Gravity Hot Water Heating

PlumbingMoose

I'm replacing an old  2 1/2" double header gravity hot water heating system damaged by Sandy.  I've read through the section in "How Come?" but was wondering how to tie the two headers together and getting an even flow through both.  Are there any special piping requirements?

Thanks.

Ironman

Gravity Conversion

Iv'e attached an article by Dan that has a lot of helpful insight on gravity systems.



I always recommend that these conversions be piped p/s even if you're not going with a mod/con, but I can't see the logic in using an atmospheric when converting.



You can pipe the supplies and returns into one or keep them split and zone them with circs or ZV's if it's advantageous.



Flush the old pipes thoroughly and install a strainer near the boiler inlet. Check for orifice plates in the top floor rads and remove them if present.



The old compression tank may still be connected in the attic and should be removed. If you can't find any tank on the system at all after diligently searching, then there never was one. The dead men would leave an air cushion in the top of the rads to receive the expanding water. You'll need to add one that has been properly sized by the manufacturer. Make sure you let them know it's a gravity conversion and you'll need to know how much water the system holds for them to calculate it.



Do a simple load calc. on the envelope and measure your EDR. Then dail in the reset curve accordingly and you'll have one the most comfortable and economical systems around.





http://www.heatinghelp.com/article/332/Gravity-Hot-Water-Heating/72/Gravity-Hot-Water-Heating-FAQ