Furnace nightmare

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cuda2
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Joined: Fri Nov 09, 2012 11:01 am

Hi, We just had our gas hot air furnace replaced in our 1000 sq ft 1960s manufactured home. With a nordyne cmf2 80 pg 75000 BTU this heater gets its supply air from the door, our old unit pull air from a side vented into our hallway. It sits in a 4ft by 3ft closet along side our gas hot water heater. Now when the blower comes on it pulls a back draft from our HW flue vent, and everywhere else in the house. They tell me I’ll need to change to an electric HW heater. There is not even a door on the closet ,because they had to enlarge the opening from 32 to 36 for access. And I’ll need a new louvered door. Our old heater did none of this. Also the upper cabinet gets to hot to touch when running and smells like burning paint. Is there a proper way to relive this supply air pressure? They don’t seem to have a clue in dealing with this type of housing. thank you
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Greg
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Is it pulling combustion air or fan distribution air?

Greg
"If I can't fix it, I can screw it up so bad no one else can either."
cuda2
Posts: 6
Joined: Fri Nov 09, 2012 11:01 am

Hi, Its pulling fan distribution air or supply air, from the vent in the heater door. When the blower comes on is when it backdrafts and pulls from everywhere. As far as combustible air,the old system had an 18in long by 2in wide vent that went into the crawl space underneath the base for combustible air.This new one has a 2in flex hose going to an adaptor in the base instead of the vent.
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Greg
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If you have a Mobile home approved water heater there should be no way that it is pulling a draft from that. The water heater is a sealed combustion unit pulling fresh & exhausting OUTSIDE air. If your water heater is not M.H. approved than it may be possible to suck exhaust gasses into the home.

Water heater aside, you may need to add a louvered door to allow enough circulation air or run with no door for now. The fact that it is too hot to touch bothers me, I think I would have it checked by a company that knows Mobile home systems.

Greg
"If I can't fix it, I can screw it up so bad no one else can either."
cuda2
Posts: 6
Joined: Fri Nov 09, 2012 11:01 am

That's the problem, I don 't seem to be able to find anyone, In the South Jersey area that understands mobile home systems. Any idea were I would look or how. I 've called some mobile parks in my area, but they couldn't help. I don't know what to do. Also do you think it needs some type of makeup supply air? Thank you, mike
1987Commodore
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Greg
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You could also contact a few Mobile home dealers in the area for some contacts.

Greg
"If I can't fix it, I can screw it up so bad no one else can either."
DaleM
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Joined: Wed Apr 07, 2010 10:07 am

As old as your home is the ducting may be too small for the additional airflow from the new furnace. The "old" furnaces blew very little HOT air into the home to heat it. Most blower switches back then were 145-155 degrees. Nowadays the blowers either come on with a board controlled timer or a fairly low switch temperature (110-120 degrees), they also move about 3 times as much air as the older furnaces. That is where your problem lies. The old ducting is not big enough to handle your new furnace's air flow because it was built to handle the original furnace' airflow specifications.

Greg is spot on about pulling air from the water heater venting...IMPOSSIBLE with the proper mobile home water heater.

You should run your furnace with the door open and also consider making the floor register openings larger or adding 1 more in each room. That will help the airflow situation some and it's cheaper than having someone replace all the ductwork in the belly of your home.
cuda2
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Joined: Fri Nov 09, 2012 11:01 am

Hi, So a smaller furnace would not be much help. Its the cfm that the blowers is pushing into the small mobile duct system that is the problem. Also I got the owner of the company involved, he wants to try reducing the gas orifice, so we can run the fan on lower speed. They installed 2 45s in the flue, where the installation manual stated direct vertical and no elbows, probably why the cabinet is hot when running he also wants to install and additional flex duct cut into the main trunk. He also gave me the option of removing the furnace and refunding my money (I had stopped payment on the check) There are some real hackers out there. Where they drilled in the floo for the direct vent for combustible air, they went to far and put holes in the duct and just covered it with the vent adaptor. I discovered various other unprofessional work. I have no confidence in there work.I read where outside units(gaspacks) are better suited for mobile home ducts. A code officer told me I did not need a mobile home water heater, but a direct vent is what I should go with.WHeaterIwas was was told byby a code officer my modular
cuda2
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Sorry for the mess at the I'm using a kindle.
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Greg
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OK, So the mess just keeps getting bigger.

I think if it were me I would keep on trying to work with the owner of the company, he has the most to loose. It almost sounds to me like he is concerned about the situation, and He should be since should anything happen he would be the one swinging.

I will stop short of calling the code officer an idiot, but if the shoe fits.... They make Mobile Home approved water heaters for a reason.

You DO have a working carbon monoxide detector don't you?

Take one step at a time, at this point I think the furnace issue is the more important problem to address.

Greg
"If I can't fix it, I can screw it up so bad no one else can either."
cuda2
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Joined: Fri Nov 09, 2012 11:01 am

I contacted someone under mobile home repair from the list. He was very scary. I kind of hit a brick wall in trying to find someone experienced in manufactured housing. With so many out there, you would think companies would be more experienced in dealing with mobile home duct work and heating. At least here in South Jersey.
DaleM
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PM sent.
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