Are we still doing Pri/Sec piping?

Bob Sweet

is the part of the system assigned the responsibility of creating enough btu's and gpm to supply the system what it needs to get the job done. The secondary is assigned the sole responsibility of supplying the individual zone what it needs to get the job done. So in essence their duties are the same, it's just a matter of degrees.


The drawing that JohnNY shows is showing the boiler on the secondary side of the system, if the system had a large gpm requirement and or zoned with a large number of circ. pumps the potential for lack of flow thruogh the boiler is possible, starving the HX of crucial flow and causing problems with hydraulics which is is going to be a problem with low mass boilers. Putting the boiler as the secondary, eliminates the potential of the system side starving the boiler of flow. With the boiler acting as the secondary side of the system, it's only concern is to create enough flow through the boiler, to keep it satisfied.

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JohnNY

Are we still doing Pri/Sec piping?

I saw what looked like a very sensible piping arrangement a few days ago. It looked just like a primary secondary loop design but the primary was incomplete.
Very smart and effective in my opinion.

Will this be the new standard?

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hot_rod

I'm leaning towards the Caleffi HydroLink

when I need a PS piping arrangement. It handles the hydraluic seperation and a bunch more.

hot rod

Unknown

That's almost exactly

how we piped this job . Worked like a charm .

S Ebels

Looks like

The gozinta is right next to the gozoutta. Whassup with that? The boiler pumps stealing some main loop flow and sending it back?

What turns on the boiler pumps and do they run only when a boiler fires?

Bob Sweet

> I saw what looked like a very sensible piping

> arrangement a few days ago. It looked just like a

> primary secondary loop design but the primary was

> incomplete. Very smart and effective in my

> opinion.

>

> Will this be the new standard?

>

> _A

> HREF="http://www.heatinghelp.com/getListed.cfm?id=

> 290&Step=30"_To Learn More About This

> Professional, Click Here to Visit Their Ad in

> "Find A Professional"_/A_





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Unknown

The boiler circs

flowed opposite of the system circs . Tekmar controls on the 2 boilers and a Tekmar O-R control to run both boilers . The 3 way mixers protected the boilers .

ABD

I'm just an amateur, but that looks like good P/S piping to me, with closely spaced tees just as is required.

I don't understand what is "incomplete", please explain! Also I don't understand what makes one loop primary and the other secondary; they are of equal status as far as I can see, they both meet each other at the closely spaced tees. I always thought the boiler loop was primary just bcause it's the boiler loop...

Bob Sweet

Isn't that how alot of the manuf.

show their pri/sec piping schematics? Seems like the Ultra and HTP schematics are drawn with that same configuration. Rather than the boiler loop being the primary loop it's the secondary loop. Similar to injection.

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jim lockard

Primary Loop

The loop with the expanison tank is considered to be the primary loop. In Ron JR photo you see the air scoop on his System loop so that would be considered to be the primary loop. That primary loop is considered to be "incomplete" as Ron's zones are served directly off of and become part of the Primary loop. So the system becomes a circle in a circle. Hope this helps thanks for the question Best Wishes J.Lockard

ALH_4

It's P/S

I see no reason why anyone would add another loop in there. Any arrangement that will allow two separate loops to circulate simultaneously is P/S. In the past it was to thermally decouple the boiler, now it's frequently to hydraulically decouple a condensing boiler. Of more importance is the arrangement of the tees so as not to induce flow in any zones when the boiler pump is running, and also whether the boiler pump directly feeds the zones or not. In JohnNY's drawing the system supply water will always be tempered down with system return water. If the supply was on the left instead of the right boiler pipe, the zones could see pure supply water from the boiler. On a high temperature system, this hurts the maximum baseboard/radiator output by piping this way. In a condensing boiler arrangement, if this was a low temperature system, this arrangement would be raising the return water temperature, hurting the boiler efficiency. Why add another loop in between the boiler and the zones, unless it's an injection loop.

-Andrew

John Ketterman

> I see no reason why anyone would add another loop

> in there. Any arrangement that will allow two

> separate loops to circulate simultaneously is

> P/S.



Yes, that's what I thought. It does the job that P/S piping is required to do.

JohnNY

Good, because I suddenly am disgusted with the idea of buying a primary loop pump.

I'm enamored with this new-to-me arrangement.

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ABD

I don''t agree

> The drawing that JohnNY shows is

> showing the boiler on the secondary side of the

> system, if the system had a large gpm requirement

> and or zoned with a large number of circ. pumps

> the potential for lack of flow thruogh the boiler

> is possible, starving the HX of crucial flow and

> causing problems with hydraulics which is is

> going to be a problem with low mass boilers.


As I understand it, there is NO requirement that flow through a boiler loop equal the flow through the zone loops. The HX CANNOT be starved of water however high the gpm requirement for the zones! Between the closely spaced tees there is never any head, so water will continue to flow in the boiler loop, however high or low the flow in the radiator loops, as long as all the piping is full of water.

P/S piping works fine whether the boiler loop has much more flow than the zone loops, or much less flow, or anything in between. The whole point of P/S piping is to make the boiler and zone loop flows independent.

Tony_23

It works well

Except when you need to mix down a zone or have multiple temp requirements. Then you need to pipe the boiler loop as primary.

terry_5

nice job tony!

Ron Schroeder

Where was the air eliminator and expansion tank?