drain pipe

[cruzeiros]

How do you set the electrical heater for drain in freezers ? To work only in defrost time or all the time ? Do you use also plastic pipes or only copper or steel ?
Thanks.

[Tycho]

How do you set the electrical heater for drain in freezers ? To work only in defrost time or all the time ? Do you use also plastic pipes or only copper or steel ?
Thanks.

I always set the drainpipe heater to run all the time. I use selfregulating cable at 20C and always extend it past the "draintrap"

Plastic, copper or steel depends on who has to do the job :D if I have to do it I use plastic, if not I don't really care :)

Just remember that plastic is easier to assemble, and if you have to remove the drip tray for some reason, you don't have to wrestle with stiff steel or copper pipes :)

[US Iceman]

If the system is a "*****" system I would use copper as it conducts heat much better. For an ammonia system I think I prefer plastic. the reason being the forklifts used to transport pallets. If a forklift hits the drain line, it just snaps off. If steel is used you can rip off the drain pan or worse!

I like the self-regulating heat tape myself.

[Dan]

Heat tape should operate all the time in freezers. I think copper is the best material because it doesn't sag with normal support methods. Most of my customers specify copper drains with heat tape and then insulated with at least 1/2 inch armaflex or equivalent. The self regulating stuff that is mentioned has an advantage (correct me if I am wrong fellows) that you can buy it in spools and just have the terminators in stock so you can cut to size. I think it is a bulky cable as compared to the Raychem pre-sized stuff which has some advantages in that you need no connectors, etc.

The important aspect is that you must be sure to wrap the heat tape up to the drain hub of the unit cooler and follow it thoughout the frozen zone.

[nh3wizard]

In one of our older facility's the NH3 hot gas line was run parallel to the galvanized drain line and insulated over both lines so when the unit went into defrost it kept the drain line warm enough not to freeze. I wouldnt recommend this, but its always an option.

[cruzeiros]

1. Thanks.
2. A link for "self-regulating heat tape" please ?
3. We do it with copper because we use it anyway (*****) and it's easier then with steel. Not plastic because we have history with melted pipes. We use heaters at 20 W/ml, work all the time and goes with the pipe until she leaves the freezer. The pipe is insulated.
4. Why do you think is not ok to work only in the defrost time ?

[US Iceman]

here is a link for some information.
http://www.chromalox.com/products/heattracing/

[US Iceman]

Here is another link also.
http://www.iheater.com/tycothermal/pipe_freeze_protection_and_flow_maintenance/pipe_freeze_protection/pipe-freeze.html

[Brian_UK]

Just a little comment....

I have come across some freezers where they have installed the heater tape 'inside' the drain pipework.

Any comments on this method at all?

[nh3wizard]

Just a little comment....

I have come across some freezers where they have installed the heater tape 'inside' the drain pipework.

Any comments on this method at all?

Ive done that myself a few times, its was easier than stripping the insulation off of the drain line:rolleyes:

Just need to make sure you use the right type of heat trace.

[US Iceman]

My only comment about putting the heat tape in the drain line is the lack of positive and continous contact with the pipe ID. I realize this is much faster to perform, however, the tape wrapped around the pipe would have better contact and more potential for heat rejection into the pipe.

That's my two pence.

[NH3LVR]

I have seen this done in the past, although it has been a while.
I did apply it in a unheated building when we replaced the 200 feet of roof drain piping (which had frozen and burst). It was originally cast iron with leaded joints. We replaced and added to it with 6 inch PVC. Insulating the line would have been difficult and expensive. I used roof heating cable and fed it through the line, up and around the vertical sections and back in the pipe. I was not under the illusion it would keep the entire pipe warm, just keep a channel open and allow for expansion if it did fill and freeze.
It worked well except when a breaker failed one winter. We then installed a light so the watchlady could see if it was on.
I will be visiting that plant in a week or so. I will be curious to see how it has survived the last ten years.

[Dan]

In one of our older facility's the NH3 hot gas line was run parallel to the galvanized drain line and insulated over both lines so when the unit went into defrost it kept the drain line warm enough not to freeze. I wouldnt recommend this, but its always an option.

We have had customers that specify the liquid line be soldered to the drain line. This provides heat during refrigeration. It works fine, too.

[taz24]

Just a little comment....

I have come across some freezers where they have installed the heater tape 'inside' the drain pipework.

Any comments on this method at all?

I always put the heater tape inside the drainpipe.
I have never had a drain ice up doing it this way.
It is quicker and also uses less tape.

The only drawback is when you get an over eager handyman cutting the drain with an hacksaw to flush them clean:D.

Cheers taz.

[Peter_1]

Same as Taz, allways a flexible heater (not self regulating) in the drain pipe.

Why energising the whole day a self regulating heater?

If you defrost 4 times a day for 30 minutes, then you need 2 hours a day a drain puipe above the freezing point of water. Well, why then not just heat it on these moments (=together with the coil heaters)?

When the freezer is at its working conditions, this heater is then heating at its max capacity because it tries to hold the drain continuously above the freezing point.

It seems a waste of energy, especially because it works the other way, less energy consuming)

We allways use PVC, easy to replace and to remove if you have to work on the heater.
I's also cheap.

[Tycho]

Just a little comment....

I have come across some freezers where they have installed the heater tape 'inside' the drain pipework.

Any comments on this method at all?

That's what we do with the self regulating cable, it's around 10 by 5 millimeter in size, and you can cut it to the length you want.