What's a WATTS?

[Donald Stauffer]

I posted this device earlier on New Members, but it appears it should be answered here. I discovered it first time in the upper corner of the garage in a high end new house. It has to do with potable water, but I'm not sure what its function is. Ideas?

[Jerry Peck]

It's an expansion tank for thermal expansion caused by water heaters and is typically at the water heater.

I think the installation instructions call for them to be at the water heater or as close as possible to the water heater ... is there a water heater below or near that expansion tank?

Funky location and the support of the tank is not visible (not known).

[Donald Stauffer]

Jerry
Thanks. Yes the water heater, a Rheems tankless, is below and to the right of the picture. It's located in a new home. My first view of one of these.
I can use your info on the inspection report photo. Much appreciated.
Don

[Ian Page]

After much discussion on another thread, I understand an expansion tank's value in a closed water supply system. Typically that involves a standard hot water heater and the volume of water increasing with heating. However, I fail to see the value of an expansion tank, in this instance, with a tankless system. As I understand, hot water pressure and volume increases without drawing off or relieving pressure within the system. However, with a tankless system, hot water pressure and any (minimal) increase in water volume is constantly being relieved as the hot water is only heated on demand and thereby perpetually relieved.

Anyone care to give a logical explanation?

[Raymond Wand]

Ian, I think you hit the nail on the head with your explanation.

[Jerry Peck]

Does not need support installed in this manor. I do however agree I have never seen one installed with pipes not visible.

And those pipes are the "support" I was referring to. Is that supported by (hanging from) PEX, CPVC, or is it copper?

Or, could it be PEX or CPVC and there is an additional support directly above the tank?

That is the support that we don't know.

[Scott Patterson]

After much discussion on another thread, I understand an expansion tank's value in a closed water supply system. Typically that involves a standard hot water heater and the volume of water increasing with heating. However, I fail to see the value of an expansion tank, in this instance, with a tankless system. As I understand, hot water pressure and volume increases without drawing off or relieving pressure within the system. However, with a tankless system, hot water pressure and any (minimal) increase in water volume is constantly being relieved as the hot water is only heated on demand and thereby perpetually relieved.

Anyone care to give a logical explanation?

Very true…

But, several tankless models have a built in recirculation pump/system that allows for hot water to circulate through the pipes. On systems that do not have a built in recirculation system a small 5 gallon electric water heater with a recirculation pump can be installed to provide instant hot water in the home. In both designs an expansion tank would be needed.

[Jim Luttrall]

Very true…

But, several tankless models have a built in recirculation pump/system that allows for hot water to circulate through the pipes. On systems that do not have a built in recirculation system a small 5 gallon electric water heater with a recirculation pump can be installed to provide instant hot water in the home. In both designs an expansion tank would be needed.
I agree Scott and good discussion guys.
One thing I would like to point out is that the expansion tanks need to be sized based on the volume of stored water. Thus a 100 gallon water heater would need a larger expansion tank than a 30 gallon heater. The more stored water, the more expansion inside the closed system and pressure build up without an expansion tank. It is doubtful that an extremely small tank would have much of an issue with thermal expansion pressures, not that the code does not require a thermal expansion device.
I believe Watts has a chart on their site.

By the way to the OP, Watts is the brand name, lots of other Watts brand devices and thermal expansion tanks under other brand names.

[Vern Heiler]

Yesterdays inspection. Not sure how to best support, but that is not my problem!

[Ian Page]

Very true…

But, several tankless models have a built in recirculation pump/system that allows for hot water to circulate through the pipes. On systems that do not have a built in recirculation system a small 5 gallon electric water heater with a recirculation pump can be installed to provide instant hot water in the home. In both designs an expansion tank would be needed.

Scott
Thanks for the info. Though I still do not see the merit of an expansion tank in your first application. Of course, if it's a manufacturers recommendation, then so be it. However, in a looped system with recirculating pump, surely the water is being heated as it is drawn through the supply lines, which typically means someone, somewhere in the household is using hot water. Or...the hot water is being stored in a large enough tank for future use...hardly, therefor, a 'tankless' system. Maybe I should take a look at the nomenclature of various on-demand systems to fully understand.

I see the rationale of the 5 gal system...but more of a hybrid tankless system.

In the OPs pic, the tank hanging from the ceiling tends to infer the application is in a looped system, as you described.

[Jerry Peck]

Yesterdays inspection. Not sure how to best support, but that is not my problem!

Vern,

How did you get a photo of what I was envisioning in my mind? :)

[Vern Heiler]

Vern,

How did you get a photo of what I was envisioning in my mind? :)
Frightening isn't it:D.

[John Kogel]

Frightening isn't it:D.Thanks Vern. Funny how that happens sometimes.

One like that, I suggest a 2 x 4 screwed vertical to the joist, strap the tank to that.

[Vern Heiler]

Thanks Vern. Funny how that happens sometimes.

One like that, I suggest a 2 x 4 screwed vertical to the joist, strap the tank to that.
Scary part is knowing what goes on inside Jerry's head:eek:

[Vern Heiler]

No thanks! I will pass on that one.
Last time I did that I could not sleep for a couple of days. ;)
All joking aside, I have learned much following Jerry's posts over the years; as I have from all who contribute to the discussions. Many thanks to all of you.

[Rick Cantrell]

All joking aside, I have learned much following Jerry's posts over the years; as I have from all who contribute to the discussions. Many thanks to all of you.

Where is that damn Like (or agree) button?



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[Raymond Wand]

Who needs 'like', or 'disagree' when you can use Post Icons at the very bottom of the reply window.

Post Icons:
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Angry Unhappy Talking Red face Wink Thumbs down Thumbs up

[Rick Cantrell]

Who needs 'like', or 'disagree' when you can use Post Icons at the very bottom of the reply window.

Post Icons:
Post Arrow Lightbulb Exclamation Question Cool Smile
Angry Unhappy Talking Red face Wink Thumbs down Thumbs up

only works on REPLY

[Raymond Wand]

Oh is that how that works? ;)

The website was working fine until you posted and broke it. Now I just got several email notifications that you posted. Go to your room and stand in the corner! :laugh: