Wild cycle, roasted tenant is good on a cold day.

crash2009

The City Mechanical Inspector had an appointment for 10:00am today.  So we shut down the natural gas at about 9:30am.  He was coming over to inspect the new gas line that was installed recently. 

I thought this would be a good time to work on a few of the leaks we had.  I used Meeco's Red Devil, high temp silicone, -75 F to +600 F on the radiator union.  So far it has worked great.  Thanks Al.  

I had a few valve stem leaks too.  The hardware store sold me some graphite valve packing (3/32" X 24")  They said that would be enough for the whole house.  Maybe a well maintained house but not this one.  I used 2 packages of the stuff on 6 radiators.  The packing nuts here likely have never been removed.  When I took off the packing nut all that was left of the old packing was dust.  I wonder how many times they have been opened and closed in 100 years. 

While the boiler was down, I drained a bit of sediment from the bottom half of the boiler, and the wet returns.  Then cold skimmed for a couple hours.  The opposite side of the boiler from the Hartford had the most sediment.  I should blow-down the far side more often.

I fired it up at 4:37pm, an hour later it had built .30psi, over the next 20 minutes the pressure rose to 3.5psi then shut off on pressure, then it took about 2 minutes to drop the pressure down to 2.5psi, then came back on for 5 minutes.  I went upstairs to inspect the leaks that were done today, and I think it cycled on pressure for 2 hours.  I guess 3.5 hours is long enough to remove the oxygen.  I have noticed a few more leaks that I need to attend to at next shutdown.  <strong>Shouldn't it take more than 2 minutes to lose 1psi?</strong> 

At about 8 pm the thermostat was satisfyed and the boiler finaly stopped cycling.  I could hear the condensate returning to the boiler.  It was making a gurgling sound as it returned.  Now that everything is hot, it is back to normal again.  <strong>I guess I provoked it huh?</strong>

I realize that 3.5psi is too high to be cycling at.  But, on a daily basis I never get that high to heat the house.  I only got that high because of the all-day setback.  The pressuretrol refuses to go any lower.  <strong>Is it now nescesary to find an alternate high pressure limit?  Or, should I just babysit the boiler after a long shutdown?</strong>

  

Steve_175

New Ptrol

"The pressuretrol refuses to go any lower. "



You may have a defective ptrol. You should consider getting a vaporstat so you can fine tune your pressure settings. Do you have sufficient main venting? Post some pics of your system.

Jamie Hall

Two minutes

isn't necessarily a short time -- in fact, it may be about par for a really big system.  Consider that what is causing the pressure drop is condensation in all those radiators, and there's a thousand to one volume change as steam condenses.



How are you measuring the pressure?  If it's on a 0 to 30 psi gauge, does the gauge read zero when the system is cold?  Most of those 0 to 30s are a little flaky at low pressures, so I wouldn't count too much on what it says.  On the other hand, 3.5 psi is too high... and you would get much better control with a 0 to 4 psi vapourstat.

crash2009

Jamie, I am using two Wika gauges

  Both are up above the boiler, with snubbers, and shut-off valves.  I normally observe the 0-3psi until it aproaches 3.0, then shut-off the valve, and start watching the 0-30. 



Without provocation, this system operates at .04psi to ocassionally .10psi, cycling off the t-stat.  Maybe the pressure will go up a bit after I finish fixing all the leaks.  Can you see any advantage to cycling off a vaporstat between .04 to .10?



So, all that condensing was normal.  It sounded like a river running through the returns.  Never heard that before so I thought I would ask. 

Charlie from wmass

Crash you had grown some large radiators

This is what I was referring to as to how the square footage of a radiator grows as the ambient air temperature drops. The fun thing with closing leaks is they other leaks show up. It is worth chasing them down though.

crash2009

Charlie, yes I know,

 I changed a rad vent during the 3.5   One of those old Ventrite's was leaking from the adjuster.  I guess thats why it was in the scrap pail.

Charlie from wmass

crash are you sure

you can not loosen that screw a bit more on the pressuretrol? the indicator arm can some times be tweeked a bit to allow it to drop lower. When you do this you may then need loctite on the threads.

crash2009

Maybe

 I'll have another look at it.  I am only hangin by 1/2 a thread right now.  Maybe I can bend the indicator arm a little.



Waddya think about going after that real small screw, the one that has the threadlock on it all ready,

crash2009

Balancing the pressuretrol

I pulled that goofy spring and indicator right out of there.  All they do is allow me to turn the pressure up.  I needed to go the other way.  I don't know the names of all the parts in there but the left side of the teeter-totter has the spring on it.  Like I said I took the spring off and sat some lead (about an ounce) on the side that had the spring.  Now it cycles at 2.40psi off, and 1.75psi on.  Then I tested it 4-5 times to make sure.  Now I'm on to something, so I added another half ounce and got it down to 2.35psi off and 1.70psi on.  Now I just need to figure out how to glue or bolt the lead to the teeter-totter.  It might be more than an ounce and a half I haven't weighed it, but the size looks like three 1/2 ounce walleye jigs.  The lead actually started out as a battery post holder.

Mark N

Btu per sqft

Charlie



I don't think the sq ft of the radiator changes. What changes is how many btus each sqft gives off at different ambient temps.

Mike Kusiak_2

EDR

Mark, I think what Charlie is referring to is the apparent increase on EDR as the room temperature drops. Actual EDR depends on the physical surface area of the radiator, how well air circulates around it, and the ambient temperature. If the room temperature is lower, the radiator can transfer more heat to the air, and thereby accept and condense more steam. I believe this apparent increase in EDR is what Charlie is describing.

nicholas bonham-carter

pressuretrol problems

try measuring the pressure both with and without the snubbers. i think the snubbers may increase the response time to any very low-pressure reading, and that may affect the apparent sensitivity of the pressuretrol. otherwise a new vaporstat should be on your list soon. i am certainly of little faith when it comes to pressuretrols, as the one supplied with my new boiler, failed in a week, in such a way as to allow the pressure to go up to the 2nd pressuretrol cut-out of 10 psi!

if there are still pockets of air in the returns, at shutdown, these will expand into the vacuum formed, and will slow down the drop to negative pressure. these pockets in my system,would be in the dry returns, downstream of the vents.--nbc

crash2009

All I know

 is that when the radiators are pumped up to 3.5psi, heatwise they feel like they are 10 times bigger.

Mike Kusiak_2

Radiator temperature

If you have 3.5 PSI steam in them, the radiators reach a temperature of 223 F, so they really are putting out more heat than the 212F at atmospheric pressure.

crash2009

Do you think

 I could fry a steak on a radiator that was 223 F?