🚀 go-pugleaf

check@dbsun.uucp (checkett) writes:

>I have a question that bothers me every morning. I wake up and go to the john
>to have a shave and turn on the hot water full blast. Over the next 20-30
>seconds the water temperature goes from freezing to quite hot as desired. 
>The problem is that the flow rate of the water drops off as the temp goes up. 
>If I don't touch the faucet the flow nearly stops. What is happening? 
>I assume it has something to do with the expansion/contraction of the pipes 
>in response to the temp. Any good plumbers out there?
>One more thing, the pipes start to scream as the water gets hotter but if
>I increase the flow by turning the knob the noise disappears.


>Dave Shine, St. Louis, MO

Not an expert opinion:  It's not your pipes, it's the faucet changing.  I had
this happen with my old cold-water faucet, until I replaced it.  So it might
not even be heat-related.  Perhaps there is some slack in the parts and
the water pressure slowly moves them.
The scream is probably caused by the faucet, too.  If it vibrates, it's likely
to vibrate the pipes.
Try turning off the water heater for a day, and see if it still happens.
Or try it after somebody has used up all the hot water with a long shower.
-- 
Every child shall be treated with complete respect.

Glen Ecklund     glen@cs.wisc.edu   (608) 262-1318 Office, 262-1204 Dept. Sec'y
Department of Computer Sciences        1210 W. Dayton St., Room 3355
University of Wisconsin, Madison       Madison, Wis. 53706  U.S.A.

In article <1992Dec14.214841.4240@dbsun.uucp>, check@dbsun.uucp (checkett) writes:
>I have a question that bothers me every morning. I wake up and go to the john
>to have a shave and turn on the hot water full blast. Over the next 20-30
>seconds the water temperature goes from freezing to quite hot as desired. 
>The problem is that the flow rate of the water drops off as the temp goes up. 
>If I don't touch the faucet the flow nearly stops. What is happening? 
>I assume it has something to do with the expansion/contraction of the pipes 
>in response to the temp.

That's what's happening.  The washer in the valve is expanding.

>One more thing, the pipes start to scream as the water gets hotter but if
>I increase the flow by turning the knob the noise disappears.

When the gap between the washer and the valve seat is just large enough, the
whole system acts rather like the woodwind instrument known as a recorder.
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Disclaimer:  Hey, I understand VAXen and VMS.  That's what I get paid for.  My
understanding of astronomy is purely at the amateur level (or below).  So
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In <1992Dec14.214841.4240@dbsun.uucp> check@dbsun.uucp (checkett) writes:

>I have a question that bothers me every morning. I wake up and go to the john
>to have a shave and turn on the hot water full blast. Over the next 20-30
>seconds the water temperature goes from freezing to quite hot as desired. 
>The problem is that the flow rate of the water drops off as the temp goes up. 
>If I don't touch the faucet the flow nearly stops. What is happening? 

When the faucet is closed, the water pressure is at a maximum.
When you open the faucet, water rushes out because of the high pressure.
But the pressure drops because youve created a leak, so the flow rate
drops off.

Potential is highest when no current flows, as soon as current flows, 
pressure drops due to internal losses and line losses.
Works the same with electricity, and air lines.

Vern Nelson

vnelson@ccu.umanitoba.ca (Gerald Vernon Nelson) writes:

>In <1992Dec14.214841.4240@dbsun.uucp> check@dbsun.uucp (checkett) writes:

>>I have a question that bothers me every morning. I wake up and go to the john
>>to have a shave and turn on the hot water full blast. Over the next 20-30
>>seconds the water temperature goes from freezing to quite hot as desired. 
>>The problem is that the flow rate of the water drops off as the temp goes up. 
>>If I don't touch the faucet the flow nearly stops. What is happening? 

>When the faucet is closed, the water pressure is at a maximum.
>When you open the faucet, water rushes out because of the high pressure.
>But the pressure drops because youve created a leak, so the flow rate
>drops off.

>Potential is highest when no current flows, as soon as current flows, 
>pressure drops due to internal losses and line losses.
>Works the same with electricity, and air lines.

>Vern Nelson

Funny, I always assumed that the hot water was making parts of the tap
expand and altering the gap that was available for the water to come
through.

Boyd.

In article <bcadamso.724920659@nella9.cc.monash.edu.au>
bcadamso@nella9.cc.monash.edu.au (B.C. Adamson) writes:

> vnelson@ccu.umanitoba.ca (Gerald Vernon Nelson) writes:
> 
> >In <1992Dec14.214841.4240@dbsun.uucp> check@dbsun.uucp (checkett) writes:
> 
> >>I have a question that bothers me every morning. I wake up and go to the john
> >>to have a shave and turn on the hot water full blast. Over the next 20-30
> >>seconds the water temperature goes from freezing to quite hot as desired. 
> >>The problem is that the flow rate of the water drops off as the temp goes up. 
> >>If I don't touch the faucet the flow nearly stops. What is happening? 
> 
> >When the faucet is closed, the water pressure is at a maximum.
> >When you open the faucet, water rushes out because of the high pressure.
> >But the pressure drops because youve created a leak, so the flow rate
> >drops off.
> 
> >Potential is highest when no current flows, as soon as current flows, 
> >pressure drops due to internal losses and line losses.
> >Works the same with electricity, and air lines.
> 
> >Vern Nelson
> 
> Funny, I always assumed that the hot water was making parts of the tap
> expand and altering the gap that was available for the water to come
> through.
> 
> Boyd.

  If it were just due to water pressure, hou come the cold water tap
doesn't do the same thing?

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Robert T. Warfield@dartmouth.edu

Robert.T.Warfield@dartmouth.edu (Robert T. Warfield) writes:

>> Funny, I always assumed that the hot water was making parts of the tap
>> expand and altering the gap that was available for the water to come
>> through.
>> 
>> Boyd.

>  If it were just due to water pressure, hou come the cold water tap
>doesn't do the same thing?

Good point.  I think it's the expansion due to temperature.  In fact, I
can pull up on the handle of the hot water faucet, (as if I'm trying to
pull off the 'knob'), and shut the flow off completely.

regarding the questions about why the hot water from the tap would at firs
flow quite rapidly, then reduce in intensity, while the cold water didn't...
  
There are a number of things going on.

1) There may be different piping systems, particularly if the building has
undergone renovation.  While steel pipes have very little pressure related
expansion (at least with thepressures normally encountered), plastic
piping will have somewhat more.

2) There may be air in the system.  This will deifinitely compress under
pressure, thus giving extra push when a valve is first opened.

3) The water heater tank may have a bladder or similar expandable
container in it.

4) there may be an extra "booster" pump on the heated water line which
added a bit of pressure which gave an extra push when the water is first
turned on.

dannyb@panix.com