Hydro Installation Guide

This guide is intended for use with our products. It is a general guide for the average user/installer. It is not written for the professional covering every possible scenario with gobs & gobs of formulas. It is the installer’s responsibility to design and implement a quality system. Alternative Power & Machine will accept no responsibility for misuse or misunderstanding of this guide or for any accidental misinformation.

Constructing a Diversion—Intake point. Source water usually from a creek or pond

A diversion can be simple or elaborate and needs to be suitable for your application; both in a mechanical sense, but also in an ecological one as well. We need to screen out the rocks and other debris ¼” and larger but nothing larger than the smallest jet size that you will be using. We also need to screen out the critters, and prevent entrance of air bubbles into the pipe where possible. Listed are some of the more common ones used for this class of hydro, with pros and cons of each. Every site is a little different and you may need to adapt the suggestions as needed to invent something that will work for you. Your diversion needs to be robust enough to withstand the worst that winter has to offer or expendable and easy to repair. Some creeks can roll boulders and float trees that can do significant damage to your installation. Your irrigation supply store can recommend skilled people in your area that do irrigation work that can help with this part of the installation process.

The simplest diversions are variations of a pipe stuck in a creek with some kind of screen over it. They all tend to be high maintenance. In some areas, it may be necessary to clean the screen twice a day after the first rains begin in the fall. If placed directly in the stream flow they should be at least 1 ft. deep for pipe sizes up to 4”, which can create cleaning issues especially during high water. I for one am not interested in swimming in January, but on very minimally sized creeks they can be reasonably nuisance free most of the year and inexpensive to install. See diagram 1.APMH_Diagram-1 The screen shown can be used in many different variations other than the rock dam. The next simplest method is an open pipe or flume to feed a large container such as a bathtub, 55-gallon drum, cistern, etc… The main advantage is easier access for cleaning. A ¼” wire mesh screen is secured over the container as a trash rack which gets the big stuff. A finer screen is used inside the container to filter out the fines. The fines generally won’t hurt the Delrin runner on our hydro unless the head is over 300 ft. Even so it will wear at about 1/5th the rate of bronze. A clean-out or pee hole can also be placed in the bottom of the container to eliminate or reduce sand or?  This is similar to what I used on my own system, except the bath tub is just under the spill way of a small dam and settling pond. I can get away with that because my stream had a maximum flow this winter of 550 GPM. At about 300 GPM the water gets a little turbulent coming over the spillway and air bubbles make their way into the pipe which reduces output at the hydro a little. On high head systems this air can actually damage the runner and lead to premature bearing failure. At 32 ft of head it is not an issue, but could be fixed by using a deeper container such as a 55-gallon drum instead. Maintenance is still medium to high in the fall but is much better the rest of the year. See diagram 2. APMH_Diagram-2See diagram 7 for a somewhat self-cleaning version.  APMH_Diagram-7If you can construct a spillway in some fashion there is a self cleaning screen ( well…almost ) that is fairly easy to install. It is a Coanda effect shear screen that works in conjunction with surface tension (skin effect) of water and a triangular shaped wedge wire to separate the debris from the water. In warm water areas it will be necessary to occasionally wipe the algae off the screen with your hand. It is not cheap but it is constructed out of stainless and should last forever sans falling tree or rolling boulder. Many state agencies are now requiring this type of screen because of its ecological benefits. Almost nothing makes it past the screen. See diagram 3. APMH_Diagram-3Contact information is Hydroscreen Co. LLC  303-333-6071 or email at RKWEIR@AOL.COM  website is www.hydroscreen.com .The next method is with the use of a screen box. They are general constructed of concrete but can be steel or plastic. They are usually installed on the side of a small dam or slow water area of a stream. They usually have 3 screens, 2 shut-offs, and a clean out. These work about as well as the bath tub idea and are less ugly or at least “hillbilly” They are harder to clean especially during high water. If constructed without an outlet shut off, debris can enter the pipe when the screens are removed for cleaning, which defeats using it in the first place. This is probably the second most common type of diversion. See diagram 4. APMH_Diagram-4Another common method is done away from the bank of a pond or slow moving stream with a fairly stable water level. A pipe is run underground or thru the dam to a screen or even a 5 gallon bucket with a bunch of holes drilled in it. Although it generally does its job in slow moving and relatively clean water it can be a nuisance problem with some types of large floating debris. Access is by boat or plank walkway…anyone for a swim? Popular in beaver areas and will tolerate some flooding as the pond level can be controlled to some extend most of the time. See diagram 5. APMH_Diagram-5It is also possible to tap the end of a culvert pipe. OK for low flow applications. Drill or cut a hole in the bottom of the pipe near the end to mount the pipe adaptor first. Bolt in a trash screen at a slight uphill angle, about 3”/ft. Bolt in the wedge to maintain a water level at your intake point. Simple, but be careful cutting or welding galvanized pipe because the fumes are toxic. Also be careful or at least mindful of the maximum volume of water the pipe needs to carry during flood season, if you wash out a road you will be responsible for the damage. See diagram 6. APMH_Diagram-6The remaining diagrams 8 & 9 are used on primarily larger streams or rivers because of the expense, but can be used on smaller ones as well. I have built diversions in a dry area on the side of the stream slightly below the existing water level similar to some of these examples, usually when doing concrete structures. APMH_Diagram-8 APMH_Diagram-9When completed simply breach the side of the creek to fill your new mini pond. The important thing is not to redirect the stream flow out of its banks, but to just pull water from it. I know of one case locally where the installer breached the side of the creek and redirected the creek thru his neighbor’s house. $$$$$  The gabion weir is used to deflect the main stream flow just enough to create a slow moving water area to settle out debris. The rule is ½ ft/sec velocity or less. The Gabions can be made with rock and mortar or built from screen and usually filled with rock. They can also be purchased flat and assembled from most irrigation supply stores. No…not the local plumbing and electrical retail. Sorry, I will not describe how to build a dam other than the two foot version illustrated. This is skilled work that should be done or at least supervised by someone in your area with experience. There are a number of methods used usually for pumping water out of rivers uphill and some have been used in hydro applications that rely on suction and the greater down hill run of pipe to maintain flow. The problem is that they require a foot valve and a priming process (hand operated pump) to expel the trapped air. While this works fine for pumping water, usually a day at a time, they tend to lose their prime constantly in a hydro application. They are used with a simple screen type filter as part of the foot valve. Use if you must, but I strongly advise against it…you will hate your hydro. There are also some canister type screens that work very well. They are constructed usually with a clean out port and full face flanges for connection. $$$  I have used some made by AMIAD corp. but you should see what is available in your area in case you need spare parts, seals, etc…  See diagram 11  APMH_Diagram-11One thing that does not work is water filters intended for households or drinking water. They plug up much too fast as they are much too fine. We really don’t need to remove stuff that small.

Upper Penstock shut-off and venting penstock = pipe

Sometimes omitted to save expense, it is highly recommended. Pipe failures do occur and it makes life a lot nicer to be able to shut the system down in a panic. Most any type of valve will work other than a plastic slide gate. A rubber compression union also works nicely to separate the penstock from the main supply pipe but is slower. Rubber hose works OK too, but make sure that it is suction rated with a wire spring molded in the rubber. A screw-apart union with an expansion joint can also work instead. Venting should be done on any design that uses a shut-off valve or has a risk of the screen becoming blocked enough to collapse the penstock. It is actually easier to suck a pipe flat at 200 ft of head than it is to explode the pipe from water hammer. Diagram 10 shows an automatic air vacuum operated release valve. APMH_Diagram-10They are spring loaded. If a vacuum occurs, it allows the penstock to drain without damage. 4” and smaller penstocks should use a ½ or larger valve. Larger pipe should have a valve sized no less than 1/6th the diameter of the penstock


The actual “engine” in a hydro is not the generator, but the pipe. The pipe is the most important part of your hydroelectric system. Saving money or avoiding hard work here will cost you performance, output, and efficiency.  There are many different types of pipe available and almost anything will work. The most common types are white PVC and black PE or HDPE ( poly pipe ) which come in several classes and pressure ratings. Drain pipe is not rated for pressure but will work up to about 30 ft. of head if you are careful opening and closing valves. Not a wise choice. The pressure rating should be your first criteria. Allow an extra 40% above the static water pressure.   Example   200 ft of head = 86.6 psi  X 1.4  =  121.24 psi.  Aluminum pipe is sometimes easy to get in farming areas but generally is only used up to about 125 psi. and it should not be buried unless treated. Steel is very high pressure but should also not be buried. Common PE pipe is usually good to about 80 psi and HDPE a bit higher. Aluminum, steel, and PE/HDPE have relatively high resistance values per hundred feet, so it is important to factor pipe loss in your cost analysis. For my money, I rarely consider anything else except PVC. There are a lot of hydro people that disagree with me on this and this is a free country…oops… better not get started on that one.  There is a pipe loss chart in the site survey that applies to one class of PVC it is a little on the low side most of the time so add some to your calculation for higher pressure ratings, subtract a little for lower. As a general rule figure 2” poly pipe has the same pipe loss as 1.5” PVC and 3” poly pipe about the same as 2 inch PVC. Steel and aluminum pipe is general at least double the values of PVC. In an effort to avoid talking about and calculating in great detail; flow velocity, pressure rise, critical time, pressure wave velocity etc… I am going to make a very simple recommendation about pipe size to address all the other concerns about pipe that is frankly nothing less than a physics course. 200 ft of head or higher can use 1.5” PVC up to about 25 GPM, bigger is better. Any head, up to about 45 GPM can use 2” PVC. Any head, up to 75 GPM can use 2.5” PVC. Any head, up to 110 GPM can use 3” PVC. Any head, up to 190 GPM can use 4”. Any head, up to 300 GPM can use 5”. Any head, up to 430 GPM can use 6”.  When selecting pipe, just remember to multiply your static head by 1.4 first, and make sure the pressure rating is greater. A very rounded suggestion and not without flaws, so if you are pushing the envelope within a pipe size, it is usually better to go bigger because you will almost always gain in system performance. This is not the place to cut cost. The same holds true for long pipe runs. Bigger = more power and greater water efficiency.

To bury or not to bury?  Well, buried is always preferable but not always possible. Buried pipe is more stable for expansion and contraction and offers protection from freeze and falling trees and critters. PE pipe is famous for being chewed on by rats. raccoons and bear to name a few, but PVC has been attacked too. PE pipe is more freeze tolerant than the other types and can be a little tougher where abused or installed improperly and can be an advantage when laying over some treacherous terrain. The recommended trench depth should be 2 ft deep for pipe up to 4”. For larger pipe common to our hydro applications 2.5 to 3 ft. Check frost depth in your area. OK, moving water general won’t freeze, but sometimes things can happen, that force the hydro to be shut down or become blocked and then you are in trouble. The pipe bed should be free of sharp rocks. A layer of sand or pea gravel is good. The trench should not curve beyond the recommended curve rate for that pipe. Thrust blocking is usually unnecessary for 3” or smaller pipe that is buried in most soils. See diagram 12 and 13 for some recommended thrust blocks for different types of bends commonly found in hydro penstocks. APMH_Diagram-12APMH_Diagram-13For pipe up to 5”, I usually cheat by just digging a little deeper at the critical points; build a makeshift form and poor concrete over the whole mess. Simple and no thinking required but it does make pipe replacement difficult. For 6” and larger, better do it right.

The following tables are used to calculate thrust block size

Soil type Safe Bearing Load
Shale 10,000 lbs/sq.ft.
Cemented sand and gravel, hard to pickCemented sand and gravel, hard to pick 4,000 lbs/sq.ft.
Good mix compact soil 3,000 lbs/sq.ft.
Clay medium 2,000 lbs/sq.ft.
Clay soft 1,000 lbs/sq.ft.

Pipe fitting Thrust factors in lbs/sq.ft.

Nominal pipe size Dead Tee 90 45 22.5
1.5 2.94 4.16 2.25 1.15
2 4.56 6.45 3.5 1.8
2.5 6.65 9.4 5.1 2.6
3 9.8 13.9 7.5 3.8
4 16.2 23 12.4 6.3
5 24.7 35 19 9.7
6 35 49 27 14
8 59 84 45 23
10 92 130 70 36
12 129 182 99 50

example: A 4” pipe operating at 87 psi is buried in a medium clay type soil. For a 45 degree bend what is the minimum thrust block size needed ?

pipeline thrust for a 4” pipe and a 45 degree fitting is 12.4 lbs/psi. from the table

Pipeline Thrust   =   12.4  lb/psi    X    87 psi    =     1078.8  lb

So Thrust block area  =   pipeline thrust/soil bearing strength from table

Thrust Block area    =     1078.8 lb.    divided by     2000 lb/sq.ft.  =  .5394 sq.ft.

Pipeline Side Thrust

Use this table for soft soils and unburied pipe to support the ends of pipe sections. This is usually not necessary for our purposes if the pipe is buried.

Nominal Pipe Size Side Thrust in lbs at 100psi/degree of deflection
1.5 5
2 8
2.5 12
3 17
4 28
5 43
6 61
8 103
10 160
12 225

Side Thrust  =  Side thrust from table per 100 psi per degree of deflection  multiplied by actual degree of deflection  multiplied by actual operating pressure.

Example:    a   6” pipe operating at 139 PSI    and has 8% of deflection   has a side thrust of

61 lbs per 100 psi per degree of deflection   X   8 degrees   X   139 psi   =    678.32 lb

As you can see almost any soil type will do if buried, but if above ground that can be enough to break a fitting, which is a relative weak point.

Diagrams 14 and 15 show some of the concerns about routing and support of the penstock. APMH_Diagram-14APMH_Diagram-15In very steep areas sometimes there is no ordinary support of any kind possible. it will be necessary to support the pipe on wire rope and anchored to the rocks or trees off the cliff or suspended. The wire rope is attached to the bell end of the pipe on truck muffler clamps with turnbuckles. Straight, round sweep, and steady decline is the rule, but sometimes you have to break the rules. There are performance and maintenance issues if you do however. Sediment traps need to be blown which involves opening up the pipe at the bottom and letting it rip full volume. Air pockets are simply bleeding it off.

Lower penstock and hydro pipe connection

There should be a pressure gauge in the line on the uphill side of the shut-off valve. The gauge helps to diagnose problems. A higher than normal reading usually indicates a plugged jet. A lower than normal reading can mean the pipe or filter screen is plugged, or you are trying to pull more water than is in the creek. A pulsating gauge indicates turbulence usually caused by running a higher flow rate than the penstock is designed for which includes installation errors such as to many bends or back up the hill runs. I prefer to use a gate valve for the main shut-off because they operate slower with less risk of creating water hammer than a ball valve. I usually place a screw-apart union close coupled to the gate valve so I can clear any debris that might get in the valve. Most gate valves do leak a little. Plastic ball valves tend to seize and break off the handles. The exposed end of the penstock, valves and hydro manifold are susceptible to freeze damage if the flow is stopped, so keep the drains or bypass open if you are going thru a freeze. Moving water is usually good to 20 F continuous and 0 F for short periods. This applies to all 4 jets on the hydro not just the ones you may be using. Re-jet if necessary and open them all. If you can’t, it is better to shut the whole thing down and drain everything. Not paying attention here can cost you several hundred dollars. Connecting the hydro to the penstock usually involves correcting an odd little angle of down hill pipe run to the hydro, which is horizontal. The easy ways to do this are: King nipples and a short high pressure rubber hose section, or the use of two 22.5 degree elbows which will allow any corrective angle up to 45 degrees. This may or may not be applicable to hydros built with a gang manifold at the end of the penstock instead of built around the hydro. Gang manifolds are optional on our units. Connection to the hydro is by high-pressure hose. The valves are located on the gang manifold at the end of the penstock instead. We usually put a clean out valve on the end also. See diagram 16. APMH_Diagram-16This option also reduces the risk of freeze damage somewhat. This option is not listed in the price sheet due to the custom nature of it. The average cost is about double that of the standard manifold built around the hydro. The nicest installations have the pipe exiting the ground at 22.5 or 45 degrees inside a shed or protected area. If you keep your hydro out of the weather it will last longer and need less service, especially the wound field models.

Hydro mounting and tail water concerns

Our turbine is meant to discharge water out the bottom or floor. The cut-out must be 14” X 14” square. Any inside ledge will deflect water back into the runner and reduce performance. The water must be allowed to flow away by gravity with no back-pressure or restriction of any kind. It will blow water out the sides or around the shaft opening. It won’t do any harm to our hydro. We use a cooling fan as a slinger to prevent that from happening. This feature is a huge advantage over our competitor’s products. In addition, our hydros run cooler and are capable of higher continuous outputs than most. The nicest mounting platforms are probably metal plates on permanent cement structures with the tail or wastewater exiting the bottom or side as in Diagram 17. APMH_Diagram-17a APMH_Diagram-17bThis version can be adapted to include a drain pipe instead. The drainpipe size should be at least twice the diameter of the supply pipe with a reasonable downward slope. A vent may be necessary. The most common mount most people seem to choose is simple plywood and 2 X 4 structure close to the creek. Some are a bit more elaborate with masonry spillways or drain into a yard water feature. Sometimes the water is used for a second purpose such as maintaining a pond or irrigating a garden. Let your imagination be your guide, but remember, you cannot re-pressurize the tail water. Once you have extracted the energy for charging batteries, gravity has to take it away.  Diagram 18 shows another popular method of modifying a 55-gallon drum for use as a hydro mount. APMH_Diagram-18The bottom third is cemented into the creek bank, or loaded with rocks. The middle third has a whole cut in it to act as a discharge. The top of the drum has a 14 X 14 square hole cut out and the hydro bolts to the top of the drum. The drum will usually last about 10-15 years. An up-ended culvert pipe 24” or larger can be used in place of the drum, but it is a little more work fabricating a top. A good substitute for the plywood or metal base is a high-density polyethylene plate at least ½” thick. This is what I prefer to use. It is a specialty item and a little “spendy”. I don’t generally stock it, but it is easy to get. Some protection is needed on the wound field models to protect the electrical stuff on the control panel. We need to keep the rain off but not seal it up too much and create a sweating problem from condensation. A roof and three sides will work the best, leave the control panel side open and accessible. Most of the PM models are built for outdoor operation, but will be better off if protected the same way. A make shift roof structure over the hydro that you can stand under in the rain while cleaning out or changing jets is also nice.

Hydro wire connection

Aluminum wire is not flexible enough for direct connection to the power head. The stiff copper wire commonly used for direct burial is better but I prefer flexible welding lead, which is not code compliant. For direct burial, the wire should be USE-2, RHW-2, or UF types. Many other types can be used in conduit. Romex or NM is a mistake. Chair lugs and corrosion inhibitor can be used on all the wound field models if using copper wire of any size. I prefer soldered copper lug connectors. If using Aluminum wire it will be necessary to run a short section of copper wire from the power head to a junction box. Inside the junction box, use split bolts and corrosion inhibitor to attach to the Aluminum wire. Sometimes it is easier to use an outdoor rated disconnect with the Aluminum wire on one side of the breaker and the Copper on the other. This is just a service disconnect. Size the breaker at least twice the amperage of the hydro. An open circuit hydro can develop very high voltages. The wound field models have electrical terminals that are fairly exposed, some caution is advised. The wound field models are modified automotive and truck alternators and they are difficult or impossible to make 100% safe or free from shock. I have been shocking myself since I was 8 years old on a regular basis and have no fear of it, but it is up to you to take safety or security precautions as you see fit. Most of the PM models have an enclosed weatherproof box with all electrical connections inside. On request, some of the 12 and 24-volt units have exposed studs however. The maximum wire size intended is 6ga. copper or 4ga. flexible. If you are using larger wire for your main wire run, it will be necessary to use a junction box or service disconnect as described before. We have made this change in preparation for an attempt at listing our hydro. There are no listed DC hydros in existence at this time. Most electrical inspectors don’t know that so… Some states like Oregon require it. It is a very expensive process, and we probably will never be able to pay for it. Most people building an off-grid home install the hydro after everything else has passed inspection. I can’t recommend that you do something outside the “straight and narrow” but it’s a free country…oops…there I go again.

Power House wire connection

Some areas of the country may require specific depths for entrance as well as metal conduit up to the first disconnect or something similar. If you are faced with something weird or expensive here, you may be able to run up the outside of the building first to an outside disconnect, and then an entrance less costly. If using a breaker, size at least twice the amperage of the hydro. In any event, the wire run should exit the ground in some form of conduit, up to a disconnect or main inverter panel, for connection eventually to the battery thru a DC circuit breaker. Oversize is the rule. We do not need to size for the hydro output. We need to size only for the ampacity of the wire, which due to longer wire runs than normal, is on the excessively big side. It is undesirable to open circuit a hydro under power. I like to see a breaker sized no less than twice the amperage of the hydro. The wiring diagrams are very general. There is simply too many possible scenarios here to get specific. We would be glad to answer any questions if you need help or consult an experienced alternative power equipment installer in your area for help. Most conventional electricians do not understand DC well. Which sadly include the people writing code and doing electrical inspections. See diagrams 19 and 20. Diagram 21 only applies to the long distance high voltage models.

APMH_Diagram-19 APMH_Diagram-20 APMH_Diagram-21

General Wire run

Check local codes, but usually the wire run must be buried 18” if in conduit and 30” if direct buried. I have seen plenty of systems installed with the wire run on top of the ground with out any problems, but it is not a good idea. Any amount of burial would be preferable to none, even if it doesn’t meet code. In lightning ground strike prone areas it is a good idea to zigzag a bare copper ground wire in the trench (18” width) to help dissipate induced currents in the main wire run. Drive a ground rod at the hydro and connect to the terminal provided for that purpose. Do not connect the negative to ground at the hydro. This should only be done in the main power panel, if at all. That said; some of the economy units are modified automotive types that already have that done by design. The risk is introducing a lightning strike or ground differential thru the power system, which can do significant damage to inverters and power system components.

Voltage Control

The hydro electric generator must remain loaded at all times, which means that we can not use an automotive type voltage regulator. We will allow the alternator to run at its full potential and use a diversion or shunt type control instead. When the battery is full, the control will send energy to a heating element to “ burn off “ the excess. The excess can also be sold back to the utility if you are grid connected thru an Outback GTFX or Xantrex SW inverter with a sell function, to name the two most common. You must use a battery-based system for our hydros. AC direct systems are much more expensive requiring special switch and safety gear. AC direct also requires much larger water supplies. We build air-heating units and sell water-heating elements in 12 thru 48 volt. The Morningstar TS series controllers are our first choice for reliability but the Xantrex C40 and C60 hold up well too. Code requires a primary and a back-up control. The primary can be “Sell mode“, or a diversion control like the Morningstar. The back up can be tripped off of one of the inverter or charge control relays in diversion mode, to control an AC or DC load, or a second diversion control like the Morningstar TS.

There are also some MPPT type controllers that have been used successfully in a hydro scheme. Such as; the Hydromaxer from Australia, and the Outback MX 60 to name two. These are sophisticated and expensive electronic devices that can be damaged by accident. They have an upper voltage limit that is difficult to control at a reasonable cost. The MX 60 has the ability to operate our PM at a higher than normal voltage and then convert it down at the battery. This ability allows our regular PM model to function the same as our high voltage long distance transmission models, but to a lesser degree. While the MX 60 is a fine charge controller, I prefer the simplicity of the step-down transformer. Reliability is better, net efficiency is the same, and cost is less.

You can also use voltage sensing relays (active high) like the ones made by Solar Converters to operate other AC or DC loads such as: water pumping, lighting, or motorized gate valves at the hydro. The motorized gate valve is used to shut down the hydro when the battery is full, saving water behind the dam. The same valve can also be wired thru a float switch to monitor pond level. The pressure operated shut-off valves for sprinkler systems suffer from contamination because the water in the pipe actually closes the valve which is quit dirty by comparison to a household water supply. The electrical connection is just a relay. Most everything else I have seen is too small and restrictive for use on the hydro.

That just about covers everything you will need to know, but if there are any questions, or you want to criticize my grammar and punctuation, please give us a call or email. I promise to do my best with the former. The latter is beyond my science, math, and music brain.

Jerry Ostermeier
Alternative Power & Machine
4040 Highland Ave
Grants Pass,  OR  97526