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[E Yoder]

If the house needs 50,000 btu's at the coldest day then at a 20℉ Dt it would work out to 5 gpm. Easily done on a 1" line, small circ.  If the hot tub and domestic kicks in it might go up to 30-40 Dt for a bit but no big deal.
But I might be missing something... My mind gets swimmy after a long day.

[BIG AL]

It's amazing what you guys down there can get away with in heating with Luke warm water, I would caution against those practices  in the north country!

 

[mlappin]

Here is a PDF from Taco on selecting the right circulator and figuring head pressure.


http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf

Well shoot, I had another page I was gonna link, went to explain the wonders of primary/secondary loops, T spacing to eliminate or allow ghost flow, etc but it appears the page is no longer on the web.

[reggart]

I'm glad you posted that link because it reminds me of another question I have.  I ran through that whole taco circulator selection step by step and I got stumped when you determine the length of the piping.  Are you supposed to include all piping from the the boiler to the header in the house and are you supposed to times that by two because it is a supply and return?  Are you supposed to add all of your circuits together or just use the longest run? 

[aarmga]

It's amazing what you guys down there can get away with in heating with Luke warm water, I would caution against those practices  in the north country!

I agree.  Water temps at 130 and my house drops under 70 quick

[slimjim]

The point is Eldon, in Virginia you may be able to heat your home with 5 GPM and your 20 degree diff, you may even do that here with a new, tight, small building on a reasonable day in early December, this forum however serves us all and some of us live a long ways north of the Mason Dixon line, most homes that I service up here have a heat load of 100,000 -300,000 BTUs, believe me, you will not get 30 GPM through your 1 inch nominally sized pipe with those short pex 90s that you use down there and you certainly won't be heating a 4000 square foot 200 year old home with a fieldstone foundation in February here in the North East with that same setup.

[E Yoder]

The 50,000 # came from what he said he had calculated for the house heat load. Somewhere back on this thread I thought I read that. The other buildings were on separate lines I thought? If not then I'm definitely off.

[slimjim]

Your reply number 13

[E Yoder]

You are correct. That would be for situations where there's maybe a forced air duct for the main house, radiant in the basement slab, hot tub, etc. Where the loads are different temps.
I should have explained it was for specific situations. Your concern is very valid.

[slimjim]

Well Thank You for that, there are some folks in this industry that are so pigheaded that they cannot be prodded into admitting that they made a mistake, I think we may both know a few!

[mlappin]

Well Thank You for that, there are some folks in this industry that are so pigheaded that they cannot be prodded into admitting that they made a mistake, I think we may both know a few!

So what gives? Your in my area, met my pigheaded in-laws, father, aunt, and a  few of my uncles but you didn’t stop in for a cold one here? Not cool dude.

[slimjim]

You know darn well that if I were in your area, we would be having a few cold ones, I'm thinking that perhaps we aren't talking about the same folks!

[reggart]

so anyone got an answer to my circulator sizing questions?

[RSI]

If you are only going 80' with 1-1/4" then you shouldn't need a real big circulator. The zones may determine size though. What is on each zone?
If all the zones are fairly low heat load, it should be fine. If you need multiple gpm in each all at once you would need a pretty large pump.

Without knowing all the details and only going off what I am assuming, I would use an Armstrong 20-20CI pump.
Also, I would mount the pump in the back of the boiler, not in the house. If the house is lower than the boiler, that should work but if higher it won't.

[slimjim]

Again, there are many variables and one of the very important ones to consider is one that you have not answered, where are you at? Eldons place in Southwestern VA. Heats a great deal differently than my place here in the Northeast or Marty's place in Indiana.