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Old 02-02-2014, 04:32 PM   #31
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Central AC/Furnace Repair Question


If the rust is inside the heat exchanger. The A/C coil is not causing it. Even if its on the outside of the heat exchanger, the A/C may not be causing it.

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Old 02-02-2014, 04:57 PM   #32
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If the rust is inside the heat exchanger. The A/C coil is not causing it. Even if its on the outside of the heat exchanger, the A/C may not be causing it.
I dont know if there's any rust inside the heat exchanger. I did just go snoop around the AC coil and I'm positive there's some leaks coming from its casing and dripping down to the furnace. I see rust lines where water left streaks on the casing. I'm guessing the water was leaking out of the AC coil casing and leaking down to the floor as well into the furnace burner and electrical compartment. That's why there's noticeable rust in that compartment. Also, the model I provided in one of my earlier posts was for the AC coil not the furnace. I just found the sticker for the furnace information.

Looks like mine is model 58PAV135-16. Manufactured in March 2000. It has a rated 132,000 BTU input/hr and 107,000 BTU output/hr.
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Old 02-02-2014, 05:45 PM   #33
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I figure if youre going to all the trouble to replace a furnace and build a new transition to make everything why not change the A-coil at the same time to avoid having ro redo it down the road and having to fight with the tin twice, did I mention I hate sheetmetal work?
Especially if its a carrier coil thats known to have problems already.
Thats just my thinking anyway
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Old 02-02-2014, 06:07 PM   #34
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I dont know if there's any rust inside the heat exchanger. I did just go snoop around the AC coil and I'm positive there's some leaks coming from its casing and dripping down to the furnace. I see rust lines where water left streaks on the casing. I'm guessing the water was leaking out of the AC coil casing and leaking down to the floor as well into the furnace burner and electrical compartment. That's why there's noticeable rust in that compartment. Also, the model I provided in one of my earlier posts was for the AC coil not the furnace. I just found the sticker for the furnace information.

Looks like mine is model 58PAV135-16. Manufactured in March 2000. It has a rated 132,000 BTU input/hr and 107,000 BTU output/hr.
Without actuall walking through your house it would be a total shot in the dark for anybody to size equipment for you.
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Old 02-02-2014, 06:14 PM   #35
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Without actuall walking through your house it would be a total shot in the dark for anybody to size equipment for you.
Of course. I was more along looking for information on my current model. But just recently, I found the correct model number for my furnace and have since looked up information specific to that model which I posted in my previous post. So if I decide to go with a new furnace will look for something in the similar range or 100000+ BTUH. The current rated efficiency of my furnace is 80%. This furnace had done an OK job so far in heating the home but my 2nd floor is always the coldest in the house. The furnace is in basement. Maybe I'll look at something in the 120K output BTUH range which would be a bit more than my current furnace's rating. Not sure if that'll make any difference. I'll also be looking for one with 95% + efficiency.
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Old 02-02-2014, 06:34 PM   #36
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If you go with a 90 plus furnace you could probably get by with something in the 110, 000-115, 000 btu range and come up eith the same numbers.
As far as the upstairs being cold heat tends to rise making the upper levels the hotter part of the house.
Have you checked the insulation in the attic?
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Old 02-02-2014, 07:13 PM   #37
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If you go with a 90 plus furnace you could probably get by with something in the 110, 000-115, 000 btu range and come up eith the same numbers.
As far as the upstairs being cold heat tends to rise making the upper levels the hotter part of the house.
Have you checked the insulation in the attic?
I had someone come in and do an audit on the attic insulation a few months ago. He estimated by current R-value to be 20 in the attic and recommended and R-value of 49. Looking at my last month's gas bill, it's around $278 with a used of 349 CCF and 10.3 CCF average daily usage. Any ideas on how I can estimate the cost savings on gas bill if I upgrade to a 95%+ efficiency furnace.

Thank you.
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Old 02-02-2014, 07:37 PM   #38
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1) You don't need to replace the AC coil just find out where the water leak is. Could be the drain line or it froze up from lack of Freon or poor airflow. If the drain pan has holes in it and that is rare for them then it needs replacing but I doubt it.

2) You should do a heat loss calc yourself and come up with the proper size. I would upgrade the attic insulation later and that does not necessarily mean you need a smaller furnace then. It may run less often but as long as the ducts are big enough now then go with what you have now for insulation. Try this calculator

3) A private contractor may get the job done sooner just depends on how backed up they are. The big box guys may be busier and yeah you would have to get in line and wait. Usually if you have no heat most companies will try get you to the front of the line. I would not trust that online stock info as it may not get updated often, the salesman who comes to your house will know the availability and first install date so don't panic.

4) I would recommend a 2 stage furnace with an ECM variable speed fan. That will give you longer more even cycles as it runs on a low fire (2/3 of normal) a lot of the time and goes to high fire when it is very cold outside. The variable speed fan is stronger and gives you better airflow. Amana/Goodman makes a good unit and won't break the bank.


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Old 02-02-2014, 08:05 PM   #39
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Quote:
Originally Posted by plummen View Post
I figure if youre going to all the trouble to replace a furnace and build a new transition to make everything why not change the A-coil at the same time to avoid having ro redo it down the road and having to fight with the tin twice, did I mention I hate sheetmetal work?
Especially if its a carrier coil thats known to have problems already.
Thats just my thinking anyway
Replace the A/C coil now, and limit his choice of efficiency and possibly brand later.

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Originally Posted by sumit381 View Post
Of course. I was more along looking for information on my current model. But just recently, I found the correct model number for my furnace and have since looked up information specific to that model which I posted in my previous post. So if I decide to go with a new furnace will look for something in the similar range or 100000+ BTUH. The current rated efficiency of my furnace is 80%. This furnace had done an OK job so far in heating the home but my 2nd floor is always the coldest in the house. The furnace is in basement. Maybe I'll look at something in the 120K output BTUH range which would be a bit more than my current furnace's rating. Not sure if that'll make any difference. I'll also be looking for one with 95% + efficiency.
That would probably give your new furnace a short life span. Your upstairs being colder is a duct problem. not furnace size problem.
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Old 02-03-2014, 07:38 AM   #40
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Originally Posted by beenthere View Post
Replace the A/C coil now, and limit his choice of efficiency and possibly brand later.
Not sure what you mean by this. Can you explain a little more?

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Originally Posted by beenthere
That would probably give your new furnace a short life span. Your upstairs being colder is a duct problem. not furnace size problem.
What sort of duct problem could it be? I recently had the all the ducts and returns cleaned as part of the mold remediation that was done due to the water heater leak. So I wouldn't think there's any blockage in the duct? Any other ideas on what the duct related problem would be?
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Old 02-03-2014, 07:55 AM   #41
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1) You don't need to replace the AC coil just find out where the water leak is. Could be the drain line or it froze up from lack of Freon or poor airflow. If the drain pan has holes in it and that is rare for them then it needs replacing but I doubt it.
There is a drain line that comes off of the AC coil and goes into the ground. I've noticed that sometimes there a little puddle of water there. Maybe that drain is getting backed up? I never really thought much of it until you mentioned it. When the drain pipe goes into the ground, would it lead to the sump pump?

Quote:
Originally Posted by yuri
2) You should do a heat loss calc yourself and come up with the proper size. I would upgrade the attic insulation later and that does not necessarily mean you need a smaller furnace then. It may run less often but as long as the ducts are big enough now then go with what you have now for insulation. Try this calculator
Thanks for that link. I'll give it a try.

Quote:
Originally Posted by yuri
3) A private contractor may get the job done sooner just depends on how backed up they are. The big box guys may be busier and yeah you would have to get in line and wait. Usually if you have no heat most companies will try get you to the front of the line. I would not trust that online stock info as it may not get updated often, the salesman who comes to your house will know the availability and first install date so don't panic.
I'm just waiting for the guy from the energy company to show up today and see what he says. Like I said before, I'm not too concerned with going with big box or local contractor. I just want a furnace that's reliable and someone who can get here the fastest.

Quote:
Originally Posted by yuri
4) I would recommend a 2 stage furnace with an ECM variable speed fan. That will give you longer more even cycles as it runs on a low fire (2/3 of normal) a lot of the time and goes to high fire when it is very cold outside. The variable speed fan is stronger and gives you better airflow. Amana/Goodman makes a good unit and won't break the bank.
I will keep that in mind. If variable speed fan gives better airflow, do think that'll help with the issue of the 2nd floor not getting as much heat as the 1st floor? Also as a side note, in the summer months, the 2nd floor is warmest which is somewhat expected I guess since cold air falls.
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Old 02-03-2014, 08:10 AM   #42
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1) Your AC coil if it is 14 yrs old will be a 10 SEER and nowadays they are all 13 SEER or up to 21 SEER which is an efficiency rating. the 10 is obsolete and any other coil is a mismatch. The replacement is 13 SEER and a mismatch for your outdoor unit now. Plus later if you want a 14 or 16 or higher SEER outdoor unit it won't work with a 13 SEER coil. Just get it properly checked for Freon level , dirt and where the water leaves the coil/drain fitting to make sure it is not plugged. Also you don't really want to start mixing a Carrier coil with a Trane unit later etc. You want a matched set or it won't dehumidify properly etc etc. Can also cause warranty problems later.

2) Your problem upstairs is they way they build houses and sometimes the ducts are too small or by the time the air travels 50-100 feet and thru 5-6 elbows it slows down and loses velocity. A skilled contractor can look at the ducts and see if there are any improvements that can be made. This is where the el cheapo guys that some of the big box stores use fall short technically. The high end contractors don't do big box work as they don't get paid enough.

3) A ECM variable speed fan will help get more air upstairs but you REALLY need a skilled contractor to check the supply and return ducts to see if they are large enough or properly done. An oversized furnace will overheat and the cells will crack very soon. DO NOT go that route.
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Old 02-03-2014, 08:41 AM   #43
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A properly sized 2 stage will help to get your upstairs temp closer to the downstairs.

If you get a 2 stage furnace. insist on a 2 stage thermostat to control it.
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Old 02-03-2014, 05:27 PM   #44
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Ok, so a repair man from my energy company came and checked out the furnace. I told him about the other HVAC guy refusing to start the furnace due to cracks. The repair guy today mentioned that this particular furnace will not start up if the crack is significant. He did some work on it. I think he said that he changed a motor? Then he started the furnace up and it's running as it did before. To be one the safe side, I purchased CO detectors. None of them have gone off yet.

Here are my knowns:

1. the guy today didn't check the state of the cells. He simply said that if the crack is significant, the furnace won't start up.

2. I have CO detectors (new batteries and in working condition indicated by green light flashing every 30 sec) and none of them have gone off. I put one about 5 ft from the furnace and that didn't go off either.

3. I don't have any of the symptoms I've read about on epa.gov website of CO exposure at low or high levels.

4. The detectors I have go off at or above 70 ppm of CO. epa.gov states that "Average levels in homes without gas stoves vary from 0.5 to 5 parts per million (ppm). Levels near properly adjusted gas stoves are often 5 to 15 ppm and those near poorly adjusted stoves may be 30 ppm or higher."


I'm left a little confused now as to what I should make of this. The 1st guy said I need to repair the furnace right away and by law he can't turn it on. The 2nd guy says no big deal, changes a part, and starts it up. For now, my plan is to monitor the sensors closely and see if any go off.

Any thoughts would be appreciated.
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Old 02-03-2014, 06:58 PM   #45
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This guy is giving you WRONG info. It will not start up if the crack is so huge that the flames rollout the front of the furnace and hit the rollout sensors or it cannot produce enough draft to prove the pressure switch. By that time you are getting CO in the house. A smaller crack and it could start up but still leak CO into the house. Once it gets bigger then the fan forces air thru the crack and pushes the flame and CO out the front of the furnace. He could not see the cracks because he could not look down from the top and do a thorough check like the first guy plus now the AC coil is close to the top so you cannot go in there and look down. If he pulled the fan out and crawled in and looked up he may see them. Sounds inexperienced to me. The gas code says that if it is cracked and there is flame disturbance then it must be shut down ( in my area). All depends how big the crack is and it may get bigger soon. You are the one living there so if it was me and my family at risk I would get a new furnace ASAP or fix it. He is off the hook as he documented it and shut it off.

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