--
Dave Knight
dknig288@comcast.net
Hook'em Horns 1969
-------------- Original message --------------
From: "r1j2nicky" <r1j2nicky@yahoo.com>
> Have to chime in,Bruce, you are correct about the expansion,but the
> air gap or accumulator tank doesn,t slow down the pressure rise,it
> prevents it,well most of it anyway.It just simply gives a place for
> the expansion to go, Ron-- In Diesel-RVs@yahoogroups.com, Bruce
> Sherman wrote:
> >
> > Gary,
> >
> > When water or another liquid is heated in a confined space, the
> pressure can
> > rise very quickly because the liquid wants to expand, and there is
> no place
> > to go. The pressure rises much more slowly if there is a gas space
> in the
> > system. The fluid expands into the available space and the gas
> compresses.
> > System pressure rises much more slowly. Both the gas and the liquid
> will be
> > at the same pressure by definition. That¹s why accumulator tanks
> are used on
> > liquid systems.
> >
> > Bruce
> >
> > On 1/24/08 8:24 AM, "Chuck & Mary Boros"
> cleverly
> > wrote:
> >
> > >
> > >
> > >
> > >
> > > Gary,
> > > The information was given to me by the head engineer at
> Shurflo. Don't think
> > > that Shurflo would spend all that money and time redesigning
> their high end
> > > pump heads plus the cost of changing out all the existing new
> inventory in the
> > > market place. Chuck B
> > >
> > > Gary Brinck > wrote:
> > > Chuck,
> > > Unless I flunked my physics courses, the pressure in the hot
> water tank will
> > > be the same whether there is an air head or not. Like everything
> else, water
> > > expands when heated. For that matter, so does the air head - it
> reaches the
> > > same temperature as the water in the tank. The air gets
> compressed, increasing
> > > the pressure throughout the tank and back along the cold water
> inlet.
> > >
> > > This does not dispute the notion that back pressure could cause
> pump failures.
> > > However, maintaining a good air head won't alleviate that
> problem. What it
> > > will do is prevent water leakage at the pressure/temperature
> relief valve.
> > >
> > >> > Many water pumps that fail has to do with high back flow
> pressure from the
> > >> > hot water heaters. Hot water heaters need to have the top of
> the tank head
> > >> > space of air. If not, the heated water expands from heating
> and puts high
> > >> > pressure back on the cold water input to the tank. That higher
> pressure
> > >> goes
> > >> > back to the output side of the water pump causing internal
> failure to the
> > >> > water pump parts. A accumulator tank on the output side of the
> water pump
> > >> > will compensate for the back flow pressure. Some folks have
> recommended a
> > >> > back flow valve attached to the input cold water line at the
> water heater.
> > >> > Most water heater manufacturers advise against that. Shurflo's
> high end
> > >> pump
> > >> > line had high pressure back flow failure problems and the
> water pumps had
> > >> to
> > >> > be redesigned so that the pump can withstand the higher
> pressure. All known
> > >> > vendor stock was to be replaced as of last August. Camping
> World now has
> > >> the
> > >> > new designed pumps in stock. You can tell the new design by
> the pump
> > >> > housing. Shurflo warrentee's their high end line for 3 years.
> Aquahot
> > >> > equipped coaches do not have that problem. Chuck B
> > >
> > > Gary
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
>
>
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