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A somewhat expensive lesson learned the hard way

MagicPorkchop

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Joined
Apr 28, 2011
Messages
4
Back around 2004-2005 I installed an electric tankless water heater. Now I know some here will probably snipe me for going electric, but even though I could use gas, I chose electric because it was going to be easier for me to install due to proper exhausting.

Anyway, to make a long story short(er) my tankless heater is about 7 years old and one of the three heating elements went out. My replacement arrived just yesterday so I'll be replacing it tomorrow. Why was the heating element going out? I reset the element several times last week and it would kick back on, operating normally for a while. Then it would trip again and I'd have to reset it, again. This went on for several hours until finally it would not reset, thus why I ordered a replacement. This heater never once gave me any troubles and has always been able to keep up with demand without breaking a sweat, though my electric meter would spin like a gyroscope at times...that was pretty fun to watch. :bounce:

Anyway, I suspect the problem was one of mineral deposits or calcium building up inside the small little cylinder tanks that house the heating elements. I checked the annual report at my water utility (I'm on city water) and our water has a hardness of roughly 6-7 parts per gallon, or whatever it is...ppm maybe? Anyway, that's essentially moderate hardness.

When I installed this heater way back when valves such as these tankless isolation and flush valves weren't even available because no one made them. I only learned about them maybe 2 years ago just browsing around the web one night and didn't understand what sort of benefit these things provided because to me they looked like a fancy ball valve setup and I remember thinking I could plumb in my own ball valves a lot cheaper than they were asking for online (around $120 at the time). It wasn't until I spotted a set at Home Depot a couple weeks ago that I truly understood the benefit these things provide and that is the standard garden hose hookup on both valves that, when you shut off the main water to the heater, you're then able to flush out the heater with vinegar or CLR or whatever in order to remove the scale buildup inside.

So, to summarize, please remember to purchase some valves like the ones I bought, Watts TWH valves which can be found at Home Depot for around $80. You will need to purchase the pressure relief valve separately for the hot side. It's cheap insurance when compared to the price of a new tankless heater.

edit: here's a link to the valves
http://www.watts.com/pages/_products_details.asp?pid=6556


Update #1: Got everything installed yesterday and the heater is working fine. Only problem is I noticed there are a couple of very slow leaks on both of the new valves, so I'm going to have to remove those today and put on a little extra teflon tape and hopefully that should stop the leaks. I'll try and tighten them just a little more too.

One interesting thing happened that I wanted to ask here. This was the first time I've been able to completely isolate the hot water lines in my home with these new valves. In other words, I had the water turned on at the meter, had the ball valve on the cold inlet side shut off and had the hot water outlet side completely disconnected at one point. I was still able to turn on the hot water side of any faucet in the house and still get a small stream of water, not hot obviously but nonetheless I was getting water on the hot side. Was this deliberate when they installed the plumbing when they built the place? My place was built in '72 and it's on a slab, so pretty much all piping is run through the slab. I can't see how difficult it would be to keep them separate.
 
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rickairmedic

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Joined
May 31, 2005
Messages
4,165
Location
louisville ,Ky
Well as long as we are talking water heater maintenance . I will put info in here for regular Tank water heaters ( I have a Gas Tankless myself :D ) . Once a year hook a garden hose to the valve on the bottom of the water heater and open the valve and let it drain for 5 minutes or so . I tell most of my customers to watch the end of the hose and when they see reasonably clean water ( no chunks ) turn it off . Calcium and other mineral deposits are what kill tank water heaters as well ( mostly calcium ) . I have seen old water heaters cut open and the bottom half of the tank looks like its full of Noodles .


Rick
 

nate379

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Joined
Feb 2, 2009
Messages
7,279
Location
Palmer, AK
Anything under 8 gpg (grains per gallon) is considered soft water, or if measured in ppm that would be anything under ~135ppm
 

eurokid

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Joined
Dec 20, 2010
Messages
104
Location
Tacoma, WA
Hard water/mineral deposits are the number one cause of failure in tankless on-demand water heaters. It may be a good idea to invest in a water softener as it would help your plumbing, faucets, shower heads, and tankless water heater last longer.
 
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lsupcar

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Joined
Aug 24, 2006
Messages
45
I just last week had to have isolation valves installed on my tankless gas water heater because the unit was cutting off apparently because of scale build up. It was quite expensive, so I looked back at the original installation instructions, and the isolation valves were listed as accessories and offered as an installation option. I imagine it would have been cheeper to install them during the initial installation.
Bill
 
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M

MagicPorkchop

New member
Joined
Apr 28, 2011
Messages
4
Update #1: Got everything installed yesterday and the heater is working fine. Only problem is I noticed there are a couple of very slow leaks on both of the new valves, so I'm going to have to remove those today and put on a little extra teflon tape and hopefully that should stop the leaks. I'll try and tighten them just a little more too.

One interesting thing happened that I wanted to ask here. This was the first time I've been able to completely isolate the hot water lines in my home with these new valves. In other words, I had the water turned on at the meter, had the ball valve on the cold inlet side shut off and had the hot water outlet side completely disconnected at one point. I was still able to turn on the hot water side of any faucet in the house and still get a small stream of water, not hot obviously but nonetheless I was getting water on the hot side. Was this deliberate when they installed the plumbing when they built the place? My place was built in '72 and it's on a slab, so pretty much all piping is run through the slab. I can't see how difficult it would be to keep them separate.
 

VHF

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Joined
Oct 27, 2008
Messages
420
Location
NW Wisconsin
...had the hot water outlet side completely disconnected at one point. I was still able to turn on the hot water side of any faucet in the house and still get a small stream of water, not hot obviously but nonetheless I was getting water on the hot side.

Sounds like you've got a single-handle mixer valve somewhere that is allowing a little bit of "cross-over" between the hot and cold side even when shut off. This would be due to worn seals in the valve assembly.

You could try to isolate it be turning off the stop valves under your various sinks one at a time until the cross-over flow stops (although it could also be caused by a shower valve.)

If you have brand-name faucets (Delta, Moen, etc.) then replacement cartridges are readily available, although sometimes you need a special puller tool to get the old one out after 39 years!
 
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