Question about adding a Air Blower

Gupone

Active member
Sep 29, 2019
36
Texas
You should be getting a little over 12 GPM/jet with the jet fittings removed. Keep in mind that when comparing to the pool returns, there are half as many so they will feel ~2x stronger (for the same total flow rate). If the flow from the open spa jets feels like a trickle, as I mentioned before, there is likely something wrong with the plumbing. Perhaps a clog in the return lines. Have you actually run the spa without the jets installed? This can sometimes clear the lines of debris. Also a pressure measurement at the spa pump return drain plug should tell us if there is an obstruction or not. Can you also post a picture of the equipment pad?


Yes, that is one way to increase the flow per jet. But before doing that, the OP needs to make sure everything is working is it should.
mas985, I have taken the inserts out and still they dont give off much pressure. You Mention doing a pressure measurement at the pump return drain plug. How exactly would this be done (I'm a newby) is the plug the one on the front of the basket?
 

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mguzzy

Well-known member
Jul 8, 2015
790
OV, CA
I have a passive Venturi air system.. there is no blower, there is a air intake pipe a few feet from the Spa that feeds the air side of the Venturi nozzles. I think that is how your lower spa jets are constructed.
So, Yeah, I understand what the PB did to your Spa and what you are trying to accomplish. The proper fix is to tear it up and plumb air lines to the nozzles per the instruction that @mas985 posted. And I totally get that you are looking for a work around given that there is no way the PB will cover it. So given that you have 2" plumbing which is not really big enough pipe to support 8 jets regardless of the pump (also per Mark). I thought I would suggest reducing the number of Jets. It would be easy to test. plug every other Jet and see if you get sufficient pressure on the others with the equipment you currently have. just an idea.
 

Gupone

Active member
Sep 29, 2019
36
Texas
I have a passive Venturi air system.. there is no blower, there is a air intake pipe a few feet from the Spa that feeds the air side of the Venturi nozzles. I think that is how your lower spa jets are constructed.
So, Yeah, I understand what the PB did to your Spa and what you are trying to accomplish. The proper fix is to tear it up and plumb air lines to the nozzles per the instruction that @mas985 posted. And I totally get that you are looking for a work around given that there is no way the PB will cover it. So given that you have 2" plumbing which is not really big enough pipe to support 8 jets regardless of the pump (also per Mark). I thought I would suggest reducing the number of Jets. It would be easy to test. plug every other Jet and see if you get sufficient pressure on the others with the equipment you currently have. just an idea.
You are correct about the original Jets and how they are connected. I was going to find some plugs and close off a couple jets to see how it did. I am also going to get a test bladder and see if there might be any clogs. mas985 requested to do a pressure test at the pump suction drain. Do you know much about this and what will it tell me. I'm guessing he means to screw in a pressure gage in the drain plug hole and see what the pressure is reading. If thats correct, do you know what pressure it should be reading for my setup?
 

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mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,800
Pleasanton, CA
mas985, I have taken the inserts out and still they dont give off much pressure. You Mention doing a pressure measurement at the pump return drain plug. How exactly would this be done (I'm a newby) is the plug the one on the front of the basket?
The one in front of the basket is for a suction measurement. There is also one on the other side of the basket but in the volute (return pipe connection) of the pump. You can get pressure gauges at Lowes and other places like this one:
It may be a tight fit between the basket and the pumps so you may need and extension line. 1/4" male one one side and female on the other side of the tubing. Like these:


Also, many autoparts stores will carry dual gauges that can measure vacuum and pressure albeit at different times. This may also need similar adapters to fit the drain plug.

With the jets removed, pressure should be about 8 PSI and vacuum about 18 in-hg.

Again, a picture of the pad equipment might be helpful to spot any issue with the setup.
 

Gupone

Active member
Sep 29, 2019
36
Texas
The one in front of the basket is for a suction measurement. There is also one on the other side of the basket but in the volute (return pipe connection) of the pump. You can get pressure gauges at Lowes and other places like this one:
It may be a tight fit between the basket and the pumps so you may need and extension line. 1/4" male one one side and female on the other side of the tubing. Like these:


Also, many autoparts stores will carry dual gauges that can measure vacuum and pressure albeit at different times. This may also need similar adapters to fit the drain plug.

With the jets removed, pressure should be about 8 PSI and vacuum about 18 in-hg.

Again, a picture of the pad equipment might be helpful to spot any issue with the setup.
mas985, Awesome. Thanks so much for clearing that up. I will work in it this weekend. As for as a picture of the Pump setup, I can get one for you however, its prety straight forward. There is only one 2" pipe going into the suction inlet and a 2" pipe coming out of the return on the pump. No real bends or turns except maybe a couple 90's There is a 2" shut off valve on each line but thats it. (See Pic. Not mine but close)
 

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mguzzy

Well-known member
Jul 8, 2015
790
OV, CA
... mas985 requested to do a pressure test at the pump suction drain. Do you know much about this and what will it tell me. I'm guessing he means to screw in a pressure gage in the drain plug hole and see what the pressure is reading. If thats correct, do you know what pressure it should be reading for my setup?
I'm sure you already sussed this; Mark is walking you through getting specific pressure readings for your pump/plumbing so he can definitively tell you what and how many jets can be supported...
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,800
Pleasanton, CA
It would be more helpful to have an actual picture of your setup.

Are you sure the valves are set properly. What brand/model are they?
 

Gupone

Active member
Sep 29, 2019
36
Texas
Is the pump below water level? Why did the PB use valves?
I would say the pump is below water level, but not by more then a couple feet. I don't really know why he used Valves. My guess is so that you can shut off the water flow if you need to change out the pump or do repairs. I know on my main pump, I have a ball valve on the main suction line coming out of the ground that is tied into the skimmer and floor drains. If you would think it would help, I can take out the valves. Do you think there is that much restriction with the Valves?
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,800
Pleasanton, CA
If the pump is below water level, you need to have the valves. I was just curious as to the reason. That will also change the pressure that you read on the pump.
 

Gupone

Active member
Sep 29, 2019
36
Texas
If the pump is below water level, you need to have the valves. I was just curious as to the reason. That will also change the pressure that you read on the pump.
By how much do you think? I can remove the return valve and just leave the suction unless you think water will still back flow from the jets to the return line.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,800
Pleasanton, CA
Pressure changes by 1 PSI for every 2.31'. So instead of 8 PSI, it will be 9 PSI.

Suction changes 1 in-hg for every 1.13'. So instead of 18 in-hg, it will be 16 in-hg.

You need both valves. Otherwise, water will flow out of the pump basket when you remove the lid.
 

Gupone

Active member
Sep 29, 2019
36
Texas
Pressure changes by 1 PSI for every 2.31'. So instead of 8 PSI, it will be 9 PSI.

Suction changes 1 in-hg for every 1.13'. So instead of 18 in-hg, it will be 16 in-hg.

You need both valves. Otherwise, water will flow out of the pump basket when you remove the lid.
Thanks for that info. Just to be clear in my situation, if the PSI is below 9, then that's a problem? If so, would it be the Pump or Plumbing to look at. If it is reading 9-10 psi at the pump then what kind of pressure would you think I should be getting out of the Jet orifices (Thats without the Jet inserts in, so its just a 1" opening).
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,800
Pleasanton, CA
If the pump pressure is significantly higher than 9 PSI, it indicates higher than expected head loss on the return side of the pump. Same for the suction side measurement. Higher head loss results in lower flow rates. So lower pump pressure and suction are desirable for higher flow rates.

Water pressure at the surface of the spa (or any body of water) is always 0 PSI because it is at the air water interface. At the location of the 1" jets, about 2' down, the pressure would be about 1 PSI due to the weight of the water. But I don't think that is what you meant. I think what you are really talking about is the force that the water exerts on the body. This is due to a change in momentum which in turn is determined by the velocity of the water. Higher water velocity exerts higher force on the body. This is why spa jets are rated by GPM and it is this flow rate that makes the jet strong or weak.
 

Gupone

Active member
Sep 29, 2019
36
Texas
Folks, I had some time this weekend to work on a few things to see if I could get more pressure out of the jets on the spa. On thing I did was block off 6 of the 8 jets to see what it would do and I can say the pressure was nice and hard. I then unblocked another two for a total of 4 jets going and it still was not bad. Finally I tried with 6 unblocked and it did have more pressure then with all 8 unblocked but it wasn't as strong as 4 unblocked. Now this was tested without any of the spa inserts in so I am in the process of getting 6 of the 3/4 - 1" hole only (see pic) inserts to see how that does for 6 jets. I know for now I will have to block off 2 of the 8 jets to get any type of pressure but until I can afford to have the spa ripped apart to fix the plumbing mess the PB caused, it will have to do. Per the request of mas985 I am posting a pic of my pool plumbing setup. Also a pic (Sorry it would not let me upload a video) of what the pump for the Spa is doing. I looks like a little tornado going in the basket. Lastly, I was thinking about changing out the impeller as I have no idea what condition the one in this old pump is in. Can it be upsized? and if so how much and will that create more water flow to get better pressure at the jets?
 

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mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,800
Pleasanton, CA
If you are see air in the pump basket, you have an air leak. If bad enough, that could reduce the flow rate as well. Make sure the pump lid and drain plug gaskets are lubed with silicon pool lube.

Also, you cannot upsize the impeller without upsizing the motor. But again, doubling the HP of the pump (impeller + motor) results in only about 20% increase in flow rate. Equivalent to blocking 2 jets. However, it increases the motor power draw by about 50%-75%.
 
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Gupone

Active member
Sep 29, 2019
36
Texas
If you are see air in the pump basket, you have an air leak. If bad enough, that could reduce the flow rate as well. Make sure the pump lid and drain plug gaskets are lubed with silicon pool lube.

Also, you cannot upsize the impeller without upsizing the motor. But again, doubling the HP of the pump (impeller + motor) results in only about 20% increase in flow rate. Equivalent to blocking 2 jets. However, it increases the motor power draw by about 50%-75%.
Thanks for the info. I wish I could upload the small video of the pump basket. I looks like a swirling tornado and not just a air pocket. Weird.