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Thread: Does the skimmer weir (door) have any purpose?

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    Does the skimmer weir (door) have any purpose?

    So I have a hayward standard skimmer. When I bought the house the skimmer weir was missing. I bought a new weir and placed it in. I noticed it requires a higher water level. It seems it dose something to the water, almost like restricts water coming into the skimmer?
    13,500 gallon above ground round pool. Vinyl Liner. Hayward S244T 3.1 cu ft sand filter. Hayward Powerflo 1HP pump (single speed induction). HTH 6-way test kit.

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    jeffchap's Avatar
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    Re: Does the skimmer weir (door) have any purpose?

    Yes, once debris passes through the weir, it keeps it from floating back into the pool once the pump shuts off.
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    Re: Does the skimmer weir (door) have any purpose?

    The door is to increase the amount of water taken from the top of the water where the floating debris are. Without the door on, most of the water is taken to the filter from beneath the surface and would leave a lot of the floating stuff on your water.

    Mark
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    Re: Does the skimmer weir (door) have any purpose?

    I'm sorry, but that's pretty much nonsensical. If the bottom drain valve is open as well as the skimmer valve(s) the amount of water passing thru the skimmers is not greater because of the door.
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    Re: Does the skimmer weir (door) have any purpose?

    Quote Originally Posted by timerguy View Post
    I'm sorry, but that's pretty much nonsensical. If the bottom drain valve is open as well as the skimmer valve(s) the amount of water passing thru the skimmers is not greater because of the door.
    Yes, but what the skimmer does take in will be from the water surface with the weir door in place. Otherwise, the skimmer would pull most of its water from the floor of the skimmer box. It's not the amount of water in question, but where it's taken in. The purpose of the weir door is to force the bulk of the water entering the skimmer box to be from the surface, regardless of the water level in the pool. It's up to the pool operator to adjust the skimmer/lower suction ports mix to utilize the skimmer function correctly.
    Last edited by jamis; 08-03-2014 at 07:40 PM. Reason: added text
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    Richard320's Avatar
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    Re: Does the skimmer weir (door) have any purpose?

    Quote Originally Posted by timerguy View Post
    I'm sorry, but that's pretty much nonsensical. If the bottom drain valve is open as well as the skimmer valve(s) the amount of water passing thru the skimmers is not greater because of the door.
    That may be true; but we're talking skimmer action here. Velocity, not flow.

    The skimmer weir limits the flow coming in to maybe the top 1/2" of water. If the cross section area of the skimmer throat is 3"X12", that's .25 sq ft. Let's say the skimmer is pulling a measly 10 gallons per minute. That's 1.3 cubic feet per minute. That means the flow coming through the skimmer throat will have a velocity of 5.2 ft/minute or .087 feet per second to maintain the water level. Now reduce that opening to 1/2"X 12". That's 1/6 the area so to maintain the water level - and water will seek its own level - that water is moving six times as fast or 5.2 feet per second. That's a pretty good clip - 3.5 miles per hour - enough to overcome slight breezes and currents and pull water into the opening. Unless you have a return jet pointing straight at the skimmer throat, any surface debris being shoved along by the return flow will just go right on past the skimmer otherwise.

    Look at it from an economics standpoint; if the weir served no good purpose, don't you think they'd leave them out at the factory and charge the same?
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    Re: Does the skimmer weir (door) have any purpose?

    Quote Originally Posted by Richard320 View Post
    That may be true; but we're talking skimmer action here. Velocity, not flow.

    The skimmer weir limits the flow coming in to maybe the top 1/2" of water. If the cross section area of the skimmer throat is 3"X12", that's .25 sq ft. Let's say the skimmer is pulling a measly 10 gallons per minute. That's 1.3 cubic feet per minute. That means the flow coming through the skimmer throat will have a velocity of 5.2 ft/minute or .087 feet per second to maintain the water level. Now reduce that opening to 1/2"X 12". That's 1/6 the area so to maintain the water level - and water will seek its own level - that water is moving six times as fast or 5.2 feet per second. That's a pretty good clip - 3.5 miles per hour - enough to overcome slight breezes and currents and pull water into the opening. Unless you have a return jet pointing straight at the skimmer throat, any surface debris being shoved along by the return flow will just go right on past the skimmer otherwise.

    Look at it from an economics standpoint; if the weir served no good purpose, don't you think they'd leave them out at the factory and charge the same?
    I'm impressed with those calculations !! 😎
    Jeff
    24'x54" AG Morada RTR (by wilbar) 13'500 gal. Hayward Powerflo Matrix 1hp 2 speed. Hayward Perflex EC65 DE filter.

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    Re: Does the skimmer weir (door) have any purpose?

    Welcome to the forum Mark H.

    As for the door, yup keeps the debris in the skimmer when the pump shuts down. It's like a floating dock staying always at the top of the water so it's pulling water from the very surface. It doesn't increase the amount of water drawn into the skimmer but it does increase it's velocity and you could say it's ability to suck things in that get close irregardless of any bottom drain and however much suction is allotted to that bottom drain. The door makes the most out of the suction it has to draw in debris off the top of the water.
    Were are only talking about the water right at the entrance to the skimmer.
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    Re: Does the skimmer weir (door) have any purpose?

    That's information overload I'll take your word for it!
    Pool size: 24000gal inground Vinyl-Taylor k-2006 and k-1766 test kits and-speed stir
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    Re: Does the skimmer weir (door) have any purpose?

    I think Richard ought to be working for NASA !😜
    Jeff
    24'x54" AG Morada RTR (by wilbar) 13'500 gal. Hayward Powerflo Matrix 1hp 2 speed. Hayward Perflex EC65 DE filter.

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    Re: Does the skimmer weir (door) have any purpose?

    agreed! !
    Pool size: 24000gal inground Vinyl-Taylor k-2006 and k-1766 test kits and-speed stir
    Intermatic P1353ME digital timer w/freeze sensor
    CircuPool Si-45 SWCG System
    Polaris 280 vacuum/Polaris PB4-60 boost pump
    Pentair IntelliFlo VS 3hp Pump--Pentair sand filter

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