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
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
Originally posted by docholiday
If his total static is high, he will indeed have noise issues
From a different thread:
Originally posted by Irascible
I went back through eisey's previous posts. It seems that he admitted that only one diffuser was actually noisy
It wouldn’t be so bad if only you missed what was said several times in this thread Doc. But the fact that eisenberg forgot that he said it this thread just takes the cake.
Originally posted by eisenberg
To be honest the only register that is loud is the register which is first in line off of the air handler
Thank you for acknowledging my considerable efforts to educate you eisenstein. Dealing with homeowners like you makes all the effort put into giving free advice worthwhile.
hey...hey.. give me a chance to reply...I am at work ya know. Gotta do at least 15 minutes of real work a day.
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?
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]
Irascible - Shortly after you posted the above I printed it out along with the linked chart for the techs when they arrive Tuesday....and is greatly appreciated.
My last post was simply a follow up after the origional HVAC guy came by last evening. I was going to get around to responding to your post during my lunch break.
The only reason that I harped on the 3ton blower issue is that some of the guys brought up some good issues like humidy removal....the air passing so quickly across the coils that moisture removal is effected.
..I am totally with you on the fact that it really doesn`t delivery 3tons of air when you have to figure in ESP which they will be measuring. If they can get it to work I will be fine with the extra air flow.You make a good point on why doesn`t the system cool...we measure the register temp at 60...why doesn`t the house cool beyond 73??? That is what I hope the guys on Tuesday can answer.
determining External Static Pressure
Could someone let me know how the HVAC guys are going to determine the ESP?
Although they say they test this I want to make sure that it is done.
Originally posted by dash
Before he comes out,ask If he can test/measure the ESP(external static pressure) of the furnace.
Many can't and if you say ESP,and he's not sure what you mean,he's one of them.
He may not have the fan data for Carrier,best to ask about that as well.
The chart includes .1 for a factory type filter,he will need to adjust for this ,if it has a different filter.
Test points are entering and exiting of the furnace,The exiting point is between the furnace and the coil.A/C needs to be running(wet coil) during the test.
Excuse my premature sarcasm eisenberg. Though I enjoyed sharing it nonetheless.
one down one to go
OK... I had one guy come by and right off the bat he said the system was not matched correctly and that the CFMs were way to strong....the blower was set on its lowest speed at the time. He did not perform the ESP test just feeling confident that he was correct in thinking that the CFMs were way to high.
He said that what is happening is that the air is going across the coil so fast that only about 1/2 of the moisture is being removed and that the air was not getting as cold as it should due to the speed as well..although the temp of the air at the register is 60...he said that low temp could be due to the high CFMs giving a false reading. When the system finally cycled off we both noticed that the air was humid in the house even though the system had been running for hours.
He recommended that I have the origional installed remove the 58STA070-12 inside unit and replace it with the 58STA070-8 which he says should have been done in the first place. He could not understand why someone would over size the blower in a house that is 900sq ft. with 5 / 52inch ceiling fans running. The installer told me that the reason for the oversizing was to get the air to the floor in the cold season (the ceiling fans could easily do that for the correctly matched system). He thinks that when the installer got to the supply house they were out of the correct model and he settled on the -12 unit since he wanted to get the job done that day. I do recall the installer picking up the units half way through the job and told me that he installed the -12 unit after it had already been put in place.
At least I have the origional signed by both parties proposal that lists the correct unit in case this end up in court.
I will let you know what the company that can measure the ESP says after they arrive Tuesday
Irascible - I showed this guy your post and he did agree with you on that it is OK to go 1 ton over in some situations, but he said mine was a special case since my house is incredible small. I will check the survey on my house, something is telling me that it is actually 850sq ft. rather than 900sq ft. He also agreed with you about most houses being .8 ESP and was happy that other folks recognize this common oversight.I let him see the Carrier CFM chart as well
[Edited by eisenberg on 07-02-2005 at 11:09 AM]
next time you see the guy who sold you that big a furnace, please strangle the heck out of him for me!!! the furnace has too big a drive for your ac. what i think is needed is a bigger temp split. that is, there should be a 15 - 20 temp split between return and supply. if its 80 in house, 60 - 65 F coming out of the register will suffice. something to slow down air flow would be to restrict it. throttle the registers in your house back to about 50%. that should slow down the air. or shove a piece of cardboard in with your filter. dont cover up more than 50% though. we dont want that coil to freeze up!
as i have said erlier i have done this on ocasion
gentalmen 4 pages on air flo and cfms and all the goes along with it. my question is what is the superheat, subcool, presures, line temps both. how can anyone say it is blower related without the rest of the info. if the charge is correct yes you will loose on td and humidity but the house should still cool. 2 ton condenser 3 ton drive and the house isnt cooling but load calls for 1.5 ton
he is pushing 1200 cfms through a 2 ton system and if the td isnt enough ok slow it down. put if the charge isnt correct it wont solve a thing
also the duct work is restricked and is cutting back on cfms also but i will bet the air is blowing stong out of the registers. please give us the rest of the info
something is wrong here and i dont think it is airflo related
With whatever due respect eisenberg, that last guy didn't do a damn thing except walk in and tell you what you wanted to hear. A freakin magnahelic (pressure measuring tool) is less than $100. Why didn't he or any of these other clowns have one and measure the pressure?
Furthermore, IF your system is at .8" ESP then that airflow is PERFECT. IF your system is at .8" ESP you do NOT have too much airflow. That's what my long post above was about. That's why you have a link to the blower chart to see for yourself. I certainly understand why your contractors don’t get this. The trade is chock full of hacks, clowns and idiots. The guy that installed your furnace may be one of the same. But I don’t understand why you’re not getting this.
Furthermore, your complaint has been about temperature drop. IF that's still your complaint then that furnace helps you, not hurt. Yes, increased airflow will decrease the temperature drop. But it's more than made up for by the increased airflow. AC capacity is a product of temperature drop AND total volume. If you decrease temperature drop by X but increase airflow by 2X then you have a net gain in capacity. I’m talking sensible capacity (temperature reduction) and not latent capacity (humidity removal). Your sensible capacity is helped by the extra airflow.
I'm NOT defending the installation of an oversized blower when he didn't even discuss it with you ahead of time. But IF your complaint is about temperature drop then putting in the -08 furnace WILL MAKE IT WORSE. That is a fact. Put it in your pipe and smoke it.
yes, we could use some more data. it has occured in my thoughts that the blower is not quite the problem. we do need to know what the charge is, but a question, did your contractor do a heat load calc? sit down and talk to you about your new system. ( i dont do sales, but my companies sales people spend like 2 hours at the customers house. they make sure that the units they tell the owner will work are correct. we sell Trane and Gibson. both good units, trane more $$$$!) if the guy didnt heat calc, then perhaps your unit might be to small / large? i dont know, but then again, i'm just a new service tech!
You really need a contractor/tech to check the ESp,you are no better off ,then when you first posted,until it's checked.
..I have someone coming out today
I have a reputable company sending there design/test guy over at 1pm EST today to eval/test the existing install.
Yes... he is able to perform the ESP test
I will let you guys know how it goes
..First off I want to thank all that contributed to my posting.
The contactor ended up enlarging all 7 of my flex duct vents from 6 inch to 8 inch. Turns out that the biggest problem was where he positioned the return. It is now located in a place that allows the system to breath.
The system works great