Pressure Cut-Off Testing

Curt11

Just had my 16 year old Peerless boiler changed from oil to gas (Carlin EZ Gass) on my single pipe steam system.  Seems to run well, quieter for sure.  Noticed recently that it just runs and runs til the thermostat is satisfied. Checked at one point and the pressure gauge read 5#'s.  The system has a Honeywell pressure cut-off unit set for 2#'s.

  Called the plumber who did the work and he said that those gauges always fail over time and he knew  that mine wasn't working.  He said he wasn't surprised that the pressure cut-off never kicked in and that I shouldn't worry because there's another pressure relief valve on the system.  Very cold last night and after a couple hours of heating, pressure was at 5# and water had dropped to very bottom of the sight glass.  Something doesn't seem right to me.  How do I know if that pressure cut-off switch is working?  Thanks.

nicholas bonham-carter

plummmmer ignores nonfuctioning boiler control

this like the mechanic saying,"i knew your tires were leaking, so i put more air in them to compensate". what other parts of your boiler has he neglected---pressure relief valve?

to test the pressuretrol, you need an accurate gauge, whose range spans the pressuretrol range, as the 0-30 psi gauge is just not accurate enough. then you can observe the action [or inaction] of the pressuretrol.

if the pressuretrol is not shutting down the boiler at the cutout, it may be due to a clogged pigtail, which should have been checked, and cleaned by the plummmmer.

if the pressuretrol is mechanically broken, then consider replacing it with a 0-16 ounce  vaporstat, so that you are not paying for extra gas to over-pressure the system.--nbc

Curt11

Pre

Thanks for your quick answer.  Is the proper pressure gauge something to be bought and installed permanently on the boiler or something a plumber has in his tool box and uses to diagnose the problem?

BobC

Does the gauge ever read zero?

What does your gauge read when the boiler is cold? If it doesn't read zero the gauge is probably shot and you should consider installing an auxiliary 3PSI gauge that will let you see what is really going on. You have to leave the 30PSI gauge in place because there are regulations that require it.



To see if the pressuretrol is capable of working try the following - if you have the Honeywell PA404 pressuretrol. Do this when the system is off, kill the circuit breaker that supplies the boiler. Take the cover off the pressurertrol and find the lever that goes between the microswitch and the pressure diaphram that senses the boiler pressure. If you move that lever up at the microswitch end you should hear it click - that is the sound the microswitch makes.



If it does click, turn on the power and turn up the thermostat so the system starts to run. Do not touch the switch terminals because they might have 120v on them and you don't want to come in contact with that. Now if you actuate that lever the system should stop, when you release the lever the system will restart after a short delay - assuming the thermostat has not been satisfied. All this does is verify the microswitch and the lever are free and appear to be working, it does not mean the pressuretrol is still working.



If that works then nbc is right about it probably being a clogged pigtail or perhaps a bad pressuretrol, most of the time it's a clogged pigtail. The plumber should correct that but if you don't trust him you can do it yourself. Cleaning out the pigtail is not hard, if you would like to try cleaning it out yourself post some pictures so we can explain how it's done.



Bob

Curt11

Pressure Cut-Off

Hi Bob -

Did as you suggested.  The pressuretrol does click and I when I manually activated it, the burner shot down. Attached is a picture of the system.  Looks like the pigtail threads into the top of the low-water shut-off unit which I just had replaced about 18 months ago.  I am up for trying to clean that out myself.  What are the steps?

And the gauge seems to read about 1/2 # when it's cold.



Thanks in advance.



Curt

BobC

Cleaning the pigtail

Curt,



First shut off the power to the boiler at the circuit breaker panel. Also you might want to find a source for a replacement pigtail just in case you can't clear the old one (sometimes they get fouled really bad). Yours was disassembled recently so you should be ok. Start early so you have time to hit a supply house if you have to.



Make sure it looks like you have enough room to unscrew that pressuretrol from the pigtail, some installations had that done before the low water cutoff was installed and they don't give you enough swing room.



Start by unwiring the pressuretrol and removing the cable from the pressuretrol. make sure you make a note of how the pressuretrol is wired so you can put it back. Next use a small pipe wrench to hold the pigtail while you use an adjustable wrench on the brass hex at the bottom of the pressuretrol to loosen and remove it.



Next unscrew the pigtail from the low water cutoff, a Jorgenson clamp is really handy for this step. just apply steady pressure to get it going because you really don't want to snap anything off. Once you have the pigtail off run water through it to clean out any crud. Use stiff wire to help clean all the crud out. If you look at the bottom of the pressuretrol, inside the brass hex, you will see a very small hole - mike sure that is clear. Then make sure the low water cutoff port is clear of any debris.



Once everything is clear just reverse the steps to reassemble everything using pipe dope or teflon tape to seal the pipe threads



good luck,



Bob

Steve_175

Venting

The pigtail is important to check. Once you have determined that it is clean I would check your venting. From what you described it sounds like your main vents may be non functioning/insufficient. This would make the rads have to do all the venting which will lead to rad vents clogging either shut (no heat) or open (loss of water).



There could also be problems with the way the boiler was set up. Post some pics of your boiler from different angles and far enough back to see all the pipes connecting to it. Also measure the diameter and length of your main pipes as they go around the basement. See if there are any vents near the end of them and see if they get hot after the boiler has been running awhile.

Curt11

Pressure Cut-Off

I will try taking this apart sometime in the next couple of days.  Any chance that the pigtail breaks off where it's threaded into the low water cut-off?!



The System is venting at 2 of the 3 main vents.  The 3rd vent is on the shortest loop where I need the least heat.  Does it still make sense to fix that vent?



I'll post a few pictures in a couple of days.  Thanks again.

Steve_175

MAin Venting

Venting is very important. Gill explains it well here:



http://www.gwgillplumbingandheating.com/webapp/GetPage?pid=415

BobC

Slow and steady

Since you had that low water cutoff replaced 18 months ago, that pigtail should come out ok, you might want to put a bit of penetrating oil on the the joint between the LWCO and pigtail a day or two before you go at it. Wipe any excess oil off before you remove it so the oil doesn't get into the boiler. Just apply steady increasing pressure and it should start to turn.



On your venting setup, give us the approximate length and diameter of each main and what make and model of vent you have on them so we can see if you need larger vents. i would be suspicious of the vent that doesn't appear to be working but lets determine the pipe volume before replacing anything.



Bob

Curt11

Pressure Cut-off Testing

Attached is a not-to-scale drawing of my steam system.  The main vents are installed up between the floor joists where I can't seem to read any information as to what they are.  I am thinking I'll wait till this heating season is over to change them out.  I appreciate the help sizing them.

BobC

Venting

If we average out the three mains at 44 ft that gives us 1.66 cu ft of air that has to be expelled so steam can fill each main. The faster you vent those mains the better so I would start with Gorton #2's and be prepared to add more if needed.



Be warned that the Gorton #2 is a large vent, make sure you have room for them. If space is an issue you could use 3ea Gorton #1's mounted on an antler, that would cost a liitle more. The Gorton #2's come with a 1/2" male thread (Gorton #1 can be had with a 3/4" male) so you may need to adapt that down which will need even more height. http://www.pexsupply.com/pex/control/search?SEARCH_STRING=gorton+no+2



Does the system heat ok now, especially in that right hand loop? If that loop return really does tap back into the main it might be starved for steam and be slow to heat. Steam always favors the path of least resistance.



Bob

Curt11

Evennes of Heat

Hi Bob -



That right hand loop is where we spend most of our time.  It's not only the furthest area from the furnace but it has a lot of outside exposure and a colder crawl space under it.  The radiators out there are definitely the slowest to heat.  Would increasing the size of the vent to that loop increase the speed to heat those radiators, and what's the downside?

Steve_175

Yes

is the answer to your first Q.

How well insulated are the pipes in the crawl space? How thick is the insulation, are the elbows and T's insulated?

The down side is your other rads will be slower to heat up.

Curt11

Pipe Insulation

Pipe insulation in that are is older honey-comb asbestos about 3/4".  It's generally intact, falling off on a few places.  Got a price to remove it, ($2,000), not wild about spending the money or crawling in there to fix it up either!

BobC

drip that right loop?

I'm assuming you have single pipe steam. Does the steam main slope down as it goes away from the boiler? Make sure all the steam mains are sloped correctly, especially that outer loop.



Increasing that loops venting will help but I'm not sure it will be enough - try it and see. use twice the venting on that loop that you do on the other two. The problem I see is that it that right hand loop comes off and then reconnects to the steam main it is not going to be easy convincing enough steam to go down that loop because it's just easier for it to continue around that main loop. If you could disconnect the return side of that right hand loop and send it down to a drip I think you would get better performance out of it. Increasing that loops venting will help but I'm not sure it will be enough - try it and see.



Getting asbestos removed is very expensive unless your old enough to do it yourself (with mask and ventilation). I've done it myself by wetting everything down with a surfacant to keep any fibers from getting airborne. one person spays while the other removes the asbestos. Not recommended but sometimes you've got to do what you have to do.



Bob

Steve_175

On that crawl space loop

Are there any branches coming off the main loop between where the crawl space loop starts and stops?

Curt11

Drip loop

Actually, I think there is a drip loop there.  The returns on the main loops are overhead, but from that right hand loop a return drops to the floor and runs around the perimeter of the basement to the boiler.



The Vent on that right hand loop is easier to get at than the vents on the 2 main loops.  What could I change it out to to increase the speed of the heating to that loop?

BobC

Gorton #2

Curt,



If you have a drip at the end of that lop then increasing the venting is likely to help . Your diagram indicates that right hand loop is 42 feet if I'm reading it right, put a Gorton #2  there and see what that does for you. just keep in mind it's a large vent as I said earlier.



What are you using for radiator vents?



You should still do what you can to get that piping insulated.



Bob

Steve_175

Loop Mod

It might make sense to cut out the section of main in-between the crawl space loop so that the steam has to go thru there first. You would have to move the drip loop over a bit but that should not be a big deal.

I am curious what the pros think of that idea.

Curt11

Radiator Vents

I am using Vent Rite model 1. 

BobC

Good

Those are great vents, if one does clog try boiling it in white vinegar for 15-30 minutes



Bob