Saturday, October 15, 2011

Teller Headstart Water Pump

The Headstart building in Teller has it's own water system with a pump to provide pressure to the building.  The setup is similar to having an on site well, but in this case the pump draws from a large storage tank.

Recently the pump quit working, when I inspected it I discovered that the impeller was broken.  I suspect that someone let the water tank run dry and left the pump running for too long.

Normally you can replace the impeller on these pumps easily, but on this one the heat wrecked the impeller and also some of the other internal parts. When I checked on parts there was going to be a long lead time and a lot of shipping cost to get them from the lower 48.  Luckily I found a complete pump and pressure tank in Nome that was an exact replacement.

The first thing I found in the box was a set of instructions that tell you to stare directly at the tank if  it explodes.  There was also a picture of a snake biting someones hand, or maybe that was something about electrical safety.

Since the new pump was a direct replacement all I had to do was switch the piping over from the old to the new unit.  In different parts of the country there are several types of pipe that are commonly used.  In this area potable water systems are normally plumbed with brass.  Brass is nice to work with and is very corrosion resistant.

Threaded plumbing connections need some kind of sealant on the threads.  Teflon tape works well for potable water systems.  Put a few wraps around the pipe and screw them together.  Teflon tape seals well and allows the joints to be taken apart easily if repairs need to be made.  There are also many different types of paste or dope for sealing pipe joints.  These also work well, but some of them harden with age and can be very difficult to take apart later.

Some of the connections in this system use unions.  A union allows you to put the pipe together without having to spin the assembly around.  The seal in a union relies on a cone shaped fitting pressed into a tapered seat.   

The arrow in the above photo points to the location of the tapered seat on the lower half of the union.  In a union the threads are only used to force the two parts together, they are not part of the sealing surface.  Because of this there is no need for a sealant on the threads.

Here is the complete union on the top of the pump.  In this photo you can see the Teflon tape on the pipe threads and the hex nuts of the union with no Teflon.

This pump assembly is connected to the pressure tank with a compression type packing gland with an o-ring in it.  Whenever I put an o-ring assembly together I like to coat the surfaces with a little bit of silicone grease.  This makes the parts easier to assemble and should keep things from sticking if it needs to come apart later.

The last step is to connect the wires to the pressure switch.  This is a very basic 110 volt connection, a green ground wire, a black hot, and a white neutral.

Here is the completed installation.

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