My standard two lever faucet not cutting it.

[sruddy]

I want to make or purchase a single lever very accurate water adjustment valve assembly with temperature gauge. I need to keep the price down so the gauge can be analog. Give me ideas, or show me what you have done. My issue is that I can't adjust the water temp to 68 degrees. I can get 62 degrees or 100. I may also need to purchase an under the sink on demand heater that will work with a low flow rate. I have a whole house on demand water heater, that requires a certain amount of flow before it turns on.

 

[voceumana]

When I built a darkroom in San Francisco area, I check into temperature regulating valves--turns out the water temperature incoming needed to be 10 degrees colder than the lowest desired regulation temperature for the cold supply and 10 degrees higher on the high side. My ground temperature was about 58 degrees in the winter, so I abandoned the idea of using a regulator.

So depending upon your ground water temperature which will vary with location within California, that may be part of the problem, in addition to the on-demand water heater. You might need to go to a standard water heater of small capacity just for the darkroom.

 

[Luis-F-S]

So depending upon your ground water temperature which will vary with location within California, that may be part of the problem, in addition to the on-demand water heater. You might need to go to a standard water heater of small capacity just for the darkroom.

Yup and an Intellifaucet which will work with low flow and minimal temperature difference between the hot and cold water taps. There's a discussion on this at the LFF. The Intellifaucet works. The other choices kind of work some times. It's your money and time.

 

[mshchem]

How much money do you want to spend? The Intellifaucet is the real deal, you will pay 700 bucks for the valve, plus electrical and plumbing. I have a couple photo thermostatic mixing valves. One I salvaged, the other I bought nos off Ebay.
These valves do a decent job of holding temperature within a degree or so.
The cheapest way is to buy a in line thermometer and a decent faucet. I use mine for washing prints and film

 

[ic-racer]

I use a thermostatic valve designed for a darkroom, but these $20USD units might also work. They go from 20C to 50C.

 

[bdial]

My house water heater is a tankless too, I have a 2.5 gallon under-sink water heater for the darkroom, it’s plumbed on the hot water line, so it can replenish from the main water heater when I’m using a lot of water. For low-flow situations like film or print washing it does fine for providing just enough hot water. This has worked out quite well.
A single-handle faucet will be easier to work with for temperature control and is the cheapest option. You can probably pick up an analogue control rig on eBay, for reasonable money. A pressure compensated shower mixing valve would work if you want to cobble up a DIY solution that’s cheaper than a photo/lab specific controller. Intellifaucets are great, but very dear to buy new. I lucked into one on Craigslist.

 

[Arklatexian]

I want to make or purchase a single lever very accurate water adjustment valve assembly with temperature gauge. I need to keep the price down so the gauge can be analog. Give me ideas, or show me what you have done. My issue is that I can't adjust the water temp to 68 degrees. I can get 62 degrees or 100. I may also need to purchase an under the sink on demand heater that will work with a low flow rate. I have a whole house on demand water heater, that requires a certain amount of flow before it turns on.

In my darkroom, I have a 5 gallon, electric hot water heater with a filtered, cold water feed line. Hot water from this, I mix with cold water to get 68 F, In August and most of September, the cold water is considerably warmer than 68 F, sometimes reaching 90 F. That is when I have problems. The 5 gal. water heater is not expensive, once the wiring is done and last a long time especially if you turn the power off when the heater is not needed. You could mix the hot water from the 5 gal. water heater with your 62 F water to make 68 F...............Regards!

 

[adelorenzo]

You can buy a thermostatic mixing valve for about $100 from a plumbing supply place. Mine is a Honeywell. Pay close attention to the specs as they have different temperature ranges and plumbing fittings. If you want a temperature gauge you can add one in for a few more bucks.

 

[mgb74]

There are a number of inexpensive solutions IF you input water temps are constant and IF the input water pressures are constant. It when those attributes (temp and pressure) vary while the mix valve is in use that you require more sophisticated options.

Are you on city water or a well? If city water, your cold water temp should be fairly constant in any given darkroom session (but might change with the seasons). If on a well, your water temp may vary within a session depending on depth of well and size of your pressure tank.

How long can you run your hot water before the water temp drops? Is your on-demand water heater gas or electric? If using a on-demand water heater that is not underpowered, you should be fine. But electric on-demand water heaters aren't as responsive. And if there are other concurrent demands for hot water, you'll have more variability.

Are there other water loads on the same water line (from water heater) as your darkroom? If so, intermittent uses on that water line (like flushing a toilet) might create a change in water pressure that your mixing valve might need to compensate for.

So what works for one person might not work for you.

 

[Mainecoonmaniac]

One way is to get the water up to temp and put it in an insulated cooler. You can get stable temperatures 5 gallons at a time.
https://www.walmart.com/ip/Igloo-5-...90vOQbGBTIyYERCTnatVaVaI6QEOUU_UaApihEALw_wcB

 

[Marco Buonocore]

I agree with others above that a thermostatic valve can do the trick very well. I use a Watts brand LFL1170M2 - it's designed to work for temps between 60F and 120F, It also will function when using a relatively low flow rate, say 2.5/L per minute. Other thermostatic valves are designed for much higher temps or much higher flow rates - they just won't mix properly at lower flow rates. I have an inline thermometer to keep an eye on the temp. You can swap out the plastic handle for something more useful, and you get good control of temperatures.

For the most part, it stays at 68F or thereabouts. It does a good job of mixing the water to keep it within an acceptable range. I've used a Hass valve, and it does an excellent job, but I just couldn't justify the price. I also have separate hot and cold taps for other tasks in the darkroom. The thermostatic valve is mostly for the print washer.

I have the hot water supply in my darkroom from a EcoSmart Eco 11 tankless heater. So far so good. It's quiet and seems to play nice with the thermostatic valve. The only downside to it is that it needs a 60amp breaker and used a big fat 6AWG wire.

 

[Luckless]

When deciding on a solution to this kind of problem an important question is going to be "How much water do you need at specifically controlled temperature?"

If you're only ever needing a few gallons at a time that is used over relatively short periods, then a holding and tempering tank may be the most reliable and accurate solution with fewer points of failure:

Fill a local holding tank with water roughly to the temperature you're aiming for. Use an accurate submersion heater of some kind to raise to and maintain final hold temperature, use the water as needed, and then only refill and re-establish your working temp between uses.

Main reason why I prefer a holding tank style solution for processes like this wherever practical: If all the water temps are preset, and tank is reasonably well insulated, then you remove the risk of your mixing valve failing mid-run and introducing a sudden and excessive temp swing. You might get a slight drift by a degree or two, but with a properly isolated tank you can't have your water suddenly switch to your hot water tank temp in the middle of a batch...

 

[sruddy]

.Wow! thanks for all the replies! I wasn't expecting this much info. Here is the info I should have included in my original post. My water heater is continuous, so we never run out of hot water. The water heater needs a flow rate of .40 gpm to turn on. I have well water with the pressure set to 50 psi. Before I replace the hard to adjust faucet I'm going to determine the minimum flow I can get away with and see if that flow will work for my Nova Academy Print washer. If not I'll need to come up with a heating source that doesn't have a minimum flow requirement and go from there. I am remodeling in the spring so maybe then I'll upgrade the system.

 

[sruddy]

You can buy a thermostatic mixing valve for about $100 from a plumbing supply place. Mine is a Honeywell. Pay close attention to the specs as they have different temperature ranges and plumbing fittings. If you want a temperature gauge you can add one in for a few more bucks.

Nice Thanks

 

[bdial]

.Wow! thanks for all the replies! I wasn't expecting this much info. Here is the info I should have included in my original post. My water heater is continuous, so we never run out of hot water. The water heater needs a flow rate of .40 gpm to turn on. I have well water with the pressure set to 50 psi. Before I replace the hard to adjust faucet I'm going to determine the minimum flow I can get away with and see if that flow will work for my Nova Academy Print washer. If not I'll need to come up with a heating source that doesn't have a minimum flow requirement and go from there. I am remodeling in the spring so maybe then I'll upgrade the system.

Based on my experience with a demand water heater, it will not come on at the flow rates you typically use for washing. Mine needs .5 gal/minute minimum. I am on a well, so my cold water is quite cold even in the summer, so I always need some hot water in the mix. I use a small under-sink tank water heater in my darkroom for hot water. For things like print or film washing, its recovery rate is sufficient that it doesn't run out. It's plumbed on the hot line for the house, so for high flow situations like setting up a water bath or just washing up, I draw enough that the household water heater comes on and replenishes the under-sink unit.

 

[Kilgallb]

Based on the water rate I pay, the sous vide device I use to keep just 9 litres of water at 104 has paid for itself.

 

[sruddy]

I wanted a panel like one made by Delta, but I didn’t want to spend $1000 for it. I did some research on the parts used and made my own built with the same valve and filters at a fraction of the price. I cover it here:

Are the filters necessary? Maybe not easy to answer without knowing the specific waters content, but wondering what minerals will affect the print. I use reverse deionized water with no TDS showing after filtering. The filter produces very slow rate so I only use it for my chemical mixing.

 

[markbau]

I had an Intellifaucet when I lived in the US, one of the best purchases I ever made. I've been looking into a thermostatic valve here in Australia, none of them are suitable as their lowest temp is usually 35C. I've decided to get another Intellifaucet, they are so well made and perfect for a darkroom, also, their customer service is second to none!
Regarding filters, I've lived in places where I absolutely needed filters and I've lived in places where they were totally unnecessary so it really depends on your local water conditions.

 

[John51]

The easiest way to get 68 degree water is to put it into plastic jugs and keep it in a 68 degree room for a day or so. That's what I do. I have 2L milk jugs filled with tap water and wash the film with 10 changes of water over a period of a few hours. After processing, I refill the jugs and they'll be ready for the next time. If the room temp is above 68 degrees, I refer to the time/temperature chart. Can't fault that chart so far.

If it has to be flowing water, the biggest problems will be changing water pressure on the incoming and excessive hysteresis in the thermostat. Temps of the incoming water will change with the seasons but should be negligible during a session.

One way of stabilising the water pressure is to use a header tank and float valve. Small scale would be a 1/4" float valve from aquarium supplies. Large scale would be the ballcock used in most toilets. Constant head of water = constant water pressure.

Almost anything can be used for a water heater as long as it can go a bit warmer than you need.

Inkbird has a good rep for solid state thermostats. Set and forget. If you want to go to the nth, have a 2nd heater and Inkbird stabilising the temps in the header tank.

 

[Mal Paso]

I have an Inkbird controller and for a few dollars more Auber has a better product with better documentation. Auber also has customer support who helped me custom program their PID controller for a large gas fired water bath. The controllers I'm speaking of are Thermocouple Based and can learn the heat cycles to very accurately control temperature for less than $100 for controller/thermocouple/solid state relay.

I am setting the darkroom up again from scratch and am reading this thread with interest. I used to have a bunch of equipment including a Kreonite water chiller but all that stuff would be 30+ years old now. Lots has changed.

I have worked on demand water heaters from the early Paloma to the electronic Paloma/Rinnai and when I bought a new water heater it was a conventional tank. Thinking I might be alone in my convictions I asked a Master Plumber who does most of the high end hydronics here about demand water heaters. "You spend too much money, to spend too much money" "Too much to buy them, too much for service" He has a tank water heater too.

 

[sruddy]

I comnpleted an assembly and it's not working. I get better control with my crappy faucet. I either got a bad valve or the valve won't work with my heater. I could have missed some valuble info here but I played with it for an hour and could never get a stable temp no matter the flow rate. I'm assuming it's a bad valve. It was purchased used. The other issue is getting the assembly water tight. The flow meter seems to have same thereafs but no matter how much tape I use it doesn't seal. It was listed as 1/2" female thread but doessn't say pipe thread.

 

[mgb74]

1. It may be a bad valve, but maybe it doesn't operate at the temp range you require. These are typically used for water heaters. Some don't work lower that 90 deg F. Others go down to 70 deg. But none are intended to work with the precision you would expect for darkroom use. Doesn't mean you won't get lucky and find one that does, but you can't depend on it. It may have worked for others but it's still the wrong tool for the job.
   
2. I recently replaced the one on my water heater because it was no longer reliable. I would have to be without water for too long to take it apart and clean it (and I didn't want to hassle with redoing pipes on an interim basis). I threw the old one out. But I suppose I could have sold it as used. At a minimum, take your used one apart and clean it.
   
3. I assume you run the water for a while (to stabilize hot and cold input) before you try to set it. And I assume you run the water at a high enough flow rate to actuate your on-demand water heater. What is the temp of your cold water input?
   
4. Someone may have buggered up the plastic threads on the flowmeter. Try using pipe dope AND thread tape. Shouldn't need to use both but sometimes helps.
5. I'm not sure why you have the flowmeter. But if it's to make sure the flow is high enough to actuate the water heater, it needs to be placed on the hot water input, not the mixed water output. If your cold water is 60 deg, the amount of hot water to reach 68 deg may be very little. The valve will open further on the hot side to allow hot water in, then the heater kicks in and now the water is too hot. The valve now closes on the hot side, the water heater turns off, and water is too cold.

 

[sruddy]

1. It may be a bad valve, but maybe it doesn't operate at the temp range you require. These are typically used for water heaters. Some don't work lower that 90 deg F. Others go down to 70 deg. But none are intended to work with the precision you would expect for darkroom use. Doesn't mean you won't get lucky and find one that does, but you can't depend on it. It may have worked for others but it's still the wrong tool for the job.
   
2. I recently replaced the one on my water heater because it was no longer reliable. I would have to be without water for too long to take it apart and clean it (and I didn't want to hassle with redoing pipes on an interim basis). I threw the old one out. But I suppose I could have sold it as used. At a minimum, take your used one apart and clean it.
   
3. I assume you run the water for a while (to stabilize hot and cold input) before you try to set it. And I assume you run the water at a high enough flow rate to actuate your on-demand water heater. What is the temp of your cold water input?
   
4. Someone may have buggered up the plastic threads on the flowmeter. Try using pipe dope AND thread tape. Shouldn't need to use both but sometimes helps.
5. I'm not sure why you have the flowmeter. But if it's to make sure the flow is high enough to actuate the water heater, it needs to be placed on the hot water input, not the mixed water output. If your cold water is 60 deg, the amount of hot water to reach 68 deg may be very little. The valve will open further on the hot side to allow hot water in, then the heater kicks in and now the water is too hot. The valve now closes on the hot side, the water heater turns off, and water is too cold.

Thanks for the reply. This is the Leonard 270 and specs are:

• PRESSURE-TEMPERATURE: 5-1/2" 140mm H C
•  Minimum Flow: 0.25 GPM (0.95 l/Min)*  Maximum Pressure: 125 PSI (8.6 BAR)
•  Maximum Hot Water temperature: 200F- (93°C)
•  Approach Temperature 5°F (2.8°C) above set point.
•  Temperature adjustment range, 90-140ºF (32-60ºC) **

So maybe it's the wrong valve for my needs. The water heater I have needs a min.4 gpm flow to operate which is within the valves specs but I see temperature range of the mixing valve is 90-140 degrees and I'm trying to get 68 degrees. I dont think that will ever work! I dont know how delta is selling this valve in their dark room mixer assembly. Something could be going over my head though! My cold water is from a well, and is around 51, and gets about 5 degrees warmer in summer.
Theads are are in good shape, but they aren't pipe threads with a taper. The thread count is the same but no taper. I may try an o-ring seat or hose gasket.
The flow meter was for me to know how low I can run the water. I see what your saying about it being in the wrong path but I did run the water way faster than I normally do when running 68 water using just my faucet.

 

[Deleted member 88956]

Since standard pipe thread in USA in tapered type, what are the chances flow meter came from outside US and has parallel pipe thread? This is esy to see just by looking at its side profile (or put calipers to bottom and top part of the thread to see if they differ or are the same. Parallel thread is very hard to make tight without old school approach or special compound (teflon tape won't cut it, not long term anyways) Just a thought of possible mismatch..

 

[mgb74]

Thanks for the reply. This is the Leonard 270 and specs are:

• PRESSURE-TEMPERATURE: 5-1/2" 140mm H C
•  Minimum Flow: 0.25 GPM (0.95 l/Min)*  Maximum Pressure: 125 PSI (8.6 BAR)
•  Maximum Hot Water temperature: 200F- (93°C)
•  Approach Temperature 5°F (2.8°C) above set point.
•  Temperature adjustment range, 90-140ºF (32-60ºC) **

So maybe it's the wrong valve for my needs. The water heater I have needs a min.4 gpm flow to operate which is within the valves specs but I see temperature range of the mixing valve is 90-140 degrees and I'm trying to get 68 degrees. I dont think that will ever work! I dont know how delta is selling this valve in their dark room mixer assembly. Something could be going over my head though! My cold water is from a well, and is around 51, and gets about 5 degrees warmer in summer.
Theads are are in good shape, but they aren't pipe threads with a taper. The thread count is the same but no taper. I may try an o-ring seat or hose gasket.
The flow meter was for me to know how low I can run the water. I see what your saying about it being in the wrong path but I did run the water way faster than I normally do when running 68 water using just my faucet.

If your valve operates at 90-140, you have your answer as to why it's not working for you. If it's the same one delta uses, it's probably accurate enough. BUT - it's also probably used for E6 and C41 processing which uses 100 deg (IIRC).