Constant pressure circ selection

icy78

I have a system where they have lost numerous heating pumps over the last 12 years, 4 pumps, I believe. Single heating loop pump. I'm looking at putting a constant pressure pump in. There's two zones, one in the basement by the boiler the other zone is up in the third floor attic. I measured the equivalent length for the upstairs as nearly as I could and I come up with approximately 14 to 15 feet of head resistance. The downstairs Loop is about 8 feet of head resistance.
(Both loops go to AHU coils that get approx 5 gpm.)

Taco VRs seems to fall on the high side. Grundfos Alpha 15 too small and 26 too big. (I think)
System recieved a new boiler and PS piping.
Currently has Armstrong S35 bolted to 1¼" flanges!

Any recommendations?

hot_rod

How are they failing? Can you gauge up the current one to see where it’s running.

icy78

> @hot_rod said:
> How are they failing? Can you gauge up the current one to see where it’s running.

Well a new boiler was just installed and piping changed so it'll be different. It's also not wired yet.
The pump is Armstrong S35 which is a 2". The present flanges are adapted to 1¼" and 1¼" piping. Heres an S35 curve.

hot_rod

So is this the primary or secondary circ? Mid curve is where you ideally run, so somewhere between 25- 40 gpm is the requirement?

Zman

That is a very low head/high flow circulator. It doesn't seem like a good fit for your application.
The best way to do this would be to put a balancing valve like the caleffi quicksetter on each loop and then use something like this for a circ. https://s3.amazonaws.com/s3.supplyhouse.com/product_files/Taco-VR3452-HY1-FC1A00-Product-Overview.pdf

icy78

> @hot_rod said:
> So is this the primary or secondary circ? Mid curve is where you ideally run, so somewhere between 25- 40 gpm is the requirement?

I need 11 gpm at 14fthd.

icy78

> @Zman said:
> That is a very low head/high flow circulator. It doesn't seem like a good fit for your application.
> The best way to do this would be to put a balancing valve like the caleffi quicksetter on each loop and then use something like this for a circ. https://s3.amazonaws.com/s3.supplyhouse.com/product_files/Taco-VR3452-HY1-FC1A00-Product-Overview.pdf

That's too high dollar for these guys.
I agree the S35 is terrible.
Would an alpha do the job?
Otherwise the closest I found was TACO fixed speed 0014.

And yes, getting BVs installed will be another battle.

Zman

In a fixed speed, I like the 0014

SuperTech

> @icy78 said:

> I need 11 gpm at 14fthd.

Perhaps a VT2218 would provide the required flow on fixed speed mode?

I'm certainly wondering what is going that you have gone through so many circulators. I'd like to see the boiler piping. Do you have water quality issues? Is a Dirtmag installed to protect ECM circulators?

icy78

Guys the first time that I've seen this was yesterday. Like I said the near boiler piping is new, that actually looks pretty good, altho a bit " busy".
The boiler is brand new, the piping out to the two zones is existing. The existing heating Loop pump was left in there and when I walked in and saw it I just was astounded at how big it was so I looked into it and the history that we have at the shop says that guys have changed that pump four times in the last 12 years. The system itself is probably around 20 years old with R22 A coils in series with the air handler coils.
There are no BVs and I'm asking for one on the lower loop at least.
I really enjoy this kind of job. This type is when I can really learn on the job, and seeing as I am pretty Limited in my experience I come here and ask you guys about it.
A few years ago I wouldn't have known any difference and just let it rip and said that it was a poor quality pump when it failed in another year. But I know that's not the case now.
A few years back when I started getting interested in why pumps fail, maybe 4 years ago, I had a boiler where they lost numerous boiler circulation pumps. I think they were 0011s . And someone on here that's a TACO rep came on and told me flat out that it's not a TACO failing and it turned out that he was right much to my surprise LOL!
So anyhow I like to pursue the pump data and try to evaluate piping whenever I can if I happen to be sent to a hydronic situation. It's been very enlightening and Ive learned a few things, one being that I've a lot more to learn! LOL so anyhow.... appreciate the continued support!

Zman

I love the jobs where they are wondering why the pipes are pinholed and they can't figure out why. There is usually a humungous DHW recirc pipe and the carcasses of the failed pumps on the floor being used as a doorstop.

icy78

Well, finally went back to the site. ( due to owners concern about Co19.)
I went with the VR3452 in constant pressure mode. What a nice circ!
I'm at 14fthd and 9 gpm on full load. I installed a BV on the low head loop.
4 gpm on zone 2 and 5.5 on zone 1.
What really pleased me was the 14 ft matches my calculation, which I sure cant take for granted! 🙂
Thanks for the help all.