I had a furnace installed in my house (1984, 2400 square foot) to replace the following furnace in March, 2009.

Old furnace:
Ruud UGLH-10EAMER - 100,000 BTU, 80% AFUE, single speed 1200 CFM blower

New furnace:
Ruud UGGD-09EZCMS - 90,000 BTU, 92.3% AFUE, variable speed 1200-2000 CFM blower

By the way, I was given the new furnace information by the contractor, so I'm not 100% sure that the information is correct. He also removed the yellow EnergyGuide sticker when he put in the new furnace, and there is no model/serial number anywhere in or on the furnace that I can find.

When they first installed the furnace, it had a loud harmonic noise coming from the ductwork. To solve the problem, they bent all the fins on the cold-air intake.

Does this sound like they put in too large a furnace/blower, or do you need additional information?
Is bending the fins on a cold-air intake standard practice to correct a noise problem like I mentioned above?
Why would a contractor remove the EnergyGuide sticker?
Why would a furnace not have a model/serial number in it?

Well a 100,000 at 80%= 80,000 BTU available

and a 90,000 at 92.3 =83,070 or there about

The furnace size is close but what you do not really know for sure is what size exactly do you really need for your home to start with. Many times the original furnace is to large to start with so you never use the old furnace size to calculate what you need gor the new furnace size. You actually do a manual J

Your furnace information is on a permanent sticker/plate that is located on the inside of the front door around the furnace burner area. You have to lift and remove the door to read it.

Does this sound like they put in too large a furnace/blower, or do you need additional information?

The furnace was sized according to the old one so see above for that info.

Is bending the fins on a cold-air intake standard practice to correct a noise problem like I mentioned above?

If that got rid of the noise and caused no other problems it worked.

Why would a contractor remove the EnergyGuide sticker?

No idea here but I believe those are to stay on the equipment but many times for appearance they are removed. It is used as a indicator to the end customer what the energy efficiency/energy rate.

Why would a furnace not have a model/serial number in it?
The furnace has to contain a factory label containing model,serial number,gas rate,BTU in and out and other items. If there is not a factory label on your unit then it is time to start asking questions since the unit could have been stolen etc. This will also have the UL/CSA information. This label is required by law.

Thanks for your answer.

I posted another question on Manual/J that gives more details on my house to try and see if my understanding of Manual/J is correct. I think the furnace was properly sized when the house was built. A couple of months prior to the furnace installation, I had the ductwork sealed and insulated and the ceiling insulated (floor was already insulated). The next month my gas bill went down about 30% compared to the year before with the same average outside temperature. The contractor didn't take that into consideration because he didn't ask or look when he made the estimate, and I didn't know because I hadn't done any research.

My main concern is the blower. When they replaced the furnace, they kept the original old filter box and 16x20 filter. When I was trying to find the source of the noise, I opened the filter box while the furnace was blowing, and it looked like the filter was going to be sucked into the furnace it was sagging so much in the center. The furnace manual lists two 12x20 filters in a 'V' formation. When I complained about the filter, the came in and replaced the filter box with a single 20x20 filter. I don't know if that is good enough either.

I already know that the contractor is inept and crooked and that I was ripped off. I'd list everything that he did wrong, but I don't want to waste space here. I will list a couple things, though, just to give you an idea. He wrote on the contract that the furnace was eligible for a $1500 federal tax credit. I found out 3 months later that the furnace had to be 95% efficient to qualify for that credit (the installed furnace was only 92.3%). I found out just 2 weeks ago that his address listed on the contract hadn't been valid since January, 2007. I found that out when I decided to drive by his business to see if he was there (he seldom answers his cell-phone). I was pretty shocked to see that the address didn't even exist any more. The building was demolished more than 6 months before I signed the contract, and a new complex is in the process of being built on the site.

Right now I'm trying to determine if I need to replace the furnace and blower again. On the low speed (1200 CFM), I can't even hear the furnace in the house. But as soon as it ramps up I am able to hear it. I don't know if my only problem is noise, or if I need to worry about the blower failing. It seems that going from a furnace that had a 1200 CFM blower to one that has a 2000 CFM blower (67% larger) using the same ductwork would create a lot of stress on the blower and could cause the blower to fail sooner. I have 12 vents, and heard that the normal flow should be around 100 CFM per vent. On full power, I'm getting an average of 167 CFM per vent based on the output of the furnace.

I found the UL/CSA sticker that you mentioned, and it is the model he said. At least I know for sure which furnace I have installed.

Thanks again for your help.

You or a professional who has the correct tools can lower the CFM down if you wish. Just because the unit is capable of doing 2000 CFM does not mean it has to for proper operation. My main system in this house operates at just about 1/2 of its blower capability and actually performs better at the lower speed. The air does not need to scream out of the register to get the job done and besides I hate blower noise. You can sit in my living room and never know the blower is running.

As I said the blower can be adjusted and the design of the blower can be changed so that it will run at different speeds depending on weather the unit is providing heat or cooling.

It sounds like you are somewhat a perfectionist like me. I like to do things the best that they can be done. This is what I specialized in with my HVAC company and my bids were never the lowest and in most cases were 20% higher than the competition but my reputation always sold the job. I always figured if someone wanted a cheap trouble prone job let someone else do it since I always had plenty of work to start with.

Manual J for size of equipment and a manual D for the size and placement of the duct are the best way to go. Then you have a real engineered system that will perform and save energy at the same time. Good luck with your system and for anymore work find a true HVAC contractor who knows exactly what they are doing. You may spend a few more $$$ but the end product will be well worth it in the long run.

Here is a Duct cheater tool. Not perfect but a quick estimate tool.

Amen to getting a qualified contractor. This guy was actually referred to me by the gas company when I filled in a form on-line for a referral. I figured that since the gas company referred him, I couldn't go wrong. Boy was I wrong! Turns out that the gas company's only requirement for referral was that the contractor had a valid license.

On one of the contractor's visits back to my house to replace part of the vent pipes (that they had installed wrong), they decided to replace one of the cold air intakes with a larger unit. They put in a larger diameter flex-duct in the attic. When they replaced the flex-duct, they scooped up insulation into the flex-duct and ran the furnace without the filter in place, sending insulation into the wiring in the furnace and into every vent of the house. I had to have the ductwork professionally cleaned. They paid for it because I already had the ducts professionally cleaned right after they first installed the furnace.

I was able to reduce the blower speed by 15%; one of the dip-switches in the unit allows you to modify the max blower output by +/- 15%, so it's now maxing out at 1700 CFM (when I tolld the contractor that I had done that, he said it wasn't recommended). If there is a way to slow the blower down even further, then that would definitely be the cheapest option for me. I don't have the tools or knowledge to do that, so I'll have to call someone in for that.

I'll have to check the dip-switches to see what the air conditioner blower is set to. The manual shows that it can be set as low as 1200 CFM.

I did a lot of reading on Manual/J, but nothing for Manual/D. I have a wide variety of duct sizes, so even your quick cheat is going to take time for me to figure out. I definitely appreciate your taking the time to answer my questions.

Thanks again for your help.

Blower speed minimums are necessary to maintain and actually the use of tools during blower speed changes are mandatory in my opinion.

On heating a minimum amount of air over the heat exchanger is necessary to prevent damage to the furnace and the same can be said especially when the A/C air flow is set.

On the A/C end you need to maintain not only a minimum amount of air movement across the coil but in most cases you also have to have guages installed on the unit to check for a proper superheat or subcooling which means the refrigerant charge will possibly need to be adjusted. This is why I suggested you contact a professional in your area to provide that service. There is a lot more to HVAC than fliping switches for proper blower speed adjustment if you know what I mean.

Yes, I know there is a lot more to installing a furnace than just hooking it up and setting switches - you need to have the skills and knowledge and tools to make proper adjustments. The contract I had just hooked up the furnace without making any adjustments or measurements.

It's even worse when you have a contractor that doesn't know what is going on or flat out lies to you. On the day I discovered the filter almost being sucked into the furnace, I looked inside the furnace but couldn't find the model number. However, I did see that the blower was 1 HP, and the listed CFM for several different items. I assumed the blower was 2000 CFM, and when I confronted the contractor, he told me that it was actually 1600 CFM. Because one of the configurations inside the unit showed 1600 CFM as one of the options, I accepted his answer. I recently looked at the installation manual, and it shows 2000 CFM for every blower for that furnace ranging from 90,000 BTU to 120,000 BTU - there is no difference for the different heat outputs. That tells me that unless he did some modifications to reduce the blower output, it would be 2000 CFM.

Since they didn't know about changing the filter box for a larger filter, didn't install the venting to manufacturer specifications, didn't seal the duct-work attached to the furnace, didn't seal the leaks around the furnace, and installed the thermostat wiring wrong (then lied about the cause of the problem), I'm very confident that they do a blower speed modification (I was the one that found all the above problems by reading the installation manual, then had to convince them they needed to correct them). They probably didn't have the knowledge or skills to do that type of modification, and based on the shortcuts they did, probably wouldn't have done it even if they knew how. As far as the actual CFM of the blower, I don't know if the contractor just didn't know about or was just lying about the CFM. Based on the rest of the installation, the evidence points more to the lying than the lack of knowledge.

The manual gives a lot of information about the furnace, and even included an installation checklist. One of the groups of items on the list is to check the duct static pressure on heating and cooling, and the amount of temperature rise, and had a spot to put the numbers. Had they done these tests and compared it to the numbers included in the manual, I'm pretty sure that they would have found that the furnace was not correct for this house.

I understand your situation BUT all the blame comes down to the people who hired the contractor to start with especially if they were shopping price or were in a hurry. The same holds true for the heating business as for any other industry in the fact that there are good and bad contractors. Usually the good contractors charge a bit higher price since they have to pay there workers more money as well as covering education overhead to keep those good workers educated on all the new items that arrive in the HVAC business every day. The HVAC industry is a very complex mix of many trades and truthfully 80% to 90% of the folks in it have no real idea of all that is involved since it changes rapidly and for most getting further education is almost impossible due to there working all the time.

Below is something for you to keep for future reference.

Thanks for the document, I wish I had that when I hired the contractor. I learned a lot of things about the whole process, and what could go wrong - unfortunately I gained the knowledge after the fact.

In my case, I wasn't trying to find the cheapest contractor, the problem was I got a little lazy and wanted to get the work done as soon as possible. I learned the hard way to get multiple bids and ask questions. It was also a problem with my lack of imagination - I was thinking "what could possibly go wrong with a furnace installation" - I figured the whole process would be easy - like replacing a refrigerator, stove or other appliance.

I have hired contractors in the past and had minor problems, so I didn't blindly just pick a contractor - at least not completely blindly. The way I found the contractor was through the gas company. I filled in an online form, and they called me back with the name of the contractor. I figured that since they were referring contractors, they would stand behind them, or at least try to help if problems came up. They gave almost no help in resolving the problem.

I checked with the construction contractors board on the company, and there was one final order against them in the last 7 years. Again, because I was in a hurry, I didn't request a copy of the file because it had to come through the mail and I didn't want to wait. I did the second thing wrong next - I asked the contractor to explain the circumstances around the claim. That was when the first of the lies started - he said that he wasn't being paid by the customer, and that he forced the claim to the construction board in order to get paid. Not knowing the claim process (I sure know it now!), I trusted him and took his word.

The real story around the other claim filed against him was he did some work and didn't do a good job. The homeowner filed a claim, and the contractor was forced to come back in to redo some work (sealing and insulating ducts). The work he did continued to be substandard, so the construction board told the homeowner to get estimates for repairing the work. Most of the contractors the homeowner called wouldn't fix the work - the gave estimates for completely removing the insulation and starting over. The homeowner kept getting bids until he found a company that would repair the damage rather than replace all the original work. I don't know how the homowner picked the contractor I used, but I found out that the homeowner was also a contractor. I don't know what the homeowner did in construction or how good he was at what he did, but it shows that even contractors, who should know the construction laws, make mistakes.

I also figured that once the installation had started to go bad and the furnace distributor came on site that things would get better. I was wrong on that too. I even wrote to the manufacturer with the details of the installation, but was only contacted once to get the model and serial number from the furnace. They did nothing to help. In fact, the contractor is still on the Ruud site and listed as a "Recognized Local Top Contractor". Ruud is no longer a brand that I will buy.

I even thought that going through the construction contractor dispute resolution process would get things cleared up. Unfortunately, they seemed to be more concerned about closing the case rather than resolving the case fairly.

Anyway, it's been a process that is still ongoing. A furnace that should have taken less than a day (at most 2-3 visits to correct minor problems) involved at least 9 visits over 3 months, major changes to the installation, two failed inspections, and a claim with the construction board. Live and learn.

This happens every day. For years I have turned down lawyers that want to use me as a professional witness (PW in our neck of the woods) but I do go out for manufactures when they are up against the wall with problems. I try not to make it happen to often and it cost them big bucks but the money I donate for educational purposes in my area. You guessed it I give the $$ for HVAC education. It sometimes buys a tool or some books. I made my bones in this industry years ago so I do not chase the dollar anymore. There is one man that posts here and helps many people. I have met him and so far he has only done a small job for me but I can tell he pretty much knows his stuff about HVAC and hopefully there will be more work from myself and a few others in this area since he enjoys what he does.

Good luck and now that you have learned some lessons on HVAC you will be much smarter the next time around. Merry Christmas

You stated that you are heating 2400 sq ft. My house (which I designed & built) is 1280 sq ft main floor with a full basement; 2560 total. We keep the main floor at 68* - 70* , and the basement at about 60*. The original furnace was 60,000 BTU HE and installed by a contractor. I always thought it was bigger than needed because it cycled so much, so when it finally died, I installed a 40,000 BTU HE furnace. It is adequate down to -10*, which is the coldest it has ever been since I installed it a few years ago.