remote diagnose HVAC humidity

SVreX said:

What’s your average relative humidity outside?  If it’s LOWER than the 77% you are measuring in the building, then sealing your fresh air intake doors is not helping you, it’s hurting you. 

I would think it is not normally that high in your part of the country. 

I can't say exactly what it is, but the outside average RH is higher than what someone would want in a building.  Tuesday it was a high of about 88 and we had little storms passing through and it was so humid it started to haze a bit, so 85-90% that day.  We have our share of hot and dry, but I would say we have more days above 60% than we do below.  Not to mention, 60% RH at 90 degrees is 85% RH at 72 degrees.

The fresh air blend doors are supposed to open up to supply fresh cool air on a day when the outside is cool and dry.  Since summers here are never cool and dry, I don't understand how opening them would help.  Also, this problem existed in the same exact way both before and after we sealed the blend doors.

In reply to Curtis :

"The outside average RH is higher than what someone would want in a building"... That's completely irrelevant.  The only thing that matters is the delta from outside to inside.

Picture this...

Test 1: Set a dry sponge on the counter.  Put a soaking wet sponge on top of it.  We all know the moisture will migrate from the wet sponge to the dry one.

Test 2: Set a dry sponge on the counter.  Put a mildly damp sponge on top of it.  The moisture will still migrate from the wet sponge to the dry one. It doesn't matter how wet the sponge is.  Only that it is wetter than the dry one.

Curtis said:

The fresh air blend doors are supposed to open up to supply fresh cool air on a day when the outside is cool and dry.  Since summers here are never cool and dry, I don't understand how opening them would help.  Also, this problem existed in the same exact way both before and after we sealed the blend doors.

Right. So you are saying that disabling the doors did not help the problem.

It doesn't matter if summers are cool and dry.  It only matters if they are coolER and dryER.

I did a little research....

Harrisburg PA average temp:                            Harrisburg PA average humidity:

June        81F                                                                 67.7%

July         85.5F                                                               68.6%

Aug         83.4F                                                               72.2%

ALL of those are lower than the 77% you are measuring in the building.

But there is a more important factor...

Harrisburg PA average 7:00 AM humidity:                            Harrisburg PA average 4:00 PM humidity:

June         78%                                                                                      53%

July          80 %                                                                                     53%

Aug          84%                                                                                      55%

Your primary load for cooling is in the afternoon (and evening).  The average humidity in the afternoon is MUCH lower than the 77% humidity you are measuring in the building.  The doors should be open.  

The doors are not the problem.  The problem is most likely the insulation and sealing of the ductwork. It's the only thing that explains the excess water production.  But sealing the doors disables one of the system's tools for dealing with the problem.

Curtis said:

SVreX said:

How about a non-working exhaust fan?

 

Interesting thought. The exhaust fan in the boiler room is pretty isolated (and has always been there) behind an overhead door and two fire doors with minimal air exchange.  The only other vents are the two bathrooms and they have residential style 3" bathroom fans.

No.

The building does not NEED exhaust to function properly.  The boiler room exhaust fan is not related to the AC system.

I suggested that idea not knowing how your building was designed.  Your response tells me that your building was not designed with an exhaust and ventilation system being an important integrated part of the building's humidity control system.

It may have been back in 1953 when it was built, but in 1999 it was extensively updated, expanded, etc.  The boiler was decommissioned, RTUs were installed (not the current ones; they're only about 8 years old), floor raised, office wing added (with it's own RTU), costume shop added (again, its own RTU).

I'm digging the stats on the morning/afternoon humidity.  I get that the A/C can take a certain percentage out and I agree that (since there are some times when the outside is drier than inside) there has to be some water being artificially introduced.  Right now it is 80 degrees and 50% humidity outside.  Inside it is 72 degrees and damp enough that one of the actors' shirts is still wet from his sweat from last night's performance.

UPDATE!  Problem solved.

I had an HVAC company come out (needed annual service anyway) and I asked them to diagnose the humidity issue.  They sent their best guy.  He has been working with the company for 45 years.  Not kidding.  He's 70 and started working there when he was 25.  We went up and pulled the panel and he saw the problem immediately.  Y1 and Y2 had a jumper wire between them effectively causing both stages to run all the time and cycle too short.  I told him I was getting 1 hour cycles and he said that 2-4 hour cycles is better.  He said that a unit that size doesn't even start condensing until about 15 minutes and peaks it's condensation at 30 minutes.  He said if it cycles for one hour, it basically puts back in the same amount it takes out.

This morning I came in to a floor that was much flatter and curtains that didn't feel like a dishrag.

Downside:  Now I have to adjust the trim on all the curtains in the theater :)

In reply to Curtis :

I'm sure this has you feeling good this morning.  Have an awesome day!

In reply to Curtis :

That’s awesome!

old guys rule!!

Curtis said:

UPDATE!  Problem solved... effectively causing both stages to run all the time and cycle too short.

Floating Doc called it 12 minutes in.  Duke seconded less than an hour later.  I friggin' love this place.

1988RedT2 said:

In reply to Curtis :

I'm sure this has you feeling good this morning.  Have an awesome day!

Well, it has me feeling less cold and sweaty  :)

Thank you all.  I just didn't know that a 1-hour cycle was too short for a unit this size.

Dangit.... not fixed.  Today was 78 degrees and 38% humidity.  Went in to get ready for the show and there was a 3' diameter puddle of water that had dripped from the duct.

E36 M3.

Back to the drawing board.  Looks like I will need to call that engineer, Duke.