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  1. #27
    Join Date
    Mar 2004
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    Gone
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    5,340
    The book only showed three taps.

    You need the 8 inch duct to even come close to your required CFM’s, and that is if you are lucky enough to have .5 TESP.

    Do not waste your money on a service call unless the guy knows how to check all your ESP readings like Dash said earlier. Like Doc said also, you are probably oversized on your heat with that furnace. They make a 070-08 furnace. After glancing into the Manuel J book, I see you have a winter design temp of 17 there in Richmond, VA. Not knowing what the heat load is on your brick structure, I would still guess you are close where a 45-08 furnace would work for you.

    After reading your other thread, you really need someone who is knowledgeable to come setup your system correctly and check everything out, heat rise, combustion, refrigerant charge since you have messed with the blower speed if it is a piston metered system, CFM’s.

  2. #28
    Join Date
    Mar 2005
    Posts
    56

    To All

    I called the guy that installed the system and he is coming over tonight.He is going to read the tempature at the registers which gives me an isdea of his true skill level.

    I do not think that he is nearly as schooled about the HVAC as all that have contributed to this thread.

    I figured I`d give him a chance to make good and explain his side.

    I will post all of what he does and you can decide.

    [Edited by eisenberg on 06-30-2005 at 05:00 PM]

  3. #29
    Join Date
    Mar 2002
    Location
    Concord, CA
    Posts
    2,633
    The extra ton of blower capacity is NOT your problem. It's not A problem. It's not ANY problem at all! Am I being emphatic enough?

    HVAC 101:

    Your three ton furnace blower delivers three tons worth of air ONLY if the back pressure exerted by the ducts is .5" water column or less. Water column is just a measure of air pressure. There are almost no HVAC systems out there that have only .5" of back pressure (external static pressure). There aren't even that many that have .6". In my experience the .7" to .8" range is VERY common. Many go higher than that.

    Take a look at the blower chart on page 10 of this document. At .8 inches water column that furnace would be perfect on med-low speed if your target is the industry standard 400 CFM per ton. I've got ten bucks that says your pressure is that high. The other way to look at it is to review the data for the -08 furnaces. Not one of them is capable of delivering 800 CFM at .8". They even fall a little short at .7".

    There may still be plenty of reason to criticize your HVAC guy. As was mentioned things like temp rise should be addressed. It wouldn't surpise me at all if (as Dash talked about) your guy doesn't even know how to measure ESP. But at least he gave you a solution to your airflow problem. A typical hack would have put in a smaller blower and not have addressed airflow at all. Perhaps he's an above average hack? And it also wouldn't be unusual if he didn't address the ducts with you as he should have prior to the sale. But were you willing to pay double the price to replace your duct system?

    Plus... At least one OEM doesn't even make a furnace with a two ton blower anymore. The minimum they make is 3 tons. If other OEMs follow suit then what?

    Plus... The extra airflow robs from latent capacity (moisture removal) and gives to sensible capacity (temperature reduction). That fact alone proves that the system's inability to reduce the temperature to your liking is not because of the extra airflow. If anything the extra airflow enhances the system's ability to drop temperature.

    To sum it up: Let go of the three ton blower issue. It's a red herring. There may be a dozen reasons why your system isn't working right. The oversized blower is NOT one of them.

    [Edited by Irascible on 07-01-2005 at 03:46 AM]

  4. #30
    Join Date
    Apr 2005
    Location
    San Luis Obispo County, CA
    Posts
    215
    Originally posted by Irascible
    The extra ton of blower capacity is NOT your problem. It's not A problem. It's not ANY problem at all! Am I being emphatic enough?

    HVAC 101:

    To sum it up: Let go of the three ton blower issue. It's a red herring. There may be a dozen reasons why your system isn't working right. The oversized blower is NOT one of them.
    The H.O. has never said there is a problem with the unit, he is just second guessing the install.

    Nobody has asked the obvious questions.
    1 How does it work?
    2 What problems do you have?
    3 What do you want to change and why?

    We don't even know if this system is broke, why are we reccomending fixes for it?

  5. #31
    Join Date
    Mar 2002
    Location
    Concord, CA
    Posts
    2,633
    Originally posted by dave_slo
    The H.O. has never said there is a problem with the unit, he is just second guessing the install.
    Originally posted by eisenberg
    even when 76 degrees outside I am unable to get the system down to 72 it just runs and runs and runs for well over an hour ...it will get to 73 ,but no further. The only way I can get it to stop running is to set it up to 75. The air coming from the registers is somewhat cool...but seems like it could be colder
    Hmm. Looks like someone was just skimming and not reading. That's OK dave. We all do it from time to time. And there may very well not be any real problems. But the homeowner believes there is at this time.

  6. #32
    Join Date
    Apr 2005
    Location
    San Luis Obispo County, CA
    Posts
    215
    Originally posted by Irascible
    Originally posted by dave_slo
    The H.O. has never said there is a problem with the unit, he is just second guessing the install.
    Originally posted by eisenberg
    even when 76 degrees outside I am unable to get the system down to 72 it just runs and runs and runs for well over an hour ...it will get to 73 ,but no further. The only way I can get it to stop running is to set it up to 75. The air coming from the registers is somewhat cool...but seems like it could be colder
    Hmm. Looks like someone was just skimming and not reading. That's OK dave. We all do it from time to time. And there may very well not be any real problems. But the homeowner believes there is at this time.
    yeah, i missed that, and the noise post too... but found it interesting that no problems were mentioned in the original post.

    If this were my system, and I just had it installed, I would be telling the installer that 73 degrees on a 76 day with the system running all the time is unacceptable. And the problem needs to be fixed... don't care how you do it, just "git 'er done..."

  7. #33
    Join Date
    Jun 2005
    Posts
    37
    Thank god for this post.

    I have to say I have been having comfort/cooling problems with my house. I have a 2.5 ton unit and evap coil. I have the same furnace and blower. Model number58sta070. I just changed the blower setting to med and it already seem's like its giving me better readings from the vent.

    What should I set the blower speed to?

  8. #34
    Join Date
    Mar 2002
    Location
    Concord, CA
    Posts
    2,633
    No worries Dave.

    I went back through eisey's previous posts. It seems that he admitted that only one diffuser was actually noisy.

    It seems to me eisey that I've explained this to you before. So my apologies for wasting both our time. But I have explained it VERY thoroughly this time. If temperature reduction is your issue then there is NO WAY on this planet or any other that an oversized blower would cause that. NO WAY AT ALL. PERIOD. If you can't accept that this time around then you are beyond help.

    What an oversized blower can do is cause noise problems. You've said only one diffuser is noisy. And it can cause a lack of humidity removal. Your focus has been on temperature reduction and not humidity removal. It's time you and your tech thought outside the (furnace blower) box.

  9. #35
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Originally posted by smp7015
    Thank god for this post.

    I have to say I have been having comfort/cooling problems with my house. I have a 2.5 ton unit and evap coil. I have the same furnace and blower. Model number58sta070. I just changed the blower setting to med and it already seem's like its giving me better readings from the vent.

    What should I set the blower speed to?


    1.Have the static measured and then,using the fan data chart it can be set on the proper speed for heating and cooling.

    2.If the static is too low,for the furnace,it can easily be increased,in most cases,by adding damper(s),to the main supply/return.

  10. #36
    Join Date
    Apr 2004
    Posts
    7,680
    OK, Im close to richmond, and I may have to make a trip. If I find his static is below .08 Iris can send me the 10 bucks. I'm always up for a little jack here and again. We may have to agree it can go into the plate on sunday to keep it on the up and up. And of course a survey fee.

    My deal is I pull no punches, and calls em as I sees em. Judging by the equipment selected, this job was driven soley by price. That furnace was not intended as a replacement unit, it is a builders unit. The contractor just doesnt realize that the lower btuh furnace would have cost even less and done a better job.

    I do concede that so far there is not a cooling complaint, In fact, I think he said he is not complaining, it is a matter of the OP second guessing the installer as mentioned. However, Richmond is a very hot humid area, not as bad as Houston but probably as close to as miserable on a regular basis as anyplace else in the US. His airflow should be around 360-400 cfm per ton (closer to 400 if a HP). If his total static is high, he will indeed have noise issues. If its low, he will not find comfort at a setting of 75 degrees becuase he will have a problem removing any moisture. I leave it at this, if he is comfortable at 75 or 76 degrees and the noise level is not objectionable, then we've all wasted our time here on a precieved problem.

    None the less the selection of equipment is wrong and come winter he may have other issues.

  11. #37
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    The higher the static the lower the air flow,and noise.I'd think lower static more cfms,more noise.

  12. #38
    Join Date
    Mar 2005
    Posts
    56

    Re: To All

    Originally posted by eisenberg
    I called the guy that installed the system and he is coming over tonight.He is going to read the tempature at the registers which gives me an isdea of his true skill level.

    I do not think that he is nearly as schooled about the HVAC as all that have contributed to this thread.

    I figured I`d give him a chance to make good and explain his side.

    I will post all of what he does and you can decide.

    [Edited by eisenberg on 06-30-2005 at 05:00 PM]
    ..so the guy comes over last night.

    All that he did was check the freon level with his gauges and said that it had the correct reading for the current outside tempature of about 88. He also attached a totalline brand mechanical thermometer in one of the registers. After leaving the thermometers sensor inside of one of the registers it read right at 60 degrees.

    I have schedule a reputable company to come in and evaluate the system on Tuesday....I will let you know how it gos

  13. #39
    Join Date
    Mar 2005
    Posts
    56
    Originally posted by docholiday

    I do concede that so far there is not a cooling complaint, In fact, I think he said he is not complaining, it is a matter of the OP second guessing the installer as mentioned.
    I did fail to mention that I was having cooling issues. At the time I just wanted to get an opinion on mixing different sized Carrier units.I mentioned cooling issue later in the thread as things escalated.

    There are so many issues here that I have scheduled reputable company come out and evaluate the system and determine why even when it is only 80 outside the system cannot go below 73 and runs for hours just to get to 73.

    As you guys requested I have verified the companies ability to measure ESP.

    Since this is a gas burning furnace I may be able to test the heating side as well while they are there.


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