Heat

[ponytug]

High Relative Humidity is my biggest problem now in the operating rooms… 20-60% is my range and no surgery can start outside this range.

My readings with the new HVAC are consistently 57-60%

Contractor has been trying all kinds of things with little success.

68F is ideal operating room temp so warming the room not an option.

The old system was always plus or minus 50% RH
View attachment 3817922

Does the new system condition all of the air, or does it run and mix in recycled air as needed for temperature? Do you know what the Freon temperature is at the evaporator, and what are the air temperatures (in/out)?

Might be a Freon fill issue, or that the new air flow velocity that is too high, or the controller isn't getting the right inputs and not calling for enough cooling, or possibly poor drainage. One way or another, your evaporator is either not getting cold enough, or the air flow is too high, and the air is not getting cold enough. With more modern refrigerants, (non-R22), similar cooling capacities don't always get the dehumidification that one might be used to. Evaporators often get sized for efficiency these days, and that often leads to a lack of humidity control. Sometimes the "simple" way is a separate dehumidifying system.

I've been on this sort of snipe hunt more times than I like to recall.

All the best,

Peter

 

[ultrarunner]

All of the above… built for efficiency and energy standards… problem came to light with new air handler installed.

The flow was much too high so a VFD added.

R22 is now 410a

Air is 100% outside air.

The new air handler coil is physically closer to the blower which is of a totally different design.

The preheat air handler coil was not not tied in until last week.

The pneumatic 7 zone reheats are now electric.

The Johnson Controls still not dialed in.

Several field modifications to the condenser unit such as hot gas by-pass

The new boiler was on default setting turning off… ideal for efficiency but not a process application.

Old system made 54 F air and all was good… contractor has new system making 44 F air and it sounds like it’s working hard.

The first thing I noticed is the new air handler condensate line flow is a trickle instead of a stream.

Also, several Carrier under warranty component failures such as one of the new compressors replaced, contactors, circuit board plus a defective valve vented 30 lbs of 410a

I didn’t plan to go out like this but as of this week it’s been a year project and still fighting it.

The alternative would have been 7 package units but that would have involved new electrical, altering ducting, structural engineering, building curbs, condensate lines, etc.

HVAC team said make the rooms warmer… Docs gowned up working in lead aprons or 6 hour plastics cases are not going to work at 75… truth is they would love 65 F

The weekend the new blower went in it sounded like a jet engine with static pressure of 9

Some quick action taken to reduce flow… designed for the required air exchanges of 12 requires 13,500 cfm and new unit much greater prior the VFD which is now 40% of previous volume.

Contractor always responsive but I have lost credibility with medical team…

On install weekend humidity was 78-80%

 

[ponytug]

I have seen it here, too. Folks don't pay any attention to the humidity target until after the cooling package is installed.

To me, the trickle instead of a stream is the giveaway in my view. Either the evaporator is too warm, or the air speed is too high, or both. Regardless, the system isn't getting the water out.

And above all, I know that the humidity specifications is critical for keeping surgeries successful. Higher humidity dramatically increases the viability of microbes. That's an expensive path to go down, and it rarely even ends ok.

I hope it doesn't come to having to rip out the newly installed system. How deeply is Carrier involved in making this right? Do they have someone non-local on site?

Good luck!

All the best,

Peter

 

[grsthegreat]

All of the above… built for efficiency and energy standards… problem came to light with new air handler installed.

The flow was much too high so a VFD added.

R22 is now 410a

Air is 100% outside air.

The new air handler coil is physically closer to the blower which is of a totally different design.

The preheat air handler coil was not not tied in until last week.

The pneumatic 7 zone reheats are now electric.

The Johnson Controls still not dialed in.

Several field modifications to the condenser unit such as hot gas by-pass

The new boiler was on default setting turning off… ideal for efficiency but not a process application.

Old system made 54 F air and all was good… contractor has new system making 44 F air and it sounds like it’s working hard.

The first thing I noticed is the new air handler condensate line flow is a trickle instead of a stream.

Also, several Carrier under warranty component failures such as one of the new compressors replaced, contactors, circuit board plus a defective valve vented 30 lbs of 410a

I didn’t plan to go out like this but as of this week it’s been a year project and still fighting it.

The alternative would have been 7 package units but that would have involved new electrical, altering ducting, structural engineering, building curbs, condensate lines, etc.

HVAC team said make the rooms warmer… Docs gowned up working in lead aprons or 6 hour plastics cases are not going to work at 75… truth is they would love 65 F

The weekend the new blower went in it sounded like a jet engine with static pressure of 9

Some quick action taken to reduce flow… designed for the required air exchanges of 12 requires 13,500 cfm and new unit much greater prior the VFD which is now 40% of previous volume.

Contractor always responsive but I have lost credibility with medical team…

On install weekend humidity was 78-80%

Are you planning to retire?

 

[ultrarunner]

Word was we were closing December 2024 and I was ok with that.

Corp noted the overall decline in the area and changing demographics.

To me it looked like a good way to wrap things up.

Last June it was about face and corp committed to another 15 years and aging equipment that was not a problem became center stage.

The place is kind of my baby since I was part of the design build and owners agent in 1992.

So far I have not provided a hard no or retirement date to my boss who is much older with boundless energy…

 

[Complete Turf Care]

Hottest day this year. Outside temp did get to 100 today, but I was not able to catch what the heat index was at that moment.
It has not been as hot this summer as it has been the past 2 years.

 

[ultrarunner]

So far the SF Bay on track for one of the coldest summers… weather very Fall like…

I’m not complaining.