HVAC-Talk: Heating, Air & Refrigeration Discussion banner
Cancel
Create thread New Forums

Dehumidifier Wye duct sizing

Jump to Latest
1 - 7 of 7 Posts
L

ltoemmes

· Registered
Joined
·
7 Posts
Discussion starter · #1 ·
Using the Aprilaire 1870 as an example, it is rated at max 310CFM through a supplied back flow dampered 10" supply duct.

I need to split that - 50/50 - into two separate HVAC supply plenums.

What should the size of the WYE splits be: 10" or 8" or...?

Thanks,

Pete
 
#2 ·
ltoemmes said:
Using the Aprilaire 1870 as an example, it is rated at max 310CFM through a supplied back flow dampered 10" supply duct.

I need to split that - 50/50 - into two separate HVAC supply plenums.

What should the size of the WYE splits be: 10" or 8" or...?

Thanks,

Pete
Click to expand...
310 cfm at what static pressure.
This means a lot... ;)
 
Save
Like Like
Discussion starter · #3 ·
behappy said:
310 cfm at what static pressure.
This means a lot... ;)
Click to expand...
Yeah I figured that. That’s the rated cfm per specs at 0.0” w.c. The min cfm is 175 at 0.6.

If I need to know what my current static pressure is with only HVAC on then I’ll bug my HVAC guy.

Is it reasonable to answer the question based on an assumed w.c. of 0.4 yielding a cfm of 225?

I haven’t decided if I will force the DH off when the HVAC is on. I think I’d prefer to just let the HVAC and DH run independently.
 
#4 ·
Why would you assume you have 0.4 TESP?
What have you done to assure you won't be recirculating?
Why would you run them independently?
Have you run the numbers to size your ducting?
 
Save
Like Like
#5 ·
A 10" yee would be kind. A 10" Tee will work but cause more pressure drop. Here is another suggestion. Draw the air for the dehumidifier return from the open part of the home instead of a/c returns. This decrease the pressure on the dehumidifier. If you have quality home with the windows close in the mild seasons, include fresh air as part of the dehumidifier return. Fresh air change is needed to purge indoor pollutants and renew oxygen.

One more personal favor, consider using the higher efficiency Ultra-Aire dehumidifiers. Aprilaire is a good company but Ultra-Aire started this concept in 1992 and is also made in the USA.

Keep us posted.

Regards Teddy Bear
 
Save
Like Like
Discussion starter · #6 ·
teddy bear said:
A 10" yee would be kind. A 10" Tee will work but cause more pressure drop. Here is another suggestion. Draw the air for the dehumidifier return from the open part of the home instead of a/c returns. This decrease the pressure on the dehumidifier. If you have quality home with the windows close in the mild seasons, include fresh air as part of the dehumidifier return. Fresh air change is needed to purge indoor pollutants and renew oxygen.

One more personal favor, consider using the higher efficiency Ultra-Aire dehumidifiers. Aprilaire is a good company but Ultra-Aire started this concept in 1992 and is also made in the USA.

Keep us posted.

Regards Teddy Bear
Click to expand...
Thanks Bear. Yes, in fact my choice will likely come down to the UA 120V or UA 120H just based on SQ foot ratings. I might actually get by with an UA 98H.

Not so funny side note. One of the two thermostats from the two separate hard zone/systems were moved (after 10 years) from about a foot apart and around the corner to each other adjacent to the return grill to down the hall - still in the return air flow from the bedrooms - but closer to the bedrooms. The change in longer run times and lower RH in the house has been dramatic. It's mild in SE Florida now but the inside is held at 75F and 45-47 RH (with the ailing SF RX blowing in the hallway below the return). Which probably will not surprise the pros here.
 
#7 ·
ltoemmes said:
Thanks Bear. Yes, in fact my choice will likely come down to the UA 120V or UA 120H just based on SQ foot ratings. I might actually get by with an UA 98H.

Not so funny side note. One of the two thermostats from the two separate hard zone/systems were moved (after 10 years) from about a foot apart and around the corner to each other adjacent to the return grill to down the hall - still in the return air flow from the bedrooms - but closer to the bedrooms. The change in longer run times and lower RH in the house has been dramatic. It's mild in SE Florida now but the inside is held at 75F and 45-47 RH (with the ailing SF RX blowing in the hallway below the return). Which probably will not surprise the pros here.
Click to expand...
Connecting to two a/cs requires more fan power than a simple single connect. The UA 120 has a stronger fan then the UA 98H. Suggest a couple of balancing dampers to portion the amount of dry to each area. The 120 more efficient also.

Keep us posted.
Regards Teddy Bear
 
Save
Like Like
1 - 7 of 7 Posts
You have insufficient privileges to reply here.
About this Discussion
6 Replies
4 Participants
Last post:
teddy bear
HVAC-Talk: Heating, Air & Refrigeration Discussion
posts
5M
members
275K
Since
2000
The #1 HVACR Community
Full Forum Listing
Explore Our Forums
AOP Residential HVAC/Refrigeration(Beenthere Zone) General Discussion Tech to Tech Chat - Residential Controls Refrigeration & Ice Making