Pumping away ? I must have something messed up! Help

Badger896

So new boiler install and i followed the pumping away guide to avoid pressure issues but something is not working. Piped as follows boiler, ball valve, air purge with vent on top water fill and expansion tank on bottom, inlet side of primary pump,(taco 0011) ball valve and then back to the boiler. piped as primary secondary system. two secondary loops with closely spaced tees and each have their own pump, one with another taco 0011 and the other small loop with a b&g?

So with the boiler and pumps off the static pressure of the boiler is at 12psi. turn the boiler and pumps on and the pressure climbs and climbs until it eventually pops the p/t valve at 30psi. i have eliminated the press red valve and the bypass valve by closing the system off between the p.r.v. and the boiler with a guage on the prv side the pressure maintains and does not climb until i open the valve to the system and the pressure starts climbing again.

WHAT AM I DOING WRONG???

SWEI

30 PSI

is 69.3 feet of head.  The 0011 maxes out around 31 feet.  Unless you somehow managed to pipe the two pumps in series, and even that is dicey, I'd be looking at a leaking indirect or tankless coil.

Badger896

Got a pic if it helps

this is it

Gordy

Circ orientation

Are you sure all circulators are pumping in the right direction?

Badger896

Yep

made sure they are all going in right direction.

SWEI

Grundfos pump at lower left

does that feed the indirect?  If so, try powering it down and valving off both lines.



0011 is an unusual selection for a primary loop -- what size is the boiler? 

Badger896

Circulator sizing?

Is it possible the taco 0011 circulator is oversized for the primary loop and as mentioned before the pumps are in series or something??

Badger896

Pumps

not sure what is meant by indirect (it is one circuit feeding fin tube).

the boiler is 175000.

icesailor

Pumps

I don't know what the reason is however,

Is the primary pump (011) pumping INTO the boiler or out?

The two secondary pumps are not connected the same. One is supply to return, the other is return to supply. It depends on the flow. They both should (IMO) be the same.

It is possible for any two pumps to "multiply" and cause the pressure to rise but also cause the suction/lower pressure end to allow the pressure on the PRV valve to go less than the set pressure, allowing the PRV to add water.

Unless there is a reason that you can't, flip one of the secondary circulators so they both go in the same direction off the closely spaced tee loop, and see if it improves.

Does the pressure rise if just one circulator is running? It should be running with the primary pump. Switch the running circulator. Does it add water or stop?

The few boilers that I did, I always tried to have places I could install cheap temperature/pressure gauges so I could see how the system was behaving. If there is a boiler drain connection on either side of the circulators, you can determine what is going on in the system.

IMO, if the primary pump is in backwards and not pumping into the boiler, the pressure can reduce between the boiler (with high resistance) and the PRV.

The system in the pressure isn't like an open system like a potable water system. If you understand about Hypertension in humans, it is similar. If you cut yourself, the pressure drops as you lose blood. and the heart pumps harder to keep the pressure up. If there is no loss, the heart can raise the pressure with the same amount of blood. That may be confusing. Like compressed gasses in water under pressure.

Somehow, the pumps are multiplying. You need to figure out how. Its in the locations and which directions they are pumping.

SWEI

Pumps and pipes

I see two green pumps, presumably Taco 0011's.  One is on the primary loop, the other off a set of closely spaced tees, probably feeding your baseboard.



I see one red pump, presumably a Grundfos, off a second set of closely spaced tees. What does it serve?



If all you have is one zone, it's quite likely you don't need primary/secondary piping at all.  How much pipe head does that zone have?  How much fin tube of what type?  Was a heat loss calculation done?

icesailor

Pumping Away:

I think you got confused with the concept of "Pumping Away".

It never happened to me and I don't agree with the total concept of pumping away from all boilers. These "mini-Boilers" call for the primary pump to be pumping INTO the boiler so that you don't get flow problems through the boiler. If the primary pump is pumping away, rather than into, check the installation manual and see if they don't require that pump to be pumping into the return of the boiler. Not pumping OUT of the supply. The exception to the rule of Pumping Away.

Many years of perfectly working hydronic systems are pumped with the circulators on the returns so they pump into the boiler, with the least amount of restriction. The ones that have "Issues" usually have other unrelated problems. Like oversized pumps.

I know that ME considers me a Heretic, but I have never installed a circulator on the supply but only and always on the returns with the fill into the bottom of the boiler into the coldest water. I have NEVER encountered any of the problems I see here all the time. But I sure see a lot of problems with circulators on the supply's coming directly out of boilers with air issues and the need for microbubble scrubbers. That circulator may have to be moved to the return and pumped INTO the boiler.

Badger896

Corculators

ok so ghe primary pump is pumping away from the boiler (i.e. it is on the supply of the boiler) it the leaves the pump and goes to the first set of tees and the 0011 is also pumping away into the baseboard heat and returning to the primary loop, the the next set of tees (bottom of primary loop) have a grundfoss pumping away into baseboard heat and then returning to the primary loop and returning to the inlet side of the boiler.

Badger896

Circulators

i guess i dont understand how moving the pump to the return will help, with the primary loop isnt it in effect in the return and pumping back into the boiler? the fill valve and expansion tank will ultimately end up in the same arrangement the only difference being that the supply side of the pump will see the boiler first and then the two circuits.

Will that make a difference?

SWEI

Pumping Away

from the Point of No Pressure Change is what matters.  The short version is that you pump away from the pressure tank.  The firetube heat exchanger utilized by Triangle Tube has almost no head loss -- I've attached the curves for the 175 and 250 below.



Just because they show a curve for a 0011 doesn't mean you should actually install one.  There's a funny bit of pipe detail at the upper right-hand corner of that loop I can't quite see -- is it an offset in the Z dimension with a couple of tees?



I doubt you have more than 40 feet of developed length in that primary loop.  If it's 1-1/4" copper, you're pushing at least 24 GPM and 6 FPS there.  Believe it or not, I'd probably use a 006 for that.



If I were starting from scratch, I'd dispense with the primary/secondary piping altogether, install two zone valves and use a single ECM smart circ.

Gordy

pressure reucing valve

I think Ice may be on to it. Quite possible the circ differential is making the fill valve dump into the system.......unless the make up water is off.



One other thing is x tank pressure properly set?

Badger896

z dimensio

the primary loop is 1-1/4" , there is about 20' straight pipe and (7) 90's.

do you think changing the pump to a 006 will help?

Sorry, im still learning.

SWEI

Learning

can get expensive when you are paying for the parts.  Before you start swapping them, get the system properly designed.



What is your calculated design day heat loss?



How many feet of what type of baseboard in each loop?  How are they piped?  Do the emitters in each room have any relation to the room's heat loss?

knotgrumpy

Another Pic

Can you take another picture of the piping near the inlet to your primary pump and the pressure reducing valve?

Badger896

Learning

The install was a rush (previous boiler leaking like crazy) due to the fact that it is in an assisted living house and could not go without heat. The boiler is their only source of heat. You know, never have time the first time but always have plenty the second.

knotgrumpy

PRV

Might just be the picture but it almost looks like you are feeding supply water into the vent of the pressure reducing valve.

RobG

Boiler piping

On the 175 the primary piping calls for a minimum of 1 1/4 piping, is it? As well with a boiler of that size you must have an awfully large house with ALLOT of baseboard. Is the expansion tank sized correctly? And the manual does call for the pump to be on the supply side, but the fill valve and tank should be on the return or on the secondary side. I'm still trying to grasp why you piped it with two sets of closely spaced tees. Piped that way it will ensure that the second set of tees sees lower water temps.



Rob

Badger896

Size

yes the primary piping is all 1-1/4", the boiler is in an assisted living bldg. there are probably 20 rooms or so. all with baseboard heat.

RobG

Boiler fill

Have you tried shutting off the boiler fill valve? Does the pressure rise with it closed?

Badger896

Valve

I did shut off the boiler feed and the pressure will stay at whatever psi (12+). But as soon as you turn the valve back on the pressure will continue to rise to 30psi when it opens the p/t valve. Now if the boiler and pumps are off it will fill to 12psi and stop. As soon as the pumps come on it will start its increase. I feel that the 0011 pump is dropping the inlet side below the 12psi causing the fill valve to let water in ultimately increasing the pressure but according to pumping away and the x tank placement vs fill vs pump it should not let it do that. Obviously I'm confused about what's going on.

Paul48

Description

The install definately needs work, but the only things that could cause what he has, is the auto-fill regulator, or lack of circulation, or lack of expansion capacity.

Badger896

Needs work

Not being a smart @$$ but what else did I do wrong? If I did something else blatently wrong please tell me, I'm not a hack. I was crunched for time, I know that's no excuse but I'm certainly not trying to walk away from it either. Any constructive criticism is welcome.

SWEI

Constructive criticism

requires more information, or we will just be guessing.  I'll repeat myself:



What is your calculated design day heat loss?



How many feet of what type of baseboard in each loop?  How are they

piped?  Do the size of emitters in each room have any relation to the room's

heat loss?

Ironman

Expansion Tank

There are charts and formulas for sizing the expansion tank. The main factors are the volume of water in the system, the delta T from coldest to hottest water temp and the maximum pressure differential from cold static fill to high limit cut off. You can find the formulas on this site or online.



That being said, I can almost certainly assure you that a 20 unit facility with a 175k btu boiler and high temp emitters is gonna require far larger than an x30 tank. I would guess it would take at least a 90, but doing the math is the only way to get it right. There is no way to get things right in hydronics without doing the math properly.



And, I concur that 011 circ on the primary is way too much. The fire tube heat exchanger in the T.T. Boiler has very little head loss and does not require a large circ for that size boiler. Probably a 007 or Grundfos 15-58 would be more than enough. But, do the math and check the boiler manual for the head loss at the required gpm and follow their pump sizing charts. You probably did not need p/s piping unless the second loop off of the secondary has very different temp or flow requirements than the first loop.



Neat workmanship is nice, but proper design is the foundation everything is built upon. Even on a replacement, the job is not done right without proper design. Except for doing a heat loss calc, the other design factors would not have required more than 15 minutes time if you know the formulas and/or follow the charts in the manual.



Please, we want you to excel in this trade. So, take some time to learn the math and how to size and design things.

Badger896

More info needed

My boss did the heat loss, but I will find out. I will also look at fin tube in each room. I know that the piping in the rooms has a primary run under the fin tube and each room has its own thermostatic valve tee'd into the primary run. Out of the valve it goes through the fin tube. The piping is original from the 60's or so, it appears that some rooms share a return and others do not, part of the problem is the majority of the piping is in the walls and finished ceilings so it's hard to tell just exactly how much is there and exactly where all of it goes.

What do you mean by "do the size if emitters in each room have anything to do with the rooms heat loss"? If I understand then yes, the corner rooms have twice as much fin tube as the internal rooms do.

Badger896

X tank size

So how does an undersized expansion tank affect the pressure on a system? I don't disagree with you at all, that's not the first time I heard it. I understand that if the water in the system when heated has nowhere to go it will increase in pressure. But the pressure climbs up with very little change in temp, and only when the pumps are turned on. Oh and all three pumps always run continuosly. I totally agree that proper design is crucial. I will look for the calcs and charts.

Thank you

Paul48

In General

I was refering to the things that had already been touched on in others posts.Beyond design considerations, look at the I&O manual, and see how much you varied. They call for the primary circ to pump at the boiler for a reason. It prevents it from cavitating. Is that expansion tank mounted hanging off the side of the pipe, unsupported? Is there any provisions for power purging those loops?

Ironman

011 Circ

The 011 circ is probably throwing too much pressure into the heat exchanger also.



The expansion tank will NOT "absorb" any pressure created by the circ. That's why it's connection to the system is called the Point Of No Pressure Change (PONPC). The tank will only receive the expanded volume of water that's created by heating it. So, whatever pressure differential the 011 is creating will effect the relief valve.



It may be a combination of BOTH an under-sized x tank and an over-sized circ on the primary.



If you have a 007 or 15-58 on hand, it would be relatively easy to swap out the primary circ and see how that effects your situation.



Regarding the X tank: you will not hurt the system by over-sizing it and you can hook multiple ones together at the same point for more capacity. Just make sure the air pressure on each bladder is the same with no pressure on the water side.

SWEI

Sizing emitters

I make a spreadsheet listing each room with it's heat loss and installed emitter capacity.  From that, we can determine what the required system water temp is and also if there are rooms which are likely to become too cold or too hot when the system is running on ODR.  For series baseboard, a bit of math is added to the spreadsheet to allow for temp drop along the loop.  It's unfortunately rare to find those sized correctly, at least in our neck of the woods.  This is a key component of our initial analysis, and from it come recommendations which are reviewed with the owner(s) before a contract is even offered, much less signed.  If recommended repairs or improvements are declined, waiver language gets added to the contract to protect us.

SWEI

Expansion tank sizing

There's a bunch of math, but http://www.amtrol.com/support/extrol_com_sizing.html makes it easy.

Badger896

Math

I did find that before but once again I'm just guessing at the total volume due to the fact I can't see all the piping.

On another note, from my math you were right in approx 40' equiv in pipe and the head loss should be around 1.5 to 2 for 8gpm but if I'm reading the chart right I'm at like 8fps with 29 or 30 gpm. So if like some of the other posts also suggest in order to get the velocity down with the gpm vs head loss I should move to the 006 pump? Along with possibly increasing the x tank size.

I appreciate the help I have rcvd

knotgrumpy

Are you able

To take another picture closer to the primary pump/prv/tank?



Thanks,



Mark

knotgrumpy

Accumulative pressure

From one of my favorite Dan Holohan stories:



“Just one of those things,” I said. And we poked around the boiler room some more. And that’s when we spotted the bypass valve. It was up high, between the main supply and return lines. It was just a motorized two-way valve, and it had two operational choices: open or closed. We traced the wiring over to a pressure-operated switch in the main supply line. When the pressure got to a certain point, the two-way valve would open, allowing the water to flow back to the boilers.



“That’s there for when the thermostatic radiator valves are closed,” I said. “The water needs a place to go because the TRVs can’t talk to the pumps. The pump backs up on its performance curve. The pressure switch senses it, and opens the valve. The pumps now have access to the butt end of the boilers.”

 

“And the TRVs are going to be closed more often in the spring and the fall then they are in the dead of winter,” Joe said.

 

“Right. And when that two-way valve opens, eighty feet of pump head, or about thirty-five psi, hits the boilers.”



“Which are already seeing twenty-eight pounds of static head pressure,” Joe said.



“And that makes the total pressure sixty-three psi.”



“On fifty-psi relief valves!” Joe said, and he smiled. Problem solved.



It’s not just one of those things. Not at all. It never is when it’s mechanical. There’s always a reason for things." 

 

http://www.heatinghelp.com/article/364/Boilers/142/Boiler-Failure-after-Two-Years



It's a great story starting with 20 blown boilers sitting in a parking lot.

SWEI

Boiler circ on P/S loop

If I were starting from scratch, I would specify a 006, but be prepared to swap that for a 005 if it proved necessary (translation: if boiler tripped off on high ∆T.)   If I did not have either of those on the shelf, a 007 would be a far better choice than a 0011 (and certainly useable until I had the correct circ in hand.)

Badger896

Accumulative pressure

So thats what doesnt make any sense to me, why when the valve opens does the head loss go up? why doesnt it go down, you have less restriction in the piping right? so why would the pressure on the boiler increase. according to the charts as the head loss increases the gpm decreases, so if you have less head loss and your psi is about 43% of your head loss then why when you decrease the head loss would your pressure increase??

Badger896

Accumulative pressure

Ok, please correct me if I am in error, so let's say that the 0011 can pump at 31ft hd which is approx 13 psi, is this the pressure differential across the pump that it will create regardless of where the pump is on its performance curve?

Paul48

Wild Goose Chase

Is this climbing to 30 psi, a slow process? Is the whole system coming up to temp when this climbing starts?