Spa Blower Help needed -pics attached!

JamesW

TFP Expert
Mar 2, 2011
16,334
Ok, so we've confirmed that the pressure is too much. The brochure says 50" is the maximum pressure that the blower should have to do.

The motor generates heat and compressing air generates heat.

As the pressure increases, the amount of airflow decreases. Airflow helps cool the blower. Lack of airflow causes overheating.

Both together are creating too much heat and causing the blower to overheat and shut down.

The next step is to see if there is some way to lower the pressure.

You could bleed off air, but that tends to be loud and might reduce the air flow to less than desired.

You probably have to go back over the design and redo the calculations.

Maybe there's some sort of blockage?

You could go to a more powerful blower, but that might give you too much air.

Maybe contact the blower manufacturer technical department for some help.
 
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AustinPool2018

Silver Supporter
Apr 22, 2018
45
Austin, TX
Okay, a few more tests and some progress!!

I drained the spa to below the jets, and I took out the "jet internal" aka jets, leaving just the jet housing.
Then, I turned on the blower -- it blew out water, overheated, and then stopped.

About an hour later, I tried again -- it blew out more water, but this time it kept on going. The manometer measured 24" water differential just blowing the air in steady state.

The blower kept running for 20 minutes, so then I started filling up the spa by putting the valve on 50% pool, 50% spa. Obviously, this caused a spray of water into the spa. The manometer then read 28" water differential even with water above the jets.

Then I turned the valve to 100% SPA (the pump was running at high speed) -- the manometer went up to 52" water differential, but still stayed on.
Then, I started screwing the "jet internals" aka jets into back into the jet housing. I couldn't measure the manometer at that time, but it stayed on until the 6th and last jet internal, then the blower shut off.

I've drawn a few conclusions here:
1. If the air line is completely clear of water, and no jets screwed in, even with water above the jets, the pressure is acceptable -- 28" of water.
1a. Water must be getting into the air line. I know this to be true because at the equipment pad, there is a small amount of water in the blower pipe at any given time. I suspect that when the blower is first turned on with water in the pipe, it is working extra hard to get the water out of the pipe, and isn't successful doing so completely until it overheats. Any ideas what could be done about this?
2. The jets that I have may cause too much back pressure. I wonder if there are jets with higher flow rates.

Here's a video of the blower running with the pump, with water above the jets:
 

JamesW

TFP Expert
Mar 2, 2011
16,334
Maybe put a Jandy check valve as close as possible to the hot tub to keep water from filling the air line.

The jets inserts should be working on a venturi principle and should be pulling in air.

Maybe the nozzles are not the correct ones or maybe not adjusted correctly?

What is the model number of the jets?

Can you get a manometer reading with the jets in?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
9,696
Northern NJ
We have seen the water and air lines reversed. Also the wrong jets installed in spas. Sure sounds like you have some construction problem.

I have never measured the pressure on my blower. Do you have a friend with a spa and blower that works correctly and put your rig on his blower and get some pressure tests?
 
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AustinPool2018

Silver Supporter
Apr 22, 2018
45
Austin, TX
Maybe put a Jandy check valve as close as possible to the hot tub to keep water from filling the air line.

The jets inserts should be working on a venturi principle and should be pulling in air.

Maybe the nozzles are not the correct ones or maybe not adjusted correctly?

What is the model number of the jets?
Unfortunately, the closest I could get a check valve without ripping up pavers & concrete underneath them is probably 60' away from the spa. :(
The Model number of the jet is 229-8127, which is the grey version of 229-8120. Link to catalog, and side view picture below:

IMG_5259.jpg
 

AustinPool2018

Silver Supporter
Apr 22, 2018
45
Austin, TX
We have seen the water and air lines reversed. Also the wring jets installed in spas. Sure sounds like you have some construction problem.

I have never measured the pressure on my blower. Do you have a friend with a spa and blower that works correctly and put your rig on his blower and get some pressure tests?
Really interesting idea re: swapped air and water. I may be able to unscrew the jet housing and see if water and air are coming out of the right place. Will add that to the list, that certainly could explain the pressure problem and also explain why water could be getting into the line, as the water line sits below the air line, and if swapped, could cause an issue. God knows the plumber was not the best, so this is a real possibility for me to check.

Regarding a friend -- my neighbor has a 1.0 HP blower, but I'm not sure he'd be thrilled with me sticking it on my disaster of a pool. However, with the test run where the jets aren't screwed in, the pressure seems okay. I think that effectively eliminates a defective blower.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
9,696
Northern NJ
Regarding a friend -- my neighbor has a 1.0 HP blower, but I'm not sure he'd be thrilled with me sticking it on my disaster of a pool. However, with the test run where the jets aren't screwed in, the pressure seems okay. I think that effectively eliminates a defective blower.
I meant to take your pressure measuring rig and put it on your friends pool and blower. What is the pressure in his pool with no water in jets and with water in jets?

I agree, your blower is not defective. Your plumbing may be.
 

AustinPool2018

Silver Supporter
Apr 22, 2018
45
Austin, TX
I meant to take your pressure measuring rig and put it on your friends pool and blower. What is the pressure in his pool with no water in jets and with water in jets?

I agree, your blower is not defective. Your plumbing may be.
ah. That's pretty easy, and good point. I think I'll try to see if I can confirm whether water/air lines swapped first, then give that a try.
 

AustinPool2018

Silver Supporter
Apr 22, 2018
45
Austin, TX
Okay, here's an update.
I purchased one of the "Poly Storm Thread-in Tee Body Assemblies", which is effectively the venturi connection for my spa. This let me look at how big the air holes were, and see if I could determine if the air and water lines were swapped.
1568476273052.png
By unscrewing the jet body (for lack of a better word, part 215-1190 in pic above), I was able to determine that only water should flow through the 1" tube (the tube in the middle of the 2.5" tube), if the plumbing was done properly. If the air and water lines were swapped, then water should come out of the 2.5" tubing but not the 1" tubing.

As you can see below, water is coming out properly. So, back to square one :(


IMG_5272.jpgIMG_5273.jpg

As a summary, here's what I know:
1. Air and water lines seem to be plumbed properly.
2. When draining the Spa such that air & water lines clear, then turning on blower a few times to blow out lines, blower will work even after water fills up -- until the last jet internals are installed.
3. Unnecessary 90's have been removed.
4. There is water at the equipment pad which is below the water line. This indicates my hartford loop isn't 100% effective, and the blower is likely having to work overtime to blow out the water in the line.

A new observation I made was that when in Spa mode, the water visible in the blower line at the equipment pad gets "sucked in". This to me means the venturi effect is working to an extent. There is a small amount of air in the spa with the blower off, as seen in the video below. However, if I put my ear to the standpipe where the blower goes, I can hear water 'gurgling', which I'm sure means some of it is still in the pipe -- the same water that the blower has to blow out.



At this point, the only thing I can think left to do is to let the Spa run in Spa mode, and then "pulse" the blower -- run it for 20 seconds, wait 20 seconds, run for 20, wait 20, etc., for maybe 3-4 times to see if that allows the water to get blown out of the air pipe without overheating the blower. Then see if I can get it to run for longer.

The only other recourse I think would be to chip into my masonry/concrete, etc., to install a check-valve near the SPA, in the hartford loop. I honestly don't think extra air bubbles are worth that, or the mess/additional problems that would come as a result.

Any other suggestions are welcomed.