plumbing questions

[jvdb]

So I'm trying to make some final decisions on my sump plumbing, and have a few questions:

I only want to buy 1 diamond bit, so I was going to do both my drain and return bulkheads 1", but the output of the pump I want is only 1/2" (Eheim 1250). So do I need to run 1/2" pipe (I was thinking spa flex) and then just get some kind of 1/2" to 1" PVC adapter right before the bulkhead?

I can get the bulkheads with slip or thread on either side. I assume the slip is for glue, right? I think I don't actually want to glue the spa flex, wouldn't it be better to have some kind of screw coupler so I could clean or replace it if needed? If so -- does anybody have links or pics online of what I need?

Thanks,
Jake

[kgross]

Jake,

You have some great questions. On the pump, if you want the max flow out of your pump, use a 1/2 to 1inch adapter on the pump and use 1 inch line to the tank. You will get a lot more flow out of the pump that way.

On the bulkheads I would get threaded ones myself, then you can screw a fitting in, and remove it if needed. Make sure you also put some unions in the mix to make it easy to unscrew from the bulkheads also.

Kim

[jvdb]

<a href=showthread.php?s=&postid=11158653#post11158653 target=_blank>Originally posted</a> by kgross
Jake,

You have some great questions. On the pump, if you want the max flow out of your pump, use a 1/2 to 1inch adapter on the pump and use 1 inch line to the tank. You will get a lot more flow out of the pump that way.

On the bulkheads I would get threaded ones myself, then you can screw a fitting in, and remove it if needed. Make sure you also put some unions in the mix to make it easy to unscrew from the bulkheads also.

Kim

Kim, thanks for the response, that is exactly what I was looking for. I now have one more question though. :)

I don't know if this really matters or not, but the reason I was thinking of putting the 1/2" to 1" adapter right before the bulkhead is that I'm concerned about how much water flow will be lost to additional head.
If I go with the Eheim 1250 I was planning for, maximum head is rated at 6.5 ft, but I assume this rating is based on the 1/2" output? Since a 1" pipe will hold almost 4 times as much water as the 1/2" -- that is a lot of extra water weight for the pump to push. I'm worried my 3' of head might be too much for this pump.
I could always email eheim, but I was wondering if anyone here would have a quick answer.

Thanks again,
Jake

[jvdb]

Nevermind, I think I answered my own question.

http://www.advancedaquarist.com/2007/5/aafeature2

Based on this I guess their aren't much losses to using a larger diameter pipe like I had thought.

[kgross]

The head pressure is based on the distance it has to push the water up against gravity. The size of the pipe has nothing to do with the static head pressure. So if you went to a 6 foot pipe, the static head pressure would be the same as with a 1/2 inch pipe. The weight of the pipe would be a lot different, but the pipe and adapters would be holding the weight of the water not the water in the outlet of the pump.

With that out of the way you also have dynamic head pressure or friction loss. A larger pipe has much less friction loss than a small pipe at the same gph flow rate. So by increasing the pipe size you get less friction loss and more flow out of the pump.

Kim