Laying up chilled water coils
Blaine Mayo
are trying to get away from using glycol in our chilled water sytsem and use
water with a corrosion inhibitor. We are worried about freezing the coils in
the winter time. If you drain coils some water still remains in tubes. We
were going to either pump compressed air from our plant through the coils a
few times a day or connect a duct from the air handler to the coil and force
air through the coil. Please note that the compressed air is using a desicant
air dryer to drop the dew point of air to -40. Please comment to myself via
email or newsgroup. Thanks.
Stuart Mcneil
all at the same time PROPYLENE(non toxic) Pump it in drain then you are
all set for turning on in the spring. One thing you must do is input at
the top of the coil or you may get some pockets of water!
The company in Mass is Houghton Chemical..
Stuart..
Blaine Mayo (ma...@unb.ca) wrote:
: Has anybody had experience with laying up chilled water coils in winter? We
Larry Mackey
>
>Has anybody had experience with laying up chilled water coils in winter?
We
>are trying to get away from using glycol in our chilled water sytsem and
use
>water with a corrosion inhibitor. We are worried about freezing the
coils in
>the winter time. If you drain coils some water still remains in tubes.
We
>were going to either pump compressed air from our plant through the
coils a
>few times a day or connect a duct from the air handler to the coil and
force
>air through the coil. Please note that the compressed air is using a
desicant
>air dryer to drop the dew point of air to -40. Please comment to myself
via
>email or newsgroup. Thanks.
This may be a dumb idea, but what about pulling (and maintaining) a
vacuum on the coil? Any residual water would "boil" off and the
remainding vapor which might form ice I would expect would not impact the
tubing?
Just a thought:-)
-------------------------------------
Name: Larry Mackey
E-mail: lamackey
Date: 04/24/95
Time: 21:21:11
This message was sent by Chameleon
-------------------------------------
Joseph Benning
Requires: Glycol (choose your flavor), positive displacement pump,
sufficient hoses, recovery drums, hose bibs, a specific gravity reading
device, and immagination with thought for a valve system arrangement.
1. Isolate the CHW coil.
2. Drain the CHW medium.
3. Fill and flush the coil with fresh water.
4. Drain again.
5. Now, fill the coil with a 50/50 mixture of glycol/water.
6. When the drain off from the vent line equals a 50/50 mixture, (recover
this weak product too) drain off the coils.
7. Next spring, recover the remaining glycol from the vent line, as you
refill with water. Don't dump the glycol down the drains. It's wasteful
and an EPA violation too.
Any remaining liquid in the coil is freeze protected. Always test
the fan freeze stats. Plus, clean and lubricate the OA dampers too.
: This may be a dumb idea, but what about pulling (and maintaining) a
: vacuum on the coil? Any residual water would "boil" off and the
: remainding vapor which might form ice I would expect would not impact the
: tubing?
1. This probably requires many hours. Time is money.
2. CHW coils are designed to hold water under pressure. Pulling a vacuum
might be a costly experiment.
A friendly tip from your Engineering Brothers of Local 399, Chicago.
Be wise: Unionize!
Joseph Benning
Dave Munro
>
>This may be a dumb idea, but what about pulling (and maintaining) a
>vacuum on the coil? Any residual water would "boil" off and the
>remainding vapor which might form ice I would expect would not impact the
>tubing?
>
>-------------------------------------
>Name: Larry Mackey
>E-mail: lamackey
>Date: 04/24/95
>Time: 21:21:11
>This message was sent by Chameleon
>-------------------------------------
Your idea of pulling a vacuum on the coil is good for removing the water.
An alternate to maintaining a vacuum would be to pressurize the coil with nitrogen
or other dry gas; maintenance personnel could routinely check the pressure (note the
pressure will vary with air temperature), and refill as needed...
Using vacuum pumps would be easier and more economical than using glycol.
Dave Munro
Allenbau
Glycol. Unless your system is living totally at the edge of its capacity
You'll be able to run with Dowtherm and not see any difference - except it
lasts 20 years to Glycol's three and it is easier on your chilled water
pump.
Been there - done that - case solved - went on to other stuff.
Don't know who sells Dowtherm - haven't had to buy any for years.
Have fun - Mike A.
Opinions are entirely my own and most other sane people !!
Joseph Benning
: Your idea of pulling a vacuum on the coil is good for removing the water.
: An alternate to maintaining a vacuum would be to pressurize the coil with nitrogen
: or other dry gas; maintenance personnel could routinely check the pressure (note the
: pressure will vary with air temperature), and refill as needed...
: Using vacuum pumps would be easier and more economical than using glycol.
: Dave Munro
Dave, I'm curious. Have you performed either evolution, or is this just a
hypothetical opinion?
Joseph Benning
--
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Joseph A. Benning / \:/ \ Chicago, Illinois, USA 60625
/ [ ] \
"I've seen it before Joe.../ /{x.x}\ \...You're an Internet junkie;
Roadkill, on the / U \ Information Super Highway!"
Joseph Benning
: After all else fails (and I expect it will) use Dowtherm instead of
Mike, this is interesting. Sounds like the story a former building
manager I worked for was saying the year before he was fired. A 5% loss
of efficiency in a large property is BIG BUCK$. Winter layup of coils
requires far less Dowtherm (glycol) than filling the entire system.
I believe the three year estimated lifespan is for non-tested, internal
combustion service.
Allenbau
Benning) writes:
>
>Mike, this is interesting. Sounds like the story a former building
>manager I worked for was saying the year before he was fired. A 5% loss
>of efficiency in a large property is BIG BUCK$. Winter layup of coils
>requires far less Dowtherm (glycol) than filling the entire system.
>I believe the three year estimated lifespan is for non-tested, internal
>combustion service.
Touche,
I believe the Dowtherm is not glycol and does cause much less of an
efficiency loss than glycol. Once we brought the system up to its
capability, we had cooling to spare so we were more concerned about being
able to run year round rather than shutting down and going to outside air
(with all its problems).
Building owners were happy, occupants were VERY happy that we were able to
supply year 'round conditioned air and the comptroller was quite pleased
that his net cost for HVAC went down substantially.
I was not fired as per your example but I did get a $3,000.00 performance
bonus.
I wouldn't begin to presume that this is the answer for all buildings - it
just worked for us.
Mike A.
Dave Munro
direct experience.
Vacuum is used to evacuate air and moisture from refrigeration systems. Similarly,
vacuum is used to remove air and moisture in industrial processes used by the
electronics industry to manufacture integrated circuits.
Nitrogen is used to fill dry type fire protection systems serving refrigerated
portions of warehouses maintained at temperatures of -20F, approx. For the
suggested application, the chilled water coil could be brought down to the
appropriate vacuum level, and pressurized with with nitrogen, so the vacuum pump
could be disconnected. I would suggest an 'appropriate vacuum level' corresponding
to the vapor pressure of condensed water found in a thermodynamic properties table
at a temperature 20 degrees less than the anticipated low outdoor temperature.
I remember a project, that I did not work on, in which coils were shipped to a
project in eastern Montana. The coils were stored outdoors, the water had not been
drained from the coils at the factory or the jobsite. The water froze and burst some
of the tubes. I heard that it is common practice for coil manufacturers to blow the
water out using compressed air to avoid similar instances from occurring.
You might try discussing the issue with your favorite coil manufacturer(s) to
discuss their recommendations for protecting coils prior to installation as well as
winterizing existing coils.
If I get a chance I will contact a local coil manufacturer as well.
Jim Storm
>
>lama...@pop3.interramp.com (Larry Mackey) wrote:
>>
>>This may be a dumb idea, but what about pulling (and maintaining) a
>>vacuum on the coil? Any residual water would "boil" off and the
>>remainding vapor which might form ice I would expect would not impact
the
>>tubing?
>>
>>Just a thought:-)
>>-------------------------------------
>>Name: Larry Mackey
>>E-mail: lamackey
>>Date: 04/24/95
>>Time: 21:21:11
>>This message was sent by Chameleon
>>-------------------------------------
>
water.
>
>An alternate to maintaining a vacuum would be to pressurize the coil
with nitrogen
>or other dry gas; maintenance personnel could routinely check the
pressure (note the
>pressure will vary with air temperature), and refill as needed...
>
>Using vacuum pumps would be easier and more economical than using
glycol.
>
>Dave Munro
for removing water..It won't.. It is made to remove vapor only and would
need to convert water to vapor first. Could take a real long time. As a
little show i hook up a test tube to my pump. It boils quickly for a
short time and then just sits there. Sometimes with the right amount in
the tube I can even freeze it solid.
Stormy
Dave Munro
damage a rotary vane type vacuum pump. The coil should be drained down, and maybe
blown out with compressed air before hooking-up a vacuum pump. The connection detail
used should eliminate any chance of sucking a slug of liquid into the vacuum pump.
Yes, if you vaporize the water quick enough you can freeze the remaining water.
Joseph Benning
response posted in the thread, I'll share it with everyone.
Allenbau (alle...@aol.com) wrote:
: In article <407ed6$2...@news.ecn.bgu.edu>, ujbe...@uxa.ecn.bgu.edu (Joseph
: Benning) writes:
: >Mike, this is interesting. Sounds like the story a former building
: >manager I worked for was saying the year before he was fired. A 5% loss
: >of efficiency in a large property is BIG BUCK$. Winter layup of coils
: >requires far less Dowtherm (glycol) than filling the entire system.
: >I believe the three year estimated lifespan is for non-tested, internal
: >combustion service.
: Touche,
: I believe the Dowtherm is not glycol and does cause much less of an
: efficiency loss than glycol.
Isn't Dowtherm "propelyene" glycol, what does the MSDS report? A
glycol/water mixture doesn't freeze because of its ability to resist
heat transfer. This is where chiller efficiency is lost.
: Once we brought the system up to its
: capability, we had cooling to spare so we were more concerned about being
: able to run year round rather than shutting down and going to outside air
: (with all its problems).
On one hand, I should have asked first, where is this property located?
In Chicagoland, chilled water coils require maximum protection. If this
property was in let's say Texas, simply circulating the water would prevent
coil freeze-up, without glycol. On the other hand, if your building cooling
system is oversized, this is the exception, not the rule. For buildings
constructed during the seventies and eighties, DOE energy saving guidelines
suggested an indoor design of 78 degrees. Needless to say, occupants like
it cooler. Oversizing cooling systems increases the overhead, reducing the
building owner's profit margin.
Next, what problems? Shutting down mechanical cooling when outdoor air
enthalpy permits saves the owner money. It sort of justifys an operator's
job the way I see it.
: Building owners were happy, occupants were VERY happy that we were able to
: supply year 'round conditioned air and the comptroller was quite pleased
: that his net cost for HVAC went down substantially.
What did I miss? Where are the savings? I see:
Increased expense from unnecessary glycol.
Increased operating expense from an earlier daily startup, compensating
for the loss of efficiency.
Increased operating expense from lost on-line efficiency.
Increased expense from operating mechanical refrigeration, when outdoor
air enthalpy permits "free" cooling of building space.
: I was not fired as per your example but I did get a $3,000.00 performance
: bonus.
Can I work for this guy? :)
: I wouldn't begin to presume that this is the answer for all buildings - it
: just worked for us.
Please describe the occupancy, general location, approximate square footage
and tons of cooling capacity available, for a clear picture. I'm not from
Missori, but "show me," and others using the newsgoup.
Allenbau
Benning) writes:
>Subject: Re: Laying up chilled water coils
>From: ujbe...@uxa.ecn.bgu.edu (Joseph Benning)
>Date: 10 Aug 1995 18:58:39 GMT
>
>Mike and I discussed this by e-mail, however, since I found the
>response posted in the thread, I'll share it with everyone.
>
>
>Isn't Dowtherm "propelyene" glycol, what does the MSDS report? A
>glycol/water mixture doesn't freeze because of its ability to resist
>heat transfer. This is where chiller efficiency is lost.
>
Ahh - you have me there - didn't look at the MSDS - the product was sold
because of longer life in the system and lower viscosity than ethylene
glycol preventing undue added load on the circulating pumps. As the
situation developed, we would have used ethylene glycol or anything at
hand since their previous annual shutdowns had been described to us as
"disastrous" and not to be repeated. - Mike>
: Once we brought the system up to its
>: capability, we had cooling to spare so we were more concerned about
being
>: able to run year round rather than shutting down and going to outside
air
>: (with all its problems).
>
>On one hand, I should have asked first, where is this property located?
Middle Iowa - probably milder than Chicago but not enough to be
significant in this case. - Mike
>In Chicagoland, chilled water coils require maximum protection. If this
>property was in let's say Texas, simply circulating the water would
prevent
>coil freeze-up, without glycol. On the other hand, if your building
cooling
>system is oversized, this is the exception, not the rule. For buildings
>constructed during the seventies and eighties, DOE energy saving
guidelines
>suggested an indoor design of 78 degrees. Needless to say, occupants like
>it cooler. Oversizing cooling systems increases the overhead, reducing
the
>building owner's profit margin.
Not your typical building - it is a medical laboratory, surgical hospital,
clinic and administration building - each area reasonably well separated
and not too hard to zone. Lab did, however, require 100% outside air -
Mike
>
>Next, what problems? Shutting down mechanical cooling when outdoor air
>enthalpy permits saves the owner money. It sort of justifys an operator's
>job the way I see it.
>
Problem was "when to shut down for winter". Heat load and enthalpy
requirements caused them to typically require some air conditioning until
outside ambient was down to ten degrees above zero. Early in the process
they were running an 80 ton chiller with an outside ambient of zero
degrees. (I saw it run) - Mike
>: Building owners were happy, occupants were VERY happy that we were able
to
>: supply year 'round conditioned air and the comptroller was quite
pleased
>: that his net cost for HVAC went down substantially.
>
>What did I miss? Where are the savings? I see:
>
>Increased expense from unnecessary glycol.
Absolutely true - Mike
>Increased operating expense from an earlier daily startup, compensating
>for the loss of efficiency.
No daily startup - ran the system 24 hours because the complex was running
24 hours and if late night surgery occured (often) the entire surgical
wing had to be ready in an instant. Two wings did operate on standby a lot
of the time but demand could be instant so we could not allow for "run up"
time.
>Increased operating expense from lost on-line efficiency.
?? - Mike
>Increased expense from operating mechanical refrigeration, when outdoor
>air enthalpy permits "free" cooling of building space.
>
We "dreamed" of all that cool air out there and available - the building
was already built and IAQ was not a big issue at time of erection. Add to
that the fact that the complex just "grew". Would have been a lot
different if it had been built all at once. There are areas in the
building where it is simply not possible to bring additional outside air -
if cooling was needed in an area they
Allenbau
Cooling in central areas of the building had been accomplished by hanging
an air handler and running water pipe. No outside air ducted in other than
through the hallways. Building heat load required cooling at anything
below 30 degrees - it gets above 30 degrees fairly regularly here and in
Chicago year round.
Used our infra red heat sensors to locate a pretty good number of leaking
steam traps that , when repaired, allowed us to discontinue use of one
boiler. This is HEAT/vent/ac, remember? We do heating too.
I addressed the issue of laying up a chiller coil in my earlier response -
there was more to the job I was referring to than the chiller.
During previous annual shutdowns the plant supervisor said he pumped hot
air from the boiler room slowly through the system all winter. Said he
felt that he was not adding or subtracting heat to/from the building and
had never cracked a coil. I believe he never cracked a coil but I don't
know about the other.
We took the contract at a (hopefully) break-even price plus a percentage
of the following year's decrease (if any) in HEAT/vent/ac cost - thus the
performance bonus.
I don't know if I've answered all your questions - if not, ask away - Mike
A.
Allenbau
We used infra-red sensors to locate quite a number of leaking steam traps
which , when repaired, brought down the HEAT cost.
We balanced the system, added economizers as possible, made existing
economizers work properly, all the normal stuff. Possibly our best gain
was the lowering of HEAT cost since the boilers ran a lot lighter.
Contract was about break-even plus percentage of HEAT/vent/ac net cost
reduction.
My post was about laying up chiller coils, not the entire job.
Since this response is chopped into two messages, I may not have covered
all your questions - if not, please re-post.
Thanx
Mike A.
Robert Eden
From the MSDS (#002952) section 2:
** PERCENTAGES **
HIGH % LOW %
ETHYLENE GLYCOL >90%
DIETHYLENE GLYCOL < 5%
DIPOTASSIUM PHOSPHATE > 5%
WATER < 5%
--
-------------------------------------------------------------------------
Robert Eden 817-897-0491 Glen Rose, TX
Comanche Peak Steam Electric Station rob...@cpvax.cpses.tu.com
^^^^^^^^^^^^^^^^^^^^^ politicese for a nuke plant
-------------------------------------------------------------------------