Carrier moduline 37A VAV

Is anyone familiar with this equipment named in the title?

I'm fairly new to the industry, just finished up my level 3 NVQ so i have never heard of these units before today. The building located in London has over 500 of these units installed in 1986 and relies on these operating in tandem with the perimeter LPHW heating, currently they are struggling to keep the office warm due to the Moduline units letting in to much cold supply air. It's to my understanding that the AHU's supply a fixed set temperature of air to each moduline unit, which then self regulates its own air flow based on the setting temperature for the thermostat.

I have found a few manuals on them but there's not much information on the correct calibration and how to check which, if any component is faulty. I have broken it down to the following components which regulate the air flow through the unit..
- control air filter (assumed to never have been changed)
- volume regulator (the commissioning lines are still in place, but since have all been adjusted)
- thermostat with bimetallic strip (i sense these may be causing a majority of the control issues)
- bellows

how would i go about checking the correct operation of the above components, when i adjust anything the air flow just seems to run wild and not act accordingly. Is there a certain procedure i can follow to go through and check each one individually?

I realise they are all probably well past the life expectancy and no longer efficient compared to todays new technologies available. But the client is insisting on trying to get it all working effectively, so if i can go round and list all the issues that need rectifying it may be the incentive the client needs to replace it all with a modern system.

Goodness me, these take me back far to many years.

http://eto.carrier.com/lit2.asp

You can download manuals for the different 37A models at the above site.

Seems like you've started the correct way however have you checked the main AHU performance such as, duct pressure controlled within the design requirements.

The supply air temperature can also be adjusted for the season.

Generally if the units do not control the airflow then check the filters, air flow regulator and the thermostat. Ensure that all control tubing is correctly fitted and/or plugged as needed.

The first check is to set the thermostat to maximum so that the unit goes to minimum airflow.

I would suggest that if possible try to find a unit that you can work on without being disturbed or disturbing the occupants. Check duct pressure and airflow from the unit.

Remove and check the controller items, refit and test.

Good luck.

Thanks for your help brian.

After spending a good few hours checking over a few different units it became clear that to get the Moduline set up back to how it should be would very costly and time consuming!

It seems a large number of them are suffering from bellow leaks and therefore not able to fully inflate to dampen down the air flow through the moduline, this in turn seems to cause the AHU supply fan to ramp up to a high speed and throttle air throughout the building creating a lot of noisy units. It was also discovered that numerous filters have clearly passed there serviceable life span and need replacing and all of which comes at a cost so... still, Not bad for a installation that dates back to 1986

Sounds like normal non-maintenance of a Moduline system and yes, someone is going to be spending a lot of money to get it back as it could/should be.

Good luck with it.