Custom Wet Sink
It took a fair bit of time for me to get to the point where I decided to build or buy a wet sink. Trays on a countertop were messy and inconvenient. I had a friend who was in the chip making equipment supply business and he built a welded plastic sink to my specification. The material is 1/2" thick and is a strange acid proof plastic that must be hot welded, it is nearly impossible to glue it together with the sorts of adhesives available to the home user.
The joints look like they are calked, but are welded with a hot air welding machine. The joints must be welded on both sides of the material. He welded a pipe fitting on the bottom in one corner so I could attach a drain tube.
Underside view of the right front corner of the sink, showing the welded drain fitting. The branch to the right connects to the drain of the laundry sink, the branch from the left is the drain from the print washer. I have a poor man's water temperature/flow system built up from brass fittings, this is mounted on the back splash of the sink area. The small ball valve feeds the print washer solenoid.
I found a nicely priced K Type thermocouple module on Amazon and 3D printed a mounting bracket using PETG filament.
3M mounting tape completed the installation. The module is easily removed from the bracket to change the 9V battery when needed.
An extension with a 1/8" npt tap was installed between the pipe tee and the ball valve at the top. A threaded fitting was inserted in the 1/8" npt tap to sense the water temperature coming out of the hot and cold mixing valves.
A wire drain rack sits over the wet sink. The surround for the sink is melamine paneling and is sealed to at the edge of the sink to prevent water damage behind the sink. A commercial glassware rack is mounted above the laundry sink. The glassware rack has a catch tray and a drain which is routed into the sink.
The wet sink was built into the existing bedroom closet and shelving was installed above the sink. In addition to room lighting attached to the underside of the shelf, two safe lights are mounted there as well. A much larger safelight is mounted on the wall above the closet opening. Before you ask I did NOT paint the room dark blue, the house came that way when I bought it in 1987!!
Point of Use Hot Water Heater
As the darkroom is in the exact opposite corner of the house from the water heater I decided to add a local hot water heater. George Carlin said it best, "you don't want to buy a hot water heater, you want a cold water HEATER" or something to that effect, so I just bought a "water heater". We had added a POU water heater to the kitchen to reduce the amount of water run down the drain waiting for it to get hot and this actually made a noticeable change in the daily water consumption.
After researching units, I settled on the Bosch Tronic 3000T unit with a 4 gallon tank size. About $200 from Amazon and other sources. Plumbing the unit was pretty simple and straight forward. I split the 3/8 copper line coming from the bathroom on the other side of the wall at the Tee fitting that feeds the wet sink and the laundry sink. The hot water line from the bathroom was fed into the cold water inlet of the water heater and the outlet connected to the the tee fitting that feeds the two sinks.
Once connected I needed to hook the pressure relief valve on the top of the unit to the sink drain. I 3D printed a fitting using PETG and drilled a hole on the top side of the drain pipe going back to the bathroom. Using solvent weld, I attached the fitting to the pipe. Some 3/4" ID heavy duty silicone tubing is used to connect the vent valve to the fitting.
At either sink it only takes 2-3 seconds to get hot water, a huge improvement!