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  1. #101
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    Re: Buffer Tank Assisted Defrost



    I would advice that you install a accumulator, turn your fan off.
    I only showed how it could be done using a buffer, that it had benefits and to help you to understand why/what you had drawn was wrong.
    If you want to understand refrigeration, you must first understand that the system is a loop and not a number of components joined together.



  2. #102
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    Re: Buffer Tank Assisted Defrost

    Quote Originally Posted by Emmett View Post
    Whoa Cowboy, the gent pilko is north of the border not one of ours!!!
    Ha ha Emmett, tis true, but he is using a Carrier system......not Canuk built, last time I checked

  3. #103
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    Re: Buffer Tank Assisted Defrost

    Hi Mike, have a look on HVAC TALK, for me please "I have been banned."
    any comments from them
    search barbar.

  4. #104
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    Re: Buffer Tank Assisted Defrost

    Will do, I haven't been able to register on it as it keeps kicking me out. I will try to re-register tonioght.

  5. #105
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    Re: Buffer Tank Assisted Defrost

    You are a bad boy as well. Get to the back of the room with me.

  6. #106
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    Re: Buffer Tank Assisted Defrost

    I never learned anything in school because i kept passing girly pictures to you at the back of the class. Now look where we are...

  7. #107
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    Re: Buffer Tank Assisted Defrost

    Quote Originally Posted by MikeHolm View Post
    Ha ha Emmett, tis true, but he is using a Carrier system......not Canuk built, last time I checked
    True however the comment was in reference to Mr pilko not his equipment and I suspect that if it is a carrier unit it was engineered in asia or europe and built in mexico anyway so the the equipment is likely American in name only. It is just about impossible for a manufacturer to manufacturer in America these days. Any way you too shall have a pint for the great assistance and patience you have shown our new friend Pilko.

  8. #108
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    Re: Buffer Tank Assisted Defrost

    And a pint to you as well, tis the season as you know.

    I believe his is a standard split and it is many years old so i suspect it was made in the US of A. I will check it out at Xmas and bring him a pint (I'll be in the neighbourhood).

  9. #109
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    Re: Buffer Tank Assisted Defrost

    @ mad fridgie,
    Just took a look into my heat pump, It does have an accumulator. Is it OK to go ahead and run defrost with indoor fan stoopped? If yes:-

    1 What precautions should I take?

    2 What if anything can I monitor to reduce risk of damage?

    regards

    pilko

  10. #110
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    Re: Buffer Tank Assisted Defrost

    Quote Originally Posted by pilko View Post
    @ mad fridgie,
    Just took a look into my heat pump, It does have an accumulator. Is it OK to go ahead and run defrost with indoor fan stoopped? If yes:-

    1 What precautions should I take?

    2 What if anything can I monitor to reduce risk of damage?

    regards

    pilko
    OK, firstly lets look at control, and also taking note of the "Pros" concerns. (remember I do NOT know your particular equipment)
    Because of how you measuring ice, you could but a defrost fail safe in (If after "x" mins the coil is not defrost slowing bring fan on. (you will still have a cold draft when the fan is on, but is a "just in case")
    That covers all issues about the ability to defrost.

    As far as protection, firstly look at the size of your accumulator (volume), is the volume greater than the total volume of liquid refrigerant in your system. ( again not quite a true fact but thing of the volume of refrigerant as water "2kg of refrigerant = 2 litres") The weight of refrigerant should be indicated on the outside unit. If the accumulator volume is over or close to the refrigerant volume, then no worries.
    If it is greatly smaller, then install a larger one.
    We could look at electrical protection, but would be expensive and very complicated software.
    pressure transducers, temp sensors, comp current sensor, with pressure/temp comparability.

  11. #111
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    Re: Buffer Tank Assisted Defrost

    Thanks mad fridgie,
    There will be some frost tomorrow morning, so will check the accumulator and if OK, will do some testing then.

    pilko

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    Re: Buffer Tank Assisted Defrost

    Pilko, did you get the weather bomb yesterday?

    Your defrost control is probably on one board with the pressure switches terminals and RV output etc. I don't know what board in on your unit but on the one I have been working on, the fan stops during defrost. If it doesn't stop, I have a simple defrost control which will trigger the RV and stop the fan.

  13. #113
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    Re: Buffer Tank Assisted Defrost

    Hi Mike,
    The original Carrier board inside the heat pump operates the RV, stops the outdoor fan, and controls the time between defrosts (No demand defrost). The indoor fan is controlled by the room thermostat.
    I control frost-level defrost, and temperature controlled indoor fan with a home made board in my "cave"
    My board logs coil inlet and outlet temperatures, outdoor temperature, frost level on outdoor coil, fan CFM and Heat pump power.
    Protections are still operational on the outdoor board.

    pilko

  14. #114
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    Re: Buffer Tank Assisted Defrost

    No weather bomb and none forcast.

    BTW How do I edit a post?

    pilko

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    Re: Buffer Tank Assisted Defrost

    @ mad fridgie

    "As far as protection, firstly look at the size of your accumulator (volume), is the volume greater than the total volume of liquid refrigerant in your system. ( again not quite a true fact but thing of the volume of refrigerant as water "2kg of refrigerant = 2 litres") The weight of refrigerant should be indicated on the outside unit. If the accumulator volume is over or close to the refrigerant volume, then no worries.
    If it is greatly smaller, then install a larger one."

    Nameplate charge = 4.94 Kg
    Volume of accumulator = 3.6 L
    Using density at 21*C = 1490 Kg per cubic metre
    Capacity of accumulator = 3.6 X 1.49

    Capacity of accumulator = 5.4 Kg

    Should I go ahead ?

    pilko

  16. #116
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    Re: Buffer Tank Assisted Defrost

    Well covered, go for it!

  17. #117
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    Re: Buffer Tank Assisted Defrost

    Thanks mad,

    Forecast a bit of frost overnight. Will give it a try in the morning.

    pilko

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    Re: Buffer Tank Assisted Defrost

    @ mad fridgie,

    Did a defrost without indoor fan this morning ----SUCCESS !!!!!

    Outdoor temp was -4*C

    Restarted fan when indoor coil reached 40*C.

    pilko

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    Re: Buffer Tank Assisted Defrost

    How did it feel in your house?
    Last edited by mad fridgie; 11-12-2011 at 10:57 AM.

  20. #120
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    Re: Buffer Tank Assisted Defrost

    @ mad fridgie,

    "How did it feel in your house?"

    Very comfortable.

    BTW defrost did not take any longer than with fan running.

    I will check after several defrosts that deep frost (ice that forms deep in the coil due to incomplete defrost) does not start to build up on the outdoor coil.

    pilko

  21. #121
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    Re: Buffer Tank Assisted Defrost

    Does this mean that only compressor heat is being used for defrost? Pilko, are you wanting to make the tank storage as well?

  22. #122
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    Re: Buffer Tank Assisted Defrost

    mike ur dragging this post out arent u- just pop to pilko's and have a maul with his kit! or are u trying to get a sticky post haha

  23. #123
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    Re: Buffer Tank Assisted Defrost

    I'm dropping in at Xmas with a pint or two of cheer. Were are no where near a sticky anyway, haha.

  24. #124
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    Re: Buffer Tank Assisted Defrost

    @ Mike,
    "Does this mean that only compressor heat is being used for defrost?" --- also the heat in the lines,the vapour in the "A" coil and the "A" coil itself."

    are you wanting to make the tank storage as well?---only if the outdoor coil fails to defrost completely.

    pilko

  25. #125
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    Re: Buffer Tank Assisted Defrost

    i guess you will have to see how it works without the extra heat source of the the room air. The other possible benefit of a tank (Mad, correct me if I am wrong) is that some of the tank heat could be used to do some floor heat if desired.

  26. #126
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    Re: Buffer Tank Assisted Defrost

    The coil is not defrosting using the compressor energy only (energy is still coming from the system)
    Hot gas defrost, is more a compressor only defrost.
    Using energy for more than one application, really means you study the applications to design the right system.

  27. #127
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    Re: Buffer Tank Assisted Defrost

    UPDATE,

    Had 12 Defrosts with indoor fan stopped ---everything OK,

    Writing some code to stop fan automatically at defrost start and restart fan when "A" coil temp >40*C.

    pilko

  28. #128
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    Re: Buffer Tank Assisted Defrost

    Great news!
    I am not normally into one up-man-ship, but in this case i think the "Pros" on HVAC TALK need to be told of your results.
    In this industry things are very rarely black and white, so for one of the "pros" to say i was "wrong" was just pure arrogance and ignorance of the fundamentals.
    Others gave opinions based upon what they know and seen, and that is fair comment.

  29. #129
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    Re: Buffer Tank Assisted Defrost

    @ mad fridgie,

    If I respond to the other forum now, he will probably tell me that it is "OK for now but the compressor will
    fail after a short time"---- so, I would prefer to give it more time and be able to tell them that it has been OK for a month for example.

    pilko

  30. #130
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    Re: Buffer Tank Assisted Defrost

    I'm still unsure where the heat for defrost is coming from. I can't see enough heat from the local piping so there must be a high percentage of compressor heat going through.

  31. #131
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    Re: Buffer Tank Assisted Defrost

    Mad, I haven't see and "barbar" posts on the HVAC forum

  32. #132
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    Re: Buffer Tank Assisted Defrost

    Hi Mike,

    good question.

    What is the weight of the "A"coil and what temp is it, what is in the coil (hot refrigerant), you also have the interconnecting piping, and of course the mass around the all this. So you could work out the energy in all this. This energy is also is pumped (compressor uses energy) so the combination is rejected into the outside coil to melt the ice.

    Reply on HVAC TALK, were removed and I got banned for a few weeks (Thats the rules, which I did break)

    Pilko, fair comment

  33. #133
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    Re: Buffer Tank Assisted Defrost

    I'm back,

    I am still defrosting without the indoor fan and everything is OK.

    I just posted the following message on the other forum:-

    "Update:-
    I have been defrosting with the indoor fan shut down for the past 5 weeks . (approx. 120 defrost cycles). It works fine and I have had no problems.

    pilko."

  34. #134
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    Re: Buffer Tank Assisted Defrost

    Good news
    more comfort and less power

  35. #135
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    Re: Buffer Tank Assisted Defrost

    This a reply form HVAC-TALK
    "Quote:
    Originally Posted by pilko
    Update:-
    I have been defrosting with the indoor fan shut down for the past 5 weeks . (approx. 120 defrost cycles). It works fine and I have had no problems.

    pilko.

    I've been reading through this thread & though I haven't read it all it is a lot more interesting than I thought it would be. Any HP manufacturer or tech support would say as a fact that the indoor blower should always run during defrost & I would agree. You have evidently done significant research & found some conflicting data to support the alternate view which most anyone who works on HP's would disagree with. You have to remember HP's are designed for a variety of climates & yours may be such that a defrost is not needed very much so you mat be able to get away with stopping the blower while someone in another climate may not. There is no question that stopping the blower motor during defrost will lower the added cooling btu's entering the structure & also lower power consumption during that time but it also will make the defrost less efficient if it is really needed. Also compressor flooding should be a serious concern.

    [FONT=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif]__________________[/FONT]
    [FONT=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif]Gary[/FONT]
    [FONT=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif]-----------"[/FONT]
    [FONT=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif]I wonder if you could forward this response.

    Thanks Gary, for being a little more open on your thoughts.
    It would seem that only North American heat pump systems continue to run the indoor fan on defrost, much of the rest of the world, turn off all the fans during defrost. These system are designed to run as low as -15C ambient. This is limited to refrigeration compression ratio limits, and not defrosting limitations.
    Your concern on flood back is valid, in this case total charge and size of the suction accumulator was taken into consideration. Liquid flood back would not occur. How ever vapour at saturation may enter the compressor, but this is not really an issue, as the refrigerant passes over the comp motor, picking up sufficient superheat to ensure that oil dilution will not occur for the short defrost period.
    Technically there is no reason why all systems in your neck of the wood s can not be converted, but there are practical limitations, such refrigerant distribution (primarily the out door coil), defrost sensor position and general control scenario. How do we determine defrost efficiency, defrost should be slower without a fan running (less energy picked up from the evap), so it would be fair to say efficiency is less, but if we include the energy to recover after defrost, then defrosting without a fan is more efficient.
    cheers
    mad fridgie (barbar)
    [/FONT]

  36. #136
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    Re: Buffer Tank Assisted Defrost

    Thanks Mad,

    I have posted your / my response on the other site.

    Regards

    pilko

  37. #137
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    Re: Buffer Tank Assisted Defrost

    Quite a few rude answers on the other site.
    It would be quite nice to know what sort of energy savings you are making.
    Maybe you could be on to a winner converting systems. When you do, and make your millions, do not forget poor mad fridgie, at the bottom of the world.

  38. #138
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    Re: Buffer Tank Assisted Defrost

    Quote Originally Posted by mad fridgie View Post
    Quite a few rude answers on the other site.
    It would be quite nice to know what sort of energy savings you are making.
    Maybe you could be on to a winner converting systems. When you do, and make your millions, do not forget poor mad fridgie, at the bottom of the world.
    You are only upside down, not on the bottom of the world

  39. #139
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    Re: Buffer Tank Assisted Defrost

    I think you could install another external heat exchanger that will be replacing the internal one at the time of defrosting.

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