Demonstrating the PONMIPC...

Mark Eatherton

For those who don't understand why pumping away from the expansion tank is important, here is a video showing exactly what the difference is. Thanks to Dave Holdorf of Taco for providing me with the link. Enjoy, and feel free to comment.

https://www.youtube.com/watch?v=tZRuqiQkukE&app=desktop

ME

Mark Eatherton

What Bill DIDN'T demonstrate, is how the auto air vent acts as a vacuum relief, and actually introduces excess air into the system. He does not that the pressure at the point is sub atmospheric, but doesn't open the vent. "It's just a pressure differential machine, and it doesn't care if it creates positive pressure or negative pressure"

ME

Mark Eatherton

Microbubble resorber demo...

https://www.youtube.com/watch?v=W2ZxR7MM3Y0

ME

icy78

Thank you Mark for posting that great demo. I would also like to see a demonstration with primary secondary and how the closely spaced tees also act as a point of no pressure change ? Am I correct in that? Would it act the same way?

RayWohlfarth

Mark Thanks for posting That was one of the best visual lessons I have seen.
Ray

unclejohn

Yep. Nothing like seeing it.

Mark Eatherton

Icy, the closely spaced tees are not a PONMIPC per se. Their function is to keep two pumps from "seeing" each other and having influence on each other, when you don't want or need it.

But do know, that ALL pump MUST pump away from the PONMIPC if they are expected to produce positive pressure changes. So if the expansion tank is on the load distribution loop, then the boiler pump MUST pump away from the common connection to that loop in order to produce all positive pressure.

ME

EBEBRATT-Ed

Great video! Visually it is good to see the proof of what we understand.

We get a lot of homeowners here who will think they all have to immediately change there expansion tanks from pumping toward to pumping away. is the change better? Yes. should it be done during a boiler change or repiping? Yes

Does it mean every old installation is wrong or won't work properly? No.

Depends on the system pressure drop

Gordy

I like it! I still like the idea of clear acrylic piping to observe air removal, and how sub atmospheric system pressure can draw air in through vents etc. when not pumping away.

Harvey Ramer

I would bet my house and everything i own, that there are still plumbers out there who, after seeing the video, would scoff at it and say there way is better.

Mark Eatherton

My grandpa did it this way, and my dad did it this way, and by golly, I'm going to continue to do it this way. "Jeez, your family has been doing it WRONG for 3 generations! Congratulations!" Nothing like a family legacy :-)

ME

Solid_Fuel_Man

@Harvey Ramer @Mark Eatherton I see that ALL the time with wood burners. I'm sorry, but you've been doing it wrong for 50 years, not trying to be a know it all, but people smarter than I have proven it.

Early in my career I was led to believe putting the circulator on the return was best for wood if it boiled over. which is actually probably the worst place to put a circulator pumping towards TPONPC. Superheated water anyone?

hot_rod

Pumping on the return is fine, in fact required on most mod cons. On any system it keeps the circulator in the cooler fluid.

But of course the expansion connection needs to be at the circulator inlet, regardless of supply or return pump location.

I think the confusion is that the expansion tank is always at the air purger, which should always be at the hottest point in the piping, the boiler outlet, or chiller inlet.

No reason not to split up the expansion and air eliminator.

Mark Eatherton

Solid_Fuel_Man said:

@Harvey Ramer @Mark Eatherton I see that ALL the time with wood burners. I'm sorry, but you've been doing it wrong for 50 years, not trying to be a know it all, but people smarter than I have proven it.



Early in my career I was led to believe putting the circulator on the return was best for wood if it boiled over. which is actually probably the worst place to put a circulator pumping towards TPONPC. Superheated water anyone?

And then theres the need for net positive suction head...(NPSH) Difficult, if not impossible to achieve if the connections to the WB are high and low. Having the pump pumping away from the WB will have the pump high in relationship to the standing water column, and the pump probably won't have adequate NPSH to guarantee it will perform as chartered.

Suddenly, NPSH takes on a new meaning, that being Not Pumping So Hot...

Choices and decisions everywhere...

ME

hot_rod

But we need to differential the difference between open and closed wood boiler systems. On open systems the PONPC is at the level of water in the boiler.

In closed pressurized it is the exp tank connection. Either can boiler or flash under the right temperature, pressure conditions.

Really complicated is determining the PONPC on the push/ pull GEO pump stations

Harvey Ramer

hot rod said:

But we need to differential the difference between open and closed wood boiler systems. On open systems the PONPC is at the level of water in the boiler.

In closed pressurized it is the exp tank connection. Either can boiler or flash under the right temperature, pressure conditions.

Really complicated is determining the PONPC on the push/ pull GEO pump stations

Most closed loop Geo runs about 40 to 60 psi. At those pressures in the top of the system expansion tank location and pump placement are less critical.

There are a lot of variations however. One that is pure insanity is the atmospheric expansion tank flow centers. They have a 4" diameter vertical insulated cylinder with a loose fitting cap at the top. The return from the ground loop enters the top side of the cylinder. There is a pipe coming out of the bottom side that turns upward and has 2 pumps in series (flange to flange) that pump through the geo unit and then back into the ground loop. The first pump has, at best, 18"wc pressure on the suction side when it is not running. Guess what happens when it turns on.

Mark Eatherton

hot rod said:

But we need to differential the difference between open and closed wood boiler systems. On open systems the PONPC is at the level of water in the boiler.

In closed pressurized it is the exp tank connection. Either can boiler or flash under the right temperature, pressure conditions.

Really complicated is determining the PONPC on the push/ pull GEO pump stations

You're right Bob. I should have been more clear in my explanation. I was presuming an fully open WB system. That is all I've ever worked on.

I've seen people do a barometric loop, keeping the pumps as low as possible, and they seem to work, but I suspect the NET is less than ideal due to friction drop of piping, fittings,wye strainers etc.

And I'm just guessing Harvey, but cavitation?

ME

leonz

Mark Eatherton said:

hot rod said:

But we need to differential the difference between open and closed wood boiler systems. On open systems the PONPC is at the level of water in the boiler.

In closed pressurized it is the exp tank connection. Either can boiler or flash under the right temperature, pressure conditions.

Really complicated is determining the PONPC on the push/ pull GEO pump stations

You're right Bob. I should have been more clear in my explanation. I was presuming an fully open WB system. That is all I've ever worked on.

I've seen people do a barometric loop, keeping the pumps as low as possible, and they seem to work, but I suspect the NET is less than ideal due to friction drop of piping, fittings,wye strainers etc.

And I'm just guessing Harvey, but cavitation?

ME

=====================================================

Hello Mark, hello hot rod,

Thanks for uploading the the video Mark and thank you Hot Rod for pointing out the PONPC location in open system forest eaters(water stoves/un-pressurized outdoor wood boilers(UOWB).

I hope that there is also a video somewhere that also describes the use of a steel expansion tank as well which in turn will also show the viewer how much easier a steel expansion tank is incorporate in a closed heating system in my opinion. I certainly do not miss crawling around on my knees to bleed my baseboard-which I absolutely hate anyway after reading four of the books Dan Holohan has written).

If not, I would be glad to be the person to do one if someone would be willing to come by as I have a dual fuel coal stoker boiler in which I use kerosene as a back up fuel and a 15 gallon B+G steel expansion tank with an airtrol vlavew and a three speed B+G NRF-25 circulator without an internal check valve.

I have 225 feet of baseboard in a single loop with the heating loop being my dump zone as well and I operate at very low pressures when heating my home.

My flat grate anthracite coal stoker boiler operates with a hold fire timer assuring the coal fire stays hot with the stoker operating four times every thirty minutes to maintain the fire if there is no heat call.
I operate the boiler at summer operating temperatures to provide the heat and hot water I need for my home which was an old one room school house.

The underfed bituminous and anthracite coal stokers do not have to activate the hold fire timer as often as the underfed firepot-tuyer has a large fire burning or idling in it and needs a minimal amount of time to keep the coal fire burning and also provide heat and hot water to a home or business.

I should have installed a larger steel expansion tank and may still add one as the 54+ gallons of water I have in my system being the steel tank+ heating loop+ boiler volume are a huge benefit.

STEVEusaPA

@leonz , my goal isn't to start an argument, or derail the thread, but what's with you and the steel expansion tanks? You practically crowbar it into every thread.

You can check YouTube for videos

Gordy

There is benefits to compression tanks. Longevity. However there is also draw backs. That is air being reabsorbed into the system. Yes airtrol tank fittings help, but bladder expansion tanks eliminate this since air for expansion is isolated from the system along with the size benefit of being smaller.

Mark Eatherton

@leonz,

The only consequence of an oversized expansion/compression tank is lost money, or possibly glycol if you are so inclined. There really isn't any operational advantages to an oversized expansion tank that I can think of...
Bladder tank or compression tank, doesn't matter. Undersizing will cause problems, and additional loss of money that could have been avoided had it been properly sized from the get go.

225 feet of baseboard eh... I see what your intent is (heat dump). How big is the delta T? Have to be careful to not send too cool a water back to the heat source.

ME

hot_rod

And heat loss to the space. A 12 or 15 gallon steel compression is really a big radiator hanging in the joist space.

If you have a conventional atmospheric boiler, and combustion air from outside, you could have considerable heat loss from that large tank. Ideally a plain steel tank would be insulated.

Solid_Fuel_Man

@Mark Eatherton I was referring to closed loop systems. The "wisdom" being that when the boiler was in an overheat event the circulator would see steam if it were on the supply after the expansion tank.

On open systems the boiler itself is the expansion vessel and most have supply and return near the bottom of the boiler, and I've even pumped the supply out the lower and the return into the upper to assure NPSH. I didn't think it would work but that is what was recommended (can't for the life of me remember the mfgr.) And it has been for some years now.

I'm not a huge fan of open systems in general, but it does keep things simpler when ASME would otherwise be involved.

Isn't this stuff great! I love learning!

hot_rod

Gordy said:

There is benefits to compression tanks. Longevity. However there is also draw backs. That is air being reabsorbed into the system. Yes airtrol tank fittings help, but bladder expansion tanks eliminate this since air for expansion is isolated from the system along with the size benefit of being smaller.

Those steel tanks aren't exactly cheap either. Here is an example of a 15 gallon without any of the trim. And of course an
Airtrol ™ fitting should be used, even more $$.

A #30 Extrol in m any cases would probably replace that 15 gallon , around 50 bucks, $100 for a #60. And they both have a connection nipple included.

Extrol diaphram tanks should easily last 20 years, properly sized, installed and with proper water quality. Maybe longer than the boiler they are connected to

Gordy

I’m not advocating the use of steel compression tanks in this day, and age. However you do see a lot of diaphragm x tanks not making that 20 year mark.

hot_rod

Gordy said:

I’m not advocating the use of steel compression tanks in this day, and age. However you do see a lot of diaphragm x tanks not making that 20 year mark.

I understand you are not promoting the plain steel tank, I'm just offering observations.

What you rarely see are pics of 20 year or older diaphragm tanks that are still working fine. Why would anyone post a pic of a old, troublefree tank

I'd bet by far more tanks cross that 15-20 year mark than you see or hear about.

Pics of failed tanks are more in Vogue. When you see a job with multiple failed tanks, or short lived tanks, there are usually other issues. Properly applied tanks, any tank, should not corrode or fail in a closed loop, oxygen free systems.

gerry gill

great videos Mark- i'm going to use them in our training. much thanks for posting them.

j a_2

Harvey Ramer said:

I would bet my house and everything i own, that there are still plumbers out there who, after seeing the video, would scoff at it and say there way is better. </

Plumbers??

leonz

Mark Eatherton said:

@leonz,

The only consequence of an oversized expansion/compression tank is lost money, or possibly glycol if you are so inclined. There really isn't any operational advantages to an oversized expansion tank that I can think of...
Bladder tank or compression tank, doesn't matter. Undersizing will cause problems, and additional loss of money that could have been avoided had it been properly sized from the get go.

225 feet of baseboard eh... I see what your intent is (heat dump). How big is the delta T? Have to be careful to not send too cool a water back to the heat source.

ME

=====================================================


Hello Mr. Eatherton,

About wasting money I respectfully disagree with you.
I did not waste money investing in a steel expansion tank and airtrol valve. I added 10 more gallons of thermal mass creating a system with 54+- gallons of water. If I had Installed a thirty gallon tank would have added 20 gallons of warm water to my existing system that would make it even more efficient with low operating pressures.

Knowing what I know now I would have never let the people that installed my wood and coal boiler in 1982 rip out the horizontal open to air horizontal expansion tank that was in the ceiling and install a pressurized system.

My dual fuel coal stoker is always set at summer operating temperatures being 160 high 140 low and I have very low pressures being 4-12 PSIG at the steam chest by monitoring the replacement Marshalltown 4 inch square triple gauge I have installed in the steam chest.

My Keystoker KAA-4-1 dual fuel coal stoker has an Intermatic 30 minute timer used as a hold fire timer that maintains the fire in the event that there is no heat call.

My delta T is 15 degrees on average and the cooler water enters in the coal stoker boiler sump which is in the narrow width end section of the boiler and rises from there into the steam chest which is a large rectangular tank of flowing water with no baffles(Think of an upside down capital L).

I have a vacuum gauge on the inlet side of my circulators isolation valve and a pressure gauge on the pressure side of the isolation valve.

I have a pressure and temperature gauge on the single return line to the coal stoker boiler sump.

I have my B+G NRF 25 circulator set at speed one which is 12 G.P.M.

Aside from the plumber that I will never recommend to anyone, 2 sets of bad original Hydrostat 3250 Plus controls that I replaced with a Honeywell L8124L1011 and a Mcdonnel & Miller RB122-E Low Water Cut Off and no support from the boiler maker or the dealer I bought the boiler from I burn much less coal than I did when I had a hand fed coal boiler.

I cannot thank the electrician I hired enough that rewired the system to make it operate properly.

On average I burn about 80 pounds of Anthracite coal a day with the flat grate coal stoker. If I had a traveling grate coal stoker or an undefed "Tuyer" type coal stoker I would be using less coal to heat my home and make hot water.

My thoughts anyway.

Mark Eatherton

Um that mass is not normally considered a part of the circulation system,but you know your system better than anyone else does.

Good luck with your system.

ME

Gordy

In a nut shell the only way that mass becomes part of the system is if you don't have an air trol tank fitting. If you don't then hot water, and cool compression tank water pass each other in the connecting pipe to the system via gravity.

This allows cool water which was once hot to absorb air in the compression tank. This o2 enriched water goes back out into the system. The air trol fitting helps to prevent that, and the unintended consequences of letting that o2 saturated water go back into the system.

leonz

Thank you Gordy

Mark Eatherton

Gordy said:

In a nut shell the only way that mass becomes part of the system is if you don't have an air trol tank fitting. If you don't then hot water, and cool compression tank water pass each other in the connecting pipe to the system via gravity.

This allows cool water which was once hot to absorb air in the compression tank. This o2 enriched water goes back out into the system. The air trol fitting helps to prevent that, and the unintended consequences of letting that o2 saturated water go back into the system.

And the advantage of this one pipe thermosiphon is???

No advantage to my knowledge.

ME

Gordy

Oh I’m not seeing it as an advantage. Not at all. Unless you want to preload the floor joists it’s hanging from......my intention was to explain that with out the airtrol fitting there is more of a thermosiphon effect. Which leads to higher amounts of oxygen getting into the system.