Full Foam VS Thermal Sealed; The Facts
The American National Standard for Portable Spas
Home And Garden Show Wisdom
Water Clarity with the Copper/Silver ionizer and the Calcium test .
Filtration Systems
What Makes a Good Spa.
How we service our customers out of state
Spa Shell Structure: The most important part.
Silly Stuff: Arthritis, Glue Joints and 100% filtering.
Compare spa ideas
Installing an energy efficient spa in the ground.
Installing spas in and on decks.
What is involved in the installation of spas? Electrical GFCI vs. Breakers
About Blower and Pump Clean-out and What is the best filtration system?
More on Full Foam Spa Use
"Spa Covers and Sunlight"
"Heater Problems: Basic Heater diagram
Misconceptions About Spas and How Spas Enhance Your Life
Bromine and Ozone
Air and Jet Therapy
Winterizing Your Spa
Nature2 and Other Ionizers
Filtering Spa Water
Hydrogen Peroxide
Standard Spa Care with Bromine
Insulation, Heat Retention and Freeze damage

 1997 through 2017
hot tubs and spas
James Arjuna;
Master Spa Design Engineer.

Hot Tub Construction: Insulation Design Results

Spas And Hot Tubs

copyright 2003-2008 Havenmade Inc.


Full Foam Spas VS More Modern Thermally Sealed

Plumbing restrictions and turbulence caused by full foam




The basic design of a spa is the foundation on which the entire spa is built. If you have no integrated design you have weakness of design.

If you start with the whole picture of the design in which you integrate, incorporate all of the parts as a whole, then the only way to build a spa is with thermally closed which allows the whole spa to be used properly.

There is no other way, because all attempts at making a whole spa using foam filled cabinet, will dis-integrate the spa.  Then you find the designers trying as hard as they can to put in complicated and inadequate parts to improve on a bad basis for a spa.

If you understand software, you may understand it from this perspective.  If you take a 20 year old piece of software and try to modernize it and add features to it, it becomes a mess, because the original flow chart for the design of the software had no thought of integrating these new features.  In that case it is cheaper and better to redesign the whole software and integrate all of the new features in the flow chart, so that each part is bridged to the whole of the software.

This same principle goes in all construction of anything.   Try making changes to a house while the house is being built.  It costs about 4 times to redo the construction and get the structure correct for the new feature you are adding to the house.  If the  original design had those features, the house would build a lot better and faster.
(If the hose is build on a bad foundation, what do you have?)

1/ If you place the jet pumps in a box in front of the spa, because there is no other place to put them, you wind up with bad alignment to the suction plumbing and often to the pressure plumbing.

2/ The jet pumps never achieve the pump manufacturer's flow rates, because of this restriction.

3/ The end result is wasted electricity and less effective therapy for the money you spend on power.

So, in our spas, we use the cabinet to help us get better water flow.  If you want water flow, you must have flooded suctions with no restriction, otherwise horsepower and electricity is wasted.

Go take a look at the plumbing on a full foam spa and tell me the relationship between the suction inlets and the jet pumps.  Look where the pumps are and look where the suction fittings are.

If you don't have full access to the cabinet, you wind up with pumps that do not align with anything, and the spa are VERY difficult to fix leaks in. There are extra turns to get the water into and out of the jet pumps.  Sharp 90's degree elbows  are common. 

2 inch 90 elbow.In our spas the dynamic head loss would be close to 15 feet of loss if we were to use a 90 degree and a 45 in front of the pump. Using a 90 as in the photo at the bottom, is about 20 feet of head loss total when used with a 90 or TEE at the outlet.  That is like losing three  full size 3/8 orifice jets.

Look at this lousy design for plumbing (below).  As an engineer it makes me cringe, like looking at a madman's idea of plumbing. Everything is crammed into a small box in front and there is no room to do a proper plumbing job.  It is just plain STUPID.  It started out about 40 years ago with a one pump spa and a small control box, and this is the end result of keeping with 40 year old concepts and trying to keep that sales pitch going.

Poor Design Spa
Notice the "TEE" right at the outlet. This is HORRIBLE for water flow.  Right where the pump is working the hardest to put out water, is a WALL that the water hits and is forced to turn in two directions.  I NEVER USE TEES in this way.  I only use them on AIR systems, with almost no resistance to flow.  Notice the cheap plastic control box with the PCB connections all ready to arc and set the thing on fire, and they are noted for starting fires.

One of the rules of hydraulics, is that you must never have a direct 90 or 45 degree turn on the suction side of a centrifugal pump.  This is because the water entering the impeller (the fan that pressurizes the water) comes into the pump all turbulent and messed up.  It is much better to have it come in in a straight line with all the water molecules moving in the same direction.  It is also better if it enters under gravity pressure, rather than having a huge vacuum from restrictions.

Here are drawings of how excellent we do it.  Unlike other spa companies we actually use the laws of physics, called hydraulic engineering.


Good Plumbing
I love this arrangement (above), because it gives MAXIMUM flow from the  pump.  The outlet, pressure side has ZERO restrictions.  We arrange the pumps to be in the BEST locations for the maximum power to the jets you can get inside of a spa cabinet.   Notice the LOOOOONNNNGGG run of straight water flow before the water enters the pump!  All of the water is taken at the bottom of the spa where we have the maximum natural head pressure from the vessel (seating area). When our spas run, they sound smooth and have no pulsations ever.  Clean plumbing gives the best to our customers.

Just having a straight piece of solid 2.5 inch pipe directly in front of the suction inlet, alone, as one design feature  increases the effectiveness of a pump by up to +22% better water flow; allowing full use of the electricity and power of the pump.

Do you see how just this one thing is nearly impossible with any equipment that is forced to sit sideways and away from the suction plumbing, when the best is to face the back of the spa and towards the plumbing or to face the filter directly.

This is just one place were the full foam concept is wasteful and can't be fixed. It is a standard problem with full foam spas.  This clean plumbing is impossible in a full foam spa.

This is just on of those "dis-integrations" of design, caused by an improper cabinet insulation design. Below is a video of why we hate full foam to work on and why anyone who buys one of these archaic stupid designs is foolish. This whole process is about 4-5 hours in shop.  In the field it is 6 hours, and you are working on your knees (ouch!).


Size Of Spa VS Energy Use
Jet Numbers in the Brochure
"Modern" Metal Frames
How To BUY Quality
Multiple Pumps
Diverter Valves
Bogus Information
How Spas Filter Economically
What's Involved in Filtering?
Message Board Awareness
The Importance of Engineering
Installing Spas Indoors
Before You Buy any Spa About Controls
Read this about spa controls!!
Before You Buy any Spa
Read this about spa design!!
See the Haven Spas
Check out our very informative Message Board Forum
Hot Tubs and Safety: The US The U.S. Consumer Product Safety Commission

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Hot Tub Construction Insulation, Washington DC