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Please Check Your Onan Genset Installation

BryanValRox

Elite Member
Folks, anyone that has speced an Onan Genset installation should check the installation for compliance with the installation manual.
Specifically , the aluminum base contains 3 exhaust pipe outlet cutouts(arch like openings). Facing the genset, one is at the front right side, one is at the rear of the right side and one is on the backside at the rear right corner.
These cutouts are not used when the Genset is flat mounted to the compartment floor. The 3 openings need to be blocked off to prevent Hot Air from entering into the front genset compartment . The installation manual calls out that they should be covered with sheet metal covers that can be screwed into the base.
After checking our installation, only our front opening was covered, and it was only covered with foil tape, not the suggested sheet metal plate.

The other installation concern I found was that the genset wasn’t quite centered over the floor opening. This was allowing about a 3/8 inch gap that you could see down thru. This gap also needs to be sealed off to prevent any possibility of hot air recirculating that would reduce the cooling effect of the air flowing thru the genset.
This air flow also supplies the combustion air, so it is important to prevent hot air recirculating. There is a testing procedure called out in the manual on how to check for hot air recirculating.
One last point, a minimum of 12 inches should be maintained under the gentset when in operation for air flow.
The installation manual is posted on the Alliance Rv Academy Owner Empowerment section if you are interested in reading it.
 
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Skford

Member
Folks, anyone that has speced an Onan Genset installation should check the installation for compliance with the installation manual.
Specifically , the aluminum base contains 3 exhaust pipe outlet cutouts(arch like openings). Facing the genset, one is at the front right side, one is at the rear of the right side and one is on the backside at the rear right corner.
These cutouts are not used when the Genset is flat mounted to the compartment floor. The 3 openings need to be blocked off to prevent Hot Air from entering into the front genset compartment . The installation manual calls out that they should be covered with sheet metal covers that can be screwed into the base.
After checking our installation, only our front opening was covered, and it was only covered with foil tape, not the suggested sheet metal plate.

The other installation concern I found was that the genset wasn’t quite centered over the floor opening. This was allowing about a 3/8 inch gap that you could see down thru. This gap also needs to be sealed off to prevent any possibility of hot air recirculating that would reduce the cooling effect of the air flowing thru the genset.
This air flow also supplies the combustion air, so it is important to prevent hot air recirculating. There is a testing procedure called out in the manual on how to check for hot air recirculating.
One last point, a minimum of 12 inches should be maintained under the gentset when in operation for air flow.
The installation manual is posted on the Alliance Rv Academy Owner Empowerment section if you are interested in reading it.
I'm getting ready to install an Onan Genset I removed from my old unit. If I'm following you right I can mount it direct to the floor in the compartment after removing the opening knockouts. Also, how are the ac wires from the genset connected to the RV? There are 2 whites, a green, a black and a black w/yellow line coming from the genset. In the fifth wheel j-box marked for the generator there is a white, a black, a red and ground wire. Thanks!
 

BryanValRox

Elite Member
I'm getting ready to install an Onan Genset I removed from my old unit. If I'm following you right I can mount it direct to the floor in the compartment after removing the opening knockouts. Also, how are the ac wires from the genset connected to the RV? There are 2 whites, a green, a black and a black w/yellow line coming from the genset. In the fifth wheel j-box marked for the generator there is a white, a black, a red and ground wire. Thanks!
I hesitate to answer without knowing and model number and preferable the serial number of your genset.
If you have it, feel free to private message me with it, or post it here if you are comfortable sharing that information.
I will see if I can track down the installation manual for you. There used to be one posted under resources on this forum, but it appears the Alliance Academy Reconstruction is impacted access to these resources.
 
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Skford

Member
I got the generator in. Scored knock out panels lined up good. When I got underneath to put the bolts in I discovered a round scored knockout. It was so lightly scored that I didn't see if from above. Do you know what this is for? Is it something I need to try to get out of there now or is it for some kind of maintenance or repair issue?
 

BryanValRox

Elite Member
I got the generator in. Scored knock out panels lined up good. When I got underneath to put the bolts in I discovered a round scored knockout. It was so lightly scored that I didn't see if from above. Do you know what this is for? Is it something I need to try to get out of there now or is it for some kind of maintenance or repair issue?
If you take your access cover off of the front of the genset, would the oil filter and drain access be directly above the round hole that you describe?
 

BryanValRox

Elite Member
No, they are above the large rectangular opening in the front of the compartment.
I just went out and checked mine, I have a round hole that the oil filter sticks out of slight from below. My guess is the knock out is for the filter, so not doubting your observation , but you might do some measuring to see for sure. On mine the filter is only accessible from below once the set is installed.
Pictures might help get to the bottom of this.
 

Skford

Member
I'll go out and see if I can get pictures and measurements. Might be tomorrow. It is towards the back of the unit.
 

Skford

Member
just found it on the schematic. It's the access hole to fan bolt. I wonder if I need to get that out now or only if it needed repair?
 

BryanValRox

Elite Member
just found it on the schematic. It's the access hole to fan bolt. I wonder if I need to get that out now or only if it needed repair?
Thanks for the update, I went out and raised mine up some more to get another look. I see the round knock out you are talking about to the rear of the compartment. Mine is in tact and hasn’t been knocked out.
I am going to leave mine as is given I don’t have any issues.
 
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