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Spa Construction: Diverter Valves

Spas And Hot Tubs


copyright 2003 through 2010 Havenmade Inc.

 
Diverter Plumbing used in spas.
copyright 2003 to 2008,
(If you don't read this, you will miss out on a very important issue with spas. An issue that results in thousands of rip-offs each year!)
How many spa shoppers understand about Diverter valves used in spas?

Don't buy a spa with a premium price if it has short-cut manufacturing and most do!

One of my favorite questions to ask the spa shoppers on our showroom is:
"How much do you know about spas?"


Typically the answers are: "Nothing" or "Not much". That is why an educated consumer is a much better shopper. If you don't know about hot tubs, then you are at the mercy of sales people, who make their living by selling spas. (Most sales people know less about spas than an average reader of this site.)  How can you trust that for information? The sales person may be the nicest person you ever met, but he only knows what he knows. I prefer to know more than any sales person about his own product, particularly if the product is $7000 or more. I can only get that knowledge by researching. The amount of research I do is based upon the cost of the item.

Diverter valves are used to divide the spa into zones of therapy. That means that you cannot run all the jets at the same time with any jet pressure. You can only run part of the spa at any one time. If the spa is set up in three zones, then you would need a pump three times as powerful to get full function of the spa. Using a three way zone system is really cheap plumbing and it is a rip off for spa shoppers.

Typically a spa shopper will come into the cheap built  high priced showroom and see a spa with up to 30 jets, and it looks like it is a great spa. However, after the spa gets home, then the realization that you can't run all the jets and you wind up waiting for jets while someone else is using another seat. Is that a good design? You need to decide for yourself. The only spa I would consider like that is one that I would be the only user, because it is impolite to "steal" the water flow from your wife or guests.  One of the latest and worst I have ever seen is where they split the water from the back of the louge seat and the leg jets.  If you want leg jets, you turn off the back jets and visa versa.  That is the worst rip off I have ever seen.  The pumps are so cheap, that you can't run the full set of jets in one seat!

There are many hydraulic engineering issues with these valves today as well.
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If you have to wait for therapy, the jet pumps run longer, because they are doing half of a job. After your guests are done, you can then have a turn at the jets. If the spa is a 120 volt model, you may not have enough time before the water gets too cold. In a 120V spa the weaker heater and the jets cannot run at the same time, so the water temperature drops fairly fast. There are some spas that are made this way that sell for over $7000. I can't imaging spending that sort of money on a product with such poor performance.


There are many hydraulic engineering issues with these valves today as well. If you consider that water is 73 inches long in a 2 inch pipe per gallon and 130 inches long in a 1.5 inch pipe and each gallon weighs 8.333 pounds per gallon. If the pump is moving 70 gallons per minute in a 1.5 inch pipe, that means that 130 inches of water is passing by 70 times per minute or (73 inches passing 200 times per minute). Now go and pick up a gallon of water or a gallon of milk and lift it as fast as you can. You will get some idea the energy used and the weight of the water as it flows in a pipe.

Now imagine 150 of those 73 inches of water in a pipe, slamming into a wall (at the diverter valve) and then being forced to turn 90 degrees (as it exits the valve into a 90) and slamming into another wall as it make a 180 degree turn around. It does this 150 two 180 times per minute. This is how most spas are plumbed with diverter valves. This is why there is so much resistance to water flow in a diverter valve. Water is heavy and it has momentum, weight velocity, causing it to be restricted as it goes past any turns, much less a 180 degree turn about in a non smooth valve with lots of ridges and edges for the water to swirl against.

So, if you place a diverter valve directly after the pump, this is called "diverter first plumbing". It is not a good idea if the valve is not large enough to handle the water flow without ruining the pump's efficiency. If you paid for a 5 HP pump and you are only getting a 3 HP pump's worth of water flow, it is not efficient. The valve becomes noisy and restrictive. The valves do not last long. The valves become difficult to turn after awhile. This is what is know as placing 10 pounds of stuff in a 5 pound bag. It is very poor hydraulic engineering. This design shows up on 98% of the spas I have seen, because it saves manufacturing money and the consumer does not know what is going on inside the spa.  READ

With a poorly designed plumbing system using a diverter, you can loose up to 30% of the pumps capability by this design. It is similar to buying a 300 HP engine in your fancy new car, but it has rocks in the exhaust pipe. The motor uses the same amount of gasoline, but it is only getting 180 HP worth of work. One day a mechanic sees the rocks and takes them out. All of the sudden you are "burning rubber" as you take off from a stop light. You had no idea what the real power of the motor was until the restriction was removed.

I have done tests on diverter valves, and I hate diverter first plumbing on a modern spa pump. It makes my "mind ache" just thinking about all that wasted energy. If you are paying electricity for a 3, 4, or 5 HP pump and you paid good money for that pump, why would you want to waste so much of the power?

Why would you want to wait for the jets? Why would you not want to be able to run all of the jets in the spa at the same time on full jet pressure if you want?

The spa industry has been deluded with this design for too long. It is ridiculous to waste energy and it is ridiculous to wait for jets. When you are forced to wait for jets, the cover is left off longer while the second person gets therapy, costing more money in both heat losses out of the spa, and from the motor running twice as long. Is there any reason to put up with this. It is because you do not understand about spas before you bought. If this is something that you like, all is well and good, but I and all of the members of my family do not like to wait for jets.

We like to get in and put on the jets, get 20 minutes of therapy, turn off the jets and set back and soak in quiet. I can't imagine trying to relax while I am waiting for someone else to finish with their turn at the jets. By then the relax time is ruined by the extra 20 minutes of noise. Part of the therapy is just sitting and quietly having a nice conversation or by looking out at the stars.

The other major issue with diverter valves is how complicated it becomes to find the right valve position, and pump to turn on. I had a couple come into our store years back, they got in one of our spas and turned on the jets, with little instruction.

After a while, I went over to ask them how they liked the spa? The first thing she said was how easy it was to use. They had just come from the Marquis dealer, and she said that she could not figure out how to get the jets on in the seats.

If you design a spa correctly, you can have extreme energy efficiency and full function of the spa, by simply turning on the jets. As long as the spa is a heat capture type of spa. In a heat capture spa it takes the motor heat and forces it into the water. This stops the heater from coming on much at all..

Since the heater is 4,000 to 6,000 watts, that you are saving, you do not need to sacrifice features by cutting the Horsepower and dividing up the pump's water flow.

Since the therapy is there for each user, the spa pumps are not run as long. If the pump is doing double duty with a diverter and the people in the other seats run the jet pump for the extra 20 minutes, where is the savings? The savings is in the factory cost to produce the spa and that is all.  They do not pass this short cut saving money along to consumers, they use if for extra profits. 

Putting in two smaller pumps then divide the water flow is cheaper to build than to build with two stronger pumps that run a lot shorter time with stronger jet therapy.

The pumps last longer, because of shorter operation time to give intense therapy, and the spa owner is much more satisfied.
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Back in 82 (?) spas had One HP pumps, (about 60 GPM) and the max was 1.5 HP (about 90 GPM). You remember those old days? (GPM = gallons of water flow per minute)

Back then all the controls were pretty simple.

No one had thought about 2,3, 4, 5, 6 HP pumps, because those motors did not exist. For some reason no one thought about putting on two pumps either.  Spas had four of five jets, one in every other seat. If you wanted to have a seat with more jets, or more jet action, you had to divert the water. It was the only way. As soon as the water was turned in to the one seat, all the other jets were dead.

All of the spa's heat came from the electric heater, because no thought had been given to heat capture.

That was 24 years ago.

Now we have extremely electrically efficient motors on pumps that produce up to 250 Gallons per minute. That is above 4 times the water flow of the one hp pumps, with less watts per gallon of water flow, about 5/8 the watts used.

The beauty of a modern designed spa is that you can have all this extra pump and still have the same or lower energy use, because the larger pumps put out a lot of heat generation.

When the user is enjoying the powerful jets, the heat from the motor keeps the electric heater from coming on, except after a long period of blower use or in very cold weather the heater will eventually come on after 20 minutes of therapy.

We have large spas with twin 6.7 HP pumps, full turbo air and 20 air injectors, used more times than I do, 8 times a week in winter, and still average under $21 per month in the midwest.

That is what I mean! Why use diverter first plumbing if you can have the convenience and amazingly powerful jets with full air injection and turbo air and have it cost less than a large spa that was designed back in 1980, using more electricity because they only know to heat with a resistive heater.  This is still the typical spa design from the major manufacturers.

On the out of date spas (full foam), still being made today, the 6,000 watt heater is forced to operate at the same time as the jet pumps for a much longer period while the spa is being used and while the spa cover is on and not being used. This greatly limits the horsepower in order to keep the electric consumption down.

If you were to take the same exact equipment in one of those full foam, diverter first spas, place it in a thermally closed design, it would cost about 25% to 50% less to operate, depending on the number of times the spa is used. The more it is used the less it costs per use.

This is from posts I made written directly to spa sales people for and about this sort of nonsenst on spa and hot tub forums:
---
If you are afraid of my information so that shoppers and spa owners can learn from my perspective, that is pretty darn interesting. Why would you be so concerned? The reason why my first post on here was asking if a spa company owned the board or not, was to see if they are going to block information about spas that could affect their sales. That is the main reason I get blocked on the sites owned by the spa industry.  I am not popular in the industry, but very popular with consumers.

The shoppers are "big enough" and "old enough" to think for themselves, don't you agree? This information I share is to give a perspective on spa design and engineering, nothing more. This is my passion and I love spas. It has always been my perspective, position, and interest.

To answer to your "assuming", no, I am going to talk about spa design from the perspective of inside the spa engineering and back it up with clear statements of facts as always.

Back to topic:

The diverter valve companies have "parameters" and instruction for using their valves. The jet manufacturer, electronic control builders and the pump companies do also. This information is available to anyone who asks the manufacturer of the parts. That is because they have a vested interest in their product performing well and selling because of its acceptance. When they design the parts, they also have to follow standard engineering principles and UL, ETL, ANSI, ASTM and all the other safety organizations.

In other words the builders of the parts, know their own parts, and they want you to use it correctly so it makes them look good and the end user is safe and happy. If you do not use it correctly, and there is no law that you have to, it makes them look bad, and if voids the UL, ETL and the rest.

What I have noticed with several spa companies, is a tendency to take an idea for plumbing designs from many years ago and use the same design with modern high flow water pumps, but they don't seem to really follow the manufacturer's instructions, rather they follow the marketing people, because if it doesn't sell, what good is it? And even if it is not working according to the supplier of the parts.

Have you not seen this in the spa industry? I see it all the time, because I still run a "fix-em-all" service center here in the Denver area.

Sometimes the misuse of the parts is so bad that the spa company will change the products design somewhat.

I am not going to mention brands, but there was a spa company who took the idea of diverter first plumbing to the worst possible result, in order to make jets that almost bored holes in your back. Some people thought it was great, and bought the products after wet testing.

The only problem was the valves and the jets started falling apart in less than a year. They put a large pump on a diverter and forced the water into only a few jets at a time in order to get extreme jet pressure. You may know who I am talking about.

We still get customers coming in to get diverter valve parts and jet fittings to make the spa function. The pressure on the diverter and the back pressure on the plumbing pipes caused a lot of leaks as well. The owners report that they have to use all their might to turn the handle on the diverter. My brother, the now semi retired engineer for over 40 years, calls this the "ten pounds of stuff in the five pound bag" type of engineering. After a while the bag breaks.

I talked with an old time spa engineer, who used to work for Sundance. He and I both agree that the diverter valves are abused and pushed beyond their limits even in his company's spas. I was asking if he could build spas for me without putting more than 90 GPM though the 2 inch diverter by following my plumbing diagrams (like my present factory does), but his company could not change their production to accommodate me at that time. I really liked the molds, but I could not sell the product if it didn't follow standard designs. The owners of the factory feel that if they don't give the sales people what they are used to and what they want, they will lose sales. It is a major dilemma for the engineering department and so many concessions are made for the sake of sales.



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Water pumps have a "characteristic curve" that is provided by the manufacturer for designers to use in both choosing and using a pump for any particular use.

For instance, pool pumps are designed primarily to simply move a lot of water and not necessarily at a high pressure. Commonly the operate at lower pressures than spa pumps, designed for higher pressure and delivering jet action.

All of the pumps that I look into are designed for spas and for spa jet pressure levels. Typically one of the pumps that I use has a higher pressure curve and volume curve than most of the jet pumps I have seen. That is because, to a point, you can get much more massage action at higher pressure. Centrifugal pumps are very interesting to study. Since I am always wanting to get the most efficient use of the pumps, it is important to know how they work.

As a cross reference, like many scientific studies, the power of a pump can be compared to electricity. If you increase the voltage (pressure) and decrease the wire size (smaller nozzles), you can get the same effective power with higher pressure and lower volume. This is similar to what a pressure washer does. It uses very low volume and very high pressure to do intense work. I certainly do not recommend "pressure washer" technology be used in a spa. We don't want to massage layers of skin off! Ha!

So, if you want to get the optimum massage, you would try to use a jet pump at a higher pressure and lower relative volume, with more jets. But I don't like bullet jets with a lot of pressure. I like large rotating jets with strong massage. If you take a standard jet nozzle and increase the pressure then spread it out by a rotating nozzle, you can achieve great massage without being piercing.

Ideally you want lots of jets working rather than one or two to get an overall massage. To do this you need powerful jet pumps to run jets like this. If you use a powerful jet pump, you do not want to destroy the pressure and flow rate by running it into a diverter valve that destroys what you really wanted.

If you want to make any division of the water flow, do it farther down on the plumbing "tree". Allow the pump to have full flow and pressure according to the pump manufacturer's design for maximum efficiency. If the pump is capable of 200 GPM, let it run at 200 GPM and 20 PSI. As you go down the plumbing "tree" there is a natural loss of pressure as the plumbing pipes spread out the pumps water throughout the manifold system.

When you enlarge the opening at the end of the trunk, you drop in pressure at that point, because the space opens up to a larger pipe. This is where you want to place a diverter valve, not ever directly after the pumps pressure outlet. If you place the diverter at a lower pressure and volume point in the water system, it can be matched to a large whirlpool jet or a master massage jet or even a geyser jet. These jets typically run at 90 GPM but much lower pressure. The diverter, which is normally a terrible restriction, then becomes a good restriction. It applies back pressure to the prior "trunk" area before the diverter, allowing no loss of flow and pressure before the valve, but a loss of flow and pressure after the valve, gives us the correct volume and pressure for a large orifice jet, 3/4 to 1 inch.

How many of you "experts" are keeping up with me on this? I probably should use some drawings to illustrate what I am talking about. The point is to get the most efficiency from the pump, you follow normal hydraulic engineering principles, found in any book on hydraulics.

----

My advice is to avoid spas that are poorly engineered, no matter what the salesman says or if the "local" dealer tells you how wonderful it is.


The synopsis of the design issues with diverter valves is that they should never be placed directly after the pump's output side as is commonly done to cut manufacturing costs. As soon as a diverter is used like that it destroys the effective energy of the water pump. If you are paying for a 1.65 HP, 2 HP, 3 HP, 4 HP, 5 HP or 6 HP pump, don't you want to get the full benefit of the pump?

Water is very heavy and it has specific problems to get it to the water jets. Blocking the flow in order to have a spa with partial jetting is not a realistic way to use water pumps. It is also decieving to consumers who are relying on you to be a good person.


Because the market leaders use diverter first valves and other out of date concepts these poor concepts have become some sort of "standard" that spa stores expect. They have long sales pitches about these incorrectly implemented devices and full foam and so on. These sales pitches are directly aimed at sales to consumers who know absolutely nothing about hot tubs.

How much do you know about spas and hot tubs?

Most of the people who read my information and have read my book, know more about spas than the sales people. My book was written long before I had a web site or even a business. It was written back when all I did was fix spas for one of the largest service centers in Colorado at the time. It was my mercy offering to spa owners who bought money (repair) pits, because the salesman said: "This is the ultimate spa!"

You need to know exactly what you are buying, BEFORE you spend your money. A spa is often the third most expensive purchase most people will buy, next to your home and your vehicle.

Paying a lot of money for a spa with partial jets and inefficient use of both energy and the pumps characteristics is not a good choice. It is normally a rip off.  Those types of spas sold with any ethics sell for about $4000 in todays market and that still includes plenty of profit.

Who wants to wait for jets?

An efficient design has full therapy available to all the seats at one time and energy efficiency.

Here are some interesting posts on our forum about this and air injection use on Haven Spas.
http://www.havenspas.com/cgi-bin/forum/index.cgi?read=13509





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