Issue installing new heater element

[Bex]

I pulled the old element out after much effort. It came out in small bits and pieces. Ordered a replacement and the part arrived. When I went to fit it i realised the old element casing had "welded" itself to the tube its supposed to fit into. I pried a little of the casing out but have made quite a mess. I am now trying to figure out options and so far have come up with the following

1. Get a flexible drill shaft and drill out the remainder and then using the same shaft with a dremel type grinding wheel, smooth out the inside of the tube.

2. Cut the tube out, clean it out as above and weld it back in.

3. Cut the tube out clean out and hose clamp it back in.

4. Forget the existing tube and hose clamp another tube next to the existing tube.

Right now, 4 is my preferred option but I am wondering if the heater tube is where it is because that area has to be heated first and in preference to anywhere else? I am wondering this because of the flow of whatever is being heated.

Any input here would be appreciated. As ever a pic is worth a thousand words so I have attached one, although the orientation is wrong it should be vertical.

[lewster]

Bex,

I can't tell from your photo, but if you hunt around in there you just might find a second tube. Many cooling units were made to accept a second element to allow the unit to operate as a 3-way fridge; LP, 120VAC and 12VDC.

If you do have the second tube, you are home free!

If not, I would get another piece of tubing and hose clamp it to the boiler tube. Cutting and/or welding in this area could easily cause a rupture in the cooling unit and will ruin it: releasing the ammonia/hydrogen refrigerant. It's weak enough without helping it along.............

[Bex]

Originally Posted by lewster

Bex,

I can't tell from your photo, but if you hunt around in there you just might find a second tube. Many cooling units were made to accept a second element to allow the unit to operate as a 3-way fridge; LP, 120VAC and 12VDC.

If you do have the second tube, you are home free!

If not, I would get another piece of tubing and hose clamp it to the boiler tube. Cutting and/or welding in this area could easily cause a rupture in the cooling unit and will ruin it: releasing the ammonia/hydrogen refrigerant. It's weak enough without helping it along.............

Aw, nuts! No such luck. So placement fo another tube is not too important or critical. I was thinking of just putting it on top of the existing tube.

[lewster]

Originally Posted by Bex

Aw, nuts! No such luck. So placement fo another tube is not too important or critical. I was thinking of just putting it on top of the existing tube.

It's very important that you get your new tube to make as much contact with the 'pump tube', which is the long one at the back that the original tube is welded to. This will assure that you get the most heat transfer from the new element/tube to the pump tube and boiler tube to heat the ammonia.

[idroba]

You might use a silicone dialectric (sp) grease which is used to insulate and heat transfer in electronic parts to help with the heat transfer if you use the new tube method. It is high temp and designed for that kind of service. Available at electronic places.

[Bex]

Originally Posted by idroba

You might use a silicone dialectric (sp) grease which is used to insulate and heat transfer in electronic parts to help with the heat transfer if you use the new tube method. It is high temp and designed for that kind of service. Available at electronic places.

Thanks. I thought about that (the grease) but never bothered. I figured it might last a while but the last heater lasted 40 years, and I doubt it would go that long.
what I did do was take a piece of half inch (ID) copper pipe. I split and opened up the pipe and slid the element inside. Then I found a place just behind the original tube and slid the new tube in behind it. Had to start high and work it down. I protrudes about 2 inches above the old tube but does make full contact with the same thin tube that its welded to. Repacked it with glass fibre insulation (after checking its actually heating) and its all good.
Just need to get a new piece of metal to put across the front where I butchered the original casing.

Happy now I have it working again on gas AND electric.

[lewster]

[Bex]

I might have been a little premature with that last post. Its certainly heating up. But its dissipating too much heat around and not into that thin boiler tube I think. Might have to go back to the original plan number 1, above.

[idroba]

The silicone grease will transfer the heat better. Give it a try. That is what it is designed to do.

[Bex]

I removed the element and took it out from the copper "sheath" I had put around it. Re-positioned it lower down and touching (behind) the propane heater tube. Turned it back on and now get proper cooling of the fridge and freezer compartments. I also put additional insulation in behind the fridge, against the pipes and trailer wall and down almost to level with the floor, and found it all cooled down much quicker.