what exactly are they? I have had a few customers ask me about them mainly because they believe the smaller ducts can be advantageous to having almost zero space for duct runs etc
however looking over the site and seeing pictures etc, it seems to me the units themselves take up as much or more space then a normal hvac system but i cant be sure..
can somebody who has installed both normal residential systems and these hi velocity systems, can you give me the run down from cost to install to application on these systems??
where installing duct is not feasable. Look at Unico as an example, you still have odu, and ah. The duct will be 2" pvc
Originally Posted by acguytx
Equipment costs will be higher, but able to go into places a full sized duct system won't go. Don't think installation will be much easier, as you still have pipes, registers, ductwork etc. along with finding out how to route thru confined spaces. Have a little more air noise due to velocity of air and hard to find AHRI ratings on some units to apply for energy rebates.
has anyone here actually installed a system like this? how much space requirement does it need for the indoor equipment and is there anythng unusual? i ask because from the pictures it sure seems like theres a lot of 10 inch trunks running back and forth feeding all the 2 inch runs..
also it loks like you need a basement or attic to install these , are they all horizontal ? if not do the upflow versions need more space then a typical closet install??
where and how is the returns run, are there returns??
I haven't installed one, but I saw one finished one. They routed a trunk line pretty much around the perimeter of the attic and dropped the 2" supplies off of that. What I saw there were lots of supply drops per room all along the outside walls (to kill the heat load). Takes up alot of space to do it, but it was around the perimeter, so left the center section open for the HO to use as a storage and the like.
We've worked on a few, but never actually put a complete system in. Every time it looks interesting, however the actual finished costs forces us to look at another alternative instead. So have not put in a complete system. I'm sure there are some contractors who do older homes and are experienced with these systems.
High Velocity systems are
So inefficient that they have there rating done under a different set of rules. Why? because the fan horse power is so high for the high velocity and small duct and the fan becomes a major energy pig even though they reduce the CFMs per ton and have colder (dryer) air so you need those high velocity nozzels to mix the colder air.
Now Unico and the other company will cl;aim the lower CFMs and lower (dryer air) should be considered in their energy efficiency but the truth is you pay a premium for a unit with smaller duct. Does it really matter if the duct is 4in or 6in? When you need to cut a hole the extra size doesnt really matter and it is not like you are really going to fish those small flex ducts.
Clearly I don't get it and wonder why consumers are drinking the blue Koolaide.
Hate Mail from people who love these things is expected
You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!
We've done a few hi-velocity systems.
Spacepak mostly. Their name is true, you have no space, so you pak it in.
Houses where there is no space in the attic, no closet is big enough for a normal unit + duct, we can install a high velocity unit in a small closet, and round 10" round pipe in a corner.
I can fit 5 heat runs in a single joist space with a space pak, where I would normally only fit one.
Alot of times there will be repair work, such as drywall/flooring, but it done slowly, it's minimal.
The issue with spacepaks, are exactly as genduct has mentioned.
In all honesty, stay away from spacepaks. You'll never make money, unless your doing it time and material. There's to many "I don't like it there, I know it's the only place it can go, look somewhere else though." people. The whole time your tip-toeing through the tulips. The fact of the matter is that the people who get spacepaks are getting spacepaks because they don't want to make any drywall repairs in the home, limit your ability to do the job, and won't be happy unless it's impossible to do. Your usually working with plaster and lathe too.
Running those heat runs is like trying to pull a new stay wire. Except you have to go through the floor first, turn, and then go through your space. And hopefully not hit a header. Over, and over again.
Did I mention that EVERY JOINT must be taped/mastic'd, including the snap lock seams in the pipe, and the multiple joints in a 90?
It's not worth it.
"Better tell the sandman to stay away, because we're gonna be workin on this one all night."
"Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."
"Just get it done son."
Unico is rebranded Spacepac
When installed exactly per instructions these systems work great!Problems arise when oh it's close enough or well this should work are the installing parameters.Only real negative thing with this system is you are forever locked into it.You will never put a conventional AHU onto a high velocity duct system and have it work right.(Maybe the right description would be work period.)
We have replaced a few indoor air handlers with a Unico (Spacepac) unit however most require additional outlets in order to operate. And these blower/coil units are expensive compared to conventional. However as posted earlier, nothing else will work.
i have seen one recently what i would like to know is the pressure the same as a regular units do the fact they have smaller truck line on the supply or do thay make up for that with a txv
hvacvegas says "stay away from spacepaks. You'll never make money,"What/
My company makes 3-4 million sales yearly high velocity.
Flip67-Static pressures are higher around 1.5"wc
All have TXVs to handle the 200 CFM/ton and the SpacePaks and Unicos have freeze stats from the factory since they run that cold of a coil.
They kill SEER and lower capacity. They are very pricey. If you bid right, I don't know why you wouldn't make good money but it will be a high price tag. For less in lots of cases you can go conventional and get high SEER and full capacity.
I wonder how many replacement units have trouble because of what genduct mentioned, the new AHs require more outlets per ton and I bet nobody bothers.