Ad for side arm on eBay

[i'mstihlaguy]

Copied this from the description for a side arm for sale on eBay:

THERE ARE LOTS OF PEOPLE SELLING HOME MADE CHEAP SIDEARMS. THE INNER PART OF THE SIDE ARM MUST BE ROLL THREADED the pic is of just the inner tube you will be getting the whole system with the 1 1/2 inch copper on the outside as well.THE SECOND PHOTO SHOWS THE ROLLED THREAD. THIS MAKES THE WATER SWIRL AROUND AND MAKES FOR THE BEST HEAT TRANSFER. IF IT DOES NOT HAVE THIS INNER ROLL THREAD YOU WILL NOT BE HAPPY. IN FACT IF YOU ARE NOT HAPPY WITH OUR SIDE ARM SIMPLY RETURN IT FOR A REFUND OF YOUR PURCHASE PRICE. THIS UNIT WILL WORK ON 40 GAL UP TO 150 GAL HOT WATER HEATERS.
O ur outside copper tube is 1 1/2 inches . Our inner copper tube is very thick, much thicker than others and is a THICKER copper for long life . important as if this inside tube fails or leaks it will mix the 2 waters and could kill you.others want you to believe the thinner copper has better heat transfer.NO THEY ARE JUST SELLING YOU A CHEAPER UNIT THAT WILL NOT LAST AS LONG AND PUT YOU IN DANGER . THE DESIGN OF THIS SYSTEM MAKES IT IMPOSSIBLE FOR THE 2 WATERS TO MIX OR LEAK.

I am sure many of you have already seen this but I have two questions:
1. The inner pipe is threaded on the O.D. Looks like this would cause turbulent flow but does anyone know if it really makes any difference?

2. Is the seller just trying to use scare tactics about the inner pipe's thickness? I was told you want it to be thin to help heat transfer.

 

[ericjeeper]

The corrugation also gives more surface area

This will help with exchanging heat.

 

[derwood91]

I have his sidearm and it works really well. The inner "Roll Threaded copper pipe is really thick. The flow will never be fast enough to be considered "Turbulent". Does it work better than pipe not roll threaded? I have to admit that I'm not sure. In theory though there is more surface area to absorb heat. Just like the fins on a baseboard heater. I ordered all of my boiler installation parts from him and I'm not dissappointed. Little lacking in his communication but all of his parts were top notch. I hope this helps!!

 

[i'mstihlaguy]

Thanks for the replies. I have hard water and I am concerned that this design will give the minerals a place to "grip" onto.

 

[i'mstihlaguy]

I had it backwards. The OWB water is what runs across the threads. Turns out this is what the dealer I got my OWB from sells so I ended up with this design anyway. He took back the 30 plate BPE I bought off of him a year ago for $150 and gave me $195 credit which I applied toward the $145 side arm and more fittings.