Too Hot! Too Cold! Tales from the HVAC trenches

Too hot for some! Too cold for others!

If you operate real estate you probably get these complaints.   Some say that for every too hot, there is someone on the other side of th office feeling too cold.  So, what does it look like from the other side of the fence?   Here are some random, but real, comments from the service technicians that have responded to these complaints.

sometimes it’s the original building design

Investigated the too hot call in the incubation room and it seems the Engineer felt that tempered air from the MUA was sufficient cooling for all that equipment.  I have a call into  engineering to discuss with the tech. I believe they may have to add supplemental cooling in that room. It is south facing and has large equipment inside. The drawing shows a paltry 150 CFM of tempered air.

or, there could be a real old-school pneumatic problem, or something else completely,

Called out due office spaces on 2nd and 5th floor being too hot – Arrived on site and gained access to 5th floor – Checked pneumatic thermostat, noticed that it was turned down to lowest setpoint but VAV box seemed to be heating still – Connected gauge to incoming supply line to check pressure – Connected gauge to outgoing from thermostat and checked pressure while adjusting thermostat – Noticed that thermostat was dropping out pressure and not holding heating valve closed – Accessed VAV box in adjacent room and checked heating valve – Connected test bulb to pneumatic actuator serving heating valve and attempted to close manually – Valve would close but not all the way as it was letting some water to pass through to coil – Went to supplier, purchased new thermostat and replaced existing – Replaced valve assembly with on site spare – Tested operation of thermostat and heating valve, system is fully operational – Accessed 2nd floor office space and found that it was in the middle of a DDC retrofit – Was requested by operator to temporarily disable heating – Located VAV box serving space and closed valves for heating coil * Requested by op to purchase 4 extra pneumatic thermostats for on site spares

the trip could be completely wasted

Drove to site. Checked in with manager. She explained that the segregated office spaces along the north west side of the building were always too cold (summer) or too hot (winter). Did not have ladder to access ceiling tiles to check for dampers to re-direct air flow. Was not given access to roof at this time. Unit thermostat in main lobby area. Must return next week with ladder to attempt to change damper position, and if not progress is made suggest bringing in air balancer to balance air flow.

or an electrical problem,

Arrived on site and checked in with reception. Gained access to roof. Found no power at unit and no obvious grounds. Fan is moving freely. Went back to store and found breaker tripped. Reset and went back to roof. Cycled cooling on. Both compressor and condensor fan started up. Compressor amprages good at 13 and condensor fan good 1.34 . Pressures good at 58 and 200. It’s posible rain got into unit and created a short. Checked out with reception. She mentioned one room is always too hot. A quick investigation revealed no return grill in room. I removed a small tile to increase air flow. I will check in with client at a later date.

maybe poor layout, or just leaky ducts,

Call for too hot in the South West lab. Upon investigation tested the motor and was working correctly. Stroked the motors and set the vav boxes to the maximum on vav-10- 6. The original cooling values have been recorded in case the set points need to be reset. The entrance room to that SW lab has no diffuser and has stagnant air. A further look at the engineering plans may be needed to see if a nearby branch can supply air. A return air box may be needed on top of this room as well to allow proper air flow. A nearby main trunk supply air that was original to the building had multiple leak points and was closed off as best I could do safely. Then closed up the corresponding insulation.

or a serious water leak,

Arrived on site gained access to mechanical room. Complaint of building being too hot. Inspected control board and checked all set points for heating and cooling. Noticed cooling tower leaving and loop Temps to be the same. Went outside and checked cooling tower operation. Noticed fans running at low and hich speed and cooling tower even shutting down when satisfied. In order to drop cooling tower leaving temp, water must be turned in and sump must be filled. Started filling sump and noticed 2 major cracks in 3/4 copper lines feeding the tower. Could not continue to fill tower. Repairs needed before water can be turned on.

but could be a clogged filter,

I arrived at 14:00. I packed my tools up to the 12th floor to fix the mixing valve. I found the filter on the cold side to be plugged. I unclogged the filter and tried the water. it was a comfortably temperature. Because the 12th floor is at the top of the building and hot water rises the first people to use the faucet in the morning would get the hottest, even too hot of water. I could turn the mixing valve more to cold but then for the rest of the day the water would seem cool. Also the hot water heats up a portion of the cold water that is connected to it so in the morning practical all the water in the pipes is hot

never-the-less, the problem is seldom solved on the first trip…

One thing is certain, a too hot, too cold complaint is costly.  It almost always involves a site visit, and often a lot of discovery.   Too often the technician arrives on site armed with little information, and may need to undo work that was previously done by others.   These problems can be addressed, sometimes without a site visit, if you and your service partners are digitally connected.   Find out more at