Monthly Archives: March 2010

Installing an “On-Demand” Hot Water Recirculation Pump

Many new homes these days are plumbed with a dedicated loop that circulates the hot water, often via gravity, to the fixture that is farthest from the hot water heater.  As the water in the hot pipe cools down it becomes heavier and drops down this dedicated line to the water heater in the basement and the hot water, which is lighter, rises through the plumbing up to to the fixture farthest from the heater.  This is great if your house has a basement and the builder was forward thinking enough to plumb it this way.  If not, or you live in a one story house, then you need an electric pump to move the water.  Many of these systems operate the pump via a timer that corresponds to your regular pre-work/shower routine.  These are ok if you keep a regular schedule but I prefer a on-demand system that only circulates the water when you tell it to.

Metlund

The pump and components.

The principle is the same, but an on-demand system has a button that activates the pump, circulating the water to the fixture it is closest to and automatically shutting off when it’s temperature sensor detects the arrival of the hot water.  The pump is located under the sink furthest from the water heater and can be configured with either a wired button or as a wireless system with multiple buttons for activation from multiple locations.  This installation was a wireless system located under a kitchen sink.

The system consists of the pump, a wireless sensor that attaches to the pump, 2 fittings that attach to the hot and cold water lines, and 2 flexible stainless steel water lines that connect the fittings to the pump.  When the pump is activated it pulls hot water from the hot side and pumps it into the cold water line, pushing it back into the water heater.  When the hot water arrives from the water heater the temperature sensor turns the pump off.  Turn on the faucet or a nearby fixture (shower or whatever) and the hot water is ready and waiting.  Since the pump is electric you obviously need a place to plug it in.  Most kitchen sinks today have an outlet underneath that is half switched (for the garbage disposal) and half hot (for the dishwasher).  Get yourself an adapter that allows you to plug 2 devices into 1 outlet and you can use the dishwasher outlet for the pump as well.  If there isn’t an outlet then one has to be installed, but that is something for another post.

The area will the pump will be installed.

The plumbing portion is pretty straightforward.  The 2 special fittings attach to the hot and cold water pipes coming out of the wall, and the original shut off valves that you just removed from those pipes (after you turned off the water, or course) are reattached to the new fittings.  The fittings provided assume you have half inch copper water lines and compression shut off valves, both of which this kitchen had.  The other opening on the fitting is where the stainless flex line attaches. One end on the fitting, the other to the pump.  Once all the plumbing connections have been made, attach the wireless sensor to the appropriate color wires on the pump and attach the sensor to the side of the cabinet wherever there is room for it.  The first time you plug the pump in it will automatically activate.  You will hear a change in tone as the pump fills with water and begins the recirculation.  If the pump seems to run and run and you don’t hear a change in tone it probably has an air bubble stuck in it.  Turn the hot water on and off quickly and repeatedly while the pump is running to jar the bubble loose.  Next time you need hot water just push the button, wait a minute or so depending on your distance from the water heater, and the hot water will be right there when you need it.

The installed system after everything is back under the sink.

1963 Airstream Safari: Interior Skin, Paint, and Flooring

Once the Airstream had been rewired and insulated, the interior skin went back on.  I had numbered all the pieces and took numerous photos before I removed everything, so putting it all back on was pretty straightforward.

1963 Airstream Safari, vintage, travel trailer

The first piece goes back on.

I purchased some cool clips called Clecos that fit in the drilled holes for the rivets and held the sheets in place temporarily while I put in all the other rivets.  As one would expect these were

1963 Airstream Safari, vintage, travel trailer

Clecos holding skin back on while it is riveted.

extremely helpful for the large sheets on the ceiling.  It was basically a one day job to reattach and rivet all the panels and trim pieces around the windows.

The next day I lightly sanded all the new patches and any other areas that looked a little too smooth for painting, and primed all the interior surfaces with a good quality metal primer.  Once the primer was dry I top coated everything with a low sheen

1963 Airstream Safari, vintage, travel trailer

The painted interior with the new plywood and some flooring.

acrylic paint in a color called Swiss Coffee.  It is a neutral white that was developed for use in art galleries and museums, so it was a perfect choice for the studio use of this trailer.  Having the whole interior back in place and painted really brightened up the space.

Since the floor had numerous holes and patches I decided the best and most cost efficient route was to screw a new layer of plywood over the whole floor.  This would not only stiffen things up, but also provide an nice uniform surface for the vinyl tile to adhere to.  I cut some pieces of cardboard to template the rounded areas at both ends of the trailer and used them to get a good fit with my plywood.  Once the new plywood was adequately screwed in place I covered it with Armstrong VCT in a nice vintage looking color called Granny Smith (like the apples).  I then covered the small gap between the floor and the walls with a PVC quarter round moulding that I was able to bend around the curved ends of the trailer.  With the exception of some light fixtures that hadn’t been decided upon yet, the interior remodel was complete.  Things left to do included repairing the slightly bent door and putting new weatherstripping in all the windows.

1963 Airstream Safari, vintage, travel trailer

The completed interior, before furniture.

1963 Airstream Safari, vintage, travel trailer

Interior completed, after furniture.

1963 Airstream Safari: Patching Holes, Wiring, Insulation

Once the structure was reinforced enough to support the new air conditioner, it was time to put it on the roof and patch some holes in the exterior skin.  I had an extra set of hands to get the new unit on the roof.  It is held in place by gravity and the interior frame and control unit, which will be attached after the interior skin goes back on.  Since the plumbing and appliances were all removed there were a few holes in the exterior skin that needed to be covered.  I ordered the appropriate aluminum sheeting (.032″ thinck 2024T3) from an aircraft parts supplier, as this is the same aluminum sheeting used on many airplanes.  (Airstream…get it?)

1963 Airstream Safari, vintage

Patches in the exterior skin.

Patching the holes amounted to cutting the sheeting into pieces the right size and temporarily holding them in place while holes for the rivets were drilled (duct tape worked well).  Once the holes were drilled I ran a bead of gray polyurethane caulking over the rivet holes and around the perimeter of the patch, put the patch in place, and riveted it on.

After all the holes were patched I sprayed the trailer down with a hose to check for leaks.  The few that I found were sealed with the same polyurethane caulk.  After I was satisfied that the Airstream was watertight I ran all my new wiring.  The electrical set-up for this trailer’s use as a studio is a bit different from a camping trailer.  None of the 12v wiring is really needed except for the few lights necessary to tow the trailer if it is ever moved or sold. Otherwise it was rewired much like a small house.  A 10 gauge, 30amp extension cord connects a new waterproof outlet on the trailer to a 30amp plug on the house that is wired from the main circuit breaker panel.  Once inside the trailer the electricity runs to a small breaker panel that divides the power into 3 circuits, a 20amp for the air conditioner, and two 15amp circuits for the lights and outlets.  The lights and outlets were located in many of the original locations, but a couple were added to satisfy the needs of the studio.

With all the wiring in place, I put on my mask and gloves and proceeded to insulate the trailer with fiberglass batt insulation.  Since the walls are only 1.5″ thick I used 3.5″ R-13 batts (designed for 2″x4″ walls) that I split in half to fit in the skinny walls.  Getting the insulation to stay in place on the curved walls of the Airstream was interesting.   Unlike a home with vertical walls and regular stud spacing that you can friction fit the fiberglass batts into, the trailer has curved

1963 Airstream Safari, vintage

The fuzzy, pink cocoon of the insulated Airstream.

walls.  Some of the spaces allowed  for the friction method, but all the insulation higher up the walls and in the ceiling had to be glued in place.  The old insulation appeared to be attached with roofing tar, so that is the approach I took as well.  I brushed stripes of the tar on at regular intervals and pressed the insulation into place.  This worked quite well except for the terrible odor of the roofing adhesive.  The next step will be reattaching the interior skin.