modify Lochinvars boiler plan, by pumping on supply side, away from boiler,expansion, and make up???

keyote

Im still not clear if there's any reason I should not put the pump on the supply side upstream of the expansion as is usually recommended i believe.

keyote

The next question is I guess about hydraulic separation between the zone valves. I think this configuration type constitutes "generously sized headers"? If so my understanding is the concern would be to keep design flow below 2 fps.
7.6gpm is degree day flow, which gives 1.98 fps with the 1.25" header i made up [misreading the velocity calculator]. So i'm only barely under spec, should i redo it in 1.5" for 1.38 fps?
And if so does the return header also need to be 1.5" or can it stay 1.25?
I ask because i have seen similar configurations where the supply and return headers are more of a loop and Im not clear why, and or because back to the DBP option they show which would join the header ends.

keyote

third question regarding this pumping from return side again , the triangle tube had the pump opposite and im already piped on the indirect pumping into the tank, suppose its only a matter of moving pump I suppose the indirect and ch should pump from the same side and the smart tank doesnt really care?

BTW i put a w strainer on the indirect thinking it would be the loop that ran all year lochinvar shows one on the CH loop do you think I need a second one, and dop i need an expensive magnet type air dirt separator as well the ecm pumps claim to be self protected but i worry i wondered if a could throw a magnet into the strainer basket.

NY_Rob

I went with the caleffi dirt mag on my system since I'm using a ECM Alpha pump, and I liked that it replaced two discrete components- I was a little tight on space.
I had to reconfigure the DHW loop a bit vs. factory diagram so it would flow through the dirtmag all year round when space heating wasn't being used. The original factory piping schematic didn't provide for air separation in the DHW loop during "summer mode" either, so the reconfigure of the DHW loop addressed both issues.
Looking at your factory schematic- you'd probably have the same issues- no filtering and no air removal in "summer mode".

hot_rod

Air purged location is fine, l would rather see the exp tank connected above the boiler pump. The tank does not need to be on the air purger

keyote

so do i just copy this in 1 1/4" all the way around or do i need to make some changes? lochinvar didnt even seem to grasp that pumping towards the expansion was a little controversial or even say why they were pumping int the boiler from return so idont know why its so different from most other diagrams in triangles book or in siggys book.

Rich_49

None of the ECM ^P or ^T circs would require an PDBV . They adjust to system conditions unlike PSC circs that require bypass flow when zones open and close

Gordy

Lochinvar, or any other boiler manufactors gives 2cents about anything other than protecting their baby which is the boiler.

Their schematics usually include all pertinent components that make a complete hydronics "system". It's up to a "competant" designer, or installer to decide where they go to keep everything happy, and what will go into the system.

You want air removal close to the hottest water in the system. Supply at the boiler. You want the X tank as close to the inlet of the circulator as possible.

keyote

thanks guys i really didnt think there was anything so different about this boiler that it needed to differ from so many other sketches or common practices i had seen, then again it seemed odd people that can design a machine like that would draw a x tank in front of the pump for no reason.I know it sometimes cant be helped but.... I intended to follow all of siggys directions on placements then realized these contradictions. Do you think theres any reason to i shouldn't move the pump to the supply side with the expansion just up stream?

keyote

rich
Thanks i was afraid the dt pump would only be concerned with dt and not really adjust for dp well i guess as valves open and close and it find dt thats a byproduct that over pressure is not built.
is there a reason sometimes you see the s/r headers capped like the above and sometimes the ends are joined to make a loop, i realize the supply coming down completes a circuit anyway but i cant figure why they sometimes also just continue the supply header down into the return header.

keyote

gordy
am i again over thinking the header size by considering changing it to 1.5 inches for 1.38 fps rather than using the 1.25" for 1.98 fps?

Gordy

Yes.

Rich_49

The illustrations you see with a DPBV all assume a single speed (PSC) circ sized to the flow and head with all zones calling . When zones close the reason for the DPBV is to decrease or eliminate velocity issues in the system . With a variable speed circ this is not much of a concern as the circ will adapt to the ever changing conditions .

My advice to you is carefully look at all illustrations , then be water flowing through these circuits . Until you can be water and air you'll basically be lost .

keyote

thanks again didnt really want to upsize that header and have to buy even larger everything. i was planning on just making the whole S/R from boiler to end of headers out of 1 1/4"

so is putting the pump on the supply side ok, i dont think siggy ever shows it on the return side like lochinvar?

keyote

Am I wrong for wanting to put the pump on the supply side with the expansion and make up behind it as is I believe is usually recommended, I don't want to mess up a new boiler is lochinvar just taking the position its not critical where it is? or is there some purpose its shown like this? or I am misinformed about preferred methods?

Steve Ebels_3

Pumping into the boiler or not is of little consequence in most situations.
You are correct in wanting to have the expansion tank (PONPC) located "upstream of the pump inlet of the pump.

In you drawing, I would place the expansion tank/fill assembly between the boiler pump and the zone returns.

Or......rearrange completely to allow flow for the indirect to pass through the air sep also. It's completely bypassing it as shown on the drawing.

keyote

Thanks steve that drawing is from lochinvars book which is what confusing its as if they tried to contradict everything i thought i learned
I would have thought it would go from supply side of boiler to air separator to expansion tank to pump

hot_rod

In a fire tube boiler there is very little pressure drop, pump either end.

With tube type Sermeta HX boilers they want you to pump into the boiler so the pump ∆ shows up as pressure increase at the HX. But that only happens if you "pump away"

Maybe Lochinvar shows it that way to keep all the pump locations the same for installers that may not know which HX type they have?

Regardless the exp tank needs to be upstream of the circ.

keyote

Thanks bob thats the same diagram you posted that i keep staring at im going ahead and moving it to supply side the way siggy always shows it .