High pressure, any ideas

malex

This is my first heating season in this house with a one pipe steam system. I have had the pressure in my boiler hover around 10psi whenever the thermostat calls for heat. It goes down slowly to 0 when heat is turned off. The cut-in was always set to .5 (lowest) and I dialed down the diff to 1 (it was set to 3) but nothing changed. I just cleaned the pig tail and there was no change. I made sure the pressuretrol was perfectly level and that the pigtail curled towards the boiler so that the pressuretrol does not tilt as the pigtail gets hot and may change shape.



The pressuretrol looks brand new but it seems this is the only remaining culprit. Does anyone have any other ideas to try before I switch it out?



The main vent are old and does not seem to be venting well and I am ordering new vents but this would not explain why the preasuretrol does not cut off as the pressure goes past 1.5psi, right?



Thanks

BobC

pressure

There is a small hole at the base of the pressuretrol (up inside the brass fitting) that can get clogged, make sure you can see the diaphragm through that 1/16" hole. Also if you move the small silver lever up so it actuates the micro switch it should shut the boiler off



Your pressure gauge might not be working correctly, does the system make a lot of noise such as air vents shrieking? At 10PSi they should really make a racket and if the pressure really is 10PSI they may all have to be replaced.



Bob

malex

Thanks Bob, will check

it out (as soon as pressure goes down).

malex

And no,

radiators do not sound a lot. Sure, there is some hizzing occasionally but not more than I would say is normal and some of it probably due to poor main venting.

Jamie Hall

May I ask...

does the pressuretrol shut the system off on pressure? 



Pressuretrols do sometimes get fouled up.  However, so do gauges.  Not only can they develope zero errors (the thing reads other than zero when the system if off) but they can get scale errors -- the thing reads OK at, for instance, 0, but reads 10 pounds when it is really only two).  If the pressuretrol looks decent etc. (see BobC's remarks) I would surely try replacing the pressure gauge.

malex

Pressuretrol does not seem to

cut off at any point unless it does it at 11psi where the pressure seem to max out. It is possible that the pressure really only is ~2psi at that point but the gauge is for some reason showing 11psi.



If presuretrol looks ok per Bobs post, should I start by replacing the gauge or the pressuretrol first?

malex

Update

The lever in the pressuretrol does shut down power to the burner when manually lifted and it seems to be in good mechanical order as it makes a soft click and it gets stiffer when the cut-in is adjusted up (btw - it is the same exact unit as in Bobs picture).



The pressure is going down slowly since I shut off the thermostat but it is still at 3psi so I have not yet removed the pressuretrol to see if there is a glog in the actual connection (I don't think there will be as it seem clean when I cleaned out the pig tail.



The gauge sits directly on the boiler, does anyone know how to remove it? There is no visible connection. Do you just unscrew it by turning the body anti clockwise? It is made of thin form pressed sheet metal so I am afraid to crush it if I have to turn it hard.

BTW - it is a Peerless boiler if that information is useful. I also now notice at the bottom of the gauge (which ranges from -30 to 30 that it says:



"hg psi



This is a psi guage, right(?) and not some metric type (hectograms of pressure) which I can't imagine would have been used here.

Jamie Hall

Well now...

That is one of those questions.  Normally I'm adverse to just replacing stuff, but in this case...



Personally, I think you would be best served by leaving the existing gauge in place.  Since there is already a pigtail for the pressuretrol, I would put a T at the top of the pigtail instead, then a nipple on both sides, and elbows up, and put the pressuretrol back on one of the elbows and put a 0 to 3 psi gauge on the other one.  A low pressure gauge isn't a bad thing to have, anyway...



That way you'd still have the old gauge (you need a nominally 30 psi gauge for insurance purposes, if not code, anyway) and you'd gain a desirable gauge which would actually be useful.



If the new gauge then shows the pressure going above 3, you surely do have a bad pressuretrol.  Since this is a safety item, you will have to replace it, of course (I'm kind of a belt and braces sort of guy, so I like to put on two: one the actual control (usually a suitable vaporstat) and the other a manual reset pressuretrol, set at 5 psi.  But that's just me...)

crash2009

Gauge first

Get a 0-3 psi.  Pressuretrol if you have to, or want to.  If you are going to replace the pressuretrol, consider getting a vaporstat.  It is so much easier to replace them together.

BobC

Low pressure gauge

I agree with Jamie that a low pressure gauge should be installed on the pigtail along with a pressuretrol or a vaporstat. To replace the original gauge you will need one with an internal syphon that can take the steam directly. You can get the fittings at a hardware store or one of the big box stores.



 A 0-3PSI gauge can be bought here - http://www.gaugestore.com/products.asp?dept=1123  I used the 33020 on my boiler



Bob

lchmb

you said

you actuated the lever and it did not shut the system down? But you do hear it activate (click) If you remove one of the two wires does the unit shut down? If not it may be a wiring issue and not safe to operate...

malex

I actuated the lever and

the system DID shut down. But that brought me another thought: what if the wires are switched? Could that be causing this? Now the black is wired to the lower part of the slanted plastic piece closest to the cut-in spring. Anyone know if this is correct? There are no markings of how it should be wired and I don't have the diagrams.

malex

I checked the inside of the inside of

the connection to the pressuretrol and it looks like the small hole to the membrane is clear. That said, when I put it all back the pressuretrol is tripped and I have to push the lever down until I hear a click while having the diff high. When I dial down the diff it trips at 3 and shuts down the power. This is while the thermostat is off and there is no pressure on the gauge (and I just had the pressuretrol off the pig tail).



What gives?



I will definitely get the low pressure gauge mounted to a T as per the recommendations here (Thanks much). What is involved in replacing the pressuretrol with a vaporstat? Is it mounted and wired in a similar way?

crash2009

BobC

 has a real good explaination on how to test a pressuretrol here in this thread  http://www.heatinghelp.com/forum-thread/132867/How-do-you-test-Pressuretrol  Pressuretrols control pounds.  Vaporstats control ounces.  Both are mounted the same way and the wiring is easy.  In some cases a vaporstat can save you some $$$ on your heating bill.  Right out of the box, mine was set to stop the burner at 8 ounces.  Then allow the burner to come back on when the pressure has subsided to 3 ounces.  It does what it claims to do, and it is reliable.

lchmb

oops

guess i was a little tired reading that one...

Jamie Hall

Switching wires

on a pressuretrol (or vaporstat) doesn't make any difference, provided they go to the correct terminals (some have three terminals -- if so, make sure that you are using the correct pair (break on rise)).  Otherwise, it is just a switch, and it doesn't care which wire goes to which end of the switch.

malex

Time for virdict

So I ordered the gauge BobC recommended and I installed it this morning and I expected to get a clear idea of what is going on but that was not exactly the case so I will need the the input from the pros (and happy amateurs) in the forum.



At first I thought there must be a glog in the pigtail that I somehow missed or a clog inside the boiler as the low pressure gauge was not moving at all as the stock gauge was closing in on 5 psi. But then the low pressure started fluttering and moved up to .2psi. Still nominal, so I thought it may be sensing some pressure through the clog. After a while the low pressure started climbing slowly as stock gauge was closing in on 10psi and it actually reached .5psi at which point the burner shut off. I don't think it was the thermostat as it was showing 66 but was set for 68 (unless that is how it operates and takes into account that the cast iron radiators will keep raising the temperature).



I'm not sure what to make of this so if anybody has a good theory or better yet, a bona fide explanation I would be most interested to hear it.

BobC

Looks like the old gauge was bad.

It sounds like your low pressure gauge is working and the old boiler gauge has gone bad. You said that the pigtail was clear earlier so I would believe the new low pressure gauge, old stock gauges do fail.



Just measure across the pressuretrol switch to see if there is 120vac when the boiler shuts down. If there is 120v the pressuretrol has tripped, if not it's probably your thermostat.



Is the pressuretrol working now; you don't have to jiggle or move anything to get the boiler to fire?



Bob

malex

But why

did the pressuretrol cut-out at .5psi? The cut-in is set to.5 and diff is set to 1. I would think that it would keep running up to 1.5psi and come back in when the pressure dropped to .5psi. Now it hardly got past .5psi. I'm thinking this is not a coincidence as the cut in is set to .5psi. Could it be that the diff is not addidative? (but i still cant get the psi math to work)



Need to get a voltmeter so i can check if the circuit is closed asit shuts off.



Thank Bob!

BobC

Usually 1.5PSI or more

Pressuretrol high limits do not cut out much below 1.5PSI and many are above that. We know your system shut down and now we have to see what caused it to shut down. Does this boiler have a cycleguard low water cutoff on it? They will shut a boiler down XX minutes into a cycle to check the water level but they then restart the boiler after the test.



I suspect the thermostat is shutting the boiler down but we won't know if the pressuretrol is suspect till you can verify that it's contacts are still closed (0 vac across the switch) when the boiler shuts down. If you have a voltmeter when the boiler shuts down you can check to see if the thermostat wires at the boiler have 24vac across them, that would tell us that the thermostat had opened up because it was satisfied with the temperature in the room.



Did the system fill with steam before it shut down?

How long did the boiler run before shutting down?

What kind of thermostat do you have?



Bob

malex

Not sure

what a 'cycleguard' is but i doubt I have one as I have the old school macdonald miller float low water cut off.



Im going to see if I can get a voltmeter to test the circuit today.



When the system shut down at .5psi every radiator in the house was fully heated up so it seems it shut off at the right time but the thermostat was set 70 but as far as I can tell it had only reached 68. This is a digital honeywell thermostat so Im assuming it should not stop calling for heat until the display reaches 70.

BobC

Thermostat

Do you know if the thermostat was set up for steam? That means it should be set to 1 cycle per hour, most come out of the box set for hot air.



Bob

malex

According to the manual

there is a FUEL SWITCH (possible settings: E,F) and a HEATING SYSTEM switch (Warm Air Furnace, Hot Water Boiler, Electric Furnace).



It is set to F (E should only be used for electric systems, I have oil) and Hot Water Boiler. Given the options, these seem like the best set up.



On another note, I cranked up the thermostat further and got the low pressure gauge up to 1psi before shutting down. And when the burner shut off I noticed the green light on the power switch stayed on, whereas when I manually trip the pressuretrol it goes out. I am fairly confident that it is working properly.



th

Jamie Hall

At this point...

it looks as though we can be fairly certain that the pressuretrol is doing its thing.  This is good!  However, we can also be fairly certain that the thermostat is marginal for steam.  You are quite right; setting it to F for fuel (oil) is good.  However, even set for hot water boiler it may not be giving the boiler enough time to run; one of the characteristics of steam heat is that the boiler doesn't run quite so often, but runs longer when it does.  This is because there is so much stored heat in the radiators that it doesn't have to.



If the thermostat is able to hold your space to a temperature which is comfortable, and it doesn't vary too much, it may be OK -- although it may not be the most efficient choice.



If the thermostat is what is turning the system off -- and it sounds like it -- without getting up to some pressure, that's quite normal behaviour for steam.  If the steam is getting out to the radiators, that's what counts.

malex

While the thermostat

may not have the most optimal set up it seems to be doing its job. All radiators get hot and the temperature is kept fairly constant (knock on wood, February on Long Island can get cold, cold). I thought my system was running at 10 psi but it turns out that it tends to be satisfied at 1psi so after all I think I can be fairly satisfied with the system performance.



Next up is venting, which just became critical. Took off the old Dole #1933 and poked through the paint covered air hole, which is now leaking steam. A Gorton #1 is in the mail for my 15' main and a #2 bad boy for my 55'. According to my calculations both mains should be free of air at about the same time. Also ordered an assortment of Gorton radiator vents (mainly #4s and #5s and a few #6 if needed) to balance the radiators.



Fun fact: on the long main I had a Bridgeport #87 (anyone heard of this one?) and a hand written tag from 1964 instructing replacement every 10 years. Apparently this did not happen. The house is from 1939 so replacement went from 25 to 50 years.