Tenant sealed vent registers in winter to use his own heater

16 Replies

Hello,

I had a tenant last winter and the heat in his unit was supplemented by the unit above him.It gets really cold down there in winter but he chose not to have free heat and sealed the vents tightly with an aluminum foil without  letting me know , I could have easily adjusted the thermostat to lower  per his needs if he had told me and supplemented my apartment above with any additional heat but he chose to seal without letting me know inspite of my warning later on and obviously it can have detrimental effect on the tubing inside the walls due to excess pressure build up.

He also complained about high electricity Bill's (obviously he would incur high utility bills when he turns on his electric radiator without using the free heat he was getting)

 I ended up having an oversight from my end as I did not verify if sealing vent caused any damage .  The subsequent short term tenant did not report issue about air not blowing from the registers as he was "cool" with the hot summer. I ended up identifying the issue really late. Do I have to rip off the sealing now to identify any punctured tubing issue?Appreciate your inputs

Thanks

Likely no real effect in your situation, but really just depends on the volumetrics of your system. Duct burst pressures are rated 3x high yet than design pressures, and closing a register or two will not increase the pressure to the point of failure. Flow rate is a function of pressure drop. Therefore, if your pressure drop increases (because internal static pressure is higher) flow rate will also go up (all else being equal) from your other, open registers. Your system may be performing slightly more inefficiently because of the added back pressure. If this happens in the future, you can also open the other registers slightly more to compensate. I’m more interested in how a tenant was receiving cool air if the registers were closed! Is heat included in the lease?

@Zee Abbas

Thanks Zee this information is very helpful. Yes I included both heating & cooling in rent, it was the first time I rented that unit and I had no clue how best to divy up the bill since the thermostat is in my unit and I get billed for that. Do you have any troubleshooting or tuning tips to diagnose and address why some of the registers are having weak to no air flow?

Out of the 15 registers at least three of them are having weak airflow ,8 have medium flow and rest seem below at considerably higher than medium.

Originally posted by @Peter Morgan :

@Zee Abbas

Thanks Zee this information is very helpful. Yes I included both heating & cooling in rent, it was the first time I rented that unit and I had no clue how best to divy up the bill since the thermostat is in my unit and I get billed for that. Do you have any troubleshooting or tuning tips to diagnose and address why some of the registers are having weak to no air flow?

Out of the 15 registers at least three of them are having weak airflow ,8 have medium flow and rest seem below at considerably higher than medium.

 Reasons for uneven airflow: distance from unit, size of vents, obstructions, flexible vent tubing crimped from hanging, closed or partially closed dampers at main trunk, debris inside tubing. It's virtually impossible to get even air flow from all vents, and you usually don't want even air flow from all vents anyway as some areas will need greater volume and others less volume depending on a lot of factors such as where the room is located in the building, windows and other low-R value fixtures, exposure to south/west vs. north/east, ceiling height, etc.

Easy answer here is if you don't know what you're doing with venting, let a qualified HVAC company come in and get everything adjusted for you based on science rather than guessing. 

@Peter Morgan there are dampers in the duct work that can be adjusted to “throttle” the incoming air. I would check their positions if you’ve always had this problem. Is the temperature out of balance (one room hotter/colder than the others)? A smaller room will require less total airflow than a bigger one to achieve the same temperature.

@JD Martin

Thanks. I did reach out a hvac company that offer tune ups for winter and summer , the technician who conducted the tuneups seemed inexperienced ,all he did was dusted off the furnace, punctured the aluminum tube near furnace for "combustion test" when I brought up no airflow from one of the air registers he suggested the only sure way to address the issue is by ripping the ceiling off and checking the tube for any holes.

@Zee Abbas

Thanks Zee. Are these dampers accessible externally to adjust or it requires opening up the ceiling?The tenant who sealed the vents during winter enjoyed the free cooling coming from the vents with very little electric bill for the 2020 summer. He had much higher cooling needs than us above his apartment  and rejected when we offered him a window ac and was literally driving our ac for his own needs.He even asked me during summer if there is any way to optimally adjust the pressure of air flow as per his needs in one of his bedrooms.

Fast forward during winter he closed the vents in his bedroom and another one in the living room that comes before his bedroom.

Now the same bedroom which once had a high pressure air flow has virtually no airflow makes me wonder if there is a duct burst or duct got pinched somehow? Ideally i think that unit must have the highest airflow pressure because it is at the same level as the furnace. Who can help me best diagnose this problem? Are there any contractors who specialize in diagnosing issues in duct without ripping the ceiling?

The dampers mount at the collars where the flexible ducts attach to the main trunk. If the main trunk is sealed in the ceiling, then you have to open the ceiling to get at the dampers. I doubt the duct burst; it's not impossible but unless every register in the house was sealed off you would just get harder air flow at the open registers. And that's assuming the unit's fan had enough power to overcome the sealed registers to a level where it could inflate and burst the flexible ducts. Not likely - possible that make up tape or clamps where the flex ducts tie to the trunk could have come loose, though. That would give you an air leak at that particular duct and low airflow out of the duct. 

In addition to what @JD Martin has said, I would also recommend checking if your fan is running at the correct speed. Did they replace the capacitor during the tuneup? It’s an odd situation- I wouldn’t expect a tenant to mess with dampers at the air handler, but crazier things have happened. The least destructive way to check for a leak would be to insert one of those fish cameras into the register (like the ones used in cars to check cylinder condition). You can also try using a temp gun along the path of the duct on the ceiling to see if there are sudden temperature fluctuations.

There is unlikely to be damage to the tubing. I guess it is possible that a joint blew open, if it wasn't properly secured. You could have someone scope the lines with cameras. This is common in the plumbing world, so maybe call an HVAC company that also does pluming. There is no reason to open a ceiling unless a camera reveals a problem.

The big issue is that shutting vents can put extra strain on the blower fan. You can also have issues with an AC coil freezing if you don't have proper air flow. A properly designed HVAC system is meant to have all vents open when running. If you do shut a vent, it should only be partially shut or temporary.

You really shouldn't have air vents shared between multiple units. Each unit should have their own forced air system. There are multiple reasons for this. 

1. Temperature controls need to be separate, so they are not shutting and opening vents to regulate temperature. 

2. You don't want to mix air between units. A smell from one unit will be piped into the other. This could even be why they covered the vents. If someone is smoking, vaping, cooking strong smelling food, etc. they will smell it in the other unit.

3. Fire code prohibits air vents shared between multiple units in multifamily. If there is a fire or CO2 build up in one unit, toxic fumes will be transmitted to the other unit. This property was likely an unpermitted conversion.

I understand you probably don't want to add a second HVAC system, but be aware of the above concerns. Odds are good that shared could continue to create problems. I had shared vents in a unit years ago and tenants complained regularly. Too hot, too cold, too smelly, too gross sharing air with the neighbor, etc... In the days of COVID there could even be concerns over that.

@Joe Splitrock

Thanks Joe and you are absolutely right about my shared unit situation. This Mother in law unit has an excellent partition that enables me to rent short term or commuters,traveling nurses etc there is also another exclusive unit on top that I don't have any problems with.Not renting the ADU is not helping the numbers work and there are not many renters in my area who will consider the entire apartment including ADU. I need to move OOS soon due to my job and I just need to kick the can another six months as I am planning to put on sale Spring around March 2022 for all the reasons you mentioned, covid and my new job OOS.

@Zee Abbas

Thanks Zee this is helpful. I noticed one other problem overweekend , a sweaty vent, just one vent though in the restroom. Do you have any suggestions to address this?

I will order HERs test checking for leakage. It is required for heater or A/C. I was told majority of multifamily in aged units (e.g. 50 years old) had major leaks or collapsed air duct. HERs has guidelines. 

@Zee Abbas

Thank you!!! Should I put insulation vent around the external vent register or open the register and try to insulate internally? I observed the sweaty vent in summer can I expect it in winter as well?