Plumbing forum - Hot water flow problem

Author

Hot water flow problem

Sam

2005-10-30, 12:21 am

I posted this problem ages ago without getting any real solution, so I am
trying again.

Can someone offer an explanation for this problem?

The hot tap over my bath does not work unless I first run the tap over the
vanity nearby. It will run normally almost as soon as the vanity tap is
turned on. If I turn on the hot tap at the bath, no water comes out. If I
then
go and turn on the hot tap on the vanity, water comes out of the vanity tap
and then the water comes out of the bath hot tap. If I turn off the vanity
hot tap, the bath hot tap functions properly. I have to repeat the process
the next time I want to use the bath hot tap. The vanity tap need not be
left running. Once the bath tap has
started working it works fine until next time I need it.

I am in Australia. I have a gravity fed hot water system in my roof. This is
a very simple set up. The HWS has an inlet from the mains. There is a ball
cock control on the inlet to the HWS. It is gravity feed from the HWS
down a pipe to the bath. The pipe runs directly to the bathroom from the
HWS. Both bath and vanity are on
the same line of piping. Each has a separate hot and cold tap. The bath has
separate hot and cold taps but a
single outlet. The pipe then continues on to the vanity and further on to a
shower.

The pressure is not great but ok. The vanity tap is about two feet higher
than the bath tap. When they both flow, they are of similar pressure. When
these were first installed, both taps had equal flow. This change occurred
much later.

Is there an easy solution?

Any help will be appreciated.

Eric G.

2005-10-30, 9:21 am

"Sam" <sam_man@hotmail.com> wrote in news:43643662$1@dnews.tpgi.com.au:

> I posted this problem ages ago without getting any real solution, so I
> am trying again.
>
> Can someone offer an explanation for this problem?

Not knowing Jack about Australian water systems, I am willing to bet that
you have something stuck in the hot water valve on your tub. When you turn
on the hot to the vanity, it probably dislodges this small piece of
"whatever" in the bath valve and allows water to flow for a while.

Have you tried your normal startup (running the vanity first) BUT just
before you turn off the tub valve, turn the vanity back on. Then shut off
the vanity and see if the tub works the next time you turn it on (without
turning on the vanity).

Let us know what happens.

spamblackhole88@yahoo.com.au

2005-10-31, 8:21 am

Hi

>From the sounds of it, the water in the pipe needs to be hot before the
bath valve will open- perhaps the valve stem or washer is sticky? The
low pressure in the gravity system might be a contributing factor.

You could test this by changing the bath valve washer, or swapping the
valve with (say) the bath cold valve, or the vanity or shower valve, if
possible. Another way to test it would be to turn off your hot water,
dump the header tank and refill it with cold water, then see if the
vanity trick still works.

I think you can rule out anything strange about the piping arrangement,
it sounds perfectly normal to me.

Cheers
Richard

Blackbeard

2005-10-31, 11:21 pm

in a gravity-fed system, think of when you hold your thumb over the
end of a straw in a restaurant. In a gravity fed system, your water
source has to be vented.

When you open your lavatory faucet, you are providing a vent.

This is a very unusual system. I would want to know more about the
overall layout (including pictures if you have them)

It sounds like your home is being fed water through a cistern in your
attic and using a pump-switch like what is used in a pressure-washing
facility.

So how is the water getting to your cistern? Does the city provide
water or are you using well water?

Either way, if you have electricity where you are (I assume you do
since you're on the internet), if you use a submersible pump in
conjunction with your gravity-fed cistern...along with a pressure
tank, you can charge your entire system with 60-psi and this problem
you're having will be gone forever.

Send us some pics and I'm sure the guys here can take a look and tell
you how to modify your current gravity-system by "cheating" and using
a hybrid well-pump configuration.

As for the comment on having something blocking flow in your valve...I
am doubtful of that. However, if you want to test that theory,
disconnect your showerhead and screw a hose adapter where the shower
head is now. Then turn the water in your house completely off. Now
drag your neighbors hose over..and thru the window and connect your
neighbors hose to the adapter on where you used to have a shower head.
Turn the water on at your neighbors house. This will completely
backwash your system and whatever is jammed inside your valve will get
flushed out (though this isn't the problem..you're more than welcome
to try).

PipeDown

2005-11-01, 6:21 pm

Agreed, probably some debris somewhere as if it were piped wrong, it never
would have worked and you say it once did.

Try flushing the system by removing all the valve stems and allowing water
to spill out through those openings. Obviously temporarily turn off the
main supply and outlet from the tank before removing the valves.

If your roof tank is open and vented to the atmosphere, it is not
unreasonable that debris has fallen into the water and gotten into the
pipes.

Worse comes to worse, connect a hose from another pressurized source to the
tub faucet and force water or air into the faucet and up into the roof tank
(blow bubbles)

"Eric G." <NgOrSePeAnM99@Zoptonline.Znet> wrote in message
news:Xns96FF4A8576CB3NgOrSePeAnM99Zoptonl@69.28.186.158...
> "Sam" <sam_man@hotmail.com> wrote in news:43643662$1@dnews.tpgi.com.au:
>
>
> Not knowing Jack about Australian water systems, I am willing to bet that
> you have something stuck in the hot water valve on your tub. When you
> turn
> on the hot to the vanity, it probably dislodges this small piece of
> "whatever" in the bath valve and allows water to flow for a while.
>
> Have you tried your normal startup (running the vanity first) BUT just
> before you turn off the tub valve, turn the vanity back on. Then shut off
> the vanity and see if the tub works the next time you turn it on (without
> turning on the vanity).
>
> Let us know what happens.

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