We have a rather old McDonnell & Miller oil-burning boiler which serves a
six-unit apartment building.

At some point in the distant past I was told that the boiler needed to be
flushed for two minutes once a week. I was told that the system should NOT
be running when I started this operation. To flush while the burner was on
might crack the boiler, I was told. Knowing nothing abut the system, I
accepted this without question.

Recently a plumber told me it was the other way around: The burner should be
ON when I do the flushing. I should start the flushing slowly until the
water became warm, then open it fully for 30 seconds or so. Then I should
repeat twice.

Which of this advice should I follow? I can't find any help in the manual.

You must have a steam boiler and what they are describing is called blowing
it down. The burner does not need to be on for this. You are flushing
debris from the system and making sure your makeup water valve and floats
are working properly. Please have someone come out and check your system
and make sure it is in good shape and show you all the things you are to
check.

TAB Dude

"Ray" wrote in message
news:z98zf.12138$6L1.5796@trnddc02...
We have a rather old McDonnell & Miller oil-burning boiler which serves a
six-unit apartment building.

At some point in the distant past I was told that the boiler needed to be
flushed for two minutes once a week. I was told that the system should NOT
be running when I started this operation. To flush while the burner was on
might crack the boiler, I was told. Knowing nothing abut the system, I
accepted this without question.

Recently a plumber told me it was the other way around: The burner should
be ON when I do the flushing. I should start the flushing slowly until the
water became warm, then open it fully for 30 seconds or so. Then I should
repeat twice.

Which of this advice should I follow? I can't find any help in the manual.

Second guy was closer to right. You need some pressure in the boiler when
doing it so as to flush the minerals and solids. You don't want to blow it
down so far as to greatly reduce the water level. Best way is to slowly
open the valve, close it, then repeat it twice more. This stirs up the
sediment so it can be flushed. Never take the water level down more than
1/2" at a time

It can be done with the boiler firing if you don't take it down too far.
This is done on every commercial/industrial high pressure boiler on every
shift.

Thanks -- will proceed accordingly.

"Edwin Pawlowski" wrote in message
news:Gldzf.7846$8r1.6035@trndny01...

"Ray" wrote in message
news:z98zf.12138$6L1.5796@trnddc02...
We have a rather old McDonnell & Miller oil-burning boiler which serves a
six-unit apartment building.

At some point in the distant past I was told that the boiler needed to be
flushed for two minutes once a week. I was told that the system should
NOT be running when I started this operation. To flush while the burner
was on might crack the boiler, I was told. Knowing nothing abut the
system, I accepted this without question.

Recently a plumber told me it was the other way around: The burner should
be ON when I do the flushing. I should start the flushing slowly until
the water became warm, then open it fully for 30 seconds or so. Then I
should repeat twice.

Which of this advice should I follow? I can't find any help in the
manual.

Second guy was closer to right. You need some pressure in the boiler when
doing it so as to flush the minerals and solids. You don't want to blow
it down so far as to greatly reduce the water level. Best way is to
slowly open the valve, close it, then repeat it twice more. This stirs up
the sediment so it can be flushed. Never take the water level down more
than 1/2" at a time

It can be done with the boiler firing if you don't take it down too far.
This is done on every commercial/industrial high pressure boiler on every
shift.

On Tue, 17 Jan 2006 17:39:54 GMT, "TAB Dude" wrote:

You must have a steam boiler and what they are describing is called blowing
it down. The burner does not need to be on for this. You are flushing
debris from the system and making sure your makeup water valve and floats
are working properly. Please have someone come out and check your system
and make sure it is in good shape and show you all the things you are to
check.

TAB Dude

Tab,

FOOTNOTE: In blowing down the float assembly the burner should really
be ON thus verifing the burner circuit will open in a low water
condition.
P.S. FOOTNOTE As soon as the feed water makes and the burner circuit
breaks= blowdown valve goes to closed. * * If the feedwater does not
break and burner contacts make in a timely fashion and closely
tracking with the water gauge glass, this indicates the lower
equilizer line has a blockage and needs to be investigated ASAP.

You probably know this, however I thought I'd throw it out here for
others reading, too.

-zero

What you say is true but I do not say so to homeowners. If the burner does
not shut down many will not have the knowledge to know that there is a
problem and protect the boiler. If the home owner at least does the routine
basic maintenance they will have done more for their boiler than 90% the
people out there.

TAB Dude



"zero" wrote in message
...
On Tue, 17 Jan 2006 17:39:54 GMT, "TAB Dude" wrote:

You must have a steam boiler and what they are describing is called
blowing
it down. The burner does not need to be on for this. You are flushing
debris from the system and making sure your makeup water valve and floats
are working properly. Please have someone come out and check your system
and make sure it is in good shape and show you all the things you are to
check.

TAB Dude

Tab,

FOOTNOTE: In blowing down the float assembly the burner should really
be ON thus verifing the burner circuit will open in a low water
condition.
P.S. FOOTNOTE As soon as the feed water makes and the burner circuit
breaks= blowdown valve goes to closed. * * If the feedwater does not
break and burner contacts make in a timely fashion and closely
tracking with the water gauge glass, this indicates the lower
equilizer line has a blockage and needs to be investigated ASAP.

You probably know this, however I thought I'd throw it out here for
others reading, too.

-zero