Pressure never builds

G Valls

G Valls

Pressure never builds

Real quick question...

I have a 1983 EG-45 Weil Mclain boiler, that puts out 122,000 btu on the output side. House is fairly small, 1670 sqft, with 8 radiators.

I have been having trouble getting the boiler to build any type of pressure. The pigtail has been cleaned, new Vari Vents are on the radiators, and new 3/4" main vent was installed as well, new fiberglass insulation has been installed on the mains, and a new honeywell T87 thermostat.

I understand the system should not build much pressure at all (steam travels faster at lower pressure), but I would at least think that a boiler running for about 30-40 minutes should have at least be able to build .5 lbs.

Is there any reason why the boiler should not build enough steam pressure, to at least have the pressuretrol cut it out after running for 30-40 minutes?

Charlie from wmass

It may be the boiler is sized very close the actual EDR. trhe first question is are there any leaks? The second is the piping typical and as per manufacturers recommendations? Do you know what the EDR is for your system?

scrook_2

Steam mains...

Are the steam mains (and fittings) insulated w/ at least 1" thick fiberglass insulation? You may be very close to the attached EDR -- how's the radiators and the house heat?

Are you measuring w/ a gauge w/ full scale of a few (vs. 30 or 15) psi?

Could be a leaking main vent too.

G Valls

Thanks for the response.

There are no leaks, piping is typical (and in good shape), but I do not know the EDR of the heaters in the house. They are the older, 5 vent per section radiators, that are about 8" or so wide, rather than the slimmer radiators you see today.

G Valls

Insulation is actually not 1" thick, but heat loss seems to be minimal. Actually, insulation is rather cool to the touch during operation.

Charlie from wmass

You will need pics of rads, pics of near boiler piping, and height and number of sections of each rad. yourr boiler should produce 380 sq ft of steam depending on the series.

G Valls

Thanks very much.

Here are a few pictures of the boiler and typical radiators.

I realize the pressure gauge is too big, for 30 psi, but the needle never lifts off the pin.

BTW, you are right on, the boiler puts out 380 sqft of steam per spec.

bob young

improper header piping

header piping has reducing tee creating physical condensate trap. probably causing wet steam & water hammer. sepatate connections for mains would be better piping arrangement.

G Valls

Thanks.

Surprisingly, I have no water hammering. System actually, is rather quiet.

Real quick idea. I notice the flue pipe never gets super hot. Could it be a flue pipe issue?

Charlie from wmass

If this is the size of the rads then you are right on with boiler size. 8 of these ( first picture) if they are 26 inches high are 392 sq ft. 8 if they are 23 inches high are 336 sq ft. If the system is heating the home well do not worry about the pressure as long as water use is normal and you have no leaks. Comfort is the question here. How clean is the water? It may be the boiler needs flushed out so it is not actually making 380.

Timco

You should have a pro check the entire system anyway. I just did one (VERY old boiler) that was underfired and was partially heating the house with vapor, and needed more btus to make steam / pressure. This surely may not be your case, but a good boiler guy can check your manifold pressure and combustion numbers...and make sure there is not a few inches of rust in the bottom of the boiler or soot in the sections thus insulating it. A clean boiler (inside & out) will heat way faster than a dirty one...

Tim

Brad White_191

Look Outside.

Look at the chimney top, not only when it is firing but just after it is shut down. If you see white smoke, think steam. (We have a relatively new pope so you can cross that off your checklist.)

You may have a leak above the waterline. If the boiler is off, there may still be steam escaping even at low pressure and it will show. Not just the normal smoke but bright white on a cold crisp day.

Not a good sign but it may end your search.