HELP: Heat pump high pressures in heat mode.
Wesley Fisher
Sonofdawra
>Pressures in heating mode: 75/450 (just before overpressure trip)
>
>
What are your indoor and outdoor conditions when you are reading these
pressures? Pressures by themselves are not worth much. What is the temp drop
through the indoor coil on cooling and the temp rise throught the indoor coil
when in the heating mode?
Parts changing? :o(
John Mills
>
> 10-yr-old Climate Control (made by Snyder Corp.) 3 ton single package
> heat pump.
>
> Initial problem was leaking R-22 at rusted-through accumulator.
> Replaced accumulator and after recharging normally in cooling mode,
> trips out in heat mode on overpressure. Rechecked accumulator
> connections (inlet from reversing valve - outlet to compressor
> suction). Replaced (in order): reversing valve, heat cap tube
> strainer (tube not clogged), check valve (valve was found to be open -
> spring to hold ball against seat nowhere to be seen - but should have
> caused lower discharge pressure in heat mode, not higher). System is
> configured with two capillary tubes to inside coil (not bypassed by
> check valve) in series with one capillary tube (bypassed by check
> valve when cooling) to outside coil. Flow is bi-directional through
> cooling capillary tubes.
>
> Pressures in heating mode: 75/450 (just before overpressure trip)
>
> leak-check, recharge, overpressure-on-heat cycles I've made during the
> holidays.
10 year old Singer - dispose of properly!
You don't say what temps you have but 230/65 is fine for a steamy warm
day. If you are checking it at 65 and have those temps, you are grossly
overcharged. How did you get the refrigerant in? Weigh it in with a good
digital scale or dump?
--
HVAC Advice, Pictures, Links
http://www.geocities.com/~johnmills
http://www.appelheat.com
@tom
Sonofdawra wrote in message <
check your water flow rate .maybe the loop isnt designed correctly for the
groud to remove the heat. is this a new system.I'v had to put high psi.
switches on this type of equipment before. from me to the manufacture we
couldnt find a problem.
DTW
How long does it run before tripping? Do you have 1200 CFM indoor
airflow?
Here in florida, back when I did residential, old folks would and
still do, run the heat when it's 65* F or higher, this will cause
allot of nuisance trips. You can put a switch on the suction line (
hot gas going into the evap when heating ) that will cut off the out
door fan when you reach a set point say 350 psi . this will keep your
high side under control in mild weather. Hence the name "mild weather
kit".
DTW
On 29 Dec 1998 22:43:26 GMT, sonof...@aol.com (Sonofdawra) wrote:
>>Pressures in cooling mode: 65/230
>>Pressures in heating mode: 75/450 (just before overpressure trip)
>>
>>
>
Craig
Craig
DTW
accumulator.
Also you can put an auto reset high pressure switch in series with a 5
min time delay wired only to the contactor so the indoor fan does not
stop.
I found it realy isn't that often that this would actually get used.
just when it runs 20 min or so and the people have the stat set at 78
or so ( old folks do this ) and it's 70 out side. Only then it gets to
the 450 mark on a system that is otherwise OK. This set up will keep
down that kind of call back.
DTW
Craig
> just when it runs 20 min or so and the people have the stat set at 78
> or so ( old folks do this ) and it's 70 out side. Only then it gets to
> the 450 mark on a system that is otherwise OK. This set up will keep
> down that kind of call back.
By the 450 mark, Do you mean 450# discharge pressure?
Craig
DTW
about.
Craig
not lunch the compressor with this setup? Is this a factory setup or
someone's idea? I'd think you compressor would be extremely stressed at
this point. I also didnt understand the time delay set up for the indoor
blower idea. Is that just to take heat out of the coil once the stat is
satisfied by keeping the blower running?
Craig
Sandcrab
said to the other.
Sometimes you can switch the leads and reverse it yourself to see if it is
sticking halfway.
Sandcrab
Sonofdawra <sonof...@aol.com> wrote in article
<19981229174326...@ng17.aol.com>...
Marc L O'Brien
<368a8290...@netnews.worldnet.att.net>...
: Package unit? Did you weigh in the charge? What is the out door
temp?
: How long does it run before tripping? Do you have 1200 CFM indoor
: airflow?
:
: Here in florida, back when I did residential, old folks would and
: still do, run the heat when it's 65* F or higher, this will cause
: allot of nuisance trips. You can put a switch on the suction line (
: hot gas going into the evap when heating ) that will cut off the
out
: door fan when you reach a set point say 350 psi . this will keep
your
: high side under control in mild weather. Hence the name "mild
weather
: kit".
Or on the actual suction line from the out door unit to cycle the fan
when the suction gets too high, as you see it raising the discharge
at the indoor blower, this switch could also cycle the LLSV if there
is one, but as you say in the other post, an accumulator helps :-)
Also the outdoor TEV can have a specific MOP characteristic etc. etc.
--
Marc L O'Brien
Marc L O'Brien
: Yes. Allot of comfort cooling high pressure controls are set there
: about.
:
: On Wed, 30 Dec 1998 02:23:19 GMT, Craig <cmoo...@home.com> wrote:
:
: >> I found it realy isn't that often that this would actually get
used.
: >> just when it runs 20 min or so and the people have the stat set
at 78
: >> or so ( old folks do this ) and it's 70 out side. Only then it
gets to
: >> the 450 mark on a system that is otherwise OK. This set up will
keep
: >> down that kind of call back.
: >
: > By the 450 mark, Do you mean 450# discharge pressure?
: > Craig
Mmm, 450 psi is about 73 deg C or 163.4 F, that is pretty high, wow!
I have seen high HP settings on some of the York Energy Pack systems,
but they don't usually take their heat from anything colder than a 10
deg C return chilled water circuit.
Marc L O'Brien
: Wesley Fisher wrote:
: >
: > 10-yr-old Climate Control (made by Snyder Corp.) 3 ton single
package
: > heat pump.
: >
: > Initial problem was leaking R-22 at rusted-through accumulator.
: > Replaced accumulator and after recharging normally in cooling
mode,
: > trips out in heat mode on overpressure. Rechecked accumulator
: > connections (inlet from reversing valve - outlet to compressor
: > suction). Replaced (in order): reversing valve, heat cap tube
: > strainer (tube not clogged), check valve (valve was found to be
open -
: > spring to hold ball against seat nowhere to be seen - but should
have
: > caused lower discharge pressure in heat mode, not higher).
System is
: > configured with two capillary tubes to inside coil (not bypassed
by
: > check valve) in series with one capillary tube (bypassed by check
: > valve when cooling) to outside coil. Flow is bi-directional
through
: > cooling capillary tubes.
: > Pressures in cooling mode: 65/230
: > Pressures in heating mode: 75/450 (just before overpressure trip)
: > I've lost count of the recovery, replace component, vacuum,
: > leak-check, recharge, overpressure-on-heat cycles I've made
during the
: > holidays.
:
: 10 year old Singer - dispose of properly!
:
: You don't say what temps you have but 230/65 is fine for a steamy
warm
: day. If you are checking it at 65 and have those temps, you are
grossly
: overcharged. How did you get the refrigerant in? Weigh it in with a
good
: digital scale or dump?
During cooling:
230 = 111 F sat cond
65 = 37.4 F sat evap
I would hazard a guess and say that the ambient must be around 86 F,
a little higher if the unit is a higher efficiency type. But if lower
and the liquid line is warm, then the condenser is dirty, if the
ambient is still lower and the liquid line is cool then its over
charged or there may be non-condensable.
With a 37.4 F sat suction you must have a return air or room air
temperature of around 74 to 79 F ? If the room air is much cooler
then you have too much refrigerant feeding the unit and I bet the
superheat is really low, compressor must be sweating ?
Does that sound right ?
Then looking at the heating pressures, it would again seem the system
is over charged, I reckon since the indoor coil is smaller that the
outdoor coil we would need less system charge during heating that
during cooling, hence the amplified symptoms.
Can't tell without airflow conditions, subcool and superheat.
DTW
BTW Lennox sells the " mild weather kit ". One connects the fan cycle
switch ( open on rise ) to the factory port near the reversing valve
that goes to the indoor coil so it only has the chance to shut off the
outdoor fan in the heating mode. This is a non adjustable switch, I
forget exactly where it's set but 300+ comes to mind. By shutting off
the out door fan on a mild day in the heating mode there is less heat
picked up by the out door coil and in turn the head pressure drops.
I guess I should have said you can cycle the out door fan to control
the head pressure in the heating mode on a mild day.
The second solution I described Involves just cycling the compressor
with a 5 min delay. I don't recommend it over the first solution but
it beats nothing, esp. if you know that it will only happen rarely and
you don't feel like going out and resetting the HP switch.
Again this is for any unit even a new unit that due to the customers
thermostat habits will trip on high head in mild weather 65* F and up.
DTW
On Wed, 30 Dec 1998 02:49:53 GMT, Craig <cmoo...@home.com> wrote:
>So you can run 440# head and the outdoor fan off in the heat mode and
>not lunch the compressor with this setup? Is this a factory setup or
>someone's idea? I'd think you compressor would be extremely stressed at
>this point. I also didnt understand the time delay set up for the indoor
>blower idea. Is that just to take heat out of the coil once the stat is
>satisfied by keeping the blower running?
> Craig
>DTW wrote:
>>
>> Yes. Allot of comfort cooling high pressure controls are set there
>> about.
>>
>> On Wed, 30 Dec 1998 02:23:19 GMT, Craig <cmoo...@home.com> wrote:
>>
>> >> I found it realy isn't that often that this would actually get used.
>> >> just when it runs 20 min or so and the people have the stat set at 78
>> >> or so ( old folks do this ) and it's 70 out side. Only then it gets to
>> >> the 450 mark on a system that is otherwise OK. This set up will keep
>> >> down that kind of call back.
>> >
>> > By the 450 mark, Do you mean 450# discharge pressure?
>> > Craig
>> >>
>> >> On Wed, 30 Dec 1998 01:49:40 GMT, Craig <cmoo...@home.com> wrote:
>> >>
>> >> >Are you serious? Id think this would flood the compresor back.
>> >> > Craig
>> >> >
>> >> >DTW wrote:
>> >> >>
>> >> >> Package unit? Did you weigh in the charge? What is the out door temp?
>> >> >> How long does it run before tripping? Do you have 1200 CFM indoor
>> >> >> airflow?
>> >> >>
>> >> >> Here in florida, back when I did residential, old folks would and
>> >> >> still do, run the heat when it's 65* F or higher, this will cause
>> >> >> allot of nuisance trips. You can put a switch on the suction line (
>> >> >> hot gas going into the evap when heating ) that will cut off the out
>> >> >> door fan when you reach a set point say 350 psi . this will keep your
>> >> >> high side under control in mild weather. Hence the name "mild weather
>> >> >> kit".
>> >> >>
>> >> >> DTW
>> >> >>
>> >> >> On 29 Dec 1998 22:43:26 GMT, sonof...@aol.com (Sonofdawra) wrote:
>> >> >>
>> >> >> >>Pressures in cooling mode: 65/230
>> >> >> >>Pressures in heating mode: 75/450 (just before overpressure trip)
>> >> >> >>
>> >> >> >>
>> >> >> >
Craig
of residential heat pump work I havent run across it yet. When I do Ill
know what Im looking at.
Thanks
Craig
Wesley Fisher
Wesley Fisher wrote in message <76b9r5$9ft$1...@news3.infoave.net>...
10-yr-old Climate Control (made by Snyder Corp.) 3 ton single package heat pump.Initial problem was leaking R-22 at rusted-through accumulator. Replaced accumulator and after recharging normally in cooling mode, trips out in heat mode on overpressure. Rechecked accumulator connections (inlet from reversing valve - outlet to compressor suction). Replaced (in order): reversing valve, heat cap tube strainer (tube not clogged), check valve (valve was found to be open - spring to hold ball against seat nowhere to be seen - but should have caused lower discharge pressure in heat mode, not higher). System is configured with two capillary tubes to inside coil (not bypassed by check valve) in series with one capillary tube (bypassed by check valve when cooling) to outside coil. Flow is bi-directional through cooling capillary tubes.
Pressures in cooling mode: 65/230Pressures in heating mode: 75/450 (just before overpressure trip)
I've lost count of the recovery, replace component, vacuum, leak-check, recharge, overpressure-on-heat cycles I've made during the holidays.
Sonofdawra
clipping.
Have a nice day, Ron [sonofdawra]
Sonofdawra
>a little higher if the unit is a higher efficiency type. But if lower
>and the liquid line is warm, then the condenser is dirty, if the
>ambient is still lower and the liquid line is cool then its over
>charged or there may be non-condensable.
With respect to liquid line temp and overcharge, from my experience I have
found that as the system is overcharged, the liquid line temp will rise above
the normal expected temp. As you overcharge the unit, you raise the condensing
temp more than you raise the subcooling.
For example, if you have a unit that with a normal 85 degree ambient produced a
110 degree [226psi for R-22] condensing temp and 15 degrees of subcooling to
produce a 95 degree liquid line temp.
If the unit is overcharged and you drive the head pressure up to 120 degree
condending [260 psi for R-22] and raise the subcooling to 20 degrees, the
liquid line temp would then be 100 degrees.
Like I said earlier, this is typically what I have found to be the case.
Overcharged units produce elevated liquid line temps.
Marc L O'Brien
: >I would hazard a guess and say that the ambient must be around 86
F,
: >a little higher if the unit is a higher efficiency type. But if
lower
: >and the liquid line is warm, then the condenser is dirty, if the
: >ambient is still lower and the liquid line is cool then its over
: >charged or there may be non-condensable.
:
: With respect to liquid line temp and overcharge, from my experience
I have
: found that as the system is overcharged, the liquid line temp will
rise above
: the normal expected temp. As you overcharge the unit, you raise
the condensing
: temp more than you raise the subcooling.
I certainly would expect this on a cap tube system, but not with a
TEV.
: For example, if you have a unit that with a normal 85 degree
ambient produced a
: 110 degree [226psi for R-22] condensing temp and 15 degrees of
subcooling to
: produce a 95 degree liquid line temp.
:
: If the unit is overcharged and you drive the head pressure up to
120 degree
: condending [260 psi for R-22] and raise the subcooling to 20
degrees, the
: liquid line temp would then be 100 degrees.
Lol, What sort of proof is that? :-)
Too, what expansion device?
: Like I said earlier, this is typically what I have found to be the
case.
: Overcharged units produce elevated liquid line temps.
Cap tub system ?
Sonofdawra
>
> Too, what expansion device?
>
Marc, if you go back and read the original post, you would find that we are not
talking about a TXV system, but a heat pump with cap tubes at both coils. The
example I gave was to illustrate what I was talking about, it was not intended
as proof. However, on the equipment that was under discussion in this thread,
overcharging will raise the liquid line temp.
I have measured liquid line temps in relation to overcharge enough on cap
tube/fixed orifice systems to know that baring other unforseens, this is true.
It is an exercise that I have students perform in the lab. When you start
talking about TXV systems, then everything gets a little skewed depending on if
there is/isn't a receiver and where you measure liquid line temp.
Then there is the arguement I hear from some guys that on a TXV system with a
receiver, that there is no subcooling once the refrigerant hits the receiver.
Don't know how they explain the refrigerant remaining as a liquid in the liquid
line as the pressure continues to drop as the liquid flows down the liquid
line.
One thing that continues to amaze me is that I hear so many varied explanations
of how things work [some right, some semi-right and some out in left
field---oops, American slang for being way off] that it is a wonder that most
things do get fixed correctly a reasonable percentage of the time. Some of
what I read here at times scares me, but then not everyone always agrees with
me [even on the occasions that I am right :o) ].
Part of the reason for the varied perspectives is that none of us has the same
educational background, training, work experience and there is such a variety
of equipment out there that none of us has worked on it all.
Some of the strangest equipment as far as application that I used to work on
was for a customer that raised and raced standard bred horses [pacers and
trotters---harness racing]. Ever worked on refrigerated leg wrap machines or
refrigerated whirlpool bath machines for horses?
Marc L O'Brien
: > Lol, What sort of proof is that? :-)
: >
: > Too, what expansion device?
: >
:
: Marc, if you go back and read the original post, you would find
that we are not
: talking about a TXV system, but a heat pump with cap tubes at both
coils. The
: example I gave was to illustrate what I was talking about, it was
not intended
: as proof. However, on the equipment that was under discussion in
this thread,
: overcharging will raise the liquid line temp.
Yes Ron, I realised it was a meant only as an illustration, I just
thought it was funny ..... private joke, sorry :-)
If you again read below (in italics) what it was I originally said,
you'll see that I did not specifically say that the liquid line temp
would be cooler than normal, only that it would be cool, which is
like saying it would be relatively cool.
- "I would hazard a guess and say that the ambient must be around 86
F,
a little higher if the unit is a higher efficiency type. But if lower
and the liquid line is warm, then the condenser is dirty, if the
ambient is still lower and the liquid line is cool then its over
charged or there may be non-condensable." -
Then you replied saying the following (again in italics)
-"With respect to liquid line temp and overcharge, from my experience
I have
found that as the system is overcharged, the liquid line temp will
rise above
the normal expected temp. As you overcharge the unit, you raise the
condensing
temp more than you raise the subcooling."-
With regards to cap tube systems this is true and even many times
with TEV systems but also many times it is not true with TEV systems,
and so what ?
You replied to my "non specific" manor of posting, and so then I to
yours :-)
: I have measured liquid line temps in relation to overcharge enough
on cap
: tube/fixed orifice systems to know that baring other unforseens,
this is true.
: It is an exercise that I have students perform in the lab. When
you start
: talking about TXV systems, then everything gets a little skewed
depending on if
: there is/isn't a receiver and where you measure liquid line temp.
That all goes without saying really :-)
: Then there is the arguement I hear from some guys that on a TXV
system with a
: receiver, that there is no subcooling once the refrigerant hits the
receiver.
: Don't know how they explain the refrigerant remaining as a liquid
in the liquid
: line as the pressure continues to drop as the liquid flows down the
liquid
: line.
I am very much one of these people, and have found by recent very
extensive experience on a system designed by an arse hole (which was
left to me to propose a completely different liquid configuration).
It was seen by myself that although a few degrees of subcool is
achieved and kept, it is no where near as high as removing the
receiver and adding a subcool circuit in it's place. If you have just
a short liquid line of say 10m and there is no vertical lift, the
line size is adequate and the condenser pressure is not maintained by
cycling the condenser fan, then you are okay. Other than that, there
is sure to be trouble !
: One thing that continues to amaze me is that I hear so many varied
explanations
: of how things work [some right, some semi-right and some out in
left
: field---oops, American slang for being way off] that it is a wonder
that most
: things do get fixed correctly a reasonable percentage of the time.
Some of
: what I read here at times scares me, but then not everyone always
agrees with
: me [even on the occasions that I am right :o) ].
That is the grief that us less ignorant chaps have to suffer :-(
: Part of the reason for the varied perspectives is that none of us
has the same
: educational background, training, work experience and there is such
a variety
: of equipment out there that none of us has worked on it all.
True, we often tend to look at things with a system specific
prejudices in play. That is why I like to keep building on my wealth
of axioms, maxims and first principles, they allow for easy
translation of phenomena mechanics between scenarios, deductive
rather than inductive reasoning. Lol, does that make sense? :-)
: Some of the strangest equipment as far as application that I used
to work on
: was for a customer that raised and raced standard bred horses
[pacers and
: trotters---harness racing]. Ever worked on refrigerated leg wrap
machines or
: refrigerated whirlpool bath machines for horses?
Nope, but nor would I hesitate if offered the chance to design any
:-)
Back to the original post, I was only trying to say that I thought
the system was over-charged.
AUSTIN1880
>refrigerated whirlpool bath machines for horses?
I have indeed, once.
Sonofdawra
>clogged), check valve (valve was found to be open - spring to hold ball =
>against seat nowhere to be seen - but should have caused lower discharge =
>pressure in heat mode, not higher).
Just to set the record straight, there never was a spring in the check valve.
The ball type check valves that are in a heat pump system rely on the liquid
flow in one direction to force the ball against the seat. The spring didn't
disappear, it was never there to begin with.
Wesley Fisher
extraneous metal particles working their way to the compressor.
Wes
Sonofdawra wrote in message
<19981231093541...@ng-cr1.aol.com>...
purnell...@gmail.com
Stormin Mormon
2) condenser (indoor coil in this case) needs cleaning?
3) dirty air filter, low air flow through condenser
(indoor coil in this case)?
4) Closed vents, and low air flow?
Would be nice to have some temperature readings
at various points of the system.
--
.
Christopher A. Young
learn more about Jesus
. www.lds.org
.
.