Pumping Away versus manufacturers layout.

icy78

Boiler manufacturer piping layout calls for expansion tank to be in the secondary loop, with pump pumping away from that. Dans way calls for ex tank to be in the primary loop. I just read Dan's pumping away book and am convinced. At our shop we have never done it that way and always have trouble, with air, fluctuating pressures, relief valves leaking. I am a tech for the co. and am trying to instill this new way. Any advice on how to deal with the issue of manufacturer layout compared to Dans way? I will try to post photo of manufacturer piping.

icy78

Sorry, haven't found a way to post photo using my phone. No clipboard on keyboard on this forum. .hmmm.

warno

Tap the thing in the circle of attachment. Thats how to post thumbnail pics.

hot_rod

The main goal of primary/ secondary piping is to provide hydraulic separation between several, sometimes numerous circulators.

Many of the new boilers suggest you pump into the return side, so the expansion tank connected to an air purges on the boiler "supply out" piping no longer works for pumping away.

We also now have variable speed circulators, so the flow rates in both sides can be constantly changing.

Here is probably the best way to pipe modern P/S.

In this case all the circs are pumping away, and air removal is at the best, hottest part of the piping. The expansion tank could be connected anywhere on the large "blue" header pipe.

The key is to size that P/S piping large!
Think a pipe size that would allow no more than 2 fps flow velocity in those "fat" headers. This assures the secondary circs are hydraulically separated from one another also, not just from the primary loop.

The table attached gives you an idea of that sizing. If you have a total gpm of 12, you would want 1-1/2 header size.

The closely spaced tees still allows the boiler side to only "see" the flow resistance of the boiler and it's piping.

A hydraulic separator is another, cleaner method to pipe for separation, and a buffer tank option for multi, micro zoned systems.

More on basic piping here.

http://www.caleffi.com/sites/default/files/coll_attach_file/idronics_12_0.pdf

icy78

Thank you for responding. I will also say i am a refrigeration and hvac tech. Not much boiler/piping work, so big learning curve here.

icy78

Well I wrote a veritable book on the last post but it didn't show. The first pic is the manufacturers. 2nd one is mine. Is it possible that with pumps arranged like I drew them that a venturi effect could occur, where some water could trickle thru another loop, thus overheating it? Also. I think the 3 pumps shown on the return should be on the supply side of the loops. Correct? And then the circ pump pressure would be pushing water thru and not allowing air out of suspension.

Paul S_3

pipe it just like the manufacture states....ALWAYS pump away from the point of no pressure change which in your case is the expansion tank for the system pumps and the closely spaced tees for the boiler pump....i would not pipe it like your drawing....pipe it like @hot rod drawings and manufactures ...youll be fine....what size boiler? did you do a heat loss? its a 90% boiler....Weil Mclain slim fit?

icy78

Thanks Paul. I am not involved in install. I am learning so as to teach others what we are doing wrong. System pic is of system as installed, which I commissioned, and found some issues . Yes ultra boiler. As manufacturer shows it, secondary pump is pumping away and primary pump is pumping towards. I did find however where the manufacturer states that following accepted piping practice is acceptable.