efm 520 bypass loop

efm 520 bypass loop

PostBy: ted On: Mon Nov 19, 2007 1:18 am

well I have a pile of copper pipe and fittings and have been reading for two weeks and am still confused...
circulators before or after....
bypass loop with balancing valves...
I have efm 520 directions diagram they show balancing valve after tee from bypassloop is this misprinted what would valve do here?
All the new info shows circulators after supply i read some posts from early this year and souns like circuators should stay on feed side?
Any help or comments would be apreciated
Until I start soldering I am hand firing the old foxfire wood coal unit
ted
 
Stove/Furnace Make: efm new /foxfire HAND FEED old
Stove/Furnace Model: 520 BOILER

Re: efm 520 bypass loop

PostBy: LsFarm On: Mon Nov 19, 2007 9:22 am

Hello Ted. My preference for mounting the circulator pump is to put it on the inlet side of the boiler. This is 'old school'. But since you are installing an 'old school' boiler this fits... right?? I installed the circulator pump on the boiler inlet for my recent AxemanAnderson boiler install.

The theory for pulling the water out of the boiler is that if there is a lot of gasses and oxygen dissolved in the water, the slight suction of the pump may create bubbles, and pull the gasses out of solution, where the bubbles can be trapped in an expansion tank or similar device..

Well, I don't like the sound of hot spots in a boiler making steam and bubbles, and this is not good for the boiler either, that 'hot spot' is just that.. really hot, and it won't last as long as it would if it was kept cool by water circulation. Just ask the EFM boiler rebuilders if they would want a used boiler that made steam or hot water for their own..

As for the balance loop and bypass valve, I can't comment, I don't have any experience with either. If you could scan that page from your directions, and post it here, that would help.

Greg L.

.
LsFarm
 
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Re: efm 520 bypass loop

PostBy: e.alleg On: Mon Nov 19, 2007 9:52 am

The bypass loop is there for when you are heating domestic hot water and the boiler starts to get hot the water can circulate in a loop to prevent "stratification" or hot spots and without it flowing through your radiators/baseboards. I set mine up like this: Coming out of the top of the boiler is a ELL which goes to an Air Scoop, the expansion tank hangs down below it and the air valve screws on top of it. Next in line is a balancing valve TEE, one side goes to a swing check valve and then goes the radiators, the other side cuts across to the return from the radiators. The return goes into the circulator pump and back into the boiler. The other return tapping is where I have the pressure reducing fill valve and drain. I don't really think it's necessary to use both returns but I used black iron pipe and it was a pain to cut and thread so I didn't do any more than was really necessary. It can't hurt to do it the way the diagram shows, it's just some extra work. You can use gate valves as "balancing" valves, they are basically the same thing. I wouldn't use ball valves as they are meant to be all the way open or all the way shut (or so I've been told). I would mount the circulator as close as possible to the boiler.
e.alleg
 
Stove/Furnace Make: EFM
Stove/Furnace Model: 520


Re: efm 520 bypass loop

PostBy: Yanche On: Mon Nov 19, 2007 10:17 am

No matter what your old plumbing manuals and manufactures instructions show your boiler should be plumbed with the circulator on the supply line. There are many reasons, but suffice it to say, it helps remove and keep the dissolved gases out of your boiler water. Look at the attached sketch for a piping schematic. Ignore the oil boiler label, it applies to any type of boiler and any number of zones. The essential components are the diaphragm type expansion tank, air separator, circulator pump(s) and valve A. One very important principle to understand is the the concept of no pressure change. That's the job of the expansion tank. It's filled with 12 psi air on the air side of the diaphragm before it's installed. Your automatic water fill valve will also be set to 12 psi, so the pressure at the expansion tank will always be 12 psi independent of what's happening in the rest of the system.

Dissolved gases in the boiler water are bad, especially if it's oxygen. The oxygen is what promotes corrosion. The oxygen comes from trapped air in you boiler water and you need to get it out or neutralize it. Gases will come out of water whenever the water is the hot and the pressure is low. The hottest water is at the top of the boiler. By putting the circulator on the supply side you make the lowest pressure on the hot supply side of the boiler. The best combination hot and low pressure. There should be a horizontal supply line of at least 24 inches length coming out of the boiler. As the gases come out of the water they will travel to the top of this pipe and on to the air separator. There the scoop part of the air separator will divert the air to the auto vent and out of your system.

Note valve "A" and the location of the hose drain valve. The locations are important. Consider the initial water fill of the system. Air travels to the top of a system and it's sometime difficult to get it out. This piping makes it easy. Close valve A and open the hose drain valve. Pumps are off and assume a single zone. Water enters system from the fill valve regulator and travels around coming out the hose drain. If you pipe a full water pressure fill only line around your fill valve regulator you can apply full house water pressure to the system. This will force water and air out of the system just like it does in your garden hose. Just let it run until there is no longer bubbles coming out. Now close the water fill regulator bypass valve. This drops the filling to a trickle and then close valve "A". Presto the system is filled with no air. Neat. Note flow direction is such that flow checks will open when filling. If you have zones do one at at time. Start with the highest one and close the isolation valves to the others. Then open each in turn.

Now some will argue it makes no difference where the circulator pump is. This is true as far as water circulation is concerned. But consider this. If the pump is on the return side it locally increases the pressure on the water forcing any air into the water, just what you don't want. And you are doing it where the water is the hottest, at the boiler, countering the effect of the hot water wanting to liberate the trapped gases. Also by increasing the boiler's pressure you reducing the margin on the trip point of the pressure relief valve. Putting the circulator on the supply side increases this margin. Many decades ago circulator pumps, particularly the shafts seals had limited high temperature life times. It is believe this is why it was recommended to install the circulator on the cooler return side. Seals and the motors are much improved today and this in no longer a valid argument.
Attachments
Basic_Oil_Boiler.pdf
(59.91 KiB) Downloaded 145 times
Select:BBcode: [nepafile=1695]Basic_Oil_Boiler.pdf[/nepafile]
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

Re: efm 520 bypass loop

PostBy: LsFarm On: Mon Nov 19, 2007 11:26 am

And the circulator pump debate goes on... :D :) :lol:

When I called on an EFM rebuilder, he was selling a big EFM 900 model. His sales pitch to me include the fact that the boiler had been in a hot water system not a steam system.. He said that making steam was tough on the steel in the boiler..

I do understand the theory of pulling on the water to open up bubbles of steam and pulling oxygen out of solution in the water. But... My AA boiler was plumbed with the the pump pushing water into the boiler, and it was like that since 1950. That's 57 years. The inside of the boiler looked NEW... That's good enough for me...

Before I pressureized my AA boiler, I had some steam and bubbles forming, the piping would jerk and flex with the bubble formation, This is not good.... So I do everything I can to keep pressure on the boiler's water especially over the various hot spots... And I run a water/glycol mix in my boilers to reduce possible corrosion and a possible freeze-up. It's in an outbuilding, not in the house.

I know this is not the way that plumbing is taught today, but it is the way that boilers have been plumbed for more than half a century... I don't hear of many boilers rotting out from the inside, unless they have a leak and constant fresh oxygenated water is added.

Greg L

.
LsFarm
 
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Re: efm 520 bypass loop

PostBy: U235a4 On: Mon Nov 19, 2007 11:52 am

A variety of options are available when
deciding how to pump water through a system.
However, pumping away is the best
choice. There are numerous compelling
reasons to “pump away,” including
improving system performance, and reducing
contractor callbacks.
1) When you pump away from
the compression tank (steel or
diaphragm), the circulator’s
pressure differential is added to
the system’s static fill pressure.
Whenever the circulator is located so that
it is pumping away from “the point of no
pressure change,” the pressure is increased
throughout the entire piping system. This
improves the operation of any high vents
that may be present in the system. It also
prevents any high temperature water from
flashing into steam.
2) When you pump away, you drive
any air bubbles that are out in
the system back into solution. Air
(which consists of oxygen, nitrogen and
hydrogen) has to follow the basic gas laws.
One of those laws states that the more you
compress a gas, the more a liquid will be
able to absorb it. By increasing the system’s
pressure with the circulator, any air
bubbles exposed to this pressure increase
will be driven back into the water. The
water will then carry the air back to the
boiler water where it will be heated, and
the air will be released from the water for
efficient separation by an air separator.
The airless system will operate much quieter
as well. The sloshing and gurgling
noises that awake many homeowners will
be gone.
3) When you pump away, the circulator’s
pressure differential will
not affect the boiler’s relief valve
setting or the pressure reducing
valve setting. By locating the circulator
on the supply, pumping away from the
compression tank, its pressure differential
will be absorbed by the system and not
directed at the relief valve. The pressurereducing
valve should be piped into the
line that connects the compression tank to
the system. Piped in this manner, the circulator
will not be able to “trick” the PRV
with any inaccurate system pressures.
4) When you pump away, you
prevent the pump from experiencing
cavitation and other
pumping problems. By locating the
circulator so that it pumps away from “the
point of no pressure
change”
(PNPC), the pressure
on the suction
side of the circulator
will not
change. If the
pressure drop
between the PNPC
and the pump is
small, pressure
will remain at
whatever the system
fill pressure is
at the circulator.
This helps prevent
the water from
flashing into vapor inside the circulator’s
volute. Once the water flashes, very unstable
pump operation, mechanical seal
failures, and eventually, bearing problems
occur.
5) When you pump away, you
will save yourself time, money
and expensive callbacks. By
installing circulators on the supply, air will
no longer be a problem. Any air bubbles out
in the system will be driven into solution and
brought back to the boiler room. You will
not have to bleed the individual radiators. In
addition, the system will operate quieter,
transfer heat more efficiently, lower energy
costs, and make your customers happy while
reducing wasteful callbacks!
Now that you know the reasons for—and
benefits of—pumping away from the supply,
you may be interested in knowing why
it is called “the point of no pressure change.”
Because:
 Air in a compression tank (steel or
diaphragm) has to follow the basic gas laws;
a change in air pressure must be accompanied
by a change in air volume. (To change
the pressure, you must squeeze or expand
the gas.)
 A change in the air volume in the tank
must be accompanied by a change of water
volume within the tank. (The
only ways to change air volume
are to add/remove water
from the tank, or to
expand/contract the water by
heating/cooling it.)
 A change of water volume
within the tank must be
accompanied by a change of
water volume in the system.
(The only ways to change the
water volume in the tank is to
add water to the system, drain
water out of the system, or let it
expand/contract with changes
in temperature.)
 Since water is incompressible, pump
operation cannot increase or decrease system
water volume. (Simply turning on the
pump does not change the water volume in
the system.)
Therefore:
 Pump operation cannot change tank
pressure!
 Since tank pressures cannot change due
to pump operation; the junction of the compression
tank with the system must be a
point of no pressure change regardless of
whether or not the pump operates!
If you have any hydronic system
questions or problems, contact your
local Bell & Gossett representative
or “Ask Red” on our web site at
http://www.bellgossett.com.
Volume 8 Issue 1 http://www.bellgossett.com January 2001
Bell & CounterPointTM
Gossett
Five Good Reasons to Pump Away!
Typical three-zone system.
U235a4
 
Stove/Furnace Make: 1958 Axeman-Anderson
Stove/Furnace Model: 260M

Re: efm 520 bypass loop

PostBy: e.alleg On: Mon Nov 19, 2007 9:58 pm

I hate to say it but plumbers that make profit on changing circulator pump cartridges like to pump away. A standard installation will include expensive circulator pump isolation flanges and they put the pump on the hot side. I think that when the pump is circulating the coolest water it will last a lot longer than circulating the hottest water in the system. I didn't make this up myself, plumbers thought this 100 years ago. Black iron pipe lasts longer than anything else as well but you don't see plumbers using that either.
e.alleg
 
Stove/Furnace Make: EFM
Stove/Furnace Model: 520

Re: efm 520 bypass loop

PostBy: Yanche On: Mon Nov 19, 2007 10:04 pm

Greg makes some interesting empirical observations, but his data set is too small to make any conclusions. Water quality varies widely. For system reliability it's not only how well the boiler holds up but also all the piping and other components. The water where your A-A lived for 57 years had to be good, especially for the expansion tank to have survived. It looked to match the age of the boiler. The boiler and pump manufactures are all now recommending supply side pumping. Their data set of problems would be much larger and they had to have a reason to recommend a change from past practice. I place my bets on practices, which are supported by science and physics principles. My circulators go on the supply side. Your mileage my vary. :-)
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

Re: efm 520 bypass loop

PostBy: ted On: Mon Nov 19, 2007 10:46 pm

hey guys thanks for all of the information, this topic is like talking politics or religion at thanksgiving with your inlaws,, everyone has the right opinion......
Yanche thanks for the diagram that you posted.. if I were to draw in a bypass loop it could go after valve a down to the return leg, what type of valves do you recomend for balanceing valve on the bypass loop or should they just be isolation valves to isolate the heating zones during summer months all three or four of them...
ted
 
Stove/Furnace Make: efm new /foxfire HAND FEED old
Stove/Furnace Model: 520 BOILER

Re: efm 520 bypass loop

PostBy: ted On: Mon Nov 19, 2007 11:48 pm

LsFarm wrote:Hello Ted. My preference for mounting the circulator pump is to put it on the inlet side of the boiler. This is 'old school'. But since you are installing an 'old school' boiler this fits... right?? I installed the circulator pump on the boiler inlet for my recent AxemanAnderson boiler install.

The theory for pulling the water out of the boiler is that if there is a lot of gasses and oxygen dissolved in the water, the slight suction of the pump may create bubbles, and pull the gasses out of solution, where the bubbles can be trapped in an expansion tank or similar device..

Well, I don't like the sound of hot spots in a boiler making steam and bubbles, and this is not good for the boiler either, that 'hot spot' is just that.. really hot, and it won't last as long as it would if it was kept cool by water circulation. Just ask the EFM boiler rebuilders if they would want a used boiler that made steam or hot water for their own..

As for the balance loop and bypass valve, I can't comment, I don't have any experience with either. If you could scan that page from your directions, and post it here, that would help.

Greg L.

.
thanks greg for your reply i am trying to attach the piping diagram to this so here goes[
DF520%20Manual.pdf coal boiler.pdf piping.pdf
its page 12 if the whole file attaches, I am a carpenter working on my computer skills....
(832.07 KiB) Downloaded 88 times
Select:BBcode: [nepafile=1705]DF520%20Manual.pdf coal boiler.pdf piping.pdf[/nepafile]
ted
 
Stove/Furnace Make: efm new /foxfire HAND FEED old
Stove/Furnace Model: 520 BOILER

Re: efm 520 bypass loop

PostBy: Yanche On: Mon Nov 19, 2007 11:55 pm

ted wrote:Yanche thanks for the diagram that you posted.. if I were to draw in a bypass loop it could go after valve a down to the return leg, what type of valves do you recomend for balanceing valve on the bypass loop or should they just be isolation valves to isolate the heating zones during summer months all three or four of them...
I'd use a ball valve.
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

Re: efm 520 bypass loop

PostBy: U235a4 On: Tue Nov 20, 2007 11:07 am

Well Greg and I didn't get to finish beating each other up on this over the phone on this topic but here are my observations. I'll upload som drawing to better explain this.

my boiler, when the pumps were on the return side the couplers would rattle and sometime the water would goto steam in the rads closest to the pumps.

on my parents boiler which is a oil boiler they for years have had air problems, uneven heating problems, and pipes that would rattle. which for one I contribute to the taco air scoop which in my opinion are junk or any air scoop for that matter and the other part was the pumps being on the return side. We moved the pumps to the supply side which are taco 007-f5 and that solved all the problems. by the way we also changed to a spirovent air remover..

on my grandfathers oil boiler air problems, pumps are series 100 BG and we moved them to the supply side and air problems haven't returned taco air scoop stayed inplace so see which fixed my parents air problems scoop or pump placement.
U235a4
 
Stove/Furnace Make: 1958 Axeman-Anderson
Stove/Furnace Model: 260M

Re: efm 520 bypass loop

PostBy: ted On: Wed Nov 21, 2007 3:05 am

hi guys just want to say thanks for the information that you all gave me, I did some more research and downloaded all of the forum info to my brain and started cutting and soldering copper today after work...
If t
PB201562.JPG
(51.39 KiB) Viewed 218 times
View: New PagePopup • Select:BBCode
todays progress
[nepathumb]1720[/nepathumb]
his photo will upload you all can see my progress, i have mounted the circulators on the supply side and will see how it works, the science behind it makes sense to me.
Thankyou all for this great forum and your input
Have a happy thanksgiving
Ted
ted
 
Stove/Furnace Make: efm new /foxfire HAND FEED old
Stove/Furnace Model: 520 BOILER

Re: efm 520 bypass loop

PostBy: U235a4 On: Wed Nov 21, 2007 9:25 am

ted wrote:hi guys just want to say thanks for the information that you all gave me, I did some more research and downloaded all of the forum info to my brain and started cutting and soldering copper today after work...
If t
PB201562.JPG
his photo will upload you all can see my progress, i have mounted the circulators on the supply side and will see how it works, the science behind it makes sense to me.
Thankyou all for this great forum and your input
Have a happy thanksgiving
Ted



Looks good....
U235a4
 
Stove/Furnace Make: 1958 Axeman-Anderson
Stove/Furnace Model: 260M

Re: efm 520 bypass loop

PostBy: Yanche On: Wed Nov 21, 2007 10:07 am

ted wrote:hi guys just want to say thanks for the information that you all gave me, I did some more research and downloaded all of the forum info to my brain and started cutting and soldering copper today after work...
If this photo will upload you all can see my progress, i have mounted the circulators on the supply side and will see how it works, the science behind it makes sense to me.
Thankyou all for this great forum and your input
Have a happy thanksgiving
Ted
I concur, it looks good. Consider a ball valve at the expansion tank. Allows you to replace a failed tank without having to drain the system. If you use a valve with a drain port and place the drain port towards the expansion tank so you can readjust the air pressure in the tank without having to take it off. You close the valve, open the port and change the air pressure. If it's a job that will be inspected you may have to remove the valve handle and/or label it "service only, do not close". Sometimes you have to bend the valve handle to have it clear the tank depending on how long a connecting nipple you use.
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea