AxisCat
Mechanical
- Apr 7, 2008
- 29
We are experiencing high humidity levels in a new tenant finish in one space of a mini mall. This is your typical setup glass store front on one side, exterior wall on the back and demising walls separating each space.
At present this space has a Jersey Mikes on one side and an unfinished space on the other. The demising walls are fire rated and extend to the bottom of the roof deck.
The space itself is about 1700 square feet. My load calculations show requirements of 35,948 btu sensible, 8,516 btu latent, 44,465 btu total. The building is located in southwest Kentucky.
We chose to install a single 5-ton packaged rooftop with DX cooling (single stage) A 4-ton may have been a better choice but I don’t think oversizing is the issue here.
The air balance contractor measured total supply air at 2,150 cfm (direct drive motor on lowest speed tap) Outside air is set at 200 cfm.
The new tenants have not moved in yet and the system has been in operation for the last 3 weeks during final stages of finish work. The unit appears to operating perfectly with all the tests we have done so far. All the ducting is inside the building envelope so I can’t see any duct leakage contributing to pressure unbalance. The first thing we did was block off all the outside air which had no measurable effect on the high humidity inside.
The humidity level has been hovering around 80% plus or minus a couple of percent for the last 5 days with high temperatures around the upper 80’s – low 90’s. Needless to say it is effecting the interior of the building; ceiling tiles are warping, doors aren’t shutting properly, etc.
The General Contractor can’t think of any recent activities that would have added moisture to the space. I am at a complete loss of where to go from here, if anyone has any suggestions on what to check next it would be greatly appreciated.
Best regards,
Darrell
At present this space has a Jersey Mikes on one side and an unfinished space on the other. The demising walls are fire rated and extend to the bottom of the roof deck.
The space itself is about 1700 square feet. My load calculations show requirements of 35,948 btu sensible, 8,516 btu latent, 44,465 btu total. The building is located in southwest Kentucky.
We chose to install a single 5-ton packaged rooftop with DX cooling (single stage) A 4-ton may have been a better choice but I don’t think oversizing is the issue here.
The air balance contractor measured total supply air at 2,150 cfm (direct drive motor on lowest speed tap) Outside air is set at 200 cfm.
The new tenants have not moved in yet and the system has been in operation for the last 3 weeks during final stages of finish work. The unit appears to operating perfectly with all the tests we have done so far. All the ducting is inside the building envelope so I can’t see any duct leakage contributing to pressure unbalance. The first thing we did was block off all the outside air which had no measurable effect on the high humidity inside.
The humidity level has been hovering around 80% plus or minus a couple of percent for the last 5 days with high temperatures around the upper 80’s – low 90’s. Needless to say it is effecting the interior of the building; ceiling tiles are warping, doors aren’t shutting properly, etc.
The General Contractor can’t think of any recent activities that would have added moisture to the space. I am at a complete loss of where to go from here, if anyone has any suggestions on what to check next it would be greatly appreciated.
Best regards,
Darrell
