Furnace installation building code question

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  #1  
Old 03-01-15, 08:45 AM
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Furnace installation building code question

Hello, I am in Manitoba Canada and ask if the furnace installation of the 2 furnaces in our new home should pass the building codes. We have a new 2400' bungalow with a structural wood floor and 2 High efficient furnaces rated at 115,000 BTU. One furnace heats the main floor and the other heats the basement. We were concerned that both of these furnaces share a common return and contacted the manufacturer. The manufacturer provided us with a letter that says these models cannot share a common return and were designed to have there own separate ducting. We provided the letter to the building inspector that approved this installation however it seems that this is not good enough for him to understand the issue. How could it pass?
Does it say anything in the building codes or Ashrae standards that I can refer to?
 
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  #2  
Old 03-01-15, 11:56 AM
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A building code is just a general guide for some minimum standards and not necessarily the best way to do it for specific equipment. If the code gave the requirements, the code would have to have many volumes to cover all possibilities.

The manufacturer gave you the suggestions for installation and if they are not followed, you are on your own so they are not responsible for the results and you may be voiding any guarantees and warranties if you not follow the written instructions.

Very often there is a mess when people confuse the terms "vents", "ducts", "intakes" and "exhaust".

I am guessing you want the 2 different furnaces to share the same pvc exhaust pipes, which could cause some problems if one was running and the other not running. There could be some kind of back-feeding problem. - Just a guess.

Dick
 
  #3  
Old 03-01-15, 12:20 PM
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You most likely have a lot more issues than a common return. 230,000 BTUs for a new home is excessive unless you are on Hudson Bay with the windows open.

I don't understand why are you trying to get the building inspector to fail your home. Are you having issues with your builder?
 
  #4  
Old 03-01-15, 12:23 PM
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Hey thanks, I understood that these furnaces are installed in such a way that they share a common return air duct.
The letter from the manufacturer says that when connected to a common return, these furnaces that have ECM variable speed motors, will "compete" for the available air, resulting in a high static pressure condition and restricted air flow. Over time this is also likely to cause damage and premature failure to the system including the heat exchanger and blower motors.

The builder says he doesn't have to do anything unless the building inspector tells him that it does not meet the building codes and Ashrae standards. Yeah 230,000 BTU seems pretty huge for a new home with R50 insulation in the attic, R20 walls and triple pane windows. Not happy..

Is there anything in the building codes or Ashrae to support this installation should not have passed?
 
  #5  
Old 03-01-15, 12:29 PM
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As mentioned, the building codes are only guidelines to cover general circumstances relating to the many types of products available. Usually they will only quote the specs that equipment must perform at, allowing you to choose the product that meets those specs. Manufacturers instructions always supersede the building codes, provided the equipment is CSA approved and installed according to their directions.

If you have doubts about the setup, I would recommend asking another HVAC contractor to come take a look at it and give his opinion. But at the end of the day, if the manufacturer says you can't do it that way, it don't matter what anyone else says, your warranty will not cover you if the equipment fails.
 
  #6  
Old 03-01-15, 01:28 PM
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I agree with all above advice especially Astuff "You most likely have a lot more issues than a common return. 230,000 BTUs for a new home is excessive". Since it it already installed the contractor will be very reluctant to make changes, but if you don't hit the breaks now and correct some major issues you will be living with the problems.
1. The two units cannot share the same return, the letter from the mfg was very clear. You could ask the mfg for anything in their installation specifications that prohibits this.
2. Why only one return anyway? When a door is closed and there is a supply in that room there needs to be a return, especially in any home hoping to be very energy efficient.
3. Did the builder or HVAC contractor do a heat loss calculation to determine the proper size for those units? Was there a design for the distribution system? Did an architect draw up the plans? If an architect has his/her stamp on those plans s/he may have a voice in any variations.

Dig your heels in.

Bud
 
  #7  
Old 03-01-15, 02:06 PM
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In looking through the code, the only reference I can see that might help you is this...

"9.33.6.14.1 The return-air supply system shall be designed to handle the entire air supply."

In this case I would assume that means the return ducts would have to be double the size they normally would to service two furnaces sharing one duct.

or

"9.33.6.14.6 A vertical return duct shall have openings to return air on not more than one floor."

I would interpret that as one duct per floor, but that does not necessarily mean they can not be combined in a horizontal duct in the basement.

If you can show the building inspector that one of these two conditions ar not being meet, he should not be able to pass it.
 
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Old 03-01-15, 02:25 PM
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In the U.S. at least, it is pretty well established that a building inspector's silence doesn't trump the contractor's obligation to follow product manufacturer's requirements.

Here, building codes, if any, are usually invoked only by the local town or county. Believe it or not, many areas of the U.S., including mine, do not have building codes and do not have building inspections for residential construction. So, if a contractor wasn't obliged to follow manufacturers' instructions, we could be left in a big hole.

Was there a requirement where you live that the furnace installer be licensed? If so, file a complaint with the licensing authority. Or, file suit.
 
  #9  
Old 03-01-15, 03:19 PM
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Hey thanks guys very much for the info, it really appreciated. The building inspector has really not been that helpful. He went back to the builder and was supplied the following details:

The heat loss of the main floor was calculated at 98,610 btu's.

The furnace selected for main floor was a Goodman variable speed model # GMV95115

The furnace selected for the low level was also a Goodman GMV95115

The ducting system was designed at 0.4 esp

The ventilation system installed was a VAN EE 190H heat recovery ventilator

The ventilation summary report was forwarded

This system meets the total ventilation capacity of the home

Manitoba Hydro's gas division inspected the installation, approved the installation & unlocked the gas meter

The HVAC system meets all codes & requirements
 
  #10  
Old 03-01-15, 03:29 PM
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I don't have a copy of the HVAC codes, but I would be willing to bet there is a line in there that says all equipment must be installed as per manufacturers recommendations unless aproved by an engineer.

As it stands now, the manufacturer has been pretty clear they are not installed correctly. Surely something can be done, but I fear it would end up meaning you having the work corrected yourself and trying to recoup your costs in small claims court with the installer.
 
  #11  
Old 03-01-15, 05:44 PM
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The HVAC system meets all codes & requirements
Says who? No it doesn't if it deviates from the manufacturer's installation recommendations. If you think it does, then live with it.
 
  #12  
Old 03-01-15, 05:59 PM
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Gil..... you misread post 9. The OP doesn't think that.
The inspector was told that by the builder.
 
  #13  
Old 03-01-15, 06:32 PM
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That info the inspector was given is not accurate. The ventilation failed actually but that is another issue. They never installed an HRV pick up or an exhaust fan in the MBR that has a jacuzzi tub and jetted shower and sink. It was a struggle getting the building inspector to agree with that much. So I am stuck having to show him where in the building codes or Ashrae standards that the furnace installation does not meet the requirements. The filter area on these furnaces is only 16X25 and I understood from the manufacturer that the return air duct is hardly big enough for one of these furnaces never mind both of them sharing it...

Hey guys, do you think this information from Ashrae would be helpful to give the inspector?

ASHRAE Standard 62.2-2013:

6.4 Combustion and Solid-Fuel Burning Appliances.
Combustion and solid-fuel burning appliances must be provided with adequate combustion and ventilation air and vented in accordance with manufacturers’ installation instructions; NFPA 54/ANSI Z223.1, National Fuel Gas Code5; NFPA 31, Standard for the Installation of Oil-Burning Equipment; or NFPA 211, Standard for Chimneys, Fireplaces, Vents, and Solid-Fuel Burning Appliances, or other equivalent code acceptable to the building official. Where atmospherically vented combustion appliances or solid-fuel burning appliances are located inside the pressure boundary, the total net exhaust flow of the two largest exhaust fans (not including a summer cooling fan intended to be operated only when windows or other air inlets are open) shall not exceed 15 cfm per 100 ft2 (75 L/s per 100 m2) of occupiable space when in operation at full capacity. If the designed total net flow exceeds this limit, the net exhaust flow must be reduced by reducing the exhaust flow or providing compensating outdoor airflow. Atmospherically vented combustion appliances do not include direct-vent appliances.

Another section on Exhaust Ducting notes the following:
8.5.1 Exhaust Ducts. Exhaust fans in separate dwelling units shall not share a common exhaust duct. Exhaust inlets from more than one dwelling unit may be served by a single exhaust fan downstream of all the exhaust inlets if the fan is designed and intended to run continuously or if each inlet is equipped with a back-draft damper to prevent cross contamination when the fan is not running
 
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Old 03-01-15, 06:48 PM
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The way I read them.... neither one pertains to you.... especially with exhaust ducting in separate dwellings.
 
  #15  
Old 03-01-15, 06:51 PM
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6.4 deals with the fresh air intake, so that would not apply to cold air returns.

8.5.1 sounds lIke it is dealing specifically with exhust fans such as those in your kitchen or bathroom, so i am not sure that would apply here either.

if your manufacture is saying that the return duct size is only big enough for one furnace, than it seems to me it violates 9.33.6.14.1 since the duct is not big enough to handle the entire air supply.

Most municipalities have more than one inspector on staff, have you tried talking with another one? They are supposed to be there to protect you and it seems clear to me there is at least one code violation here they are ignoring.
 
  #16  
Old 03-01-15, 07:20 PM
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A technical note that might get the inspector's attention is, with the shared returns, when one furnace is running, the return connection to the second furnace will make all the supply connections of the second furnace act like return paths. Return air will be flowing backwards through the second furnace both reducing the desired return from the area served by the first and creating a pressure imbalance between the two zones. Pressure imbalances are all too often satisfied by outside air.

I believe the suggestions that code MUST follow the manufacturers requirements combined with the statement you have from the mfg is what you need. If the inspector needs something more than the communications you received, ask the mfg for additional documentation and have them direct a letter to all involved. Ask them to include how sharing the returns would affect the warranty.

If that fails to get results, include all information and attempts by you to get this properly resolved in a registered letter to the builder, the contractor, the town and the inspector indicating your intentions to hold all of them responsible for all resulting costs.

Bud
 
  #17  
Old 03-01-15, 07:28 PM
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Hey thanks guys, unfortunately there is only one building inspector in our municipality and he is reluctant to bother the builder, I think they are buddies.

I also had an air flow report done measuring static pressure and such and gave it to the inspector but he didn't seem to understand it. Does anyone here know how to read an air flow report ?
 
  #18  
Old 03-02-15, 10:31 AM
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It sounds to me like your inspector is either very underqualified, or is just making excuses. You have all the things you need to show it is not done properly. Take Buds advice and gather it all together, and start filing complaints.

The only other things I can recommend is to have a different HVAC installer come and inspect the work and see if he agrees with the installation. Maybe he can specify the codes it breaks. Also, call the manufacturer back, and explain to them what is happening. I am sure they don't want to see their equipment installed improperly by qualified companies. They may be willing to help you somehow.

Just out of curiosity, both of these furnaces run separate zones, correct? So one only comes on when the upstairs calls for heat and the other only comes on when the downstairs calls for heat, right?
 
  #19  
Old 03-02-15, 02:21 PM
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Hey thanks guys. The building inspector said today that the ventilation and furnaces were installed by a HRAI registered contractor and also said that he will seek code compliance once there is evidence of a code violation. He has asked that we have another site inspection with people knowledgeable with the installation and furnace to determine if there is a code issue.
What would he need to inspect? What possible evidence does he suggest he would need?
I think the letter from the manufacturer already determined the issue.
 
  #20  
Old 03-02-15, 02:48 PM
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See if you can get his HRAI license number. Then ask the HRAI where they stand on this installation. To be licensed they have to follow the proper installation procedures as well as codes.
How to Join HRAI

Bud
 
  #21  
Old 03-02-15, 05:26 PM
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If at all possible, get a rep from the company at that next inspection.

The research I have done indicates that with a variable speed blower, you should NEVER share ducts. Even in the cases where it is aloud, the duct still has to be sized big enough to service both furnaces at the same time.

The only circumstances I can see where it is allowed is if the furnaces are twined, meaning they are set up to both come on at the same time, or have a controller that will alternate their operation. Also they would require backdraft dampers so one furnace can not draw air from the other.

Keep us posted, but you REALLY need to get a third party in there who has no vested interest in the outcome to look at this.
 
  #22  
Old 03-14-15, 08:33 AM
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Still plugging away trying to make some progress. The furnaces installation had been passed by Manitoba Hydro (the gas company) inspectors. Manitoba hydro says the installation passes the B149 gas code and apparently could only fail if the furnaces were twinned and the guy said something to the effect that our furnaces have dual drops and they are not considered twinned. The hydro guy said it is a ducting issue that our furnaces share a common return and that is not under their jurisdiction and it would be the RM building inspectors responsibility. I don't know if the guy is just sweeping this under the carpet, from what I can understand it would seem to me the issue could be considered under their jurisdiction.

"3. Manitoba Hydro is responsible to inspect all gas appliances in the Province of Manitoba. All installations are inspected to ensure compliance to the B149.1 Gas Code, Manitoba Gas Notices and the manufactures installation instructions."

The RM building inspector is still not much help either, he says he does not know what building code under his jurisdiction this installation fails. I also asked him to provide me the license # of the HRAI registered contractor that installed the furnaces and asked if he could get the mechanical drawings from the contractor. That was 9 days ago, I followed up with him again a couple days ago and it appears he is simply ignoring me and not replying.

I don't want to have to hire a lawyer to send letters or go to court to get answers about building codes or would think that I would have to...
Who's jurisdiction do you guys think the issue is under, the gas company or the RM building inspector?
 
  #23  
Old 03-14-15, 09:47 AM
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I wouldn't think the gas company would have any problems with the duct work.
Their concern is the gas line and possibly the flue.
 
  #24  
Old 03-14-15, 04:28 PM
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No, I wouldn't say the gas company either. They are only concerned about the safety part of the appliance, not how well it functions.

As I stated in one of my first posts, 9.33.6.14 of the building code deals with return air ducts. Your inspector should be able to look at that code and tell you if it passes or not. Based on what you have described, it does not pass. In addition, the manufacturer has already said the install does not meet their requirements, and will void your warrenty. That alone shoudl be enough for your inspector to question the setup.
 
  #25  
Old 03-14-15, 04:52 PM
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Who's jurisdiction do you guys think the issue is under, the gas company or the RM building inspector?
It's yours. This is a contractual dispute which you are wanting public bodies to save you the cost of a lawyer. Move on and get over it.
 
  #26  
Old 03-16-15, 06:43 AM
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The work has to meet the building codes, if it doesn't the inspector is supposed to go back to the contractor and have them comply with the requirements. I don't think I should have to get a lawyer to try and find out information about building codes and if my installation should pass.
I am trying to learn where in the building codes it would say this installation would not meet building code and who's jurisdiction the issue falls under.
 
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