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[renoman]

Thinking my pump is greatly undersized but can't get my head wrapped around the calcs so need your expertise.
My main loop is 300' one way of 1" pex with crimp style fittings so effectively 3/4" and more or less level grade to house.
 In the total loop I have 12 90 degree fittings and a 30 plate dhw. Off the main loop in close t feeds and returns with 007
pumps I have a 20 x 20 hx in my furnace,a 4 loop radiant in floor manifold, and a 6 loop infloor manifold in my 36 x 48 shop.
The main loop pump is a 3 spd 15-58 grundfos mounted in my shop on the return side 50' before the boiler. My return temps
 fluctuate of course depending on demand but can be as much as 60 on a cold morning. Not totally concerned with the lower
return temps as my feed returns to center of boiler amidst secondary heat exchangers but thinking I could improve return temps
 and not have the thoughts in the back of my mind of cold shock possibilities.
Appreciate any thoughts or recommendations on brands and sizing.
Tony

[Scott7m]

Armstrong E9

60 degree returns are bad news

[renoman]

I realized the returns were low at times last season that is why the
pump upgrade. my return is located to minimize the shock but still don't
like it. I demand a lot of heat at times but boiler can easy do it just need to
get the flow up. Will check into that. Appreciate your reply and will post how I make out.

[Scott7m]

It's a high performance pump, one of the biggest we see in most situations.  But it's an efficient pump, only 125 watts

[CountryBoyJohn]

Do you have all that load on 1 circuit?  Have you thought about breaking your loads into 2 circuits with 2 pumps?

[Scott7m]

He has close t feeds he says that pull off with 007's

[RSI]

From your numbers I would estimate you are getting around 3-4 gpm. (estimated head equivalent to 750' 1" pex. Head pressure on that at 4gpm is 15.9' at 180°F and 18' at 120°F and at 3 gpm is 9. 5' at 180°F and 10.7' at 120°F)
The pump Scott suggested would get you up to a little over 6gpm. Not really much you can do to get much more than that.

The B&G PL36 is a similar pump but cheaper. It will probably use a little more power than the E9. I would estimate it would use about 150 watts on your system. (I have never tested an E9 but they claim 125 watts)

Another option would be to add another Grundfos 15-58 in series but it will only gain you up to a little over 5gpm.

[renoman]

I appreciate the info scott and rsi. that is the answer I was looking for. I knew
I was undersized. Ordered the E-9 today should be here in a few days.
may be a bit before I get it put in place and once the colder weather hits I'm
sure I will see the difference in the return temps. No problem with heat but on
the cold mornings the returns can be low. Will stock the 15-58 as a spare as I
have four 007 running various loops. Thanks again for your expert advice and will
definitely post the results when I get a chance.
Tony

[johnybcold]

I think my pump is under too, I need to work on that I want to get the taco bumbee

[renoman]

Pump came in today. a little pricy but if it does the job its all good. Now the hard
part is finding the time to hook it up!

[Scott7m]

Pump came in today. a little pricy but if it does the job its all good. Now the hard
part is finding the time to hook it up!

There good, it will def help your issue

[renoman]

Finally got that pump installed a few weeks back in place of the 15 58 thankfully before the real cold snap.
Now decided to move it out to the boiler room close to the boiler outlet as I was having issues with the pump drawing air in around some fittings somewhere prob due to its volume. This was another improvement as the pump is now pushing the whole loop. Return temps are much better now as well except when the shop calls heavy for heat but I can handle that.
Just wanted to say thanks for all of your advice and help in getting the right size pump in place!