I have a remote pump for my upright Duo-Art piano installed under
the house.  It is in a steel box to protect it from mice and rats.
The original pump was a steamboat and having rebuilt one of these,
I was not thrilled about doing another.

The under house pump can be almost anything as long as it has
sufficient capacity and it is running smoothly.  Since noise is not
an issue, it is possible to use a modern motor and not be worried
about overheating as is the case with old motors in bad condition.
The old motors are excellent but few people bother to check them and
repair/rewind as necessary.

I use a DC motor which allows for easy speed control.  This allows
me to match the pump volume to the requirement of the piano.  It
also allows me to use almost any pump as long as it is large enough.
I have used Ampico pumps (those that do not have that ball bearing
spider like the Duo-Arts have which is often worn out) as well as
leaking old pumps which I can get the last gasp out of by running them
faster until they die.  When I find another of those 'round tuits',
I will be putting a pretty decent pump from a Weber grand under the
house to replace the one I am currently using.

There are many ways to control the speed of a motor but the easiest
is to use a DC motor (they are a little expensive but can be found
surplus), a rectifier bridge and a Variac variable transformer to vary
the AC voltage before rectifying it for the DC motor.  You can also
buy ready-made DC motor drivers but they are expensive if not found
surplus.  AC variable speed inverter drives are much more reasonable
than just a few years ago so this is also an option.

If you are a real electronics nut and want a fun project, you could
also use a servo motor and a controller such as the Gecko servo drive
and make your own variable speed drive for about $150.  With the right
motor, you could probably make it direct drive and eliminate the belt.
This is only recommended for someone with a lot of electronics
experience and a lot of time.

If you want to use the original motor, make sure it is checked by
a motor shop and repaired if necessary.  It is definitely better to
use a modern motor rated for continuous duty and with an internal
overheat protection device.  Also, install a thermal protector.  The
pump can overheat without your knowing if it is hidden in another room
or basement.

If using a fixed speed motor, you need to make sure it is the same
speed and greater or equal horsepower rating as the original.  If you
do use the original pump at the original speed you will need to provide
large diameter pipe or hose especially if the run is long.

Complications can arise with things like a pump-mounted spill on the
Ampico or the Duo-Art spill if the total volume of air is substantially
different from that of the original system.  It is best to try to keep
the supply line as short as possible for this reason.

It is also best to use rigid pipe or hose.  Do not use corrugated hose
like vacuum cleaner or spa hose; this can set up nasty oscillations in
the vacuum pressure.

Adding thermal protection to a motor is quite easy and cheap.  Electric
water heater thermostats are suitable for 1/4 HP or less motors and are
rated for many operations, as opposed to most protection devices.  They
will not fuse closed as will some snap disc protectors, if overused.
They are also cheap and easily available.

Use something like long worm-type hose clamps to make sure the thermostat
does not fall off the motor, or if you don't mind drilling and tapping
a couple of holes in the motor housing, secure it that way but be sure
to not drill into the motor windings.  Play a lot of rolls to get the
motor nice and hot and adjust the thermostat to turn off at an
appropriate temperature.

You can run a power line from the piano directly to the remote motor
but I prefer to use a local supply and a relay operated by the piano.
This is especially true since I play my piano with E-Valves.  I have
a solid state relay at the motor which also reduces the strain on the
original piano switch.

To further reduce noise at the piano, I also relocated the spill valve
to the remote location.  The spill valve on the upright Duo-Art is very
noisy and difficult to muffle, unlike the one on the grand.  I used an
Ampico type spill which was actually taken from a very late model
Duo-Art that had a fan regulator.

Best regards,
Spencer Chase
Garberville, Calif.
http://www.spencerserolls.com/