1977 '20 Airstream
Welcome to the Forums and the world of Vintage Airstream ownership!
Since your Airstream has a floorplan very similar to my '78 Minuet 6.0 Metre, I will try to give you a little information that might help.
With your water system, the water pump will only run if you are not hooked up to city water. To run, the water pump will need a 12-volt power supply either coach "house" battery (usually found behind a rather large recatangular exterior door at the front of the coach); Univolt (power converter) <the box that makes the humming sound whenever the coach is connected to shore power>, or through the power supplied by the charge wire from the tow vehicle; in addition to power, the pump also will need water in the fresh water tank (fill opening is usually near center front or streetside very near front of coach just below waist level -- a small rectangular door that opens like a drawer to be filled with a hose or bucket. Then, once all other elements are ready, the pump should only run when water is being used "demanded" at one of the points of use -- assuming that the master pump switch has been flipped on the control panel -- a red pilot light should illuminate to indicate that power is going to the pump. If the pump runs constantly (after filling the water heater which can take quite some time if it is empty) it is an indication that you have an open low-point drain (a series of valves that permit draining of plumbing in preparation for winter), a leaky water pressure regulator (water being pumped out hose fitting at rear bumper), or a pipe/fitting has sprung a leak.
To use city water, all you need to do is connect a potable water hose to the fitting on the streetside of the rear bumper and turn on the city water hydrant. I usually put an additional regulator in the line to add an insurance policy that high campground water pressure won't make it into my coach.
It may take a magnifying glass to read the directions, but the Dometic in my '78 Minuet has the complete lighting instructions printed along the panel immediately above the controls at the bottom of the unit -- can only be seen when the door is open. If your original refrigerator has been replaced, you may be fortunate to have one with Automatic Eneregy Selection which means that the refrigerator will automatically select the energy source for the situation.
The water heater is similar regarding lighting instructions. They are printed on the housing (behind the exteior compartment door), but may take a magnifying glass to read. The water heater is behind a rectangular door on the exterior of the coach -- usually on the streetside and often to the rear of the axle. A turn-buckle type latch holds the door closed. Be forewarned that if the coach has sat unused for any lenght of time the water heater may be difficult to light as spiders and mud daubers love to build their nests in the air supply tubing for the water heater -- a small bottle brush is very handy for addressing these clogs. Any RVer near you should be able to help with the water heater as it is identical to those used in most other coaches throughout the industry.
You will want to be very cautious about the furnace if it hasn't been recently checked by a technician familiar with older Suburban furnaces -- they were recalled early in their lives and have been noted in recent times for worn out heat exchangers opening the path for carbon monoxide poisoning. I have the one in my Minuet inspected annually (it is still the original 1978 issue), I will almost be relieved when it is time to replace as the new replacement models have automatic ignition so that it isn't necessary to manually light the pilot!!
I will be away for the weekend starting tomorrow, but if you haven't gotten the necessary basic instructions, I can scan the manual instructions for you Monday or Tuesday.
Good luck with your coach!
Kevin D. Allen
WBCCI (Lifetime Member)/VAC/Free Wheelers #6359
1964 Overlander International/1999 GMC K2500 Suburban (7400 VORTEC/4.11 Differentials)
1978 Argosy Minuet 6.0 Metre/1975 Cadillac Eldorado Convertible (8.2 Liter V8/2.70 Final Drive)