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smpsmp45
10-02-2016, 06:35 AM
Our systems provide Hot gas defrost & the water is drained out through drain pipes - heater is provided in the pipe.
However sometimes the Icing takes place in the pipes & the staff does not check that out routinely.
We are considering an option of cutting off the unit based on certain ice formation in the drain pipe.

Any valuable suggestions/ practical experiences?

Grizzly
10-02-2016, 07:19 AM
Hi smpsmp45
How close to the evaps /coolers are your vapour traps?
What diameter are your drain pipes?
Do your heater tapes run inside or around the outside of the drains?
What are your defrost termination set points?
Cheers Grizzly

PaulZ
10-02-2016, 11:23 PM
Hi smpsmp45
A couple of other questions to add to Grizzly's.
How thick is the insulation on the drain lines?
How much fall is on the drain line inside the room?
Do the vapour traps have inspection / access points and are they cleaned regularly?
Regards
Paul

smpsmp45
11-02-2016, 11:01 AM
The ref units are mostly R 404A based Mono Block units. The Distance of the drain pipe inside cold store ( til the Cold store wall) is generally 700mm. There are heaters in the pie from inside. No Insulation from outside.

Main issue what we have seen is that the drain pipe get clogged & not necessarily due to system related issues, but mostly site related / user related issues.

They do have a schedule of checking the pipes , but it is not followed properly. & the U trap also gets damaged as well.

The system runs very well with its defrost cycle etc.

But still we need to tackle this practical issue.

Few clients who have many cold stores , we never face any issue, but with the clients who are having palletised/ pannelised cold stores for the first time, this is the issue, we can not ignore.

So we were thinking of putting some sensors to check if there is any ice formation beyond certain time limits & can trigger off the shutting off action.

& of course this is more serious during monsoon period as expected.

Segei
12-02-2016, 01:02 AM
What is the temperature in cold room?

smpsmp45
12-02-2016, 05:06 AM
The temp is -20 Deg C

redroge
12-02-2016, 05:13 PM
Is the drain heater on all the time if not it should be. Lag the drain and if possible move the trap to outside the room.

Segei
13-02-2016, 01:11 AM
There are heaters in the pie from inside. No Insulation from outside. You mean that at -20C temperature in the freezer drain pipe don't have insulation!!!
Heater should be wrapped around the pipe (like spiral) and it should be between pipe and insulation. Slope should be to the trap and trap should be located outside of freezer.

RANGER1
13-02-2016, 05:17 AM
There are heaters in the pie from inside. No Insulation from outside. You mean that at -20C temperature in the freezer drain pipe don't have insulation!!!
Heater should be wrapped around the pipe (like spiral) and it should be between pipe and insulation. Slope should be to the trap and trap should be located outside of freezer.



Also different wattage heaters, can get something with a bit more heat output. If wrapping around pipe, then insulating, or even running heater in pipe, ensure it's labelled so no accidents. as people have been electrocuted if cutting a blocked drain line.
Also allow water drain time with fans off.
Heaters on all the time.

Lodiev
13-02-2016, 12:11 PM
Yes that's the way to go Ranger1
We have rooms operating at -40 Deg.c and we have no issue with them.
There is a special insulation that is sealed with Alum foil tape to ensure no moisture enters the insulation material itself and get saturated over time.
Also the heater tape electrical connection start and end should be outside the freezer room itself to ensure no wet connections over time as it will condense moist and short circuit.

Segei
13-02-2016, 04:42 PM
Yes that's the way to go Ranger1
We have rooms operating at -40 Deg.c and we have no issue with them.
There is a special insulation that is sealed with Alum foil tape to ensure no moisture enters the insulation material itself and get saturated over time.
Also the heater tape electrical connection start and end should be outside the freezer room itself to ensure no wet connections over time as it will condense moist and short circuit.
I agree with you . However, I would not suggest to put alum foil. Moisture travel from warm area to cold area. Cold pipe should have insulation + vapour barrier located on warm side of insulation. Drain pipe is relatively warm and it will have less moisture without vapour barrier, because any moisture will travel from insulation to cold room.

chilliwilly
13-02-2016, 07:42 PM
How long is the drain to its termination point out side the walkin?

Had a similar problem due to drain being too long and run within the walkin and only have a small 12 volt torpedo type internal heater. Only suitable for a back to back unit, that didn't work due that cable being too long and having excessive volt drop. The drain eventually terminated into a bucket outside next to the door, that was full of tab ends as it never got wet.

The air handler was only about a foot away from the back wall so I ended up shoving the drain straight through back of air handler and through the wall out to a condensate tray and pump. As the nearest suitable termination point was 60 feet/ 18.3 M away.

The icing up and blockage problem was remedied.

smpsmp45
14-02-2016, 06:09 AM
Many Thanks for various inputs.

We have over 1000 units all over India. But this problem with our present system is more visible in only two/ three cases.

Mostly wherein the operating staff is good enough, there are no issues.

We even tried to check the currents as suction pr drops with Ice built up. But the difference is so small to act on that.

But we shall try heaters outside the pipe as well & as suggested of higher wattage.