weil.

John: Yes, there could be an issue with using the cold water pipe as the return for a recirculation system. The water in a water heater is generally not suitable for drinking, and that gets more and more true as the water heater ages. Sediment builds up in the bottom of the tank from corrosion of the tank lining or sacrificial anode rod or both. Most people don’t flush their tanks to remove that sediment, but even if you do, it will build up between flushes. And because of the warm temperatures, you could have other stuff going on in there.

By pushing water from the hot water line into the cold water line, that potentially nonpotable water could be used for drinking. It shouldn’t be in the line very ling, but it’s possible someone will open the tap to get drinking water at the wrong time and get some of it. How big a problem is it? Not huge because they probably won’t get a glass full of water from the water heater. Even if they do get some, it’ll probably be diluted by some water from the cold line. I wouldn’t want to do it myself, but some people do. My recommendation is to run a dedicated return line if at all possible.