0 Helpful?

Are 48" Baseboard Diffusers necessary?

Doing flooring and have pulled out the baseboard diffusers from 1959 house. They are 48" long but the hole in the floor is only 2" x 12". Can I replace with a smaller size or is the 48" length helping to spread the warm air around the room? Note that there are 2 of the 48" diffusers along the same wall in the 14' x 17.5' living room.

Thanks in advance!

Asked by MollyV
Posted Feb 12, 2018 1:01 PM ET



Are you talking about baseboards, or trench heaters with fin-tube? What are you calling "diffusers"? Is that the fin-tube?

Trench heaters look like this, and are usually at least 3" wide, often 6-12" wide:

Can you post a picture of what you're talking about (or find a web-picture and link to it)?

Answered by Dana Dorsett
Posted Feb 13, 2018 12:50 PM ET


If it is a register for a forced hot air system like the one in the photo below, you can probably get away with a smaller unit.


Baseboard register.jpg
Answered by Martin Holladay
Posted Feb 13, 2018 2:05 PM ET


Such a diffuser will reduce air velocity, causing the hot air to rise upward (useful under windows). Other designs move the air horizontally, increasing mixing and reducing stratification.

Answered by Jon R
Posted Feb 13, 2018 3:50 PM ET


The diffusers are what Martin posted a picture of. Everything i can find says to buy them based on the cut out in the floor. The floor opening is 2" x 12" so I bought ones that fit that. No idea why a 48" long one would be necessary.

Thanks all for your responses!

Answered by MollyV
Posted Feb 17, 2018 10:26 AM ET


A 48" long one would be a good choice under a 48" window. Or get one with louvers that spread the discharge air.

Answered by Jon R
Posted Feb 17, 2018 11:05 AM ET

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