Hi Velocity Cooling?

Steve Bergstrom

Steve Bergstrom

Hi Velocity Cooling?

Yesterday in one of the threads Hot Rod mentioned Hi Velocity Cooling.
I've been a lurker on this wall for about 2 years and I don't recall reading about such a method of cooling.
Could some of you wallies fill me in on this subject?
How does it work? What type of materials do you use to transmit the cool air.Are there any webb sites I can check out to learn more about it.
My wife and I are building a new house next to the one we live in and it may not be to late to do the rough in for AC
The house is 3000sf(ground floor,1st and 2nd floors)and we're doing all the work our selves so far.
All the space heating for the house will be radient.
Thanks in advance for any advice you can give us. Steve

ta finnegan

high velocity

Unico is one such manufacturer. The air conditioning cycle works the same and the condenser unit can be anybody's so long as it is sized properly.

The principle is this: air handler that forces the air through at higher velocities and uses smaller or "mini" duct which allows you to run it through walls, closets, joist spaces etc. It can be really great for older homes and for people who do not want to tear things up to put in standard sheet metal sized ducts.

It is expensive, but the offset is usually the cost of tearing apart and rebuilding to accomodate the standard ducts.

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

Jamie Pompetti

Steve,
High velocity cooling is a great way to cool a home! The ductwork and it's outlets take up about a 10th the amount of space as a standard cooling system. We typically use only two of the high velocity systems on the market (Spacepak & Unico) WWW.Spacepak.com or WWW.unicosystems.com. Both systems work great.

The only flaw I find w/ both companies is they have yet to introduce the GE ECM evaporator fan motor. You can go to www.geindustrial.com & click on the residential icon to find out about that. This motor is tha same to cooling as radiant is to heating. It can cut the cost of fan operation by over 50%.

Good luck with your new home,
Jamie Pompetti
Pompetti Heating & Cooling, Inc.

clammy

clammy

clammy

Mark J Strawcutter

Only advantage

is small ductwork which can save the day in a retro-fit application. If a conventional system will fit it would be my first choice - less expensive. Properly designed and installed, either one will do the job.

High velocity systems have some unique design and installation considerations. Make sure your contractor has experience with them.

Mark

Mike T., Swampeast MO

To learn more

Visit www.unicosystem.com

They have the best technical information I have seen. As detailed as you want or as simple.

One advantage (besides small duct size) comes from the nature of the system. Because of the extremely deep evaporater and high air velocity, they utterly excel at removing humidity--even with the highest efficiency condensing units.

Because of our extreme summer humidity my friendly reefer man steers people away from the super-high efficiency condensing units on traditional ducted systems. He insists that the evap on such a condenser operates at a higher temperature and does not remove as much humidity. Besides the high initial cost, he insists you have to cool the space lower in temperature to achieve the same comfort level of a unit with a "12" or so rating.

The high pressure systems claim the opposite. Because they remove so much humidity you can keep the thermostat higher while maintaining the same comfort level. The high pressure systems I've felt around here seem to verify this claim.

Peter Rothstein

Unico fan

I recently did work to my house (1930s, one-pipe steam) and while adding space and gutting the kitchen figured it would be time to take the plunge for AC. Got a Unico system, in a close to 3000 square foot house only had to box in two small areas for runs, which may be attributable to the odd placement of the new addition (had to run a trunk down to supply the new area).

I was amazed at how little disruption and destruction had to be done to get AC in, and how fairly inconspicuous the installation is. Functionally, it's great. Really does lower the humidity much better than other systems, and distributes the cool air well, so there are not really cold and hot spots. I think my installer underestimated the heat-gain and undersized the system a bit (per my results on Unico's heat-gain calculator done room by room it's about 20% or more low, and on the hottest days the system runs constantly and creeps up a couple of degrees- the installer is coming back to add a few more runs, which may fix it), but even with that, it works very well. It's a very comfortable and low-profile system that I can keep probably 4 or more degrees warmer than standard sytems I've used. Maybe check with Unico to see if they have any recommendations on installers. Also check their website.

I think even if I were building new, I might use Unico. My only concern is the fiberglass main ducts, I don't know how their longevity is.

I don't know how Unico compares to spacepak, since I had no contact with them, but I'm happy with my Unico A/C system, and I get to revel in my nice steam heat in the winter!

Mark J Strawcutter

proper design

A good A/C man should be able to design a conventional system with sufficient latent heat removal capacity to handle your humid environment.

But you're right - high velocity system by nature have a high latent capacity without and special design.

Mark

Mark J Strawcutter

sizing and fiberglass

SpacePak plenum is a standard Johns Manville product where the interior is coated. We'll see how it holds up. Cheaper if you buy the JM product instead of the SpacePak "version".

Only Ts and 90s are available ready-made. 45s would be nice.

Couple of things to watch out for with system sizing. Check the ARI tables for actual BTU and SEER ratings with condensors. You loose 1-2 SEER points from "nominal" and up to 1/2 ton. My nominal 2.5ton 11 SEER Carrier condensor gives me a system rated at something like 26.5kbtu 10 SEER

Mark

Craig_2

Peter, How many zones?

How many zones do you have? I have looked into high velocity but the local people around here want to install two systems, one in the attice to serve the second floor and one in the basement to serve the first fllor. They pretty much say it can't be run otherwise as the runs are two long or are too hard to do. They spent a lot of time steering me to conventional duct system.

-cf

Peter Rothstein

RE: Peter, How many zones?

One zone. (Caveat: I'm not a professional, just a homeowner who has done some research and lurked at the Wall a lot...) I think it may work better with two zones, depending on your house and environment. After I got the bid and it came time to install, the installer was a bit concerned whether he could get it all in with one air handler. I wouldn't have had to do any boxing in of runs in that case, and I'd be able to control the downstairs independently from the upstairs (we are usually not upstairs during the day) yielding some savings in energy, probably- but at a significantly higher initial cost.

So I have one outside unit and one air handler in my attic, and most of the runs are maybe between 10 and 30 feet max (there's also a minimum they can't go below). There was one location in the basement that was nearly impossible to get to, and there are two runs there that are maybe 50 or 60 feet (guesstimate). Those runs seem to work fine.

According to the installer (and Unico's installation guides and technical bulletins) the length of runs shouldn't be too much of an issue in a normal application. I can't remember the figure, but it seemed like the maximum run was quite long. If they route the trunk line correctly, they should be able to minimize run length anyway. One thing to watch for is taping of joints. I found a fair amount of leakage in some of the joints and in the prefabricated tees and ells. Some required a bit of extra aluminum tape. Again, my longevity question pops up, but it seems like now conventional systems, too, are being held together with tape...

Appearance, function and comfort wise, I still think I'd use high velocity even if I was building new.

Perhaps they just don't want to do the work to get the runs in difficult places. My installers were a bit skeptical about some of the spots at first, but I worked with them to figure out good places that I had noticed just in poking around the house for some years. Unico sells its system on its flexibility and how it can work into existing construction. That doesn't mean that it can go everywhere, and it can't defy physics. However, your installer may not be looking at all of the possibilites either. On the other hand, your house might need two. I certainly found out about where Unico can't go too, it (like anything) does have its limits.

Good luck, and hope this helps!

Mark J Strawcutter

zones

My experience is with SpacePak, some of the numbers may vary slightly with Unico.

Once you hit 4tons and above, there are some special plenum design considerations, the AHU gets large and the return duct is really distorted where it attaches to the AHU.

My recommendation would be if you need 4tons or more then put in two systems. I wouldn't worry about putting one of them in the basement - headroom for plenum can be at a premium there, expecially in an older house with gravity hydronic mains running around :-) Plus you always need more terminations on the second floor. Put them both in the attic.

I've got a lot of 30ft runs due mostly to putting plenum high in the attic to allow for future conversion to living space. The sizing guidelines take into consideration the length of runs. Lots of long runs means you just need a couple more.

Only one run to each of (large)foyer, LR and DR. I ran 3 to kitchen but may add another this summer. Some runs went down corner of (already small) closets inside 4in thinwall plastic drain pipe for physical protection. Had to throttle the single foyer outlet since lots of cool air falls down the stairs.

2 runs to each of 4 equally-sized bedrooms. May add another to the two with recently-added computers :-)

Rule-of-thumb is that plenum extension to shorten 2 or more runs is cost effective. But I had a situation where I had to take 5 20ft runs thru a 12in x 16in chase I created in the end of a very long/shallow closet.

Actual installation of SpacePak ductwork is pretty straightforward once the design is done. Consider finding a contractor who would let you run the flex, and perhaps the plenum, and he would do the rest (AHU and condensor).

Mark

Mike T., Swampeast MO

Runs in HV air

The reason they say two systems are required is quite valid.

{Info regurgitated from Unico technical}

ALL branch runs MUST be computed on the basis of the "standard" 10' run. While quite long runs are possible, output drops with increasing length.

Thus in a two-floor system with the trunk either in the basement or attic the runs to the farthest floor will be much longer than the other. This will require proportionally more runs to that floor--since it's a floor away it's likely the hardest to get access to in the first place.

The ideal trunk layout for HV is a pressure-balanced loop, i.e. a trunk that loops back to itself at the HV unit. This layout ensures even pressure at each branch connection. Other layouts are certainly possible but proper sizing of EVERYTHING becomes even more critical.

If you go with a single convectional ducted system INSIST that you get adequate returns on EVERY level of the structure!!!! ALL bedrooms should have a return as should all major spaces.

Mark J Strawcutter

cool air falls

While I would never consider trying to cool a second floor from a basement hi-v AHU, I see no problem with cooling first floor from attic.

Cooling load is generally less on first floor. Cool air falls from second to first floor. Both of which usually make up for having longer/fewer runs.

Excellent point about conventional system and sufficient returns. Especially with basement AHU you'll need lots of returns on the second floor.

That said :-) my previous house had single conventional system with AHU in attic and single return in upstairs hall ceiling. Worked fine.

Mark

Mike T., Swampeast MO

Hard to forget...

...the hellish summer heat/humidity here. Awful problems (old AND new) around here with inadequate A/C return in bedrooms. Single systems in older multi-level homes around here are often nearly unusable upstairs and you have to use window A/C in the bedrooms as well.

John Abbott

45's

are available I took delivery on four today.

John

Mark J Strawcutter

for spacepak

11in round plenum?

Mark

John T_2

Why Fiberglass?

Unico also sells outlet taps for use with metal duct. We won't use anything but steel. Insulate it with two wraps of 1 1/2" fsk duct insulation and I believe the R-Value is higher than fiber duct. Also don't forget a good high velocity duct sealant on all connections and elbow joints. Beats the hell out of the fiber duct.



John Taylor
Custom Climate Systems, Inc.
Whitmore Lake, Michigan

John Abbott

45

yes in my area they are available from Thermal Mechanical sales 603 537 1900

John

Craig_2

Mike, Mark and Peter

Thank you for all the excellent comments. I have studied the Unico system very carefully and thoroughly. I believe a single system would work in my 2 story house (2100 sq ft). I need to find an installer willing to work to find the correct solution. That extra bit of service would earn them the job.

Incedently, I have steam pipes running through two rooms of my house and yet the AC guy thinks running an hv tube in the open would bother me. I told him to put it right next to steam runs. They both won't operate at the same time!

-cf

[Deleted User]

high velovity plenum

Went to a spacepak seminar last spring,the rep said they are working on a system with spiral duct type plenum material (metal). The one thing that bothers me about my fiberglass plenum is the formaldehyde resins they (manville)uses to spin those fiberglass walls of the ductwork,other wise it is light weight and easy to use.

Howard

I vote for 2 Unico systems

JMHO the best way is one system serves 1st floor; one serves 2nd floor. Each system gets a programmable thermostat because 1st floor is occupied during different times of day than 2nd floor. Program upstairs for comfort overnight and downstairs for comfort during the day. Let the bedrooms climb a few degrees at lunch time. Living room can be a little warmer after midnight. Another strange thing about unico is that the conditioned air is less likely to flow down the stairs than with a conventional system. Instead of a slow moving mass of cool air, unico mixes it quickly so it's less able to stratify. Placement of the outlets isn't crucial--if you can't get to the outside corner, that's ok. Just don't aim them where people are going to be. (or above the dog bed for Spot cooling--I crack myself up) When doing a 3-ton or 5-ton startup, I'll notice a low load type condition sometimes. I suspect that if the designer isn't generous with outlets, and you ask the blower to do 100% of its capacity, you can't just fudge the restrictor open a little more. I'd be tempted to specify a 3.5-5 ton blower with a 3 ton condenser. Whaddaya think?

Howard Hansen Service Technician Extraordinaire

Mark J Strawcutter

hv tube vs steam pipes

Remember, that "2in" supply tube is ID. Together with insulation it's more like 3.5in. And it's neither smooth nor rigid like steam pipe and wouldn't stand physical abuse without protection.

You could enclose it in 4in thinwall plastic drain pipe like I did in a couple of closets. But as much as I consider pairs of 3/4 pipe for upstairs rads to be an integral part of the downstairs decor, I doubt that I'd feel the same way about adding what looks like a sewer pipe to the mix.

Mark

Alan Muller

high velocity residential HVAC

I know of three manufacturers of this stuff: Spackpak, Unico, and Energy Saving Products (in Alberta). These systems work well if properly installed, but have some limitations that may or may not matter. Zoning is usually not done; the only normal way to get zones is with independent systems. You can heat with coils (hydro-air) or heat pumps but the output with heat pumps is limited by the temp rise and low volumes. Can use electronic air cleaners or media filters but there are limitations--probably not ideal if filtration and/or continuous circulation is important.

These systems aren't cheap. I suspect this is more because they are a low-volume specialty product than because they are inherently expensive to make.

am

NCremodeler

Unico

I used a Unico for a large older home in NC. It looked good and had lots of claims. BUT is has not proved to be true in our experience. It has been trouble from day one and continually breaks. Even when it runs it does not heat and cool as promised. One of the units was replaced 2 years ago and is broken again and needs replacing. I would not use Unico again.

clammy

unico

Steve i have installed unico systems and the oldest one i personally installedon my own and not for a ompany i worked for  has been running with no issues for at least 8 or 9 years ,I personally would never use there fiberglass duct system to me it is cheap and sooner or  later it will become damaged and the other risks of fiberglass being blown into the air steam .A former boss of mine who taught me alot had this to say about fiberglass duct work you put that crap in peoples homes that you do not like  and plan on never serviing ever and i have always remenbered that and followed it to the letter . i have always installed them using exatly what they say 26 gauge round sheet metal .All seams and joints are sealed using hardcast gasket tape and then externally wrapped with a mimiun of R8 fiberglass duct wraps .Properly wrapping duct work is also a art form ,it should be wrapped loosely and not compressed all seams should have a 3 to 4 inch over lapped and stappled with a duct stapler and all wrapped seams to be taped with a fiberglass re enforced tape ..Any one can slam in a unico system but remenber this will it be installed as the manafacture suggestes? I have over the years completly redone unico system which where leakly and very noisey why cause they where never installed properly, A properly installed hi vee system should be just as quite as a conventinal system .I also have never done a 2 story home with 2 systems unless each floor needed more then 5 tons ,The big promblem with a 2 system set up is where are you pulling the return air from the 1 st floor system ? Just about ever hi vee system i have seen with 2 systems was pulling all the return air from a basement and to me that is total BS.The reason being they did not want to lose the space for a wall return .I also do not do hydro air to much heat lose and dis comfort and waste of eletric running the fan .I wish you the best of luck i personally only give quotes to those who know my work because i am to old to tried and sick of having my prices but up against a bunch of hacks who will never get it right and never ome back to get it right because they did not do it right in the first place .In losing your a/c system should be as quite as a baseboard hot water heating system if the supplty air grills and returns are loud you did not get a real system just some butchery.Wishing you the best of luck and peace and learn as much as you can cause lately most are much better sales guys then mechanics i know i see it way to much peace and good luck clammy  sorry for the long rant

joe_94

Two questions

EnergySaving Products hi-velocity system does have the ECM type motor which type is  praised in other threads on The Wall dealing with circulator pumps. 

What is your experience with that Canadian brand? Anyone? Installation? Durability?



Why wouldn't any Hi V system work up from the basement in a not terribly large two story house?  It IS high velocity after all. 

The second floor is only nine or ten feet away, vertically.

Use two horizontal plenums: one on the basement ceiling, one on the first floor ceiling [[using closets and boxed in areas], joined by a vertical plenum shaft.

Anyone else?

Thanks.

joe_94

Why

My "Two Questions" post [ above] not arrive at the bottom of the thread as hoped. Oops.

Schvenzlerman

Hi Velocity Cooling? Yes

If my wife and I had known that Jamie Pompetti did this type of installation, we would have gone with his firm. We instead chose a contractor who gave us a 7 year project that they never actually completed. It was a unique job if you know what I mean. Anyway, because hi velocity systems take so much more latent heat (humidity) out of a home, we can keep the thermostat at 82 and be comfortable when it's 95 degrees and very humid. That results in energy savings.