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[BigAlsc]

I am a long time follower and first time user and would like to preface my question with a thank you out to all the people, professionals, dealers and fellow users who offer help to each of us.  Especially members like Scott7m, RSI and a few others who give us a lot of their time.  I have a NCB175 with 200' each way of 5-wrap 1" pex from boiler to 30 plate exchanger. There are a total of 8 90's, 4 shut-offs, and 2 in-line temp. gauges in the loop, with approx. 10' of drop from top of boiler to bottom of exchanger.  I bought this unit used last fall and it came with a Wilo Type Star 16FX pump mounted in top port with return going to opposite bottom corner.  Between reading all the useful info on here and trial and error got a few of the bugs worked out and learning as I go.  The pump needs air bled out of screw in back of it every couple of days and not real impressed with heat transfer, and I'm thinking pump is to small for the distance.  I would like to replace pump, relocate it to the bottom with return going to the top.

[Scott7m]

No surprises as I'm not a fan of wilo.  When I start seeing distances like your speaking of and considering 1" pex, I start thinking of grundfos 26-99 or a taco 011.  Somewhere in that category

[RSI]

Yeah, that pump is way undersized. The models Scott mentioned above would be good choices.

The pump should be moved to the bottom port on the boiler. Nature's Comfort was originally putting the pump on the top like you have it but they were having issues with boil over and short pump life. Also, with it on the top, if the water gets low (due to a boil over or leak or whatever) your pump will be ruined once it gets down top port.

The return to the opposite corner is correct.

[yoderheating]

 I agree with both Scott and RSI. I would echo Scott that Wilo is a bad choice for hot water systems. I used them for several years and had a very high failure rate. 

[BigAlsc]

Thanks on the suggestions. Either one more efficient or reliable than the other?  Have heard both mentioned on here before.

[Scott7m]

I lean towards grundfos normally

And here I am running a taco bumble bee lol

[RSI]

The Grundfos is a 3 speed and the taco a single speed. That probably won't matter for your setup though since it sounds like you would need high speed anyway. I like Grundfos better also.

Another pump to consider it the B&G PL36. I didn't mention it before because I haven't ordered any of them in a while and the last B&G pumps (NRF-36) I ordered were made in China so not sure if the PL36 is made there now too or not. The pl36 would probably be a little more efficient.
If you don't care about the made in China thing, the NRF36 is another option that is a similar size to the 0011 and 26-99 and will be $40-$60 cheaper.

[BigAlsc]

Thanks for the help, probably going with the grundfos. Would it be practical to turn the speed down when the heating demand is lower, when temps are in the 40 to 50 range?  I usually turn the house pump on 24/7 to keep house boiler water hot.

[BigAlsc]

Now would that be a ups26-99fc or a up26-99f. Cannot seem to find any site that gives a common answer on the differences.

[RSI]

I think the UPS is the 3 speed version.
The C at the end means it comes with a check valve. You will want to remove that before you install it.