primary secondary error

How's the Delta T through the boiler? Is it cycle off on high limit at all?

Two different installers? Notice how the primary has sweat joints but the secondary has PP and F1960 pex connections.

That's probably why it did not hit HL system sucking up the btus.

Is the pex tubing O2 barrier?

That's a WH, so there was probably no real need for P/S piping. If I were re-working it, I would probably ditch the zone circs and use a single ECM pump with zone valves.

Gordy said:

The secondary side is most likely over pumped, and we series another pump to one or more in operation on a call? Just so we don't worry about enough flow through the HX? Sheer accidental brilliance!

One day we pound the table how systems are over pumped the next we find justification to over pump, and find grace in an accidentally on purpose pipe job.

The install has an extra pump for nothing, or 5 extra pumps for nothing, and missing zone valves. Which is more efficient? Less work? Less thinking? More predictable flows rates?

The OP did right by the customer suggesting it is not piped per the manufacturers schematics. I think Del knows what needs to be done, it is up to the HO to decide his course of action. I don't read that any of the comments implied it was piped properly?

Del asked for opinions, he sure got some

Thing is if you do it text book no need to be curious. The ex brother in law could get misplaced.

Steve, I guess I am confused by your statement "I have yet to see any formal representation of P/S piping from manufacturer's recommendations to Gil Carlson's papers that show P/S piping from the Bulls of tees? What am I missing Mark?"

Every Gianonni modcon boiler boiler drawing I've ever seen, regardless of the manufacturer shows flow to and from the boiler through the bulls of the tees. With them being closely spaced, they create the conditions required for hydraulic separation.

The codes used to not allow a take off or return from a bull. Until these little boilers came out, and many of them got turned down in inspection. I attempted to write a justification for the ICC IMC, but the T.C. I was dealing with decided just to eliminate that provision from the code, instead of trying to understand it.

And now, people in the field installing hydronics think its OK to use bull headed tees, and hydraulically speaking, unless it is on a priority zoned situation (like DHW heating) it is NOT acceptable. The very first article John Siegenthaler that I read wrote dealt with this.

Gil Carlsons first application, if memory serves me correctly was on a high rise. They were having problems exerting flow in a secondary branch off mains, so they piped it P/S, added a small circulator, and their problems went away.

I aslo remember back in the day, when P/S first hit the scene for modcons, we thought it was necessary to have a "loop" where the water went around in a circle, with secondaries for input and output. As time went on, we realized that "loop" was a waste of time, and started setting up the scenarios that are more common today and eliminated the useless circle pump.

I guess one question that has always stayed in my minds eye, is exactly which loop is the primary? I've always said that hydraulically speaking, the PONPC is THE one most critical element that dictates how everything else works, so where ever the expansion tank is, is what I consider the primary. Other people have said that the boiler dictates the location of the primary. I've also done systems where I had a primary, a secondary, a tertiary and a quaternary loop. All in the same mechanical room.

One thing the industry needs is consensus on exactly what and where the primary is...

The only reason for using P/S piping is true hydraulic separation. The Gianonni boiler pump HAS to move a specific amount of fluid, in its own circuit. It uses this as a reference point to determine load. If flow is constant, then the only variable is delta T. As load increases, the delta across the boiler loop increases, and the burner controller knows it is seeing a load and begins ramping up the fire.

At one point in time in my life, I stupidly said in public that low loss headers were for people that didn't know how to do P/S piping. As time went on, and microbubble resorbers, dirt separators and other things came around, I started eating those words, because of the labor savings associated with doing a LLH instead of having to pipe up all the extras.

Please elaborate on your question and I will try and help you find the answer.

One adage that hasn't changed is a Holohanism of "What ever enters a tee, must exit a tee..." And contrary to popular belief, it is possible to run water through those tees backwards, and also in opposing directions.

ME

And NOT P/S piping as I understand it.

Bob, That looks to me like closely spaced tees along a common pipe except for the top tee as you suggest. It looks like cheating to me. Siggy calls for minimum distances before and after 90* elbows on the primary loop to avoid issues. IMO, if they used a 90 there instead of the top tee, moved and turned the tee like the other one on that loop, it would have been "more" correct.

SWEI said:

Stephen Minnich said:

To avoid confusion with my customers I just refer to boiler loops and system loops and everyone gets it.

As do we.

Not a bad idea, although how many customers truly understand the concept of P/S?

I have had contractors go back on my early P/S jobs and cut between the tees and cap them off! They convinced the homeowner it could not work with a loop through the closely spaced tees.

And what about systems with 3 or more loops like injection mixing. Some P/S piping has a dedicated primary loop with a pump, a boiler loop, maybe other inputs and multiple takeoffs. This systems seems a bit like a misunderstood version of that?

Ah for the simpler days of a cast boiler, pump, and ZVs.

The whole reason for PS piping is hydraulic disconnect. In this case, if a low loss header, OR an oversized section of piping in the tweeter section had been used, it would have facilitated the need for hydraulic disconnect. So, had the installer used 1-1/4 X 1-1/4 x2 inch tees on the tweener, with the tweener piped in 2", it would have worked perfectly as it pertains to hydraulic disconnect. Would have been a PITA to fill and purge, but met the hydraulic disconnect requirement. However, and this is a big however, it DOESN'T meet the needs to provide the lowest possible return water temperatures back to the heat source. Too much traffic going through the intersection to control that issue.

Best way to ensure that (coolest return to heat source) is to use properly ported and piped LLH or buffer tank, but no one wants to go that route due to lack of space, time and money. With a mod on boiler, it probably only means a net savings of 5 to 10%, but in the case of a WSHP, it makes a huge difference in overall COP of the compressor.

As it pertains to loop names, I prefer input and output. Here at my own house, I have 3 inputs and four outputs, at present (subject to change at any time...)

I rest my case your honor...