I have a residential boiler that keeps running over 30 PSI causing the
pressure relief valve to drain on the floor.

When I first examined the system, I noticed the expansion tank (with
diaphram) was completely filled with water. I replaced the expansion
tank with a new one and turned the system on. The pressure still
exceeded 30 PSI.

How do I find the source of the excessive pressure and fix it?

There is a reducing valve that says 12 PSI on the factory label. Going

into the reducing valve is a cold water supply line with a shut off
valve. It looks as if a previous repairman has backed off the adjusting

screw a few turns from the factor setting since there is the absence of

red paint on some of the threads.

I have not adjusted the reducing valve nor cleaned the strainer.

I can drain the system, get the pressure down, fill the system to about

12 PSI and then run the system:

- If I run the system at this point with the cold water supply valve
closed the system appears to stay around 18 PSI. My gut tells me I
need to keep this supply valve open when operating the system to safely

supply new water to the system if needed.

- If I run the system at this point with the supply valve open, the
pressure will go up to over 30 PSI. If I then let the system cool, it
appears that the pressure will go down to only about 18 PSI. Why
doesn't the cooled down system go back to the 12 PSI condition as when
I started it?

Should the water supply line going into the reducing valve be kept open

when normally operating the system?

Should I try to adjust the reducing valve?

Should I try to clean the strainer on the reducing valve?

Should I adjust the 12 PSI pressure on the new expansion tank?

The water temperature appears to reach about 155 degrees after an
extended period. Should I reduce the water temperature to reduce the
pressure? What's an idea residential boilder water temperature?

FYI - the house is 3 stories above ground so I need to circulate water
35 feet from the basement. Some threads lead me to calculate that I
need about 20 PSI to circulate water that high. If that's accurate,
how do I keep the pressure between 20 and 30 PSI.

Sorry for all the details and asking too many questions here but
thought they might help give one of you experts a hint as to what the
problem may be.

Any advice on solving this boiler pressure situation would be
appreciated.

it sounds like you need to replace the pressure regulator valve with
one that operates in the 20-30 pound range - rather than the current 12
pounds in order to insure water to 3 stories.

did you pressurize the expansion tank after you replaced it?

If not, you should to maximize expansion capacity.

Have you or can you validate that your gauge is correct?
If not, you should.

Since you want to have about 25 pounds of pressure, your gauge should
have about of a 50-60 pound max, so that the working range of the gauge
is in the middle.

the water that enters the system is probably cooler than the temp after
cool down. Therefore, the pressure won't drop all the way down to the
level that it reached with the cold water used in the initial fill.

at 15 greenfield, buffalo ny altitude we need 25 pounds WHEN HOT AND
CIRCULATING to get from the basement to the third floor hot water
boiler radiators. our temperature is set to max at 180 but it depends
on your system. our expansion tank has no bladder and we set it to half
water half air when cold. you must refer to installation manuals on all
parts of your system.

bob villa says:
http://www.bobvila.com/ArticleLibrar...WaterHeat.html
"With traditional baseboard heat, water leaves the boiler at
approximately 180°F to 200°F and is sent through pipes throughout the
house via a pump or circulator. The hot water enters various heating
loops and conducts heat to the pipe, or panel to which it is connected.
Once the heat has been transmitted to the surface or fins, the air
within the room is warmed principally by convection. In this system,
cold air is drawn across the warm surface, absorbs warmth as it passes
and then moves upward. Cool air from below the heating unit is
constantly being drawn into the unit as the warm air rises and flows on
to spread warmth throughout the room.

Baseboard Heat
The most common type of hot water heat in the United States is
finned-tube baseboard heat. Located close to the floor, finned-tube
emitters are usually housed in metal enclosures that have reflective
material behind them to encourage heat transfer from the fins or slats
to the air passing over them, rather than being lost via conductivity
through the cold wall behind it. The hot water pipes emerge from the
floor and run directly behind the enclosure with thin, metal slats or
fins, placed close together all along the pipe. Heat is transferred
from the water to the pipe and ultimately to each of these fins. The
fins serve as multiple heat emitters, warming the cold air from below.
Enclosures must be located at least one to two inches above the
finished floor to allow for adequate air circulation and heat transfer.

Piping
There are actually a number of different layouts for hydronic heat, but
they all serve the same principle: Hot water leaves the boiler in a
supply pipe, transmits its heat along the way, and returns to the
boiler as cooler water (typically 150°F to 170°F) , ready for
reheating and redistribution. The basic variable in the equation is how
long the hot water stays out there before returning to the heat source.
Obviously, if there are a number of registers or panels along the way,
the water will steadily lose heat, delivering most of its heat in the
first registers and imparting less warmth to those registers at the end
of the loop.

To account for this strain on the system, different piping layouts are
used and zones are incorporated to provide more even heat throughout
the home. The simplest of all piping layouts is the series or single
loop system. Here, water simply flows through the pipes, into each of
the radiators along the way, without diversion. Since the water will
have cooled about 20°F by the time it reaches the last radiator, this
last emitter is typically sized much larger to take full advantage of
the heat remaining in the water. A one-pipe system is slightly more
elaborate and provides tees to divert water into each emitter along the
way. In this way, radiators can be individually controlled so that heat
need not necessarily always go to the first room on the loop."

If you have a new diaphragm type expansion tank, they normally come
pre-charged. It sounds like the automatic water feeder is passing water.
Shut the valve off and if the problem stops, replace the automatic water
feeder.

"Charlie" wrote in message
oups.com...
I have a residential boiler that keeps running over 30 PSI causing the
pressure relief valve to drain on the floor.

When I first examined the system, I noticed the expansion tank (with
diaphram) was completely filled with water. I replaced the expansion
tank with a new one and turned the system on. The pressure still
exceeded 30 PSI.

How do I find the source of the excessive pressure and fix it?

There is a reducing valve that says 12 PSI on the factory label. Going

into the reducing valve is a cold water supply line with a shut off
valve. It looks as if a previous repairman has backed off the adjusting

screw a few turns from the factor setting since there is the absence of

red paint on some of the threads.

I have not adjusted the reducing valve nor cleaned the strainer.

I can drain the system, get the pressure down, fill the system to about

12 PSI and then run the system:

- If I run the system at this point with the cold water supply valve
closed the system appears to stay around 18 PSI. My gut tells me I
need to keep this supply valve open when operating the system to safely

supply new water to the system if needed.

- If I run the system at this point with the supply valve open, the
pressure will go up to over 30 PSI. If I then let the system cool, it
appears that the pressure will go down to only about 18 PSI. Why
doesn't the cooled down system go back to the 12 PSI condition as when
I started it?

Should the water supply line going into the reducing valve be kept open

when normally operating the system?

Should I try to adjust the reducing valve?

Should I try to clean the strainer on the reducing valve?

Should I adjust the 12 PSI pressure on the new expansion tank?

The water temperature appears to reach about 155 degrees after an
extended period. Should I reduce the water temperature to reduce the
pressure? What's an idea residential boilder water temperature?

FYI - the house is 3 stories above ground so I need to circulate water
35 feet from the basement. Some threads lead me to calculate that I
need about 20 PSI to circulate water that high. If that's accurate,
how do I keep the pressure between 20 and 30 PSI.

Sorry for all the details and asking too many questions here but
thought they might help give one of you experts a hint as to what the
problem may be.

Any advice on solving this boiler pressure situation would be
appreciated.

Under pressure, one psi will raise water 2.3 ft. It doesn't matter if it's
Buffalo NY or Death Valley CA. The average 3rd story radiator is less than
30 ft. above the boiler, and needs no more than 13 psi. If you need 25 psi
to heat the 3rd floor radiators, they must be about 57.5 ft. above the
boiler.

"buffalobill" wrote in message
oups.com...
at 15 greenfield, buffalo ny altitude we need 25 pounds WHEN HOT AND
CIRCULATING to get from the basement to the third floor hot water
boiler radiators. our temperature is set to max at 180 but it depends
on your system. our expansion tank has no bladder and we set it to half
water half air when cold. you must refer to installation manuals on all
parts of your system.

Do you have auto water feed, it is probably bad, close it , drain to 12
when cold and see what happens. if it raises 3 lb hot leave it is
normal. If you dont get 3rd floor heat raise it manualy a lb at a
time-when cold till 3rd floor radiators get heat, you will have to bleed
radiators if there is no heat also . You only need as much pressure in
the system to get 3rd floor heat. Less pressure means longer boiler
life.