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Old 12-15-2015, 09:58 AM   #1
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Tankless Water Heater & Pex Questions


Hello! I posted this in appliances accidentally, meant to ask here


I need some help. I have a hot water heater, tankless electric w/o gas. It has two electrical lines going in at top, no gas venting and no pressure release valve either. Just two electric lines on top, and a water inlet & outlet at bottom.

Here's the manual for review, if it helps:
http://www.stiebel-eltron-usa.com/pd...tempraplus.pdf

In there #6 says that it doesn't need a P&T. So a couple questions. I have had this almost 4 years and haven't flushed it, water isn't too hard; but it is starting to get a bit of scale around the outlet threading (super-slow leak?) and I want to flush it out. I heard vinegar is great way to do this, and I can get a valve to make this quick and easy to do. I'm looking at this:

http://www.menards.com/main/plumbing...freeFormRowId=


My questions:

1) Since I don't need T&P, can i just plug up that hole? I don't have a nearby drain to drain it to, so not much I can do?

2) I thought the valves switch, meaning that water goes from top to bottom, but when turned on the main valve it goes to the isolated (forward facing) valves. But; it appears to always let water go through. Plumber said "these usually have a diaphragm that is pressure based" and that it'd be fine.

I don't want the descale solution going back into lines if he's wrong, plus, I already have super low pressure in winter; anything to affect that would be an issue. Even the slightest loss would be an issue.

3) One more question, regarding a water softener and whole house filter. My water is not very hard, seeing as I've only had to descale this once in 3+ years. Can I hook up a house filter without a water softener? The house filter plugs in easily, and would only be to protect the water heater, the water softer would be difficult for me to put in, it would include rerouting plumbing and electrical to install. Is this doable, and will a $50 filter help with the water heater at all?


And, my last question

4) I have PEX pipe going to outlet and inlet on water heater, no problems. That is until I try to unscrew the fittings. The crimp of the pex doesn't let me unscrew the fittings. Last time I needed to change filter i had to cut the pex, unscrew the end. When I changed small filter screen I then made mistake of trying to screw in pex pipe. Wouldn't turn enough, too stiff.

I had to cut another two inches off, put the nylon tape on, put an unconnected fitting on by screwing it in, and only THEN putting the pex to that already installed fitting and crimp it.


Is there no way to use pex pipe and be able to thread/unthread it? The only fittings I see at all hardware store are this type:

http://www.lowes.com/pd_314721-61002...d=3851781&pl=1


Are there any that are non-captive threaded meaning I can rotate it after crimping it on? I haven't done much pex work so I might be completely overlooking a common sense solution; but it surprises me that I wouldn't be able to undo fittings without cutting hose to allow the pipe to spin.

Last edited by jdm001; 12-15-2015 at 10:02 AM.
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Old 12-17-2015, 10:13 AM   #2
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Any help? Specifically about the pex question?
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Old 12-17-2015, 02:46 PM   #3
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USe a shark byte coupling above it and keep the decoupler that is made for it.
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Old 12-17-2015, 03:26 PM   #4
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Quote:
Originally Posted by Ghostmaker View Post
USe a shark byte coupling above it and keep the decoupler that is made for it.
Those make me nervous. I used a shark bite for toilet shutoff for small line; but for a 3/4" line I don't really trust the technology yet. I was still nervous with pex... don't want something flooding in 20 years (when i've long forgotten about it) due to a cheap part or unproven technology.

Pros don't use the shark bites; so I will try to avoid. I appreciate the idea though!
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Old 12-17-2015, 03:27 PM   #5
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I was thinking using metal braided wire; rated for dishwasher or washer/drier. I can put a male end on it, then a female to female 3ft hose from the male shutoff valve. But, I am afraid that 1) those aren't quite rated for a hot water line; and 2) the diameter seems a bit smaller even on same-sized hoses.

IE 3/4" Pex seems bigger on the inside than a 3/4" supply hose.
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Old 12-17-2015, 05:49 PM   #6
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Quote:
Originally Posted by jdm001 View Post
Those make me nervous. I used a shark bite for toilet shutoff for small line; but for a 3/4" line I don't really trust the technology yet. I was still nervous with pex... don't want something flooding in 20 years (when i've long forgotten about it) due to a cheap part or unproven technology.

Pros don't use the shark bites; so I will try to avoid. I appreciate the idea though!
You need to get over your fear of push fit fittings.
Pros do use them in certain locations- such as water heaters
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Old 12-17-2015, 08:25 PM   #7
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As long as you use the the stiffeners and a real shark byte you will have no problem.
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Old 12-18-2015, 10:01 AM   #8
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Are all the plastic pieces in one like this rated for the hot water heater?
http://www.menards.com/main/plumbing...16113614706940

I thought those were mainly cold junctions; or maybe a washing machine... but a water heater comes out much hotter. Still good?
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