boiler flow rates p/s pump or standard

clammy

alot of stuff written now i need a little imput from you guys. looked at replacement job long loops on a comtempeary house 6 section mclean i,m doing it with 4 taco's pumps 3 for heating and one for a indirect my question is should pipe a bypas between supply and return i'm using a honeywell 8124 dual aquastat and a taco priority pump controller and wiring in the low temp circ limit but what i want to know on these large residental units should i be installing a circ to guarnting proper water flow though the boiler or am i getting to crazy i figured the flow through the boiler should be around 18 gpm at a minuim for this unit or an i safe enough with the low limit and seperate pumps i have done some larger p/s pump systems using multi boiler and understand the operations and reasoning but sometimes it's hard to know where to draw the line could not find info from the mclean site any input would be great and may all have a safe and happy new year still haven't figured out how to down load photos p.s. 2 1 inch loops and 1 3/4 loop for heat and a 1 inch loop for indirect heater thanks

hr

How much heat

does the job require? Is it a hw baseboard system? If so, add up all the footage and determine how much heat you are trying to move into the various zones.

Of course a room by room heat loss is always a good starting point, to assure you have adequate emitters in each room, and zone.

Generally low mass emitters, like copper fin tube, really don't need boiler protection, again, assuming eveything is sized correctly. baseboards to heat load, and boiler to total load.

Priortize the indirect to assure rapid recovery, otherwise you may have to beef up the boiler output to handle large DHW loads when all zones are calling on a design day.

Long, uninsulated runs of copper or iron pipe through unheated spaces will cost you some big BTU's also. Look into that.


Large homes often have large DHW demands. Sometimes more DHW load than heat load! Cover all your bases with some calcs, and owners expectation on adequate DHW supply. Watch out for large capacity soaking type bath tubs. They can impose mighty large indirect or storage needs They can hold a boiler in priority for long periods of time. This may start to "chisel" into you heat needs, especially with low mass emitters. Radiant floors can coast through a long DHW call better than baseboard

hot rod

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Steve Eayrs

If the flow needed through the boiler exceeds the flow needed for the total heat load by a lot, I would wonder if the boiler is way oversized.

I believe my main concern in determining the flow needed through the boiler would have alot to do with the delta T, and not bringing too cold returns back. I would size the pump to maintain 10-20 deg. delta T.


Steve

flange

i tihnk you should be in the range of 1 gpm for every 10000 btu gross.