I could go either way on this. I don’t have a big issue with the closet being used as a plenum, but that might change depending on what is stored in there by the unknowing homeowner. If there were a gas furnace instead of what appears to be a simple air handler, I would also not want that. Gas appliances should not be inside of a plenum.
I think I would call it out as a non-standard installation method, and at least inform my client that what they store in the closet may affect their air quality. They should be aware that the entire closet is part of the HVAC system. Otherwise, I could see someone cutting a pet door in and putting the cat litter box in there, lol.
I concur. Proper hypotheses.
The return air duct termination point/end point is located in the same room as the AHU system. The HVAC Return air is not being taken but delivered to the HVAC air curculation/conditioning system to complete a cycle.
Conditioned, or ventilated air is traveling in a loop or partial loop or circle.
Convection principle, driven by the principle that, warm air rises, and cooler air sinks or settles. This natural convection process creates a cycle where heated air rises, and cooler air moves in to replace it, leading to a continuous flow of air within a space being exchanged.
The lack of a pan and no visible secondary condensate disposal/safety switch are probably the worst of the multiple defects in that installation.
FYI there is a new Code in the 2023 FBC.
I’m curious, What issues?
If this is a defect, then why arent we calling out every closet with a louvered door?
Everyone is saying this installation has “multiple defects”, yet nobody is willing to say what they are. Nobody has made a valid argument that this is wrong.
The only negative impact is that it “might” pull dryer lint from the laundry room. There is no gas service, so there is also no combustion air vent to worry about.
If they were to put weather stripping around the door, it would prevent air being pulled from the laundry room, but I think that’s such a minor issue
I’m not going to expound on this, unless you have a specific question. You can start by studying Building Science, HVAC System Design (ASHRAE, TAB etc.) and the Law of Thermodynamics. Took me about 30yrs to gather that information to where I made this statement with confidence. I didn’t just learn it, I diagnosed these associated issues and provided how to correct the situations, which I still do in my retirement.
This is new construction for one. Yes, there are plenty of HVAC units installed as retrofits that do not follow best practices. This is not acceptable in my book in new construction. If you want to put an exterior door on, it will cost more than putting the correct duct into a plenum below the unit, along with a drain pan (one of those other issues others here are referring to).
The reason for the HVAC is to provide comfort. This will not happen if not properly designed. How the return is balanced is more critical than the supply duct system.
Aside from the HVAC aspect, putting a room in a negative atmospheric pressure affects probably two dozen “potential” issues that I will not list. It affects several systems of the building all from one, "I don’t want to connect the return to the unit.
Just because the contractors says “That’s the way we always do it here”, does not make things right.
There is 1 zone in this house, since there is no zone control in that mechanical room or zone damper on the supply duct, so this is probably a small single story ranch. The room will only be under negative pressure if the blower sucks in more air than the return duct in the ceiling provides. In the pictures Donald provided, it lookes like the return is a 20 x 25. Are you saying that return is too small and that it will create a negative pressure situation in the mechanical room? I’m not seeing it.
But an auxiliary drain pan is not required though. It is ONE of the FOUR allowed choices for secondary or auxiliary condensate disposal. This unit has a water level detection device installed at the secondary drain at the evaporator coil. A water level detection device installed at the evaporator coil secondary drain is equivalent to the drain pan with drain based on what is written.
I don’t like the installation either, but we need to talk actual potential problems and implication.
The pan directly under the coil has a primary drain and a secondary overflow drain, which is what I was talking about. The exterior pan underneath the unit would be considered auxiliary drain pan with an auxiliary drain.
Units are equipped with primary and secondary ¾" FPT drain
connections. For proper condensate line installations see Fig. 3 thru
Fig. 7. To prevent property damage and achieve optimum drainage
performance, BOTH primary and secondary drain lines should be
installed and include properly-sized condensate traps (Fig. 17 and
Fig. 22). Factory-approved condensate traps are available.
NOTE: If unit is located in or above a living space where damage may result from condensate overflow, a field-supplied, external condensate pan should be installed underneath the entire unit, and a secondary condensate line (with appropriate trap) should be run from the unit into the pan. Any condensate in this external condensate pan should be drained to a noticeable place. As an alternative to using an external
condensate pan, some localities may allow the use of a separate ¾"
(19 mm) condensate line (with appropriate trap) to a place where the
condensate will be noticeable. The owner of the structure must be
informed that when condensate flows from the secondary drain or
external condensate pan, the unit requires servicing or water damage will
occur.
Install traps in the condensate lines as close to the coil as possible.
(Fig. 22). Make sure that the outlet of each trap is below its connection
to the condensate pan to prevent condensate from overflowing the drain
pan. Prime all traps, test for leaks, and insulate traps if located above a
living area. Condensate drain lines should be pitched downward at a
minimum slope of 1" (25 mm) for every 10’ (3 m) of length. Consult
local codes for additional restrictions or precautions.
Related story:
Several years after we did a new construction inspection for one of our clients, I get a call.
Hi this is “John Doe” you did our inspection 4 years ago before our warranty expired. We came home from vacation and opened our front door and half our house was flooded, there was mold growing everywhere. Long story short… half the flooring in the house had to be replaced, 2 feet of drywall in half of the house had to be replaced, all the kitchen cabinets and two of the bathroom cabinets had to be replaced. We had to live in a hotel for over a month while they fixed all this mess. Because you called it out in your report, the builder had to pay for everything including our hotel (mid-high 5 figures back then). Thank you very much, we’re so glad we had you do our inspection.
The “thing” in the report was a similar installation as the OP except it had a drain pan (yes with two safety shut-off switches). with no drain line. The primary condensate got clogged both of the switches failed and the house flooded.
I report these “normal”, “that’s how we do all of them”, “it pasted Code” installations every time.
What I find interesting in these instructions, is that it doesnt say anything about installing a float valve on the secondary line. It says to install the secondary line with trap into the drain pan. And then another drain line from the pan to the exterior. And unless I missed it, it doesnt even say to install a float valve anywhere on the unit.
I rarely see a secondary drain line installed, and when I do, its usually when the unit is in an attic.
Also, what good is a trap on the secondary line to the pan? It says to prime it, but after a couple weeks, it’s gonna be dry anyway.. there’s no advantage for a trap from the unit to the drain pan.
So the builder paid for repairs because you called out a missing secondary drain line to the exterior? Doesnt seem like they would have given in that easy.. Was this a ranch style?
Most of the manufacturer’s CYA in their instructions.
Then apply this…
M1307.1 General.
Installation of appliances shall conform to the conditions of their listing and label and the manufacturer’s instructions. The manufacturer’s operating and installation instructions shall remain attached to the appliance.
and again in Chapter 14…
M1401.1 Installation.
Heating and cooling equipment and appliances shall be installed in accordance with the manufacturer’s instructions and the requirements of this code. Air-handling units installed in attics shall comply with the Florida Building Code, Energy Conservation Section R403.3.6.
To my understanding, only 1 drain line is required in an up-flow position. Anyone else read it that way?
2 drain lines are required when: (1) Conversions; The conversion of the fan coil to downflow requires special procedures. Or (2) Accessories: Humidifier; Connect the humidifier and humidistat to the fan coil unit as shown in Fig. 23 and Fig. 24. The cooling lockout relay is optional.
UNIT OR PROPERTY DAMAGE HAZARD
Failure to follow this warning caution may result in product or property
damage. The conversion of the fan coil to downflow requires special procedures for the condensate drains on both A-coil and Slope-coil units.The vertical drains have an overflow hole between the primary and secondary drain holes. This hole is plugged for all applications except downflow, and must be used for downflow.
During conversion process, remove plastic cap covering vertical drains only and discard. Remove plug from overflow hole and discard. At completion of downflow installation, caulk around vertical pan fitting to door joint to retain low air leak performance of the unit.
There appears to be 2 different inspection dates?
One image shows the supply duct with a cutout and strips of blue tape on the ceiling.
In my neck of the wood blue tape strips is used to show areas requiring correction. IE: Paint deficiencies. Chipped tile or scrapes on trim.
The other image shows the supply duct without a cutout.
So, you’re trying to tell me that there is no negative pressure in a return duct? Without a return connected to the unit, the room is part of the duct system.
No, the air in is the same as the air out.
HVAC is a closed system. Where is this extra air coming from? Oh yea, from the obvious leakage we can see in the pictures. This leakage will increase the positive pressure of the house, not increase the negative.
So what happens when the pan does not catch all the water and divert it down the drain? Ever see the mess a frozen evaporator coil makes? You know, when duct design is wrong or a coil gets dirty.
No, it is not a choice, it is a requirement dependent on the application. It’s in a finished space of the building, and a pan is required. If the pan does not have a drain that discharges in a conspicuous place (above the kitchen window, from the ceiling above the master bathtub etc. ), it requires an overflow switch.
What do you think I’m talking about? I said that I’m not going to write a 3-day class on all the potentials. Has nothing to do with the crappy look of the installation
That is because it is above a finished space. The Aux Drain must be able to drain by gravity or another option is required ie. Condensate Pump (which has an overflow switch as well).
Why is this?
In this case, the unit is up flow and the evaporator coil is at the bottom. The fan above will prevent the drain from flowing properly because of the negative pressure (which supposable doesn’t exist in this thread). The condensate in the pan will rise above the pan and leak. This happens when the return duct is wrong, or a dirty filter directly below the fan (instead of in a return plenum).
), it requires an overflow switch.