Replies

1. 
   danski0224 | Aug 13, 2005 03:03pm | #1

   HV systems need to be installed properly to work properly. Simple as that. That's why they come with instructions :)

   Yes, they will be noisy if they are not installed properly. That is why there are so many outlets in a HV home. Keeps the velocity and noise down at each outlet, as designed by the manufacturer.

   "Not heating or cooling the room because of the velocity of the air speed" is nothing but a stream of high velocity BS. If poor performance happens, I bet you it wasn't installed right. If a load calc isn't performed, then how does the contractor know how many outlets are needed in the room?

   HV systems are designed for homes that do not have ductwork but want to add cooling, like radiant heating only applications.

   If you have ductwork, then why not just add conventional AC?

1. 
   Rampside | Aug 13, 2005 08:46pm | #4

   The existing duct work intrudes into 2 small rooms and takes-up 1/3 of the basement. (Ceiling height in that area is 72in.) The house is a split level so I'm looking into 2 seperate HVAC sysyems. The present cooling and heating are insufficient in the 2nd floor and the most distant slab floor room. I'm thinking of using the Spacepak GR8 ducts and also their hot water coil. I have a supply of the GR8 available. I haven't done the load calcs yet and haven't used the Hot H2O coil before.

1. 
   ralphk | Aug 14, 2005 12:54pm | #5

   Rampside -

   I have a high velocity system installed (Energy Savings Product), similar to Unico or Spacepack, and I love it. I wouldn't hesitate to use it again. Both the heating and cooling capabilities are great. On the heating side I have a heat pump and a hydronic heat coil with a Buderus Boiler that supplies both domestic hot water and hot water to the heat coil in the air handler.  The temperature of the air coming out of the vents (when using the boiler as the heat source) is fantastic. Much warmer than the air temp using the heat pump.

   As for the noise levels, I would agree with what's been said. If you have the system designed well ( the ducting that is) it really isn't a problem. Be careful on the install and ensure that you respect the manufacturers recommended number of outlets, duct sizes etc... and you'll have a great system.

2. 
   CloudHidden | Aug 13, 2005 03:05pm | #2

   The guy is blowing smoke. Wanna check? Come visit and decide for yourself. I have Unico HV A/C and the sound of the vents is barely audible. The fan should be off by itself, but the vents themselves are quieter than I'm used to with traditional ducts. As for circulation, the comment on velocity doesn't make sense.

   I'm not making a case for or against switching. Just correcting what appears to be misinformation and basing that on what I've directly observed.

   Edit:

   >HV systems are designed for homes that do not have ductwork but want to add cooling, like radiant heating only applications.

   Agree! The thing to not forget, though, is that they DO require a sizable trunk line depending on config, so no one should think that a mini-duct system is necessarily ALL mini ducts. Those are just the branches to the outlets, which are typically limited in reach--50' w/ the last 12' being insulated, if I recall for Unico. The main line will be 9" R or larger, so make sure the space exists.

   >If you have ductwork, then why not just add conventional AC?

   Also agreed. I can see why one would choose that up front, but not why one would incur the expense of switching.

   
   

   ---

   Edited 8/13/2005 8:28 am ET by Cloud Hidden

3. 
   Mongo | Aug 13, 2005 05:04pm | #3

   Dannski and cloud have given you good words.

   Here's what I've seen in problematic (loud)  hi-v systems:

   1) Too tight radii on the ductwork, with those bends being too close to the outlet. With tighter bends you can generate turbulent noise as the hi-velocity air tries to make the turn that close to the outlet.

   2) Not using the insulated sound deadening duct for the latter portion of the supply duct runs. Again, the insulated duct is designed to help deaden the noise generated by airflow.

   3) Tryng to squeeze too many cooling BTUs out of one outlet. Example, with a hi-v system, each outlet is rated to supply so many cooling BTUs. If an outlet can provide 600 cooling BTUs and the room needs 600 cooling BTUs it's a perfect match, right? Well, sorta/kinda. It might be bette3r to use two supply outlets, each with a restrictor plate so each provides 300BTUs. Two ducts with less airflow is much quieter than one duct at full flow. Same if it needs 800BTUs. Don't have one duct supplying 600 and the second 200. Balance them so each supplies 400. Less airflow per duct means less potential noise. And the restrictor plates go on the TRUNK end of the supply duct, not the OUTLET end. I've seen that as well.

   4) having too short of a duct run. They require a minimum run of supply duct from the trunk line to the outlet. Even if the outlet is 2' from the trunk, you don't want to run a 2' piece of supply duct from the trunk to the outlet. You need a longer piece that loops down the joist bay, then back, to the outlet. This prevents trunk line turrbulence from being transmitted as airflow noise out the supply outlet.

   5) Don't place the outlet right over a sitting area or an area that people will walk through. Hi-v is hi-v, there is a lot of flow coming out of the outlet. Put them in out of the place areas to minimize direct drafts.

   Properly done, hi-v will work well. It's a great asset for historical renovations that need A/C and a compliment to radiant floor heat in new construction.

   For what it's worth, I don't like the fiberboard duct that some Hi-v suppliers use for the trunk line.

1. 
   DDay | Aug 14, 2005 06:39pm | #6

   Not to get off topic too much, but this might also help provide so info to others.

   I'm looking at putting in a spacepak or unico, I have not gotten the sizing and pricing done yet since I'm probably going to do it during a remodel over the winter.  I have 2 friends that are excellent HVAC contractors and another that is a sales rep for a HVAC distribution company.  The two contractors have said they have a slight preference towards unico because of some install preferences but otherwise they said both are about the same quality, etc.  The sales rep friend will give me his lowest pricing possible (maybe be able to get me a unit with a small dent, etc that cannot be sold as new at a huge discount off reg price) on the spacepak equipment they sell.  If I went with unico, I would be getting it from a supply house.

   How interchangeable are the systems?  Specifically with the ducts and the outlet registers.  I would really like to hide the ducts into molding, and other areas and make them an inconspicuous as possible without compromising their positioning.  I like the slot outlet that unico makes, I'm waiting on info from spacepak, but do you know if you can use unico outlets with spacepak ducts or unico mini duct runs with the spacepak trunk, etc.

   Any help would be greatly appreciated, I have a decent amount of info from working with my contractor friends from time to time but I've always done conventional systems.  My friends do not know of the inter-action of what I am doing because they're customers have never been concerned about the visibility and they only do a few Hi V's a year.

   Thanks

1. 
   Mongo | Aug 19, 2005 09:39pm | #7

   Lemme tell you what I think:

   You have the blower or air handler.

   You have the trunk line.

   You have the 2" supply duct with outlets.

   I've never used either company's trunk line. I prefer tin for the trunk and I seal and insulate that myself. Others have their right to disagree, but for the trunk I'm just not a fan of blowing air through rigid fiberglass ductboard.

   With that said, you can connect your own trunk line to either firms' air handler. And you can connect either companies' 2" supply duct to the trunk.

   While they are simple, I wouldn't want to mess with jury-rigging a 2" duct to some other outlet that may or may not quite fit, only due to the concern of adding air turbulence at the outlet. It's one of those thing s that I can;t quite diagnose over the internet.

   If it looks to you that you can do a smooth transition then it will likely work. the main goal is to NOT introduce anything that might cause smooth airflow to instead sound like a jet engine.

1. 
   DDay | Aug 19, 2005 10:16pm | #8

   Thanks.  I've seen in some of your previous posts on Hi V systems and in talking to a few people, research, etc that keeping all the air path's turbulance free is much more important than a traditional system.

   I've seen those fiberglass trunk lines before and I cringed just looking at them.  I cannot stand working with fiberglass insulation and I don't understand why anyone would want the air in their house running though that stuff.  No matter what the manufacturers say, glass fibers have to be getting into the air and the insulation would also be a mold concern.  I like the idea of a conventional insulated metal trunk.  I'm going to stop at a manufacter rep for each and see the fittings but from what you say, I'll probably be using unico flex runs since I want the slotted outlet.

   thanks again.