HVAC-Talk: Heating, Air & Refrigeration Discussion banner
Cancel
Create thread New Forums

New aaon make up air setpoints?

Jump to Latest
1 - 17 of 17 Posts
F

fitzyfitta

· Professional Member
Joined
·
792 Posts
Discussion starter · #1 ·
I've got 2 13ton mua units feeding air to hallways of new hotel. Unit is pretty basic. Ebus oa/rh sensor, supply air sensor and room sensor with slide adjust no override. I went through configuration with wattmaster tech and have all boards setup correctly. Unit is running HVAC source=outdoor air
Supply air temp reset source= space temp My question is the set points. Unit is running stand alone, forced occupied heat mode.
Control temp 46
Cool spt 74
Heat spt 55
Space temp 71
Supply temp 122 active 123
The space temp is ok but I'm not confident and confused as to what I should have. Should I be resetting the supply air based on space temp. Should I be adjusting the min/max reset temps. Ive read all the literature on the boards and have worked on plenty of Aaons just never set one up from start up
Any help or suggestions are appreciated. I'm in the northeast. It gets near 0 in the winter and 100 in summer. I feel as if Aaon should have provided a setpoint list for the clients design. Customer wants the heat at 70 and cool at 74. TIA. I'll be back onsite tomorrow.
Fitz.
 
#2 ·
Yes. Reset the SA based on space temp.
Presently your
(Heat mode is enabled below 55f.
Cool is enabled above 74f.

When OSA temp gets to 56 the heat won't function. So you'll have 55-73 f air blowing in the space until the OSA either goes above or below those points.)

You need to set up your reset span and tighten up the mode enable.
Try your mode enable at 68Ht and 72Cl. (so the unit will allow heat at 68 and cooling at 72.)

Im assuming
you have mod cooling and mod /staged heating.

Then:

Heating:
At 72f space set for 70f SA air and at 60 reset to 120.

Cooling:
At 72f space set to 70f supply air and at 80f space, reset to 55.

Does this have dehum and reheat?

Heat wheel? Exhaust fan?

Sent from my SM-G950U using Tapatalk
 
Discussion starter · #3 ·
Icy, no heat wheel or exhaust. Only supply fan with min/max setpoins depending on mode. It does have hot gas reheat. Cooling circuits are down. I found 3 of the 4 circuits flat on charge due to leaking pressure transducers. Waiting for Aaon to get warranty parts.
 
#5 ·
Another spot to look for leaks is the solonoid valve behind the compressor. It is a pain in the butt to repair.
 
Save
Like Like
#6 ·
fitzyfitta said:
Icy, no heat wheel or exhaust. Only supply fan with min/max setpoins depending on mode. It does have hot gas reheat. Cooling circuits are down. I found 3 of the 4 circuits flat on charge due to leaking pressure transducers. Waiting for Aaon to get warranty parts.
Click to expand...
Ok. So try it as i suggested. That would be a good starting spot. I have a few hotels where those approximate numbers work.

(The manager/maint, will have to be coached into understanding that this is different than on/off ht/cool.)

It sounds like you have "dehumidify priority"
configed, with
"heat allowed during reheat"?
fitzyfitta said:
Heat type=modgasX then staged.
Cool type=refrigeration module. Type standard Humidity control- mod hgr
Click to expand...


Sent from my SM-G950U using Tapatalk
 
#7 ·
Interested where the transducer leaks are ? Couple months ago I commissioned a small Drake chiller and both circuits , both transducers were leaking through the transducer pins.
Drake did not seem surprised and sent me 4 new ones.

Sent from my SM-G950U using Tapatalk
 
Discussion starter · #8 ·
Leaks are thought the pins on mine too. Aaon wants pics of my gauges on the system to verify the leak. I told the the system has 5 psi in it and my electronic leak detector is going nuts. It's been a struggle with them. I pulled the transducers, pressurized them and filled the pin section with leak bubbles. I'll post pics if I can remember how too.
 
Discussion starter · #9 ·
The discharge transducers are mcs brand. We do a fair bit of mcs retrofits on chillers and a few rtu's. I heard from another mechanic he had a leaking transducer on a recent retro.
 
#13 ·
I’m an AAON tech rep in Chicago.
If it’s a new unit, I’m surprised they even came with those transducers. They stopped those a while back. New ones are blue and red colored.
 
Discussion starter · #14 ·
Joe645733 said:
I’m an AAON tech rep in Chicago.
If it’s a new unit, I’m surprised they even came with those transducers. They stopped those a while back. New ones are blue and red colored.
Click to expand...
This unit is out of warranty next month according to the factory. It's for a hotel that is way behind schedule. Not sure how long it's been on site. Electrician said they moved it 4 times before the found a location. It's right outside 3 rooms and you can hear the burners running inside the rooms.

Sent from my SM-G950U using Tapatalk
 
#17 ·
Okay so it’s technically out of warranty. That means it expired 2018 in October (10).
They may have given you the coverage cuz those transducers were a complete mess. We had to go around swapping all of them out.
 
1 - 17 of 17 Posts
You have insufficient privileges to reply here.
About this Discussion
16 Replies
4 Participants
Last post:
Joe645733
HVAC-Talk: Heating, Air & Refrigeration Discussion
posts
5M
members
275K
Since
2000
The #1 HVACR Community
Full Forum Listing
Explore Our Forums
AOP Residential HVAC/Refrigeration(Beenthere Zone) General Discussion Tech to Tech Chat - Residential Controls Refrigeration & Ice Making