Cold shower
cmdrde...@hotmail.com
how to fix a shower so it won't turn cold while
taking a navy shower. I can't find it. Can
anyone tell me how to fix the shower?
Your mileage may, and probably does differ. I don't know everything nor do I claim to. I have hauled all kinds of things all over the country for forty years and have made most mistakes that can be made. I call that experience. My real e-mail addy is d...@aol.com
Brian Collingwood
> A couple of years back there was a thread about
> how to fix a shower so it won't turn cold while
> taking a navy shower. I can't find it. Can
> anyone tell me how to fix the shower?
I can't tell you how to fix it but I'd sure be interested in the answer -
mine does the opposite - turns screaming hot while I'm soaping up.
I assume you do the same thing I do - turn off the flow at the shower nozzle
while soaping?
The only way I got around it was to turn the nozzle control not quite off -
so I still had a trickle of flow. That helped.
Brian
Alan Balmer
This may be what you remember -
>From: wi...@epix.net (wi...@epix.net)
>Subject: Re: That little blast of cold shower water
>
>View this article only
>Newsgroups: rec.outdoors.rv-travel
>Date: 1998/12/02
>
>In Article<3665951F...@boeing.com>, <terry.l...@boeing.com>
>writes:
>
>> Same problem with our Bounder. . .
>
>It is the same the world over. When you open both hot & cold faucets,
>you get water from both hot & cold sources. Got that? When you shut
>off the mixed water downstream from the two control valves you have
>created a situation where ANY pressure imbalance anywhere in your
>system can cause cold water to double back and enter the hot supply or
>vice versa. Factors that cause imbalance include an air bubble in the
>HWH, someone drawing water elsewhere (especially in your rig) or
>Murphy's law, corrolary 1210. [Any plumbing disorder will result in
>howls of anguish at the least opportune time.]
>
>The solution, should anyone care enough to bother, is to insert check
>valves in both supply pipes as close as possible to the shower valves,
>thus preventing "little blasts" of EITHER hot or cold.
>
>Will KD3XR
>
Others in the thread thought that leaving a trickle running helped,
others didn't.
It was also pointed out that the check valves make it difficult to
drain the system.
BTW, I found this by searching for "cold shower" in google groups.
--
Al Balmer
Balmer Consulting
removebalmerc...@att.net
cmdrde...@hotmail.com
Lon VanOstran
cmdrde...@hotmail.com writes:
There are several ways, but the best and most effective, is to put check valves
in both the hot and cold water lines right at the faucet.
Lon
Neon John
>Others in the thread thought that leaving a trickle running helped,
>others didn't.
>
>It was also pointed out that the check valves make it difficult to
>drain the system.
>
>BTW, I found this by searching for "cold shower" in google groups.
The check valves would have no effect on this problem. All the check valve
will do is prevent hot water from backing down the cold water supply line as
the heater heats up.
The root cause of the problem is the difference in restriction of the hot vs
cold water plumbing. The added restriction of the water heater and plumbing
causes the pressure in the hot water line to drop with flow faster than the
cold water line. By definition the knobs are adjusted for prevailing
conditions at the faucet to produce a comfortable shower. When the flow
stops, the pressure rises further in the hot leg than the cold one to get back
to nearly the pump pressure and so the shower leg gets filled with hot water.
Added to this is the fact that most RV valves are plastic that both expand and
contract a lot with temperature changes and store very little heat compared to
metal. The result is the hot water valve quickly cools and effectively
changes its setting. We've all seen the flow slow to a trickle as the water
gets hot through a partially opened valve. The reverse happens when the
nozzle is closed.
The first effect is by far the most predominant one and the easiest to fix.
The best fix is to install a temperature compensated valve that will maintain
the temperature regardless of the flow.
Assuming one doesn't want to do that, the next best solution is to install a
throttling valve or orifice in the cold water line. This is adjusted to make
the pressure vs flow curves of the hot and cold lines coincide. The valve is
adjusted until the temperature doesn't change as the flow is throttled.
Even with this setup there may be some momentary fluctuation when the shower
head valve is opened because the hot water tank's air bubble will maintain the
pressure in the hot leg for a second or two. Turns out not to be a terribly
bad problem and an air bladder reservoir on the cold water line pretty much
cancels the effect. I've installed this solution on my mom's MH and enjoy
very uniform temperature showers.
Another part of the solution is to make sure your water pump runs all the time
during a shower to keep the pressure constant. Assuming you don't want to
spend the $$$ for one of those variable speed pumps, the second best thing is
to install a little resistance in the pump power lead so that the pump loads
down enough not hit the cutout pressure. In my mom's MH the crappy wiring
introduced enough resistance. In my rig I had to install a low ohm rheostat
(0-2ohm, 50 watt, Ohmite, surplus) in the pump power lead and tune it to
prevent pump turn off during the shower.
John
---
John De Armond
johngdDO...@bellsouth.net
http://bellsouthpwp.net/j/o/johngd/
Cleveland, Occupied TN
Lon VanOstran
<johngdDO...@bellsouth.net> writes:
>The check valves would have no effect on this problem. All the check valve
>will do is prevent hot water from backing down the cold water supply line as
>the heater heats up.
>
I disagree. John doesn't miss much, but I think he is barking up the wrong tree
on this one. The hot, cold, hot, cold, game which most people play with RV
showers is caused by an imbalance of pressure between the hot and cold water
lines. When you turn off the shower, the water will flow from the line with the
higher pressure into the line with the lower pressure. In some RVs, the hot
will back into the cold line, so that when the water is turned on again, the
shower is too hot for a couple seconds. In other rvs, the cold water will back
into the hot line, so that when the water is turned back on it is cold for a
couple seconds. Check valves most certainly _will_ prevent both examples. Note
that this only happens when the water is turned off at the shower head, and
both hot and cold valves are left on so that the water can flow.
There may be other problems which cause similar problems in RV showers, but the
most common is pressure imbalance.
Lon