Point-of-use hot water heater ?

To what degree is the output precisely controllable? Can it be dialed to
the correct temp for film washing without any other controls (assuming you
test and find the right position for B/W (68 degrees, 75 degrees, and for
Color (105 ?) degrees). The hot water tank is too far away to be reliable
and at the ready.

I would use a thermostatic valve at the sink. I use 68 degrees F for some
processes, and 75 F for others. You can't dial in any hot water heater to
produce exact temperatures. A valve at the sink will assure the water is at
the correct temperature when it reaches the sink.

I use a Delta brand mixing valve, and its great! after the tmperature
"settles down", it stays very constant. The thermometer dial is accurate.
It really spoils me.


"winddancing" wrote in message
...
To what degree is the output precisely controllable? Can it be dialed to
the correct temp for film washing without any other controls (assuming you
test and find the right position for B/W (68 degrees, 75 degrees, and for
Color (105 ?) degrees). The hot water tank is too far away to be reliable
and at the ready.

This is the first good thing that I have ever heard about mixing valves in
35 years of engineering work. Seriously. So, my question is if you have
ever checked the temperature output against an independent thermometer? If
so, how close was the set point and what temperature variation did you see?
Some data might convince me to reconsider a thermostatic mixing valve. Also,
how long have you been running this Delta valve. My experience to date has
been that the valve seat itself would easily get mineral build-up, even
with soft water. That naturally degraded performance.

I appreciate anything further you can add.

PSsquare


"Pieter Litchfield" wrote in message
...
I would use a thermostatic valve at the sink. I use 68 degrees F for some
processes, and 75 F for others. You can't dial in any hot water heater to
produce exact temperatures. A valve at the sink will assure the water is
at
the correct temperature when it reaches the sink.

I use a Delta brand mixing valve, and its great! after the tmperature
"settles down", it stays very constant. The thermometer dial is accurate.
It really spoils me.


"winddancing" wrote in message
...
To what degree is the output precisely controllable? Can it be dialed
to
the correct temp for film washing without any other controls (assuming
you
test and find the right position for B/W (68 degrees, 75 degrees, and
for
Color (105 ?) degrees). The hot water tank is too far away to be
reliable
and at the ready.

On 31-Jan-2004, "PSsquare" wrote:

This is the first good thing that I have ever heard about mixing valves
in
35 years of engineering work. Seriously. So, my question is if you have
ever checked the temperature output against an independent thermometer?
If
so, how close was the set point and what temperature variation did you
see?
Some data might convince me to reconsider a thermostatic mixing valve.
Also,
how long have you been running this Delta valve. My experience to date
has
been that the valve seat itself would easily get mineral build-up, even
with soft water. That naturally degraded performance.

I have an old thermostatic valve that was attached to a used Calumet sink I
bought. I set it to 72F when I installed it, a year and a half ago, and I
check it every couple of weeks, so far I haven't had to adjust it. I'd say
it's within +/- 1F after a 5 min warm up. Perfect for B&W. I also have a
Hass electronic mixing valve for my color processor, it seems to be spot on
as long as the water is running. My incoming water is softened and filtered.

--
Tom Thackrey
www.creative-light.com
tom (at) creative (dash) light (dot) com
do NOT send email to (it's reserved for spammers)

I have checked my valve against both a dial and a mercury thermometer. Of
course, if you've ever checked dial thermometers in a school group darkroom
for example, no two in a group of twenty in the same tub of water will ever
agree. But both the mercury column and dial thermometer seem to indicate
that once stable, the thermostatic valve is accurate and can hold the
temperature + / - 1 degree which is as much accuracy as I can determine from
the markings on the thermometers.

I added the valve when I built my darkroom three years ago. I have treated
(softened) heavily mineralized water, and so far have experienced no
problems.

These valves come in "low flow" and "high flow" models. For a home setting
with one or two taps, you definitely want a low flow model. If a high flow
model is employed with small volumes of water, it will not be able to
accuractely maintain the temperature in a low flow setting. High flow
valves are used in multi-tap settings like school "gang" darkrooms.

With any of these type of valve, you must allow the system to become and
remain "stable." This means you run the water until the hot water pipe is
hot all the way to the valve, and the room temperature water has been
flushed from the cold line. Then (and only then) will the valve be able to
maintain the temperature you select. Temperature adjustment must be done
slowly so that you don't overshoot - avoid big adjustments and give it time
to "catch up" between adjustments.

Once the valve is stable, it will maintain the temperature very well as long
as there is sufficient flow. If, for example, I just trickle water through
a print washer, it will begin to wander off the exact temperature. However,
if I maintain a flow of 1/2 - 1 gallon per minute, it will do fine.

If you think this kind of valve is suspect, you can always get a manual
mixing valve with a built-in "well" or chamber for a dial thermometer stem,
and do it yourself. But keep an eye on it! You will have to adjust the
manual valve during your session. Trust me, this valve has made my darkroom
life much simpler.

I too have seen a couple of thermostatic valves malfunction badly. One, at
a large well known photography program. In that case, however, it was the
fact that the school's dishwasher used up all the hot water. Of course if
there is no hot water, no amount of adjustment will cause the output water
temperature to rise beyond the termperature of the cold water supply, and
since someone had left the valve in the very "hot" position, when the water
heater finally supplied hot water, the valve happily passed it on. In this
case, it was a water supply and operator error, not a mechanical one. The
valve was, in fact, functioning perfectly althought the result was a
disaster.

The original post I answered was in regard to using a demand heater in a
darkroom. Because the hot water output temperature of a demand heater can
vary quite a bit, I'd suggest using a thermostatic valve with one. I use
mine with a nearby 50 gallon tank electric hot water heater (NOT a demand
heater) with excellent results so far.

"PSsquare" wrote in message
...
This is the first good thing that I have ever heard about mixing valves
in
35 years of engineering work. Seriously. So, my question is if you have
ever checked the temperature output against an independent thermometer?
If
so, how close was the set point and what temperature variation did you
see?
Some data might convince me to reconsider a thermostatic mixing valve.
Also,
how long have you been running this Delta valve. My experience to date
has
been that the valve seat itself would easily get mineral build-up, even
with soft water. That naturally degraded performance.

I appreciate anything further you can add.

PSsquare


"Pieter Litchfield" wrote in message
...
I would use a thermostatic valve at the sink. I use 68 degrees F for
some
processes, and 75 F for others. You can't dial in any hot water heater
to
produce exact temperatures. A valve at the sink will assure the water
is
at
the correct temperature when it reaches the sink.

I use a Delta brand mixing valve, and its great! after the tmperature
"settles down", it stays very constant. The thermometer dial is
accurate.
It really spoils me.


"winddancing" wrote in message
...
To what degree is the output precisely controllable? Can it be dialed
to
the correct temp for film washing without any other controls (assuming
you
test and find the right position for B/W (68 degrees, 75 degrees, and
for
Color (105 ?) degrees). The hot water tank is too far away to be
reliable
and at the ready.

Peiter,

Thanks for the factual reply. Plus/Minus 1 degree F is pretty good for a
non-industrial use like a home darkroom. It makes a lot of sense that you
need a low flow mixing valve for accurate temperature control in these
circumstances. Since the amount of hot water needed is small to adjust
incoming water temp only a few degrees, it would seem practical to set it
up with an on-demand heater right at the point of use. I am going to look
into the Delta mixing valve.

Kind regards,

PSsquare


"Pieter Litchfield" wrote in message
...
I have checked my valve against both a dial and a mercury thermometer. Of
course, if you've ever checked dial thermometers in a school group
darkroom
for example, no two in a group of twenty in the same tub of water will
ever
agree. But both the mercury column and dial thermometer seem to indicate
that once stable, the thermostatic valve is accurate and can hold the
temperature + / - 1 degree which is as much accuracy as I can determine
from
the markings on the thermometers.

I added the valve when I built my darkroom three years ago. I have
treated
(softened) heavily mineralized water, and so far have experienced no
problems.

These valves come in "low flow" and "high flow" models. For a home
setting
with one or two taps, you definitely want a low flow model. If a high
flow
model is employed with small volumes of water, it will not be able to
accuractely maintain the temperature in a low flow setting. High flow
valves are used in multi-tap settings like school "gang" darkrooms.

With any of these type of valve, you must allow the system to become and
remain "stable." This means you run the water until the hot water pipe is
hot all the way to the valve, and the room temperature water has been
flushed from the cold line. Then (and only then) will the valve be able
to
maintain the temperature you select. Temperature adjustment must be done
slowly so that you don't overshoot - avoid big adjustments and give it
time
to "catch up" between adjustments.

Once the valve is stable, it will maintain the temperature very well as
long
as there is sufficient flow. If, for example, I just trickle water
through
a print washer, it will begin to wander off the exact temperature.
However,
if I maintain a flow of 1/2 - 1 gallon per minute, it will do fine.

If you think this kind of valve is suspect, you can always get a manual
mixing valve with a built-in "well" or chamber for a dial thermometer
stem,
and do it yourself. But keep an eye on it! You will have to adjust the
manual valve during your session. Trust me, this valve has made my
darkroom
life much simpler.

I too have seen a couple of thermostatic valves malfunction badly. One,
at
a large well known photography program. In that case, however, it was the
fact that the school's dishwasher used up all the hot water. Of course if
there is no hot water, no amount of adjustment will cause the output water
temperature to rise beyond the termperature of the cold water supply, and
since someone had left the valve in the very "hot" position, when the
water
heater finally supplied hot water, the valve happily passed it on. In
this
case, it was a water supply and operator error, not a mechanical one. The
valve was, in fact, functioning perfectly althought the result was a
disaster.

The original post I answered was in regard to using a demand heater in a
darkroom. Because the hot water output temperature of a demand heater can
vary quite a bit, I'd suggest using a thermostatic valve with one. I use
mine with a nearby 50 gallon tank electric hot water heater (NOT a demand
heater) with excellent results so far.

"PSsquare" wrote in message
...
This is the first good thing that I have ever heard about mixing valves
in
35 years of engineering work. Seriously. So, my question is if you
have
ever checked the temperature output against an independent thermometer?
If
so, how close was the set point and what temperature variation did you
see?
Some data might convince me to reconsider a thermostatic mixing valve.
Also,
how long have you been running this Delta valve. My experience to date
has
been that the valve seat itself would easily get mineral build-up, even
with soft water. That naturally degraded performance.

I appreciate anything further you can add.

PSsquare


"Pieter Litchfield" wrote in message
...
I would use a thermostatic valve at the sink. I use 68 degrees F for
some
processes, and 75 F for others. You can't dial in any hot water
heater
to
produce exact temperatures. A valve at the sink will assure the water
is
at
the correct temperature when it reaches the sink.

I use a Delta brand mixing valve, and its great! after the tmperature
"settles down", it stays very constant. The thermometer dial is
accurate.
It really spoils me.


"winddancing" wrote in message
...
To what degree is the output precisely controllable? Can it be
dialed
to
the correct temp for film washing without any other controls
(assuming
you
test and find the right position for B/W (68 degrees, 75 degrees,
and
for
Color (105 ?) degrees). The hot water tank is too far away to be
reliable
and at the ready.

"winddancing" wrote

To what degree is the output precisely controllable? Can it be dialed to
the correct temp for film washing ...

Is this for a commercial installation? I could'nt justify going to so
much expense just to wash a roll or two of film. Dan

To what degree is the output precisely controllable? Can it be dialed to
the correct temp for film washing without any other controls (assuming you
test and find the right position for B/W (68 degrees, 75 degrees, and for
Color (105 ?) degrees). The hot water tank is too far away to be reliable
and at the ready.

There are point of use ho****er systems available that will meet your needs.
They can be very pricey. I have sold several units to customers who do not have
a close source of hot water. This system uses a instantaneous hot water tank, a
solid state temp control,flowmeter,dial thermometer, 10" stainless filter
housing and a vacuum breaker. All mounted to a polyurethane coated panel. At 1
gallon per minute the heater will raise the temp of the incoming water up to 61
degrees at 240 volts. Example, Incoming water temp at 50F + 41F rise at 1.5
gallons per minute will give maximum temp of 91F. Tolerance is +/-1 degree.

"Dan Quinn" wrote in message
om...
"winddancing" wrote

To what degree is the output precisely controllable? Can it be dialed
to
the correct temp for film washing ...

Is this for a commercial installation? I could'nt justify going to so
much expense just to wash a roll or two of film. Dan

No - the one I wrote about is in my home darkroom. I develop and print a
lot. 200 rolls of film a year is not a lot for a pro, but I am just a
semi-retired amateur. I also think that there's little point in trying to do
your absolute best if your tools are poor - why bother to set out to build a
747 with a Leatherman tool? I knew that I was committed to amateur
photography when I built a basement darkroom. I also knew from a lot of
bathroom darkroom and school "gang" darkroom experiences some of the
features that are important to me. Having filtered water with a stable
temperature was one such item. Yes, the valve is expensive. But I no
longer have to look at the dial thermometer even few seconds or fuss with
baths, tempering with more hot or cold from a bucke, etc. Other "pet
peeves" I've addressed along the way: I have enough safe lights to be able
to see what I am doing, my enlarger (a rebuilt Omega B22 with cold light
head) is securely mounted to the workbench, I have a good digital timer, I
have enough trays of every size I use, I have excellent air flow through the
room. In short I enjoy spending a comfortable 4 hours in a session. It's
worth it to have "good tools" sometimes. Trouble is, however, I can't blame
any crappy results on the darkroom (or the camera either).

If you are developing "a couple of rolls of film", I'd absolutely agree that
a thermostatic valve isn't worth your while. They are expensive. I would
suggest the old bathroom sink and dial thermometer route for that.

When I set up my darkrrom in my new house, I looked around and read various
reviews on mixing valves and went with the Hass unit - it's computer
controlled - sort of a Cadillac for the job, but extremely handy and
consistent. I decided that with all the other variables to watch it was
worth it to me to get this unit and I've been pleased with it.


"LABFIX 2" wrote in message
...

To what degree is the output precisely controllable? Can it be dialed to
the correct temp for film washing without any other controls (assuming
you
test and find the right position for B/W (68 degrees, 75 degrees, and for
Color (105 ?) degrees). The hot water tank is too far away to be
reliable
and at the ready.

There are point of use ho****er systems available that will meet your
needs.
They can be very pricey. I have sold several units to customers who do not
have
a close source of hot water. This system uses a instantaneous hot water
tank, a
solid state temp control,flowmeter,dial thermometer, 10" stainless filter
housing and a vacuum breaker. All mounted to a polyurethane coated panel.
At 1
gallon per minute the heater will raise the temp of the incoming water up
to 61
degrees at 240 volts. Example, Incoming water temp at 50F + 41F rise at
1.5
gallons per minute will give maximum temp of 91F. Tolerance is +/-1
degree.