Help!!!

Joe Mattiello

Taco circulators will work as the B& G circulators. Circulators in series will double the head the flow will remain the same (approx.). Circulators are parallel will double the flow, and keep the head the same. Pumping in series may work better than going with a high head circulator. Often times I would recommend series pumping to avoid a more costly alternative. Every application is different.

Firedragon_4

Help!!!

I'm doing some research for an emergency project and need a few questions answered.

1. Have you personally ever done series pumping?

2a. Do you believe that two small circulators are better than one larger one?

2b. On average how much money is saved? Both the cost of the circulators and electricity?

3. By percentage, how many systems do you see installed this way?

Thanks in advance and if you don't want to post your answers please send them to me here where it will stay highly confidential.

www.firedragonent.com

Carl PE

.

1. Yes

2a. Only if you can't get a pump with the right gpm/head.

2b. None

3. Very few %.

Usually this is only done if you need low gpm w/ high head. You're better off with a single 3500 rpm pump.

hr

Some thoughts

I feel it is always best to pick the correct "one" pump. However, there are some cases where you may want to start two pumps then drop one off after a period of time.

Drain back solar is one instance of this, where pump head is needed only to start the siphon.

I have had a contractor tell me flange to flange applications sometimes snap shafts? Perhaps when they are not started together? I think, also, there should be a 6" section of piping between the two.

I'm not sure you can exactly double the head when pumps are in series. I think there is a correction factor involved.

I'm not sure which application you have in mind, but there are a lot of pump selections currently, and manufactures continue to add more. Seem all but the most unusual application would have a pump with a curve to match, or a multi speed, or even variable speed to adjust.

Maybe series pumping makes more $$ sense when you get into commercial applications. I'm think more along the lines of fractional HP wet rotor circs.

Doing the math in my head, it seems one 80 watt pump operating at a typical 20% efficiency would be better than two, perhaps 60 watt, operating at or below their 20% peak efficiency?

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Constantin

Some answers...

1) No, I'm a mere mortal.

2a) It depends on the application. I would buy and play with Siggy's HDS suite and read his Hydronics book to get a good feeling of what two circulators can do vs. one. It's well-explained in there.

For example, you may have a situation where multiple zone valves on a manifold are fed via two circulators (that are not multi-speed). The circulators are sized to feed half the zones each and piped in paralell. Naturally, this predicates some form of load/flow balancing.

Unless all the zones always call at the same time, the double circulator system will work more efficiently than a single single-speed circulator doing the same work - because a large, single-speed circulator will probably require a differential bypass so as not to screw up the zone valves, cause excessive fluid speeds, etc.

While the PAB will ensure good performance, it also means a lot of pumping for nothing, i.e. electrical wastage whose only benefit is heating the water in the pipes further.

Naturally, a delta-P sensing multi-speed circulator allows you to do it all, i.e. remain relatively efficient across a wide pumping range and ramp speeds up and down as valves open and close. You could do it with a delta-P sensor, some control, and a voltage-regulated Taco pump. Or, you can wait for widepread distribution of the Wilo series of pumps that allegedly have built-in delta-P sensors.

I think it was Dan Foley that had something like 5-6 zones valves on a dual single-speed pump manifold like I describe above. IIRC, it was two grundfos 15-58FC pumps that were pumping in paralell.

Pumps in series allow you to increase the head instead of the volume. Such systems are interesting when there are significant differences in head pressures. I suppose a whole bunch of zones on TRVs might cause this.

2b) If you do the math, the cost of running a 50W pump in most locales isn't that high, even if it is a constant-circulation system. Naturally, those living off the grid have a different perspective. As for the pump cost differntial, I suppose you could go look into Able distributors, etc. to see what the cost differentials are.

3) I imagine that the number of systems installed with a dual-pump setup are quite low due to the added piping expense, circulator logic, etc. As time goes on, I imagine that having a multi-speed pump with a ladder-logic (i.e. speed increases based on the number of open zone valves) is probably the easiest way to implement this elegant way of eliminating the need for a PAB while also treating the ZVs nicely.

So, who is getting sued this time?

DanHolohan

that last line

is precious.

Kal Row

the advangate of using to pumps in series...

instead of one large one would be if you want more head but want the resulting pump curve to still be flat so that the pumps dont cook themselves to death when the flow is modulated

rule:
tall thin impellors = steep pump curve

short thick impellors = flat pump curve

put two taco 0012's in series - you can move 45gpm with almost 30ft of head - but they wont cook when you cut the flow down to 20gpm - something to think about when you going to a large system with a TRV on each radiator - allows you to buy a less expensive deferential pressure bypass valve that can only bypass 20gpm max instead of a huge one


ps you might want to consider spring check valved bypasses around each pump so that the system isn’t totally down when one pump fails

Boilerpro_3

Pumping

1) NO, not yet, but I know some that have.
2)Typically Yes. Most of my larger systems (over 200,000 load) have two pumps piped in parallel. In this size range very often the installed cost of two smaller pumps is much less than the installed cost of one larger pump. Remember these applications often only need two little NRF-22 to do the job, so the pumps are realllll cheap. I also typically use zone valves on full reset systems because most zones are open nearly all the time, so the pumps are at near constant load. Using only two pumps instead of a pump on each zone also gives a nice boost in efficiency and cuts electrical costs.
I also almost always install multiple boilers at this load, for both improved efficiency, boiler life, and lower future replacement costs. To me it really does not make much sense to have built in back up for your boilers and still only have a single pump that can take a system down.
3) Probably there is some extra cost in electricity since smaller pumps are less effecient that larger, especially on systems with full reset where the flow needs are nearly constant and at high levels. However, with partial outdoor reset and a pump staging control, such as from tekmar, you can probably run only one pump nearly the whole heating season, cutting electrical usage substancially. I've read on big jobs that have added a variable speed pump control, such as B&G's, that responds to the pumping needs of the system proportionally, that electrical usage is cut by 40% or more. Payback on the new controls is often in a year or two.
4)About 100% of my 200,000 btu/hr plus jobs go in with multiple pumps. An added side benefit is that I have on the truck a replacement pump for nearly any job I have completed, so when a failure occurs, there is no need to head to a supplier to pick up a pump. This saves the customer money and they can still stay warm with only one of two pumps running in nearly all conditions. Just make sure to use non overloading pump motor sizing.

Here's a pic with twin injection pumps and further back twin zone pumps that feed an 100 year old 800 seat church sanctuary with 35 foot ceilings. I believe the zone uses 2 Nrf-22s

Boilerpro

Joe Mattiello

Taco \"00\" series

> 1) NO, not yet, but I know some that

> have. 2)Typically Yes. Most of my larger

> systems (over 200,000 load) have two pumps piped

> in parallel. In this size range very often the

> installed cost of two smaller pumps is much less

> than the installed cost of one larger pump.

> Remember these applications often only need two

> little NRF-22 to do the job, so the pumps are

> realllll cheap. I also typically use zone valves

> on full reset systems because most zones are open

> nearly all the time, so the pumps are at near

> constant load. Using only two pumps instead of a

> pump on each zone also gives a nice boost in

> efficiency and cuts electrical costs. I also

> almost always install multiple boilers at this

> load, for both improved efficiency, boiler life,

> and lower future replacement costs. To me it

> really does not make much sense to have built in

> back up for your boilers and still only have a

> single pump that can take a system down. 3)

> Probably there is some extra cost in electricity

> since smaller pumps are less effecient that

> larger, especially on systems with full reset

> where the flow needs are nearly constant and at

> high levels. However, with partial outdoor reset

> and a pump staging control, such as from tekmar,

> you can probably run only one pump nearly the

> whole heating season, cutting electrical usage

> substancially. I've read on big jobs that have

> added a variable speed pump control, such as

> B&G's, that responds to the pumping needs of the

> system proportionally, that electrical usage is

> cut by 40% or more. Payback on the new controls

> is often in a year or two. 4)About 100% of my

> 200,000 btu/hr plus jobs go in with multiple

> pumps. An added side benefit is that I have on

> the truck a replacement pump for nearly any job

> I have completed, so when a failure occurs, there

> is no need to head to a supplier to pick up a

> pump. This saves the customer money and they can

> still stay warm with only one of two pumps

> running in nearly all conditions. Just make sure

> to use non overloading pump motor

> sizing.

>

> Here's a pic with twin injection pumps

> and further back twin zone pumps that feed an 100

> year old 800 seat church sanctuary with 35 foot

> ceilings. I believe the zone uses 2

> Nrf-22s

>

> Boilerpro

Weezbo

I have had some experience with this question...

1. Yes . my pipe arrangement looks somewhat like redundant parallel with a group of valves all over the place. and T's ...so it looks somewhat like two H's for the most part...with two B's above and below...

Two pumps that mount on a wall with all the extra fittings and valves vs. one floor mount or Cradled and bypass are easier to hassel around with physically.and some ways its easier to find parts....skill sets are different on repair also... as are the tools that go with it...larger pumps require somewhat more lengthy repair and belong in an environment that has at least a cursorary eye breeze by them on occassion....for the most part commercial mech rooms for example...

2 . and as to whether two small ones are Better than one larger one...well it depends a bit on what you have in piping requirements and the zones and space... when done "on the cheap" two smaller pumps seem economical...like hot rod says though flange to flange seems to create difficulties, a six inch spreader might not even be exactly great...maybe the length of a pump body with flanges,..and about 3/16th's space...

i will post this much now as my computer keeps crashing.


i am back *~/:)...

impellers are for the most part slaving away as are the stop start cycling so,... trouble shooting is also a skill set that comes into play from time to time... with series floor mounts etc..i have been suprised to find that upon occassion having one recirc rolling was a real blessing...it is somewhat like electrical brown outs just getting Light on first helps the whole equasion.

systems with many diverter "T's" seem to fair a bit better on the Plus side ...

In residential settings .... however in commercial settings ,redundancy and "Fixes" quite often entail series pump in line to allow things to keep flowing until the part or motor or whatever gets in the hands of the guy making things "Go"....

Somewhere along the line, people pipe series pumps in and think its the way to go...to me it is just another solution that could help . if you look through the threads here or at the RPA site under 1000 foot loop lengths i think you will get a fairly comprehensive outline on the use of series pumping...the largest series pumps i have used were in potable water ,that might be another pretty good source of info...reclamation systems and mining might also have alot of good scoop. and maybe rural fire fighters have had a fair amount of experiences with series pumping at or near 90-> 200 gpm.

Kal Row

here is a pdf diag that covers all bases..

Andrew Hagen (ALH)

Bypass

What is the head loss coefficient for a dead pump?

I can see installing a bypass on the second pump for a drainback solar system, but wouldn't the system "limp" along pumping through one of the pumps even without a bypass?

Isn't the varying flow / constant head situation, a case for a differential pressure regulator?

-Andrew

Kal Row

could not find it published...

just looking at it, i suspect that it's resistance is like 3-5ft of head, besides, a piping a bypass allows the system to be working while a pump is removed

as for diff-press-bypass - they are a compromise device at best as they are typically not linier - i think of them as device to protect against the pump's volute from blowing up due to friction induced heat, or to keep the boiler reliefs from seeping from too much head - however, as a primary design item - they seem wasteful

i wish the auto variable speed double "magna" from Grundfos was avail in the usa, it's a better way to go – this is a perfect market hole for taco to fill with a little built in tekmar electronics like they use on their variable speed pumps – all they need to add is an internal pressure transducer – I suspect that an “AUTO-VARI-HEAD” pump would not be more expensive than a pump with a added diff-bypass valve – especially when you consider the piping labor

Andrew Hagen (ALH)

Circulators

I can see where it may be advantageous to be able to "hot-swap" the pumps out.

DPR's are not particularly inexpensive. However I do think that in the type of piping systems we design in hydronics, and their varying system properties, it's not possible to find a pump that fits all situations. We end up designing for worst case conditions, and throtting everything back 95% of the time. I also would like something in between a 15-58 and a 26-64.

You're referring to something like this?
Grundfos UPE15-60


So why do the Europeans get everything 5-10 years before we see it? If we all got together and bought container loads of circulators, do you think they'd make us a 110v version? ;-) Where is the break-down between consumer and manufacturer?

Or maybe since we're already stepping the power up for the Vitodens boilers we could just use them as they are.....

-Andrew

Weezbo

A while ago i heard of a Grunfos Pump Plan...

it is a 15 series pump ...so...figures i ,why not just buy a bunch of the bodies and drop 15 cartridges in them there by side stepping the 50 hz weird voltage thing *~/:) well its like a year or so later ...have you seen any on the shelves recently ? so either the guy in england didnt want to send them or theres some sort of import export deal that has to be met or just maybe they were Bushwhacked prior to leaving the country who can know these things..theres a lot i dont know ...actually i am amazed at how much i dont know..i think therefore i dont know.

Kal Row

they say it's a \"UL\" listing thing..

I say it's a demand thing, you see, this Danish company used to do most if not all their manufacturing in Germany, but with the huge demand for the common pumps in the usa, coupled with the fact the cast iron in the usa is a tiny little fraction of what it costs in Europe, they opened two plants here one in California and one in Kansas, the German produced pumps with shipping are just way to expensive for the usa market, isn’t that why we spell vie$$mann with two $ , the total US market for “maga pump plans” is maybe 5 units – so there

BTW: a gfos UP43-75 will give the same performance as two 0012’s in series – but cost you more and will fail really fast if you stall it – better off with two flat curved 0012s in series – gfos simply has no equivalent to the really flat 0012 – B&G has the NRF-33 which is close and they also make a bronze one - NBF-33

As to why europe doesnt make a pump with such a flat curve, you said it yourself they are ten years ahead, so while we are using TRV’s and zones, they have been following the hydronics mantra: “a heating system should be run at a constant flow, with a setback temp, equal to the heat loss of the space” - so they simply have no need for such a flat pump

brad rutherford_2

Series pumpimg

Keep it simple _________. This serves me well when I am thinking to hard, or when I try putting 10 gallons in a 5 gallon bucket.

Aidan (UK)

Pump Plan

You must mean this, Weezbo.

http://www.grunfos.com/web/homeUK.nsf/subCoverPage/Articles?opendocument

It's not 2 pumps in series; the inlet is in the middle & the outlets on the sides. It's 2 pumps serving 2 different zones, i.e., heating & DHWS. They are trying to sell their pumps to compete with the 3-port mid-position valves that are on about 50% of UK heating systems. Look at the 'Pump Plan Applications' page and it may make sense. If not, you'd have to be here.

I don't think the idea has caught on.

PS, Good idea with the picture, Kal.

S Ebels

What's the situation

Why does it call for two circs? Looking for high head or high flow?

Kal Row

i must have seen a picture of them with them oriented...

on the side and thought that there was a series version of it - but they make the manga in a paralel version

Weezbo

Thats the animal *~/:)...

this pump plan has what "What the heck is That?"appeal

so , in my musings at the time i could conjure up a few places in my mind that they could be used and some of my friends have places that they have "inherited"that need some creative solutions..... this looked like it could very well fit the bill. You just sent me more information with the one link than i got from the rep at Grundfos a year or so ago....Thanks. Adian

The magna also seems to have some solution written right into designe... sometimes seeing things from a different perspective is all it takes for a light to turn on in another room thank you also, Kal.

Firedragon_4

Many thanks to all who

replied on this subject especially Weezbo for researching previous posting.

Sorry for not responding sooner, but have been flat out.

Warmest regards,
George Lanthier