Questions from neophyte

Tim_39

Dave, I'm trying to understand this myself, so I may be entirely wrong, but I think what guarantees no ghost flow in the secondary loops (radiation/system zones) is that TV itself, which will prevent return flow into the boiler loop.

My question assumes a bypass loop piped after the primary (boiler) circulator and returning to the boiler as the last connection before the boiler itself. (See the attached diagram). The TV sits at the junction between the boiler return, the bypass return, and the primary loop return. I am guessing that this is what I'm looking at in Timco's picture. I have attached a drawing of what I have in mind. If the TV is closed, water can only come through the bypass into the boiler. As boiler water exceeds 140f, the valve opens permitting flow from the primary (boiler) loop proper, which means water can flow out of the secondary zones and into the primary.

But I want to stress that I don't know what I'm talking about and that's why I keep posting these questions here. I hope that, if I'm wrong, someone will straighten me out.

Buzz G.

In the midst of my install. The installer put down ells on the vent so got to go back up on roof to take it off. Using chimney for pvc chase. The P-S looks OK, but was new to him. He thought the ETank had to be high so air would go out, but finally convinced him they make ET's that sit on floor.
Would it work for the System Circ and the air separator/Ex Tank to be on opposite sides of P-S if the pumped direction (away from Ex Tank) still followed? If he comes tomorrow I'll have more questions I'm sure. Thanks

Timco

On the pri circuit, you want 1..boiler, 2..air remove / fill / ex tank, 3..pri circulator, then bypass w/ TV, then close spaced t's for secondary take-off. Pump away from the pri circulator.

Tim

Buzz G.

P-S ?

He put the Primary Tees (to and from Boiler) about 10 inches apart, but the return and supply go out to either side of the P-S. He used the center of Tee for the boiler pipes as that was what Lochinvar showed in instruction. Does that matter? Again does it matter if the air sep and exp tank are on opposite sides of the P-S loop? Thanks

Ken_40

How about a low...

resolution digital photo?

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Buzz G.

Photos of job so far

The exp tank is just sitting there to show the space is large enough for it.

Buzz G.

Heres photos

Kinda dark but you can see what I mean

Timco

The air sep should be the first thing on the supply to get the hottest water & get more air out. The ex tank can be anywhere, but you should pump away from it as in my photo. The air sep & ex tank relation ship is not as important as the pump to ex tank relationship. Always pump away from the ex tank. Typical setup is to tee the ex tank off the water fill line before it feeds into the air sep to get air out of incomming water. Secondary are always taken off with close spaced tees.

Abro

Beautiful job

I appreciate the photo as it helps me with a different thread I've got going ("Will this work?")--similar questions about piping, but on an old gravity system with new radiant loops.

I've been trying to figure out how to get boiler protection with primary secondary piping. Some people have said it's virtually assured; others have suggested ensuring the boiler loop pump exceeds the GPM needed by system pumps; others have suggested adding a bypass with valves. Your solution seems to be a bypass with a throttling valve ending a TV. Can I assume that is a Danfoss TV which permits water to return from the whole boiler loop (ie. right side) when temp exceeds 140f?

Buzz G.

Timco help

I see your P-S as the very short connection. Does it make any difference if the straight part is in the primary or in the secondary-don't you get the same hydraulic separation with either??

Unknown

Tim,

I have a question,,would your primary circs location here not have a direct-effect on the TVs operation?
I mean if the boiler was cold-start what would keep this cooler water from trying to migrate into the zones until it started to open?
Just curious.

Dave

Timco

Correct...the grey valve is a TV and opens at 140* to protect boiler. P/S piping bleeds heat out slowly anyway, but this ensures no return temps below 140*. This is how I ensure boiler protection.

Tim

Timco

My opinion is that they show the circ on the return because that's how it is typically atached to the boiler at shipping. As I have mine piped, if the TV is closed, no flow will go through the sec tapping's section of the pri loop, it will go through the bypass where there is no resistance. When the TV opens, it will favor the secondarie's section of the pri loop as the bypass will close. This system works very well as does this pictured system with the same piping setup.

Tim

Timco

Not sure what you mean. The half cocked lever is the bypass that leads to the TV. The big loop in & out of the boiller is the primary, and the secondaries are the two close spaced tee's that lead to the circs (supply) and the single pipe with the purge station (return).

Tim

Unknown

6 of 1,

½ dozen of the other I "guess"!
I`ll have to ponder this some more.

Dave

Unknown

Again Tim,

I was just curious.
As Brad always says "ahead of the pump it becomes a "diverting-valve", behind,, a "mixing-valve" and the Danfoss chart temps say similar,,higher on the flow.
Is your first pic (if I remember right),the one you had trouble with awhile back?

Dave

Timco

I thought I had problems, but ME told me to fire it and walk away, and it worked great. I was expecting the heat to just dump around the pri loop but on cold start, it bleeds through the system and this layout worked great. It did well on the Laars install as well. I am sure there are other ways to do it, but this works very well and I have watched it close the loop when a cold zone fires up to protect the boiler. I am totally cool with input / suggestions / and being asked about my method, but I will pipe my next p/s job the exact same way. It works well and heats quickly while positively protecting the boiler.

Tim

Buzz G.

P-S

The very short loop between the 2 tees is your P=S loop isn't it? The system supply and returns go off at rt angles to the right. The knight manual showed the primary (boiler) loop being the one with the right angles and the secondary (system) loop going off to either side-in other words the supply and return were at the two ends of a straight pipe. This is just opposite of your system, but apparently both work? That is why I asked question as to whether it makes a difference.

Timco

Not sure what the knight manual shows, but the pri loop is always the loop that leaves & returns to the boiler itself. It has a circ. The line that seperates the pri loop and goes into the top of the TV is the bypass, but part tof the pri loop. The secondaries tap off the pri loop and are the supply & return to the heating components be it rads or BB. You really should read Dan's book primary / secondary pumping made easy. That and Pumping Away. You will have an understanding of what you are doing, not just getting guidance or following directions. With that being said, look at my pics again, and think primary / secondary...It will click. There is no other way to do it. There are many ways to take off the secondaries, and many primary loops look different, but the pictures I posted are textbook p/s and easy to follow. Many are not so easy to follow, but still follow the same principal.

Tim

Mike Dunn

expansion tank

Are those manufactured strut clamps holding the expansion tank or did you make them?

Timco

They are manufactured. I measured the tank and bought the straps, I think they were 10 or 12"...I do not recall exactly.

Tim