HotBlast 1557 Setup

[Ryan18327]

I purchased a home last year with a Hotblast 1557 that is set up less than ideal. We used it last year during winter and it worked well enough, but not as well as I know it can. The current setup has one 8" supply line and one 6" supply line from the top into the main furnace supply line. The return air is hooked into the porpane furnace return, currently with no filter installed. I am planning on doing the following but I am have a few questions and would like suggestions of anyone has them:

1) Change supply lines to be a large plenum with one 12" duct going to the main supply line.
2) Add plenum to return with filter. One question I have here is should I keep this hooked to the furnace return lines? Or just leave it open from the filter to draw from the basement? The basement isn't finished now but will be soon.
3) Install limit switch to replace thermodisc and potentially replace the twin blowers with a single, two stage blower. Any suggestions on a good replacement blower?

Any help is appreciated!

 

[dave_dj1]

I think it will distribute the heat more evenly hooked into the return line.
If you do the math of the 6" plus 8" vs 12" duct you won't be gaining any square inches (provided 12" is round) If it's square then you will gain quite a bit.
I can't help with the blower but if it was mine I would install one the same size and rpm as the gas furnace has with a limit switch in the hot air plenum of the wood stove. https://www.wholesalehome.com/products/honeywell-l4064b2236-combination-fan-and-limit-furnace-control?currency=USD&variant=19904738689120&utm_medium=cpc&utm_source=google&utm_campaign=Google Shopping similar to this one
ETA: the blower would be wired to it's own thermostat upstairs.

 

[Ryan18327]

Thanks for the reply! I'm curious where you saw the calculations to airflow in a 6" vs a 12" round however. From what I can see, a 6" round can handle 85 CFM and a 12" handles 525 CFM. From what I can see that's a significant difference. Also, if there's two 6" ducts they would each take two 90° turns making 4 total to reach the main line. If its a single 12, thats only two 90°s. Am I overlooking something here ?

 

[Ryan18327]

Thanks for the reply! I'm curious where you saw the calculations to airflow in a 6" vs a 12" round however. From what I can see, a 6" round can handle 85 CFM and a 12" handles 525 CFM. From what I can see that's a significant difference. Also, if there's two 6" ducts they would each take two 90° turns making 4 total to reach the main line. If its a single 12, thats only two 90°s. Am I overlooking something here ?

Sorry, should say 8" is 180 CFM. So looking at 265 CFM for the two vs 525CFM for one 12". Nearly double by what I can see.

 

[cantoo]

Ryan18327, do a search on here for "hotblast" and you will find some info on them. This thread has pictures of my setup. I run an OWB now but still have the Hotblast sitting here waiting. There is a company named " fawcett" that is very close to the Hotblast too.
https://www.arboristsite.com/threads/hot-blast-1557m-blower.328601/#post-6785412

 

[dave_dj1]

Thanks for the reply! I'm curious where you saw the calculations to airflow in a 6" vs a 12" round however. From what I can see, a 6" round can handle 85 CFM and a 12" handles 525 CFM. From what I can see that's a significant difference. Also, if there's two 6" ducts they would each take two 90° turns making 4 total to reach the main line. If its a single 12, thats only two 90°s. Am I overlooking something here ?

If you're asking me I just use simple math. pi R2d
4" radius = 8" diameter = area of 50.27"
8" radius = 16" diameter = area of 201.06
roughly doubling the diameter increases the amount of area by about 4