Question about new system installation

[james l]

I am in the middle of massive home remodeling using a local general contractor. I had little control over the HVAC subcontractor selected. Removed two older hvac units, and are in the process of installing a 5-ton Bryant Evolution 16 SEER Heat PumP AC with four zones (2 upstairs and 2 down) and the Bryant EAC. All of the ductwork is being replaced also.

I have a million questions concerning the quality of the install (see sentence # 2 above), but here are the top two questions:

1. When I came home from Thanksgiving vacation, I found the new unit installed and the access panel open. I noticed "damage" to the fins on the expansion coil, but I do not know if this is typical or significant--or if I should raise a stink about it. Photo below.
http://img184.imageshack.us/img184/2994/hvacdamageoq9.jpg

2. Most of the ductwork is flex (see sentence #2 above). The HVAC isntallers used the same metal straps to hang the flex that they used to hang the hard pipe. I feel certain the metal straps will quickly cut the insulation on both the hard pipe and the flex, and eventually the flex duct inner liner also. Also it appears the flex duct is being crushed by the straps. There are several dozen similar spots, but I have attached a picture of one of the worst cases below. Should I raise a stink about this also? Photo below.
http://img373.imageshack.us/img373/3808/flexgi8.jpg

[BaldLoonie]

The marks on the coil aren't that unusual. That wouldn't scare me.

The flex hung by mechanics wire does. Should be something like a 2" mesh material, that doesn't pinch off the duct.

[james l]

The hangars are strips of sheet metal, about 1-1.5 inches wide.

Do service techs have a comb or brush to straighten these delicate fins on the coil?

New question:

The EAC is attached directly to the air handler. An insulated sheet metal plenum box (about 18" cube) is attached to the EAC, with two 10" or 12" flex return ducts plumbed to this plenum. Will the air flow to the EAC be smooth enough for it to be effective, or should the plenum be separated from the EAC by a short section of straight duct?

[davefr]

I'm speaking from experience based on a bad flex ductwork installation that I had to redo several years after it was installed.

I would not put up with those metal straps. The sharp edges could eventually slice thru the saran warp ducts causing leaks. There's a special soft woven wide tape that should be used.

While you're at it check the following:

How did he connect the flex to junction pieces? If he used duct tape then beware!! He should use metal bands, giant tie wraps, or fiberglass tape and mastic. Duct tape deteriorates from the heat and the ducts can sag off their connection. That's what happened to several of my duct runs.

Secondly make sure that the flex is adequately supported. This is especially important where it makes connections. You don't want any sag where it enters or exits a junction box because it'll put stress on the connection.

I personally hate these new "saran wrap" ducts.

[heattech]

The coil dosnt seem to be too bad (SEEN WORSE) the metal hangers would bother me though!The flex duct is a good supply duct, it does have some friction on the supply air but does have the tendency to quieten the system noise.We support our supply duct with 2" nylon webbing.not only is it more suitable for holding the fragile flex by having a wider support area so as not to pinch off the duct but dosnt corrode in damp areas.And it looks more professional!!

[4l530]

Originally posted by james l
http://img184.imageshack.us/img184/2994/hvacdamageoq9.jpg
Eh. It's not real pretty, but it's okay. They can probably use a fin comb if you think they must.


http://img373.imageshack.us/img373/3808/flexgi8.jpg
Not cool! Needs to be supported better or there will be problems later on.



The EAC is attached directly to the air handler. An insulated sheet metal plenum box (about 18" cube) is attached to the EAC, with two 10" or 12" flex return ducts plumbed to this plenum. Will the air flow to the EAC be smooth enough for it to be effective, or should the plenum be separated from the EAC by a short section of straight duct?

I think it will be okay the way it is.

[mark beiser]

Originally posted by james l
The EAC is attached directly to the air handler. An insulated sheet metal plenum box (about 18" cube) is attached to the EAC, with two 10" or 12" flex return ducts plumbed to this plenum. Will the air flow to the EAC be smooth enough for it to be effective, or should the plenum be separated from the EAC by a short section of straight duct?

Nothing wrong with installing the EAC like that, but I sure hope there are more than two 10 or 12 inch return ducts for a 5 ton system. If there are only two, they need to be more like 16 or 18 inch flex ducts.

[texas cooler]

Coil damage appears minimal. Combs are available to straighten. We always use the 2" webbing for supporting flex. It must also be supported well - there are usually installation instructions on the carton that it was delivered in. You may also want to make sure the duct sizing is correct, flex duct has inherently higher internal static pressure than smooth metal pipe and you may end up with less flow than the original system.

[dash]

Originally posted by mark beiser

Originally posted by james l
The EAC is attached directly to the air handler. An insulated sheet metal plenum box (about 18" cube) is attached to the EAC, with two 10" or 12" flex return ducts plumbed to this plenum. Will the air flow to the EAC be smooth enough for it to be effective, or should the plenum be separated from the EAC by a short section of straight duct?

Nothing wrong with installing the EAC like that, but I sure hope there are more than two 10 or 12 inch return ducts for a 5 ton system. If there are only two, they need to be more like 16 or 18 inch flex ducts.


I can't agree that there's nothing wrong with installing a filter like that.

First there's the increase in static pressure,second the airflow will not be even across the filter.If the air flow is uneven,say 70 5 of the air thru 505 of the filter,it loses efficiencny,IMO.

I do agree the return ducts sound too small for 5 tons.Testing the ESP ,by a Pro,will easily tell .

[mark beiser]

Originally posted by dash

Originally posted by mark beiser

Originally posted by james l
The EAC is attached directly to the air handler. An insulated sheet metal plenum box (about 18" cube) is attached to the EAC, with two 10" or 12" flex return ducts plumbed to this plenum. Will the air flow to the EAC be smooth enough for it to be effective, or should the plenum be separated from the EAC by a short section of straight duct?

Nothing wrong with installing the EAC like that, but I sure hope there are more than two 10 or 12 inch return ducts for a 5 ton system. If there are only two, they need to be more like 16 or 18 inch flex ducts.


I can't agree that there's nothing wrong with installing a filter like that.

First there's the increase in static pressure,second the airflow will not be even across the filter.If the air flow is uneven,say 70 5 of the air thru 505 of the filter,it loses efficiencny,IMO.

I do agree the return ducts sound too small for 5 tons.Testing the ESP ,by a Pro,will easily tell .

I should have qualified my statement about the EAC installation.
If the EAC cabinet is the same size as the opening in the air handler, or at least within an inch or so, then it is fine to install it directly onto the air handler.

If the openings are not roughly the same size, then a transition is needed.

[james l]

Thanks for all your feedback! Let me clarify the EAC installation (I'll post a picture tomorrow). The sheet metal box plenum matches the EAC inlet, and the EAC outlet matches the Air Handler inlet (by design), so I don't think the EAC outlet interface will degrade the airflow in the EAC or the coil. My concern is the air flow from the plenum to the EAC may be so turbulent that it does not allow the EAC to do it's job.

Mark--what would you suggest? Is adding a short section of rectangular duct between the return plenum and the EAC inlet necessary? How do I make the case to the installer if it is not in the Bryan manual?

The Honeywell EAC installation manual (from my last house) suggested a section of straight duct in this situation, but the Bryan manual does not. For a single return that bends just before entering the EAC, both ther Honeywell and the Bryan EAC manuals require turning vanes to keep things smooth. On my new system, The EAC is to the right of the plenum, and the return flex ducts enter the plenum from the front and back of the plenum "cube", so both returns air flows have 90-degree turns that occur in the plenum.

OBTW, for everyone that asked--I'll measure them or look for labels, but I think my estimates of 10-12" for the two return flex ducts may have been on the small side. The installer did do J and D manual calcs, so I think all of the duct sizing is OK. The returns are very large--no, make that humongous. I'll look closer and post the sizes tomorrow.

Is it acceptable to ask the installer for copies of the J and D calculations?

The installer agreed to replace the duct hangers with 2" mesh.

[davesrha]

The saran wrap is actually maylar jacket very durable, however it should be supported by nylon duct strap at 3 foot intervals with a maximum sag of 1/2" per foot and a 90 degree turn should be a 1 to 1 radius.