Rtu

[liquidtite]

Were feeding a rtu unit on a rooftop with 2 - 1/2" emt . Do rtu units have any vibrations when ran.if not do most guys use emt to unit or transfer to flex into rtu

 

[wallypiper]

Generally, an RTU may vibrate a bit but not much. Depends on the construction of the unit and the mounting. An RTU probably has a large fan in it but the fan may be mounted on a vibration base to isolate the fan from the unit and building. If the unit is mounted to a roof curb, which is typical, then vibration will not be an issue. There has to be some flex somewhere but generally only the last bit to the motor which may be factory installed.

 

[Dennis Alwon]

I guess it would depend on the length of the run. If the disconnect is close to or on the unit then I see no reason to run hard pipe. Sealtight into the unit and you're good. If the disconnect is a good distance then it may be advisable to use hard pipe to flex.

 

[Gregg Harris]

I guess it would depend on the length of the run. If the disconnect is close to or on the unit then I see no reason to run hard pipe. Sealtight into the unit and you're good. If the disconnect is a good distance then it may be advisable to use hard pipe to flex.

I would agree, mount disco on unit and run liquid tight just be aware of

440.14 Location. Disconnecting means shall be located within sight from and readily accessible from the air-conditioning or refrigerating equipment. The disconnecting means shall be permitted to be installed on or within the air-conditioning or refrigerating equipment.

The disconnecting means shall not be located on panels that are designed to allow access to the air-conditioning or refrigeration equipment or to obscure the equipment nameplate(s).

 

[Strathead]

You didn't say whether you were feeding from inside the building or running along the roof. I really just expect to flex to any RTU, but if running along the roof, I would listen to my job foreman (I am a PM) if he wanted to do it without flex, before just nixing it. If I was entering from down below, I would just flex period.

 

[liquidtite]

You didn't say whether you were feeding from inside the building or running along the roof. I really just expect to flex to any RTU, but if running along the roof, I would listen to my job foreman (I am a PM) if he wanted to do it without flex, before just nixing it. If I was entering from down below, I would just flex period.

Its being feed from 2nd floor penetrating through roof to unit .disco is built in unit

 

[Smart $]

Its being feed from 2nd floor penetrating through roof to unit .disco is built in unit

With typical curb-installed rtu's with built-in disconnects, using a flexible method makes it easier to hit the wiring compartment KO.

Another consideration is how you intend to pull the wire and whether you are going to put a pull box near the turn up. If you hard pipe without a pull box, then one end or the other of the pull will be on the roof through the wiring compartment.

 

[Strathead]

With typical curb-installed rtu's with built-in disconnects, using a flexible method makes it easier to hit the wiring compartment KO.

Another consideration is how you intend to pull the wire and whether you are going to put a pull box near the turn up. If you hard pipe without a pull box, then one end or the other of the pull will be on the roof through the wiring compartment.

Yep. That is why I asked the question I just figure it as conduit to a box, with flex from there. Then I can do the final part many ways. If the equipment doesn't come in til late, I can have the wire waiting etc.