High Velocity AC Revisited

Steve Minnich_1

With both Space Pak and Unico you need a minimum of 6 outlets per ton and your return cannot exceed manufacturer's max. length.

The difference between the two is that with Unico you need to derate each run if exceeds a certain length. For example, if you exceed the man. recommended length on a supply outlet by 15', it may be considered only 80% of an entire single outlet. Therefore, you would need to add additional outlets to compensate. You do not need to do that with Space Pak, unless you completely go off the deep end and run it a 1/2 mile. In residential applications you shouldn't have any problems.

I always try to run my trunkline as long as possible and keep branch ducts as close to the man. minimum length as possible.

Another difference is that Space Pak encourages you to use 12 SEER AC's.

You should also be sure to have at least two feet of trunkline before any tee or elbow.

The other thing that I would highly recommend is using something like Space Pak every time over conventional forced air. It is a breeze to install compared to a sheetmetal system(and I know as a former union tinner)and the end-user gets a far better product in terms of comfort as these systems remove as much as 30% more humidity.

I find it to be an easy upsell because of this and you don't have to disrupt the integrity of the house because the branch ducts are so small.

One last thing, it really isn't that much more expensive when all things are considered.

Hope this helps.

Steve,

Radiant Comfort Systems

Mark J Strawcutter

always check the manufacturer's literature

Unico documentation specifies minimum of 5 terminations per ton except for 1 and 1.5 ton units

My SpacePak application manual shows derating long runs

Unico docs (and I believe SpacePak, too) talk about return design in terms of pressure drop, not length.

On the other hand, the docs can be wrong. The SpacePak docs still talk about charging by superheat which they admit is incorrect.

Mark

Steve Minnich_1

Your Man. literature

is wrong. Call Unico or Space Pak yourself. I've been installing these for 20 years and I do my homework.

Respectfully,

Steve, Radiant Comfort Systems

Steve Minnich_1

Mark

I did not intend to sound so intense--flu bug is messing with me.

My apologies,

Steve

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Mark J Strawcutter

accepted

I can see how what I posted might have sounded like it was trying to push your buttons.

It gets really frustrating when manufacturers continue to publish incorrect instructions while at the same time blasting installers for not reading/following them. I talked with SpacePak tech support last summer about how their Inst/Ops/Maint manual says to measure charge using superheat instead of subcooling. They admitted it was wrong and made them look bad. Yet their web site continues to have the incorrect manual available as we speak.

I also remember giving my supplier a semi bad time about missing insulation pads from plenum end caps. Finally checked with SpacePak and they said "we quit including those last year since installers weren't using them anyway". Yet the included instructions still showed them.

Mark

Dave_23

Outlet quantities

Folks,
I'm confused. I have a 3 ton spacepak residential system installed in Spring, 2002. Currently, it has 15 outlets distributed between the first and second floor. AH is located in the attic.

In general, what is the recommended number of outlets for a system such as mine?

Note: My contractor sized the system with 15 outlets. Adding a few more would have been relatively inexpensive, so I can't believe cost was the deciding factor.

Drod

High Velcity Units are Expensive

Last summer I had quotes from several people for both Unico and SpacePac as well as traditional A/C. I should mention that I have a two story house (and full basement, and big full insulated attic) with single pipe steam. The average cost for the high velocity was about $15,500; while the highest quote for traditional was $6,500. I still have my three window A/C's, and they work well.
With what I've read here, if I go to central cooling, it'd probably be with a traditional system. I have lots of closets on my second level through wich I could run ductwork to the first floor. Everyone seems to prefer high velocity, though everyone who mentions traditional admits it works well. I don't get it.

Dave_23

Spacepak installation cost

During February, 2002 I had a Spacepak system installed in my house. I have a two pipe steam heat system therefore, a high velocity system seemed like a good choice for A/C.

A. I had the system installed in the off-season, which gained me a 15 percent discount.

B. The system was sized at 3 tons (it was borderline between 2.5 and 3 tons based on cooling requirements for my home)

C. I'm feeding both the first and second floors with a total of 15 outlets.

Installed cost with an electrostatic air cleaner came in at $7,800. About two to three time the cost of an add-on to an existing forced air system.

D. A/C thermostat placed in upstairs hallway.

E. The system works extremely well, especially with humidity removal.

F. Installation went well. However, I hired one of my area's more experienced firms for the design and installation.

Note: There is a debate about the required quantity of outlet installed in my system.

-Dave

Dave_23

Spacepak contact info

Does anyone have a technical/engineering contact name and phone number at spacepak?

Their website doesn't have one.

Thanks

Michael B

here you go

http://www.mestek.com/companies.htm

This site lists all the different Mestek companies. If you have any problems getting through feel free to e-mail me and I will get you in contact with a warm body.


Michael Bleier
Able Distributors
www.abledistributors.com
"The Supplier That Works With You"

Dave_23

Case for adding outlets

My system is still under first year warranty.

How might I make a case to have my contractor install additional outlets to match the Spacepak specs for minimum # outlets per ton?

I need some help here. I'm not looking for freebies. I just want the system installed properly and to spec.