Ok, here's my situation. I am
installing a utility sink in the
basement. The house is all PEX, so
there should be no problem tapping into
the lines which are about 7' away. But,
today I was thinking .... may be a
dangerous thing. I have a propane water
heater only about 8' from where the
utility sink will be. What if I
connected the hot water from the lower
drain on the WH to supply the hot water
to the sink faucet. This would
accomplish "automatic" periodic WH
flushing. I know the water at the
bottom is not as hot as from the top,
especially when it is not fired up.
But, it is just a utility sink. I know
in my previous houses I always tried to
run a gallon or 2 of water periodically,
like every month. The month turned into
2 and then maybe a year, etc. And
eventually, you completely forget about
it. Anyway, what do y'all think about
this? Have at it.
1. Why on earth would you "tap into" a PEX supply
line... PEX is most effective when used in a home
run configuration to each valve which will use water
rather that using it as a replacement for copper
piping the same way copper piping is used...
The whole purpose behind PEX is that it allows
for a single unbroken run of tubing for each line
having connections only at each end...
2. Why on earth would you connect a drain
from anything your hot water heater included
to feed a sink... That is utter foolishness...
The lower tank drain on your hot water heater
is just that, a drain, it should not be used to
supply water to your home...
That may be the purpose, but that purpose assumes new construction. A
home run in an existing structure can be somewhere between a royal
PITA and an impossibility. I'm thinking about tapping into the
plumbing in an upstairs bathroom to add a "slop sink" in a shop I'm
building in the garage attic. It could be converted into a wet bar if
the space is converted into a FROG (which I'll do if I move).
Can you use sludgy (sp?) water at the basement sink? My wife would
not allow that. I agree it is much too easy to skip draining the
water heater sludge, especially when there is always that possibility
that the valve may not close fully and then you have a real problem on
your hands. I am going to write myself a note right now to do our
water heater tomorrow morning. It has been at least a
This comes up every now and again, and my advice is always the same...
replace the cheap plastic valve with either a pipe nipple, ball valve,
and MPT to garden hose thread adapter or at least a good brass boiler
drain, BEFORE the thing fails. Also make sure you have a couple
garden hose thread caps in your junk box in case you do have a
problem. I like to leave them on the WH drains as I have ball valves,
saves the floor from getting wet in case someone inadvertantly knocks
Yes, a PEX installation does make the most sense (imo) on a "home run"
basis and the drain port of a WH is not the best place from which to
supply domestic hot water.
I can also see the ease and expedience to the quick hook up you're are
Additionally, as you mention, just by merely using the sink you'll get
WH purges for "free".
Tap water can dissolve calcium carbonate into solution by virtue of
carbonic acid (from CO2's slight solubility in water).
Heating this tap water causes this calcium to precipitate out .....
the cause of scale forming in the WH.
The stuff is more like little pebbles / sand than "sludge".
I think your concept has merit......speed & ease of installation, plus
WH sediment purges as a matter of course.
Actually, after I posted the original
question, I though of the problem with
the filter screens in the faucet getting
clogged. I don't think you'd notice the
small amount of "sludge" in the water
because is would happen so often in such
little bits. Yesterday I purged about
1/2 gallon from the WH. It hadn't been
done since moving in, in August 2009.
There was a sandy look to the water.
The 2nd 1/2 gallon was clear. But as I
said, if it were done a little every
day, you'd probably never see it. Also,
the cloths washer is in another part of
the house, so it doesn't enter into the
As to "tapping into" PEX, my whole house
is PEX and is not home run from each
faucet. They did design it with a large
diameter at the start of the run and
going smaller at it goes to each faucet,
etc. So, tapping in should be any
different than it is now. The "whole
purpose behind PEX" is that it is really
easy and cheap to install.
again, unless you use the old school faucets the little bits of stuff
will cause the fuacets to drip. The various new style faucets do not
tolerate bits of stuff gettng in them. I know, our lake house has a
community well. I had to isntall a filetr trap because occsionally a
tiny bit of sand would get into a fuacet. Then it dripped until I
took it apart and cleaned it.
That defeats the whole reason for using PEX...
You now have connections concealed inside
the walls which are not easily accessible...
And, NO, PEX was initially developed for
underfloor radiant heating applications where
it was installed in unbroken loops with no
connections that could fail... One end of the
tubing run started at the supply manifold on
the heating system and the other end of that
loop was connected to the return manifold...
Someone who uses PEX as a replacement
for copper pipes and runs it around to feed
the whole house rather than feeding each
point of use with a homerun to a manifold has
totally missed the entire point behind the
reason why PEX developed in the first place...
I don't disagree that the manifold installation is the best way to go
with pex. But it's also popular because it is cheap, installs very
quickly, if very forgiving of misaligned holes. It's hard to do a
manifold installation as a retrofit. But on new construction it's a
I see you've got a lot of interesting responses. Here's why I would *not*
do it. The sink faucet is hot-n-cold, and the washing machine is likely
nearby. Those two mixing valves will allow the possibility of a
cross-connection. I mean the water is now tapped from the tank from two
different points, coupled with the fact that there is a mixing valve nearby,
you could get water of unknown temperature from other taps in the house.
Maybe hot, maybe cold, maybe lukewarm, who knows. Water will take the path
of least resistance to get wherever. By tapping into the tank in only one
spot, you guarantee that it won't backfeed like that. However, I like your
idea of AUTO-BLEED the sediment. If you were to hook it up somehow, I'd bet
it would get used often enough so there would never be any noticeable
sediment; mission accomplished.
Good Luck, Lefty
I've never seen "good" pressure from a HW drain. Opening the PRV lets
it drain faster, but not enough for a sink faucet.
Tampering with the PRV has caused me a problem, once! It would not
seal-up and leaked after that.
Tap into the PEX.
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