different march pump models

[rtockst]

I'm trying to get a plan done for a cfc and so I'm looking for a march pump to buy. I found a pretty good deal on ebay... 113 free shipping.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220546328971&_trksid=p2759.l1259

but I was wondering about the inlet size. It has 3/8" inlet and 1/2" outlet. Does anyone around here have one of those? I thought most people have the 1/2" in and out. Just wondering if that would cause any problems. And I was also trying to think of a good way to connect the inlet and outlet to hoses without putting a metal connector on those plastic threads, because they can apparently be damaged by metal connectors. Any ideas? Thanks!

Oh and another question about my chiller design... 3/8" OD on the copper, and a regular old garden hose. Problem is the copper comes in 10' lengths. Think I would have any problems soldering on sleeves to connect 3 of these 10' lengths?

 

[Catt22]

The suction port on that pump actually does have 1/2" male pipe threads as does the outlet port. What is confusing in the specs is that the inlet is also threaded inside for 3/8". IOW, it's threaded on both the inside and the outside. It will work just fine. You can use metal (brass or stainless) connectors/adapters on the plastic threads without problems. You do want to take care to not over-tighten/cross thread them, but other than that there's no good reason not to use them. Pipe threads are not really designed for repeated connection/disconnection and they require some kind of thread sealant (teflon tape works best for our application). It's best to use an adapter of some kind to a quick disconnect. Some kind of connector that seals with a gasket rather than sealant or tape. I used brass pipe thread x garden hose adapters and my hoses have nylon hose barb x garden hose thread couplings.

You can splice the copper tubing using couplings, although you may have to hunt around a little to find sweat couplings in the 3/8" size. They are available, but not commonly. You should be able to buy the copper tubing in a continuous piece at any length you want. Most places sell it by the foot or in 25 or 50 ft coils.

I have a store bought CFC that uses 3/8" OD tubing, but I no longer use it as I wanted a higher flow rate than it could handle. I recirc back to the BK for the whirlpool chilling thing and I find that a higher flow rate permits a much faster cooling rate. The chiller I have now uses 1/2" ID pipe and teh flow rate is much improved.