this post was submitted on 12 Nov 2023
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It takes a few minutes for my tankless water heater to warm up, so we end up wasting a lot of water in our shower. Is there a way to avoid this? A friend mentioned a “comfort valve” or something? What is it and how does it work? Or is there another solution? Thx!

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[–] SheeEttin 59 points 1 year ago (1 children)

With a tankless heater, there's nothing to warm up. Hot water is basically instant when it comes out.

How far is your shower from the heater? Usually, long times to first heat are because you have to go through all the cold water sitting in the line before the hot water reaches you.

[–] crozilla 23 points 1 year ago (2 children)

Yes, that. That’s a better explanation of the problem. Thanks. The shower is way on the other side of the house and up a floor.

[–] OhmsLawn 21 points 1 year ago

They make instant recirculation pumps that cycle the water through the tankless in a loop and stop when the hot water gets back to the pump. We have one. If you don't already have the return pipes for it, you'd need some additional plumbing work. (Either way, it should be professionally installed).

It's the same system you'd have for a tank, but it can't run all the time, or it burns up the heater. You have to trigger it. They make flow switches, but mine (new construction) was cheesed. I just set up a zigbee switch with a 1 minute timer to trigger the pump.

[–] Bell 18 points 1 year ago (1 children)

If wiring and plumbing allow, install another tankless heater closer to the shower. I just put one into my one bedroom apartment and it was reasonably simple and small.

[–] crozilla 3 points 1 year ago (2 children)

Unfortunately, the shower has no exposed plumbing and the gas line is back near the ground floor heater.

[–] Fondots 6 points 1 year ago (5 children)

I don't think I've ever seen a shower in the US (assuming you're in the US) without access to the plumbing somewhere, I'm sure they probably exist somewhere, but it's not common in my experience, usually there's a little access panel on the other side of the wall somewhere, maybe hidden in a closet or behind a piece of furniture or something. If there's not, I'd consider adding one anyway, at some point if you're there long enough you're probably going to want access to it for some issue or project that comes up down the line.

They make small tankless electric water heaters that run off of regular 110V outlets for heating a single sink or shower, if there's convenient electrical nearby you may be able to just hook one of those up.

[–] [email protected] 16 points 1 year ago

This is not my experience at all. I haven't had a single house where the plumbing was accessible

[–] [email protected] 8 points 1 year ago (1 children)

Living in the US I've never seen what you're describing

[–] SheeEttin 1 points 1 year ago (1 children)

What part? Most houses I've seen in the Northeast either have some kind of access panel, or the shower is backed by a closet in another room where you could cut in if you needed to.

[–] Dozzi92 1 points 1 year ago

I'm in Jersey and I do not have that on my home. The only home I can think of that had it was my childhood home. Current home is 1920s, childhood home was probably 50s, teen home was 80s, and lived in various other places after that, and really never saw the access panel, though I agree it makes sense to have.

Form over function, can't have people judging me for my prudence.

[–] Alexstarfire 4 points 1 year ago

The house I purchased is the first time I've ever even seen access to shower pipes. I've got an access panel in my closet to a space above the garage that has access to the ones for the guest bath. I'm pretty sure it's not intentional either since the space goes to the master bath as well yet the shower is set up in a way that doesn't have access.

In my experience you usually have to tear out parts of a wall to access shower/tub plumbing. Definitely seems dumb now that someone pointed it out.

[–] [email protected] 1 points 1 year ago (2 children)

Cheapskate subdivision builders commonly build on concrete slabs anymore with no way to access plumbing.

[–] Fondots 2 points 1 year ago

Building on a concrete slab doesn't exactly make a difference when I'm talking about an access panel in a wall though

[–] HeyThisIsntTheYMCA 1 points 1 year ago

Yeah it never goes through the attic.

[–] [email protected] 1 points 1 year ago

Never seen that. Always gotta break open dry wall for that kinda work.

[–] SheeEttin 2 points 1 year ago (1 children)

You'll have to relocate the heater closer to the shower. You can have someone run the gas line to the new location. That's about all you can do.

You could insulate the hot water pipe, but that will only help when the water in the pipe is already hot, like if someone showered earlier. It only extends the time the water already in the pipe remains hot.

[–] [email protected] 5 points 1 year ago

They could install a small - around 2 gallon - electric water heater near the shower. I have a similar problem in my kitchen and it was solved quite cheaply by putting one of those under the sink.