A question about design.

heron98105

My question is about the secondary loop.

The system looks like this:

A Boiler (non-combi) with its own circ pump connects via 1-1/4" pipes to the top side of a low loss header and then out of the bottom side of the low loss header there is a magnetic/dirt trap, then its back at the boiler.

The low loss header's air valve fitting at the top is connected via 3/4" copper to an Axiom expansion tank arm above it with a tank on the bottom side of the arm and an air remover attached to the top. An axiom make up tank is attached via a 3/4" T about 75% of the way up that pipe from the low loss header to the tank arm (the system is 30% Glycol).

The secondary is a 1-1/4" loop that looks like a triangle with 8 antlers and starts from the top/side of the low loss header, then there is a Taco air separator, then making a 45 degree swing up there are 4 - 3/4" heating circuits with Taco 2218's that branch off and up using 45's to achieve plumb.

Then at the top of the triangle there is a 1-1/4" x 1- 1/4" x 3/4" brass T with an automatic air bleeder at the highest point of the triangle. Then on the downward side there is a check valve that limits flow to only flowing in the direction of from the heating supply side toward the return side, then there are the 4 - 3/4" returns 45'd up to be plumb as well and then secondary loop goes back to the bottom/side of the low loss header.

There is no pump to move the fluid around the secondary loop other than those 4 pumps pulling from the top of the low loss header and a check valve preventing it from drawing from the other side of the triangle.

It feels like from the last of the taco pumps to the top of the triangle where the air bleeder is and down the other side to the check valve is a place where the pump would be struggling to pull fluid from or would it just ignore that and pull from below?

Should there be a pump at the bottom of the triangle on the return side moving fluid back into the bottom of the low loss header?

Is having this plumbed as such going to cause the low loss header be less efficient?

Might be over thinking this… its just that I have never seen this sort of setup before.

Thanks-

EdTheHeaterMan

Photo might help

heron98105

If I go back I will take some. Didnt have a chance this time.

GGross

It's hard to follow, it doesn't matter if its a triangle or has some 45's, the shape doesn't matter. If you have zones on the secondary loop, and all the zones have their own pumps, and those zones are NOT hydraulically separated from the secondary loop (which would give you tertiary loops?) then no you do not need a pump to circulate water around the secondary loop. Each zone pump will pump its own zone, and will circulate through the low loss header, and from what you described its not really an issue to have the expansion tank piped into the LLH like that, though personally I like to have it on the return of the boiler loop on the suction side of the pump, the location you described is OK as well just makes techs scratch their heads when they see it. I would draw this out if I were you, and not draw it like a triangle or anything, just make straight lines representing each zone so you can read it easier, it will more than likely answer the question for you.

heron98105

I guess at the end of the day…. it is a loop from the top of the low loss header to the bottom of the low loss header with a check valve preventing the return water from being pumped back into the zone before returning to the low loss header first…… i.e. one direction flow only.

hot_rod

it is not so common to see a LLH on a non condensing boiler? It it a boiler with a high pressure drop HX?

heron98105

This is a non combi- but it is a condensing boiler.

One of those fancy german things…