High velocity HVAC

[Sigarms]

Two of the most common "name brands" are Spacepak (sp?) and Unico.

Most commonly used for older houses with limited space for ductwork.

Used also in new construction, upscale homes where you have radiant heat and a high velocity system for A/C.

If properly installed, you will have no issues.

There are "general rules" that the installer should follow which is not always the case (one reason why you can get "noise").

Rules such as "6 per ton rule plus two" (number of outlets per ton, 10% rule, locating the outlets so the airstream doesn't hit people or objects...there are about 12 different rules that you should follow. You would be surprised when I get a complaint that the system is to loud, go to the home, 3 ton system, and the guy only installed 12 outlets! You would be think that "professionals" would read the installation (sp?) instructions.

You would also be surprsied to find guys who actually forget to install the sound attenuators at the end of the supply duct!

Keep in mind, the "main" trunk of the system is usually 7" or 9" in diameter (rectangular duct is also available, but I dno't bother with it). The 2" duct runs from the "main" supply.

Problem is that alot of guys in HVAC don't understand the system, or they think they know it all but never put a system in.

I've been working with these type of systems since the mid 90's and never had a "call back" due to the system not doing what it's supposed to do.

Brings back memories because one of the first systems I helped a contractor with was for a chuch. He actually installed nine systems in the bulding, and this structure is only about 2 miles from where my dad lives up in Pa. Every time I go home to visit, I see those outdoor units on the building. I know for a fact that four years after they were installed the people were still happy with them.

I have however come across numerous mis-installations (sp?).

Keep in mind, you can/will lose close to half a ton in A/C when you size the system depending on the matched condensing unit. This can be a VERY important factor. Try looking up spec's on the ARI website, can be a pain. Example, your using a 3 ton (36,000 BTU) A/C unit. This outdoor unit hooked up to a high velocity system may only get an actual 32,000 btu's of cooling. This may not be important, but sometimes contractors like to "cut it close" to save money. If you have a very hot, long summer and the contractor didn't account for this "loss", the system may not cool properly.

Keep in mind, the actual "high velocity" system uses its own indoor blower and coil (2 pieces). You select what outdoor condensing unit you want to match to it. That's why it's important to check the ARI listing between the two units (indoor and outdoor).

These systems are available in A/C, Heat pump, chilled water, ground source heat pump and hot water coil.

Again, if installed properly, you will not have an issue.

Downside is that these systems run higher in price than conventional ductwork.

There are however "tricks" to save on the cost of materials, and this will not affect the system at all.

Forgot to mention that they can work wonders in a commercial setting where you want to use "spot cooling" instead of cooling the whole area. In this aspect, you can save some serious money, but you need to make sure of the application and it's intended use

 

[texbaylea]

Sigarms

Too bad you are not in my neighborhood. I have not found any contractorwith experience with these systems. I am planning a remodel/addition project and am impressed with the versatility of these systems. I would use them if I could find an experienced contractor.

Vernon

 

[BobRip]

I have an ICF house with conventional air conditioning. I would like to have better humidity control and I think the 2" system does this. There is so little air conditioning load that on moderately warm days it does not run enough to remove enough of the humidity. Now mine has a two speed compressor so it is not a major problem, but if you only had a one speed system I think it could be.

Bob Rip

 

[Sigarms]

For less money, for humidity control, I would look at Aprilaire's (sp?)"whole house" dehumidifier (sp?). Model 1700. Mounts in your ductwork, can work with or without your HVAC system running. Works throughout your whole house as well and you can even get "fancy" and run a bypass damper in the system if you just want to dehumidify an unconditioned (sp?) area as well (doing this without your HVAC system running). Does up to 90 pints a day. Has it's own compressor and coil. A little pricey, but will be less than a unico system for sure.

Also might want to look at the new Honeywell TH8000 series t-stats. One model has humidity control. A little misleading by terms, but it will actually cycle your A/C if your humidity setpoint hasn't been reached (the t-stat has a humidity reading on it as well as temp). That would be the cheapest route probably, but depending on the issues, may or may not solve the problem.

Worse case scenerio is going with variable speed.

 

[thcri]

We have installed about 50 or so of the HyVee system. This system is a high velocity system that you can use for air conditioning but also has a hot water coil that you can heat off of your domestic water heater. Great for apartments and small townhouses. As far as noise, they are not bad as one would think if installed right. The Unico system tends to be a bit noisier due to the fact they use outlets per ton of air conditioning. No matter what system you go with you will be happy as long as you don't use a central return.

murph

 

[5030tinkerer]

As long as you DON'T use a central return? I thought that it was supposed to be a major advantage with these systems that you only needed one return per zone. I take it that you end up with hot and cold spots with the single only return?

Ed

 

[PineRidge]

I'm not saying these units can't work as they do have a niche.

But over the years you hear a lot of hype that eventually comes full circle. Remember when the Pulse was supposed to be better than peanut butter. There were lots of guys selling them as "the best furnace of the era". Then the complaints started to roll in and the class action suits followed. Do a Google search and see what I mean. Still remember the first time that I saw one and wondered if they were so quiet why they needed a muffler installed on them?? So the neighbors wouldn't hear them? So the homeowner wouldn't hear them? Guess I'm one of those that doesn't believe everything that a salesman tells me, at least these days anyway.

My advice is do your own homework on this. Installing one of these systems is expensive. Just make sure that it's right for your needs because you're the one that's going to be living with it for a lot of years to come, not I.

Good luck with your decision.

 

[Sigarms]

There is a huge difference in comparing a Pulse furnace to high velocity system (actually, I don't think you can even compare the two together).

Now, if you were to compare the True Blue furnace or "old" Dornback 90 plus oil furnaces to the Pulse furnace, you'd have a valid comparison (sp?).

Again, goes to the instal.

Like I mention to some people, you could put in a Trane/Carrier/Lennox duel fuel variable speed 18 SEER high efficient heat pump with a 2 stage modulating 95 plus gas funace and have nothing but "issues" or a 10 SEER Janitrol/Goodman and it could run like a champ for 30 years. The difference in the system is not the "quality" from manufacturer, but the way it was installed (I think eveyone can agree that some units do seem to go in easier than others though).

On that note, every manufacturer has "cat tips" that come out, and yes, even to the point where there is a recall. People do make mistakes.

Again, have not seen any problems with a high velocity system if installed properly (other than having to replace a TXV or other part after years of service, which would happen with any other piece of equipment as well).

I have seen issues with a high velocity system with people not designing the ductwork properly though for the intended application (you also know you might have a problem when the guys on the jobsite look at the product and ask "whats that?").

 

[heehaw]

hey, i thought i was the only one around that used or heard of Goodman systems???
heehaw

 

[Sigarms]

Depending on the area, Goodman/Janitrol has a decent market share, particularly in new construction.

And until they were bought out last year, was probably one if not the biggest family owned manufacturer of HVAC equipment in the U.S.

Notice that I didn't call it Junkatrol /forums/images/graemlins/grin.gif

For what it's worth, same "family" as Amana, which is a better known name brand in some areas.