Shurflo warranty's their high end Smart Sensor pumps for 3 years. They were experiencing a excessive failure rate of damage to the internal pump from back flow pressure. They do not recommend the need for using a accumulator tank with that pump. Their studies and testings found that that the the pumps that failed came off RV's with hot water heaters as opposed to RV's that were equipped with Aqua/Hydro hot systems. Because of replacing pumps under warranty, Shurflo had to either quit making the Smart Sensor pumps or correct the situation be redesign. They chose the latter. I had several discussions withn their engineers on the phone and at the last FMCA International rally. That is their answer.
Therefore it appears that you are shooting from the hip trying to make your point. Chuck B
Gary Brinck <gbrinck@cfl.rr.com> wrote:
Chuck,
They replaced the pump because of the back pressure problem, which I agreed does exist. The point I disputed (and still dispute) is that maintaining an air head in the tank will have any effect on the problem. Think about it - would Shurflo have spent that money if they could have said "not our fault - increase the air head in your tank and the problem will go away". I don't think so. There is significant additional back pressure whenever the water in the tank is heated, so they had to change their design to accommodate that.
> 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 <gbrinck@cfl.rr.com> 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
--
Gary & Nancy Brinck
2004 American Tradition 40V
2007 GMC Acadia
Chuck & Mary Boros
04 Windsor 02 Ford Ranger
Shelby Dog, Miss Kitty, Mr Lucky Cat
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