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  1. Thread: Corrosion?

    by Drazen
    Replies
    7
    Views
    453

    ordinary leak testing should show where leaks...

    ordinary leak testing should show where leaks exist, and if there are only few detectable places, repair is possible, otherwise replacement is likely the only option.

    chemical action would not be...
  2. Replies
    15
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    1,091

    if i'm in charge of supervision of this, i would...

    if i'm in charge of supervision of this, i would have stripped it out manually and ask contractor to do everything properly, from the very beginning.

    of course, it much depends on which conditions...
  3. if you hunted condensation points as you...

    if you hunted condensation points as you described, i would say that you have typical example of thermal bridges. so first what you should try out to simply insulate such spots, to prevent such low...
  4. Thread: how to find cfm

    by Drazen
    Replies
    12
    Views
    1,123

    do you mean supply air cfm for cooling?

    do you mean supply air cfm for cooling?
  5. as far as i know, expansion compensation devices...

    as far as i know, expansion compensation devices for ductwork do not exist, someone would have to devise it for you.

    your concept counters some basic principles of any sort of energy efficiency,...
  6. Replies
    11
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    1,887

    much more information needed to reach...

    much more information needed to reach circumstances.

    though isuredo is sarcastic, he is right in some way, as intentional bypasses of safety equipment setups would be needed to give chance to...
  7. Replies
    7
    Views
    751

    hydraulic bumpers are usually applied with water...

    hydraulic bumpers are usually applied with water supply or lifting system, where you can have varying backpressure, and pump head is comparatively high.

    in circulation systems, however, they are...
  8. Replies
    7
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    751

    as a simplified alternative: due to the fact that...

    as a simplified alternative: due to the fact that modifications of hydraulic loop would likely have to involve reconsideration of automatic control equipment, "the most primitive" yet possibly...
  9. Replies
    7
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    751

    schematics you provided looks quite confusing for...

    schematics you provided looks quite confusing for me, third boiler even does not seem to have supply connection shown.

    could you make one more photo, focused on the very bottom of schematics,...
  10. Replies
    1
    Views
    377

    it's hard to say from distance, there could be...

    it's hard to say from distance, there could be different reasons for it. you can clear "lose casing" cause if you try to press casing firmly with few different powers exerted - taking care not to...
  11. Thread: fan help

    by Drazen
    Replies
    5
    Views
    482

    Such kind of repairs are tricky anyhow, while for...

    Such kind of repairs are tricky anyhow, while for smaller unit sizes it can hardly be worthy. the main issue is about how long repair will hold, similarly to repair of old car.

    Some question arise...
  12. Replies
    6
    Views
    776

    I am not sure what are you considering plate heat...

    I am not sure what are you considering plate heat exchanger, that is term used for water to water exchangers, while air heaters/coolers are mostly fin-and-tube exchangers.

    On contrary to water to...
  13. Replies
    18
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    2,036

    manufacturer has available and reachable data...

    manufacturer has available and reachable data that presents maximum allowed length and provisions for elbows.
    if you are within limits, rated cooling will be reached, but, of course, that does not...
  14. i am not sure whether i can understand you. you...

    i am not sure whether i can understand you. you are interesting to hear about some other duct materials where manufacturers have ambitions to have their products approved in some way? i cannot recall...
  15. Replies
    9
    Views
    1,222

    Can you be specific: what do you want to achieve...

    Can you be specific: what do you want to achieve and what problems do you have now?
  16. Replies
    5
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    2,548

    i would say that you are comparing apples with...

    i would say that you are comparing apples with onions which does not make sense.

    eer is more or less obsolete figure, and the fact that some manufacturer does not declare seer says much about that...
  17. to the best of my knowledge there is no any...

    to the best of my knowledge there is no any plastic duct material which is officially approved as adequate for supply ductwork.

    there are few manufacturers which presented their investigation, and...
  18. Replies
    6
    Views
    738

    Is those duct runs quite long? If your...

    Is those duct runs quite long?

    If your recirculating air cools down so much that it condenses on the inside, adding more insulation might be not only counter-condensation, but also counter-high...
  19. Replies
    9
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    1,200

    What is usually of primary concern is temperature...

    What is usually of primary concern is temperature rating and proper data about fitting losses, many of those fittings have substantially higher dynamic losses than copper/steel, so that should be...
  20. you certainly need guidance of journeyman as many...

    you certainly need guidance of journeyman as many stated, but if you want some readings for preparation, try to find books of leo meyer, can be found in some online secondhand shops like...
  21. well, than you have good argument, but if client...

    well, than you have good argument, but if client insists on larger size, it may be sufficient that you have an ordinary e-mail sent to client where you described what you wanted.
  22. to some point i could understand your customer. ...

    to some point i could understand your customer.

    did legislation change in time between bidding and current time? if it did not, i see no purpose for asking customer to sign anything if you...
  23. Replies
    15
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    1,392

    i can only guess that, as it is not intended at...

    i can only guess that, as it is not intended at all that such valve works when de-energized, gas pressure is not sufficient to open it, but in any case it looks like main safety valve.

    now that...
  24. Thread: System Leaks

    by Drazen
    Replies
    18
    Views
    1,507

    at least you know that you have to smash ceiling...

    at least you know that you have to smash ceiling :eek:

    installing refrigerant lines with joints through unapproachable area is one of the worst things i know where architects and dx systems sales...
  25. Thread: System Leaks

    by Drazen
    Replies
    18
    Views
    1,507

    you need soap to check joints one by one, finding...

    you need soap to check joints one by one, finding refrigerant leaks is tedious task more often than not.
  26. Replies
    15
    Views
    1,392

    i'm far away from oregon, but i believe what you...

    i'm far away from oregon, but i believe what you described is illegal anywhere in the world where there is any gas systems regulation in place.

    not only that you must not bypass solenoid valve,...
  27. Replies
    6
    Views
    1,072

    1- this looks like free cooling at winter time,...

    1- this looks like free cooling at winter time, anyhow, outside temperature is not the same as indoor temperature, most of time, so you do need insulation as per previous post.

    2- Similar to point...
  28. Replies
    16
    Views
    4,431

    pipes and units are generally covered by their...

    pipes and units are generally covered by their manufacturers' quality certificates, and if we look strictly formally, in the moment you suspect they are exposed to mechanical damage, they are not...
  29. Replies
    21
    Views
    1,363

    relative humidity of air has nothing to do with...

    relative humidity of air has nothing to do with expansion, but with thermodynamical property of air, where warmer air has more ability to hold water vapor.

    i think many people spend too much time...
  30. Replies
    26
    Views
    1,851

    the most important thing is to take all...

    the most important thing is to take all assumptions into account.

    if we assume that your fan is already selected and installed/ordered, and you want to vary ductwork, firstly you need to be aware...
  31. Replies
    12
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    974

    yes, for open loop most of the previously...

    yes, for open loop most of the previously mentioned comments apply as well.

    pressure drop over line gives you data about flow, while measuring temperature can possible give useful information as...
  32. Replies
    6
    Views
    1,072

    ductwork that carries air with state equal or...

    ductwork that carries air with state equal or very similar to design indoor air conditions is not insulated as there is no purpose to have insulation.

    there is number of occasions where carried...
  33. Replies
    16
    Views
    4,431

    in mini-split systems and many multisplit systems...

    in mini-split systems and many multisplit systems you have no any other joints but flare joints, and in such a case you can omit pressure testing as pressure tests serve to test joints, not pipes.
    ...
  34. cooling towers are quite massive by default, if...

    cooling towers are quite massive by default, if your plant have space issues, calculations should be done well in advance.

    other than that, as someone mentioned, return on investment should be...
  35. Replies
    12
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    974

    do you have balancing valves on branches? without...

    do you have balancing valves on branches? without them, you can hardly achieve desired water flows and too small branch diameter can add to trouble.

    balancing valves also have measuring nipples...
  36. hi, ginger, i assume you mistakenly changed what...

    hi, ginger, i assume you mistakenly changed what you specify as inlet and outlet, cooling tower should lower temperature, not raise it.

    your case seems to be typical case which actually calls for...
  37. Replies
    6
    Views
    807

    daikin is first to introduce their altherma...

    daikin is first to introduce their altherma system, but as competition enforces keeping up, now there is number of manufacturers who offer similar systems, air-water heat pumps with domestic hot...
  38. Replies
    21
    Views
    1,363

    hi garyed, cooling will indeed reduce...

    hi garyed,

    cooling will indeed reduce circulating air humidity only if wet cooling is used. i.e. if temperature of cooling exchanger surface is lower than dew point of air.

    this is almost...
  39. Replies
    1
    Views
    540

    yes. if you do not have someone properly...

    yes.

    if you do not have someone properly calculate ductwork, you will see what i often see in caffe bars: stains around few grills closest to exhaust fans, while the others are clear. meaning,...
  40. Replies
    20
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    6,379

    you can measure temperature by any kind of...

    you can measure temperature by any kind of wrap-on sensor, and before that you are guessing, and, what is frequent problem in maintenance work, if you stay stick by unproved hypothesis for too long,...
  41. Replies
    10
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    1,095

    i'm from atlantis, live in croatia :)

    i'm from atlantis, live in croatia :)
  42. Replies
    8
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    1,354

    ir can confirm suspicions about thermal leaks,...

    ir can confirm suspicions about thermal leaks, but in any case that cannot be replacement for thermal load calculations.

    you can burn lot of money by deciding on equipment without thermal load...
  43. Replies
    18
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    1,661

    sounds like interesting engineering issue, at the...

    sounds like interesting engineering issue, at the same time clear example how problem of engineering concept cannot be solved by improvisations without very clear understanding of pshychrometrics...
  44. You could have some small heat accumulation in...

    You could have some small heat accumulation in sheet metal casing, but there is air gap between casing and condenser coil anyhow, and it is sheer air temperature which directly affects cycle...
  45. Replies
    14
    Views
    2,689

    if you would clearly state what confuses you, it...

    if you would clearly state what confuses you, it would be easier to find exact answers.

    there are different design strategies which impose use of reheat coil - it can be main source of heating,...
  46. Replies
    6
    Views
    1,307

    This is one of rare fields where european...

    This is one of rare fields where european literature is more detailed compared to ASHRAE as far as I know.

    I have number of design books with such table, none of this related with ASHRAE.

    There...
  47. Replies
    10
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    1,095

    yes, i work as hvac engineering consultant -...

    yes, i work as hvac engineering consultant - design, supervision, consulting
  48. Replies
    10
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    1,095

    thanks, well it's not so big deal now,...

    thanks,

    well it's not so big deal now, continual crisis...
  49. Replies
    10
    Views
    1,095

    Cheers to Everyone

    I opened the site doors and now I am wawing.:putergreet:
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