Primary Pump ?

Danscrew

On a Mod /Con Boiler with a primary/seconday setup. Do you calculate the prmary pumps GPM the same way as the secondary side Pump curve ? feet of head / GPM for that particular pump ? Thanks Dan

hot_rod

correct. the boiler installation manuals have recommendations for the circa required. Usually that circ will cover some piping also.

Empire_2

Generallyy the primary for your new boiler is supplied with a pump the MFG. specifies for that particular boiler. The secondary pump requires home work by you or others to ensure the proper head/GPM can handle the job.


Mike T.

SWEI

Empire said:

Generally the primary for your new boiler is supplied with a pump the MFG. specifies for that particular boiler.

Change that to Generally the primary for your new boiler is supplied with a pump the MFG. overspecifies for that particular boiler and I'll agree. Fear of lawsuits and too many tech support calls from clueless installers result in "conservative" sizing that rarely makes for a happy boiler when supplying a short primary loop (like straight to a hydro separator.) If the pump is a three speed design, low might work out OK, but even those frequently have higher flows that prevent operating at maximum efficiency.

DO THE MATH.

ced48

Do yourself a favor, sell the pump that comes with the boiler, and buy a Taco VR1816. The pump is super quiet, energy efficient, and you can adjust it to just the right speed. If boiler makers want to include a pump, they all should take a look at this one. And to make things even better, most new england states are offering a $100 instant rebate, bringing the cost down to a 007-

Steve Thompson (Taco)

Interesting blog for sure. Here's my take...

Normally, the job of the "Primary Pump/Circ" is to provide flow through the boiler (or geo, solar, chiller etc.) with systems using secondary or system circs. A circ supplied by a boiler manufacturer is not sized to pump the system and the boiler. So, if you get a circ with the boiler the system will probably need it's own circ(s) or the boiler circ will have to be replaced with a larger circ.

Regardless of separate primary/secondary or one circ for the system, these are sized the same. How many btu's need to be moved/delivered and how much friction loss to overcome.

Primary and Secondary Application:
1) Primary - needs to meet boiler flow (135,000 BTU Output @ 20 deg F is 13.5 USGPM) and overcome the boiler and interconnecting piping friction loss.
2) Secondary - needs to meet the zone(s) flow based on BTU's and overcome friction loss of the zone that has the highest friction loss (zone friction losses are not additive unless piped in series)

Hope this helps...

hot_rod

Many installers have learned the hydroseparators are really the best way to pipe boilers. Then the circ supplied with the boiler should be able to pump the boiler requirements and the path to and from the separator.

Keep in mind boiler warranty may be tied to the pump installed.

Granted some may be a bit over-pumped, but with multiple speed circ you should be able to get what you need on most residential sized boilers.

Until we get circ that can modulate with the boiler control signal, a multi speed circ should get you real close.

Here is a typical pump selection page from a boiler I&o

Boiler manufacturers warranty more failed HXers from under, not over-pumping. Generally the pump manufacturers don't warranty failed HXers, stick within the equipment manufacturers spec.

ced48

It really is complicated or tricky. It doesn't vary from manufacturer. You have to follow the universal hydronic formula. If you do that, you can't go wrong.

Empire_2

ced48 while I respect your opinion, just the right speed to me means nothing. I personally need the pump curve, gpm, and head to at least plan my secondary zone requirements, but when new equipment is installed, the MFG. has the where with all to spec. the pump of choice so they can warranty the equipment. Imagine changing a spec. design and the MFG finds out about it,.....End of warranty. Never have I chosen a pump that just barely, but meets requirements. So many pumps to choose from and as long as good practices and professionalism is exercised, multiple pumps work well and not worth debating over miniscule figures.


Peace;
Mike T.

ced48

Empire said:

ced48 while I respect your opinion, just the right speed to me means nothing. I personally need the pump curve, gpm, and head to at least plan my secondary zone requirements, but when new equipment is installed, the MFG. has the where with all to spec. the pump of choice so they can warranty the equipment. Imagine changing a spec. design and the MFG finds out about it,.....End of warranty. Never have I chosen a pump that just barely, but meets requirements. So many pumps to choose from and as long as good practices and professionalism is exercised, multiple pumps work well and not worth debating over miniscule figures.


Peace;
Mike T.

I'm certainly not saying one should ignore all the things you have mentioned, but the boiler, once in operation, will fill in most of the blanks in the pump selection puzzle.

One thing many people overlook is the fact that all pump selections in boiler makers charts are based on full fire. If one operates at less, he will find he is over pumped.

Even when you take your pump charts and compare them to boiler makers selection, many times you will find yourself way over pumped, using the universal hydronic formula.

Empire_2

Totally agree and I think I was more concerned with the secondary side when I mentioned the specifics. I wouldn't have a clue as to the CV. values of heat exchange bends and or twists so that's why I have no problem with the MFG. specified selection.



Mike T.

SWEI

Steve Thompson (Taco) said:

Normally, the job of the "Primary Pump/Circ" is to provide flow through the boiler (or geo, solar, chiller etc.) with systems using secondary or system circs. A circ supplied by a boiler manufacturer is not sized to pump the system and the boiler. So, if you get a circ with the boiler the system will probably need it's own circ(s) or the boiler circ will have to be replaced with a larger circ.

Some are sized this way, but never for the higher ΔTs required for maximum boiler efficiency. The notable exception would be onboard variable speed pumps (Rinnai comes to mind.)

Mark Eatherton

Silly question/observation here, but what determines whether a pump is a primary or a secondary? Is the boiler pump a primary, or the system pump a primary?

Think carefully before answering. I have my own personal beliefs, but wanted to see other peoples reactions before committing…

ME

SWEI

Nothing, other than convention here in North America, as far as I know.

Steve Thompson (Taco)

Ok Mark - I'll bite. In my generation (when I started back in the mid 70's), a primary circ was dedicated to pumping through the boiler and the boiler loop. Secondary zones were piped off the primary. I get your thought though - different folks have different descriptors for primary.

BTW, anything new on your "electric glass"?

Gordy

The primary would be which ever location the ponpc ( boiler loop, or system loop) is located. I like to think in terms of the primary being the boiler loop since most times that is where the x tank is located. Keeps it straight in most conversations.

Empire_2

Same here, I agree w/ Gordy. Primary being the boiler pump, Secondary is all zoned pumps, and if loop pump, I call it loop pump. Not all designs have a loop pump if really short and or if zone pumps initiate the call for system operation. I think we can all get our meanings across when talking about a system. I have also heard boiler pump, loop pump being primary and zoned pumps being secondary.


My .02

Mike T.

icesailor

For what little it is worth, I decided when I discovered them that all systems should have hydraulic separators where the two sides can meet in the middle and work things out. Therefore, any pump installed on the side between the boiler and the separator is a primary pump. Any pump installed on the system side of the separator is a secondary pump.

What difference does it make what size the boiler pump is as long as it meets the manufacturers specifications of flow through the boiler? Regardless of how much bigger or smaller the system pump is, the issues will be resolved in the separator.

It all comes out in the wash.

hot_rod

My opinion is the boiler loop is the primary side.

There would be no heating system without the boiler, or chiller, etc so it must come first.

Like primary school, before secondary school.

icesailor

"Common sense is not a monetary value".

Mark Eatherton

My answer is multi fold.

I agree with Kurts' assertion. We are the only country that refers to it as primary/secondary. Other advanced hydronic country's consider them as load and source circulators. In reality, it really doesn't matter what you call it.

I lean more towards Gordy's assertion regarding the PONPC. I have had systems with multiple heating/cooling "sources", which would mean I'd have more than one primary pump , which doesn't make sense, unless we go primary, secondary, tertiary, quarternary etc etc etc ad nauseum.

And then there was the "dizzy" pump that did nothing other than sending water in a close circle. I realized after having done a hundred or so of those systems, that the dizzy pump really isn't necessary. The "source" or "load" pump can do that job AND move water through the source (heating or cooling) or load.

Regardless of WHAT you call them, the most single important piece of information you need to know for quiet, efficient operation is that ALL pumps SHOULD pump away from the PONPC. I pre-qualified that statement with SHOULD, because it is proven every day that even though these babies are not always pumping away from the PONPC, they still move water and deliver heat. Hydronics is VERY forgiving...

And by the way, I've determined through my own personal research that there really is no written standard that determines primary from secondary, and it varies from drawing to drawing and manufacturer (boilers versus pumps) to manufacturer.

Steve, the electric glass manufacturers are still struggling with consumer acceptance. We have proven through our own research that these beauts have the potential of reducing energy consumption of commercial buildings by 30 to 50 %. It still goes counter intuitive to human common sense (putting hot glass in an outside opening?) but through trial and error, we have determined that in most cases, these windows are not a "primary or secondary heat source", but instead when properly controlled are an excellent human comfort tool.

I run my windows at between 72 and 75 degrees F at design conditions, and sitting right next to one on a very cold day is a heart and body warming experience. You wouldn't think it would make that much of a difference, but it is sensible.

We have numerous large installations done, and I believe it is just a matter of time before the world wakes up and realizes the potential behind this product. The Federal government is also studying it, but unfortunately, the building in which they installed them into also had a significant mechanical work over, and it is hard to determine exactly where the energy savings are coming from.

Oddly enough, they US Govt) do NOT want to look at the increased comfort factor associated with the windows. I guess employee comfort and efficiency is NOT on the top of the governments priority lists, but it should be, because it is OUR money that cold, inefficient employees are wasting…

When the world catches up with us, we will be ready :-)

Thanks all for indulging me in this interesting conversation, and please feel free to continue the conversation. This is how people learn. The more you ask, the more we learn.


ME

hot_rod

Mark Eatherton said:

My answer is multi fold.

I agree with Kurts' assertion. We are the only country that refers to it as primary/secondary. Other advanced hydronic country's consider them as load and source circulators. In reality, it really doesn't matter what you call it.

I lean more towards Gordy's assertion regarding the PONPC. I have had systems with multiple heating/cooling "sources", which would mean I'd have more than one primary pump , which doesn't make sense, unless we go primary, secondary, tertiary, quarternary etc etc etc ad nauseum.

And then there was the "dizzy" pump that did nothing other than sending water in a close circle. I realized after having done a hundred or so of those systems, that the dizzy pump really isn't necessary. The "source" or "load" pump can do that job AND move water through the source (heating or cooling) or load.

Regardless of WHAT you call them, the most single important piece of information you need to know for quiet, efficient operation is that ALL pumps SHOULD pump away from the PONPC. I pre-qualified that statement with SHOULD, because it is proven every day that even though these babies are not always pumping away from the PONPC, they still move water and deliver heat. Hydronics is VERY forgiving...

And by the way, I've determined through my own personal research that there really is no written standard that determines primary from secondary, and it varies from drawing to drawing and manufacturer (boilers versus pumps) to manufacturer.

Steve, the electric glass manufacturers are still struggling with consumer acceptance. We have proven through our own research that these beauts have the potential of reducing energy consumption of commercial buildings by 30 to 50 %. It still goes counter intuitive to human common sense (putting hot glass in an outside opening?) but through trial and error, we have determined that in most cases, these windows are not a "primary or secondary heat source", but instead when properly controlled are an excellent human comfort tool.

I run my windows at between 72 and 75 degrees F at design conditions, and sitting right next to one on a very cold day is a heart and body warming experience. You wouldn't think it would make that much of a difference, but it is sensible.

We have numerous large installations done, and I believe it is just a matter of time before the world wakes up and realizes the potential behind this product. The Federal government is also studying it, but unfortunately, the building in which they installed them into also had a significant mechanical work over, and it is hard to determine exactly where the energy savings are coming from.

Oddly enough, they US Govt) do NOT want to look at the increased comfort factor associated with the windows. I guess employee comfort and efficiency is NOT on the top of the governments priority lists, but it should be, because it is OUR money that cold, inefficient employees are wasting…

When the world catches up with us, we will be ready :-)

Thanks all for indulging me in this interesting conversation, and please feel free to continue the conversation. This is how people learn. The more you ask, the more we learn.


ME

I'd say the dizzy pump may in fact be required. With high head boiler, that circ could be much different from the required system pump. Or allowing mixed head circs to get along.

Hydroseps are the best way to lose the dizziness.

Also with seps, the expansion tank can be on either the source of load side, so that may not be an accurate way to define which witch is which.

TomS

Mark and hot rod, I don't have a clue what you guys are referring to as a "dizzy" pump.

Gordy

Primary pump think circles tony.

ced48

TomS said:

Mark and hot rod, I don't have a clue what you guys are referring to as a "dizzy" pump.

I would assume they are referring to what you would call the primary pump, the pump that sends water around and around just to make sure the boiler always has enough flow. One problem from using the recommended, over sized pumps, is velocity noise. They can be loud and drive you crazy, if the boiler is in your living space. If you can maintain flow in other ways, it is the way to go-The fire tube makers are coming around to this, just look at a TT install manual. In fact, the last time I talked with someone at Lochinvar, he referred to the fire tube HX as medium mass, not low mass, and had no issues with an install piped direct, as long as minimum flows were in place.

hot_rod

TomS said:

Mark and hot rod, I don't have a clue what you guys are referring to as a "dizzy" pump.

Dizzy pump. I refer to it as a dog chasing it's tail in my trainings.

It's a tough circ to find, sometimes. Odd spec, very low head high gpm

Rich_49

I agree that Load and source would be best . However we live in this world and i think it simpler for ALL to understand referred to as boiler / system . No more confusion that way .

Mark Eatherton

But, but but… What if its a Ground Source Heat pump, or an air source heat pump, or a solar thermal system, or a hydrogen fuel cell or a CHP system Rich :-) Won't the pump/water be cornfused because its not really connected to a "Boiler"? :-)

(Just kidding ya Rich…)

See you this Saturday online?

HR hit the nail on the head. Dog chasing its tail. Unnecessary waste of equipment and power, if done right. The additional head displaced by 10 feet of pipe is negligible in most cases. Better yet, do as HR shows and go low loss header, and be done with it.

I used to think that LLH's were for people that didn't know how to do P/S piping with closely spaced tees, but I've since changed my mind. They are good for the industry. They save labor, and materials and are idiot proof, and lord knows, we have our share of those to deal with in the field...

ME

Rich_49

Well , I guess we just have to educate those unknowing of the difference between a source and a load . But what about in summer when source is load and load is source , Oh my ?!
I regularly use separation , even now on cast iron boilers doing everything possible to lessen stack losses .

In the immortal words of Mr. Ed " a source is a source , of course , of course " LMAO

everyone will be really confused when there are multiple sources if Colin and James have their way huh ?

SWEI

hot rod said:

TomS said:

Mark and hot rod, I don't have a clue what you guys are referring to as a "dizzy" pump.

Dizzy pump. I refer to it as a dog chasing it's tail in my trainings.

It's a tough circ to find, sometimes. Odd spec, very low head high gpm

Series 100, 0010, etc. work well for larger systems. Wish we had an ECM option with that kind of curve.

hot_rod

Kurt have you looked over the B&G offering lately? Last I checked they had some flat curve high performance circs. I'm not up to speed with all their numbers since their partnership with Laingl

SWEI

The Series 60 ECM and Series e-90 ECM both look great, but even the smallest E60 has a pretty big curve (30 ft / ~70 GPM.) Where's the go-to boiler pump for 399k fire tube mod/cons?

mars_6

Great thread gentleman, so in thinking of this from a practical standpoint if I have a sealed combustion boiler with turn down ratio with a primary secondary piping arraignment and i am in low fire am I not pumping this boiler to much with a fixed speed circulator designed for high fire? And if this is indeed the case what is the effect on the boiler performance efficiency considering that the HX wants or needs to see a specific gpm to meet that btuh output? Hmmm. thanks for any input Matt R

Steve Thompson (Taco)

You want a flat curve - no problem? Set a wet rotor ECM (Taco, GF, Wilo and Xylem) at constant pressure. That's the reason for proportional vs constant pressure.

Proportional (increasing head as flow increases vs declining head on constant speed) is for higher head system curves (systems with medium to high friction loss).

Constant is for systems with low friction loss (old gravity conversions, low friction loss boilers on a short "load" circuit and any low water velocity system.

Tim Potter

HR, why is connecting the ponpc to the LLH unaceptible ? as in example 3 in your post above,

Thanks,

Tim

hot_rod

Tim said:

HR, why is connecting the ponpc to the LLH unaceptible ? as in example 3 in your post above,

Thanks,

Tim

We don't want the dirt and debris that the separator pulls out to settle down against then rubber diaphragm in the tank. It is fine to put in a tee and arm over to the tank at the bottom, just not straight down from the dirt collection. Same for the fill valve.

mars_6

OK I have another question, In The European market almost all hydronic systems are constant circ ODR, at least that is my understanding. so that being said and understanding the European mind set twords the hydronic heating systems they install. I ask this simple question. how is it that they can maintain the efficiencies of there boilers with modulating gas controls and circulators that do not modulate with the HX on the boilers. Am I missing something?

Steve Thompson (Taco)

Mars, two years ago at ISH in Germany most (if not all) mod-con boilers we saw had circs that modulated with boiler firing rates - I assume ISH this year will prove the same.

Why not more over here you might ask? Local supply of replacement circs just to name one (if a "custom - OEM boiler circ fails in Alaska you better have access to a replacement in one heck of a hurry). Our 115 volt power requirement for another (it's 220 over there) requiring substantial electronic re-design (half the voltage, double the amps).

Then there's a payback issue - their energy is 2 to 3 times what we pay.

And finally, their EU standards regulation/enforcement stuff drives a lot of these things (we'll see similar regulations from DOE over the next 4 to 5 years).

hot_rod

mars said:

OK I have another question, In The European market almost all hydronic systems are constant circ ODR, at least that is my understanding. so that being said and understanding the European mind set twords the hydronic heating systems they install. I ask this simple question. how is it that they can maintain the efficiencies of there boilers with modulating gas controls and circulators that do not modulate with the HX on the boilers. Am I missing something?

On this I agree with Steve

And know from my job site visits in Europe they too are still working through design modifications and challenges with high efficiency equipment. I saw more than one dis-assembled mod-con boiler in mechanical room that had failed for one reason or another related to flow, fluid, or fuel.

Europe has a much larger engineering force working on these issues as they have more "numbers" and up to bats.
And they certainly don't want to see sheetmetal boxes with spinning fans replace their beloved "wet heat" ultra comfort systems.

mars_6

Got it, that all makes perfect sense. Thank you gentlemen this has been a very informative thread. Matt