Fixer remover (available under different names/brands) is easy and cheap to buy and saves a lot of water. I mix it myself with a little sodium sulfite and a pinch of sodium bisulfite. Costs me about a penny for a gallon. Running water is really not needed and sometimes unavailable -- just a final clean rinse. Cold water works fine. To avoid reticulation just make sure the temperature change is not too dramatic from one liquid to the next.
I can all too clearly recall the first time I tried to set up my brand new Calumet fully plumbed darkroom sink---and discovered that the mixing valve was not designed to work at less than about 5 gallons per minute. That's a lot of water, and the valve wouldn't stabilize for at least half a minute after turning it on. Since I really wanted water for mixing one-shot developer and filling tempering baths, I have been using a big tank, thermometer and stirring stick for the last twenty years or so.
I have finally bought (but not yet installed) a Hass valve, and a 1200 watt 240-volt element for a small water heater. This will draw only about 300 watts on 120 volts, so the wiring should handle it easily, and the "reserve" of twenty gallons should temper more than enough hot water for a developing session. Over the years I have schemed a number of setups using a small chiller, small water heater and recirculating pumps so that eventually I can have year-round tempered water (the water comes out of the well at 71 F but for this winter I will still count on below-68 F water incoming).
It is important to remember that tank-type water heaters are designed for acceptable "recovery rate" after withdrawal (requiring a lot of power) , and tankless heaters have to have enough power for "instantaneous" recovery, but darkroom usage can typically tolerate a long recovery time, and the working temperature is usually much closer to supply temperature than the 145--150 F that a water heater is designed for.
A little stored hot water can go a long way. With inlet water at 50 F, 4.5 gallons of cold and 1 gallon of hot should give you 5.5 gallons of 68 F water. A "dispenser" type water heater rated at 750 watts would allow around 25 gallons per hour with 50 F inlet; you could even wash paper with that.
I've seen very small inline aquarium heaters that may do the job for very small flow and small temperature rise--you won't need to heat all that much for darkroom use, so maybe one of those would be a good starting point. they are pretty cheap and require no heavy duty wiring either as the wattage requirements are much lower than the higher flow a shower would need.
I think you may have hit the nail on the head Harold_4074........my mixing valve is old-school and does seem to be reliant on a (relatively) high flow of around 5 gallons per minute (obviously controllable), but difficult to stabilise at lower flow-rates.
At this time of year, the incoming mains water is around 4-5 deg C (37-39 Deg F) so expecting a heater to raise the temperature by 15-16 deg may be asking too much.
I have one of the "point of demand" heaters as mentioned by Paul, but of course, once the reserve is gone, then the demands on the heater are too much, especially when you need to run 5 gallons per minute to get a stable wash temp.....the heater has no chance.
I'm still tempted to install an in-line electric shower, and rely of the inbuilt thermostat to control the temperature (within limits).
Add a small tank heater between the tankless heater and the mixing valve. The tank heater provides instant heated water and acts as a buffer for water coming in at erratic temperature. The tankless heater provides sustained heated water.Originally Posted by mpirie
A 10 gallon water heater with an Intellifaucet K250 control valve. If you're concerned about tank capacity, get a 15 gallon. Between the heater and a 32 gph chiller, I can get 68 deg water year round. Some of us do wash with continuous flow. I had a post on the installation under:
http://www.largeformatphotography.in...=intellifaucet
L
Don't forget the 2 filters. One hot and one cold. Hass recommends them.
An endless supply of fresh water is not an issue in my part of the world
Has anyone mentioned that your darkroom might be close enough to your central hot water heater to simply tap into it? And if you are concerned about the copper pipe leaking heat, wrap it in insulation. That would be a heck of a lot more cost-effective than installing a supplementary water heater.
.
It is an option Jac.
I plumbed in the cold water supply from the house mains, so i could do the same with the hot supply.
Distance is only some 22m from the house to the darkroom.
Mike
Posting Permissions
Reply With Quote
Bookmarks