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Author Topic: pex/pumps sizes  (Read 3135 times)

tinfoilhat2020

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pex/pumps sizes
« on: July 27, 2015, 08:43:39 AM »

what size pex are u guys/gals running with your Heatmors???? 1" or 1 1/4"?????  I currently have all 1" lines installed for house loop and shop loop. B&G NRF-36 for the house loop and B&G NRF-22 for the short shop loop. Im hoping that this is adequate....one of the dealers i spoke to kept trying to sell my on the 1 1/4...he went as far as to try and convince me that i should rip all my previously installed 1" lines because the boiler calls for 1 1/4"...I hope i will be ok!!! to much work to redo, at least for this year!

Any info or insight would be great....i would like to know what size lines or pumps you guys are currently using?????
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LittleJohn

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Re: pex/pumps sizes
« Reply #1 on: July 27, 2015, 09:57:49 AM »

Here is my $.02, since I run Central Boiler eClassic 2400

B&G NRF-36, will far and a away be enough pump, if not look at what you head pressure is.
   ;) You did not say how far away house and shop are?

Only real difference I have seen (1.25"Pex - 100' run to house & 1"Pex - 75' run to detached garage) is the difference in fittings.  I run all inslab and pump between OWB and FPHE, never pump faster than about 8GPM - Cause I used Alpha that teel me the GPM
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tinfoilhat2020

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Re: pex/pumps sizes
« Reply #2 on: July 27, 2015, 10:17:33 AM »

house is house loop is approximately 250'. It hits 3 exchangers along the way: 40plate at LP boiler, hot water side arm and 12 x 12 heater in the garage.

shop loop is a total of about 30ft. only one heat exchanger, an 18 x 24 plentum
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willieG

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Re: pex/pumps sizes
« Reply #3 on: July 27, 2015, 08:56:41 PM »

your 250 foot loop will probably do  about 7 to 8 gpm with that pump. 

The advantage offered with the larger diameter pipe would be the same amount (or the desired amount) with a much smaller pump, thus saving you money in monthly electric bills. would it be enough to make the difference in the more costly pipe, everyone is different.

smaller pump is cheaper but bigger line is more

where I live we are currently paying 25 cents per KWH and it is only going up in the future

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RSI

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Re: pex/pumps sizes
« Reply #4 on: July 27, 2015, 10:18:06 PM »

Unless you have a large house, you should be fine with what you have. Have you ever checked temperature drop on the return line while under load? If it is not too cold then you are fine.
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juddspaintballs

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Re: pex/pumps sizes
« Reply #5 on: July 28, 2015, 11:28:22 AM »

The dealer was probably saying, that in order to get the nominal BTU rating of the boiler (a very nebulous number anyways), you'll need the larger line.  You can only pump so quickly through the pipe without cavitation at the pump, and eventually you can't make up for cross sectional area with flow speed.  Does it make a difference in your setup?  It doesn't sound like it makes a difference for you as long as it's heating your house properly all winter.  Is it worth changing out at this point?  It probably does not make sense to spend that kind of money to go larger on the pipe to be able to downsize your pump. 

Now if you weren't getting enough heat, then upsizing the pipe is worthwhile because you can squeeze more BTU out of the system if you can physically move more water through. 

That being said, I went with 1-1/4" on both installations so I can get as much heat as possible out of my system if I wanted to.  I can always slow down my water speed or downsize the appliances (smaller heat exchangers), lower my water temp or narrow my delta T if I didn't need as much heat from it. 
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tinfoilhat2020

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Re: pex/pumps sizes
« Reply #6 on: July 29, 2015, 03:28:50 AM »

^^^^makes sense. I am only heating about 4000 sqf total. So the load should not be overbearing for the boiler. I have an inline thermostat to see the temp of the return  temp after it has hit all the exchangers. I will just have to keep an eye on that i assume. Im not worrried about the shop loop...it is very short and only one exchanger. Also it is well insulated.

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