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Andy AC
02-06-2007, 09:09 PM
Hello guys, got a bit of an annoying problem with a rheem rooftop ducted a/c system. Problem is its pissing water into the supply ducting which then goes down into the pub below and pours through the ceiling.

I checked the drain and it was clear, cleaned all the sludge and rust out of the tray. I even drilled holes in the bottom of the unit and the outlet of the supply duct to deal with any potential overspill from the tray. Just to make sure I drilled a hole through the drip tray and casing close to the drain outlet ( drips straight on to roof, unit 18 inches in the air.) Thought that would be the end of it but had another message about it flooding the pub again.

This happened the same night we fixed the fridge circuit,- blocked drier so full degass new driers etc. also evap fan belt tightened, so masses of airflow. Condenser fan pressure switch has been by-passed on cond fan 2 so both fans run all the time( about 2 years ago).
Evap coil is clear, no return air, chills outside air (total loss system)
It seems to be the best the fridge circuit has worked for years.
System installed 15 years ago and is stiil "as installed" originally)
Drain was not trapped, but never has been

Any ideas anyone?

Andy

Brian_UK
02-06-2007, 10:59 PM
Original cooling circuit was not running at peak efficiency prior to your repairs.

Your repair combined with possible high humidity didn't help the beast.

al
02-06-2007, 11:11 PM
By shorting out the second cond fan motor is your suction pressure dropping too low and icing the coil? i'd also trap the drain.

Al

Andy W
03-06-2007, 08:01 AM
Has the machine had problems for a long time, evap icing up, water carry over due to incorrect fan, pulley size, speed etc, as said in low ambient conditions over condensing will contribute to freezing up, drains big enough, trap installed with water in trap, is it controlling. You need to decide if it is excessive condensate or icing up and melting, could even be a rotted drain pan, some basic checks will identify all the problems.

Lowrider
03-06-2007, 08:57 PM
Is there a gob interceptor behind the evaporator? If not then it's possible that since you've done some repairs the unit is finally working correct and velocity across the evap so large it's blowing off the condensate!

Andy AC
03-06-2007, 09:56 PM
I've never had the evap fan belt so tight, so its definitely running faster than it ever has + greater air flow. It hasn't got any form of adjuster, it is tensioned by wedging the motor away from the scroll casing, ran like it for years and years with a big old belt on always maintaining a good tension and airflow. however while I was doing the other repair it was starting to get loose and slip, so i wedged it a bit more. Unfortunately it seems to be too much. Also we had the motor rewound a couple of years ago , the guy that did it said that it was only possible to have it wound for max speed, which I agreed to , and hasn't been a prob until now.

None of the other rooftop units on the site have traps on the drains, including this one.

I accept that the over condensing problem may be an issue, need to get another fan control switch, but as is said before, it ran like this for at least a couple of years.

Controls wise, it cuts in and out on stat no problem, however have no idea where the indoor sensor is - nobody does, and also no idea if the evap coil probe works.

The unit is a real pile of poo but until the coils finally rot out from salt air corrosion or the compessor dies we are stuck with it, so we have to to whatever it takes to keep it running.

Andy

Andy W
04-06-2007, 07:24 AM
When water starts to blow in the room, when you open up the casing is there water in the drain pan or if you switch the unit off does water gush out of the drain?

Andy AC
04-06-2007, 09:00 AM
Yes, switch machine off you do get some water, there is always water in the pan - machine slightly out of level, but always has been.
I'm going to reduce the air flow and try and get a trap on it.

Andy W
05-06-2007, 07:30 AM
When you fit a trap make sure you fill the trap with water or else air is drawn in the AHU and stps water flowing through the trap, when it was explained to me years ago I thought someone was pulling my leg until they showed me the technical article about it.

Cofreth
05-06-2007, 12:09 PM
Sufficient charge in the system? Entire evaporator coil is wet? Otherwise water will get carried away by the air instead of flowing downward to the drain pan.

Andy AC
05-06-2007, 09:55 PM
I put a trap on it, water flowed and flowed and flowed, couldn't believe how much water it was producing. Thought it would be fine so went for lunch, came back opened the inspection hatch and found water making its way down the duct:mad: Tried many different belt tensions/airflows and finally put it back how I found it originally before the fridge circuit repair - slack. Anyway, nearly a day and a half without a call back to it.:)

Andy