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Thread: Spa blower is too hard

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    Spa blower is too hard

    I have a 6' raised spa on my pool with a Air Supply 1.5 HP blower. The spa has six jets and it blows WAY too hard. The spa vibrates bad and water bubbles out. How can I slow this down? Is the blower a two speed or do I have to put a 2" ball valve in and throttle some of the flow?
    20,000 gallon gunite with colored plaster,
    Hayward 60 DE filter, 2.5HP Hayward pump, Hayward Phantom cleaner, Rainbow 320 Chlorinator, Nature 2

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    mas985's Avatar
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    Re: Spa blower is too hard

    It might not be the blower at all but the 2.5 HP pump. That is a little large for 6 jets. Blowers create air but not flow. If you are getting too much air but the jet strength feels ok then it is probably the blower. If the jet strength feels too strong, then it is the pump.

    To find out, unplug and remove the blower and see what happens.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Spa blower is too hard

    Thanks. I had a feeling that might be a problem. I took out the 2.5 HP impeller, diffusser and replaced them with a 1.5 HP version which did bring the flow down. I didn't replace the motor and I assume that might be an issue. What do you think of putting a ball balve below the blower and throttle it? May have an issue with back pressure. I argued to no end with my PB that a 2.5 HP pump was too much
    Quote Originally Posted by mas985
    It might not be the blower at all but the 2.5 HP pump. That is a little large for 6 jets. Blowers create air but not flow. If you are getting too much air but the jet strength feels ok then it is probably the blower. If the jet strength feels too strong, then it is the pump.

    To find out, unplug and remove the blower and see what happens.
    20,000 gallon gunite with colored plaster,
    Hayward 60 DE filter, 2.5HP Hayward pump, Hayward Phantom cleaner, Rainbow 320 Chlorinator, Nature 2

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    mas985's Avatar
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    Re: Spa blower is too hard

    Running a 1.5 HP impeller on a 2.5 HP motor should not be a problem and won't cause any issues. The larger motor will simply run at the required power for the impeller.

    But are you saying the flow rate is still too high? It shouldn't be with just a 1.5 HP impeller.

    However, I would still suggest that you try the spa without the blower. Blowers are not always required especially for short air pipe runs. My spa does not use one and gets plenty of bubbles with just the venturis. Blowers simply add more air which is not always desirable.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Spa blower is too hard

    If you run the jets without the blower, you should feel significant decrease. Air introduced to the jet stream makes the stream feel stronger. Do the jets pull air without the blower? Some pool builders plumbing systems in the spa wont allow the jets to clear all the water out of the air line, so they fudge it with either putting in a higher HP pump, or to put a blower on the air line. You either need to run the blower all the time to get air, or you run the blower to "get the air going" then shut the blower off and let the jets take over & pull the air by themselves.

    Once you get the air going through the jets good, turn off the blower and see if the jets still draw air and work by themselves like they should. You'll probably be happier if you can run w/o the blower.
    Factory Warranty Station for:
    Jandy/Zodiac, Pentair, Sta-Rite, Raypak, Polaris,
    and Paramount pool cleaning systems.

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    mas985's Avatar
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    Re: Spa blower is too hard

    Air introduced to the jet stream makes the stream feel stronger.
    Air has virtually no momentum but water has a lot of momentum and is what generally makes the spa jet feel strong. It is the exit velocity of the water which determines how strong a jet will feel. This is why Waterway has pressure charts for spa jets which shows how strong a jet will feel based upon the flow rate and pressure loss through the jet. The only function for the injection of air is to break up the continuous water stream into a pulsating water stream. Now I agree that this can make a jet feel different than a jet without air injection but in terms of jet strength, that is determined by the water exit velocity.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Spa blower is too hard

    Quote Originally Posted by Pool Clown
    Air introduced to the jet stream makes the stream feel stronger.
    I wrote it this way purposely because i know the air does not affect the flow rate, but it feels like it does.

    If you run the jets, and you put your hand over the jet, it will feel stronger than if you caped off the air line and the jet ran only water. That is the fact i was trying to state here. This seems to be the OPs' problem, too much force.

    I get what you are trying to explain mas.

    It was my thought that if he were able to reduce, or eliminate the forced air (blower), the venturied air may be more acceptable. But i realize that valving a blowers' output in most cases voids the blowers warranty. It almost sounds by the OPs explanation that perhaps if the jets could run and pull air themselves(no blower), he wouldn't get blown off the seat anymore. Possibly the OP cannot run the jets independently from the blower. That IMO would indicate that the PB had trouble getting the jets to draw air on their own. That, and the fact that a 2 1/2 hp pump was installed.
    Factory Warranty Station for:
    Jandy/Zodiac, Pentair, Sta-Rite, Raypak, Polaris,
    and Paramount pool cleaning systems.

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    Re: Spa blower is too hard

    I typically just drill a hole in the side of the pipe below the blower with a step bit, until I get the desired amount of action. Sometimes it may require more than on hole.
    20X40 30,000 gallon gunite pool

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