steam question, can't build pressure

steve_6

hey guys, I have a new install I've just completed. Boiler is sized to the connected load. Piping exceeds manufacturers specs, producing nice dry steam.Everything is working great, house is heating well, steam to every radiator. average burns 10-20 minutes to satisfy t-stat. System is quiet, and home owner is happy. But I can't build any , I mean "0", zip pressure. My gauges read in oz.'s and both read "0"one at the boiler and one at the end of the main. I've checked gauges against a manometer and the water collumn doesn't move either. The only time I have built pressure is when I've closed the king valves on the main. I 've never had this happen before. I have not had to add water to the system. The system is a Mouat Vapor system with 2 Gorton #2's installed on the dry return. The reason I'm concerned is the old boiler rusted out above the waterline from O2 corrosion and it was only about 15 years old. There are no buried wet returns, no vents to the chimney that I can see. All the piping and radiators look to be tight. Do you guys have any idea's?? thanks in advance!!! Steve

[Deleted User]

did you try

unscrewing the airvents and putting a plug in the opening to see if then the system would build pressure? thats the only way i would think to tell if the Mouat dead man put a pipe into the chimney in the attic, or wall space instead of above the boiler..i'm thinking of something like that house on edgehill where the boiler flooded and i found the mouat chimney vent cause i heard water running in the chimney..if the pipe was put in before the plaster ceiling it may be buried, but there...tho i would think you would still not have a problem as long as the steam never hits the mouat trap..

Big Ed

Just thinking

Maybe with the mild wheather the thermostat is satisfied before pressure could build .Did you try jacking the thermostat all the way up ?

[Deleted User]

he ran the system

for a twenty plus temperature rise, with no problem, and built up no pressure. (i talked to him on the phone). i'm thinking if there is no mouat chimney return piping vent pipe that he is firing dead nuts to the connected load..the plugging off of the air vents should tell us this, i think..does that sound right??

Unknown

Yes

That's what I was thinking, too.

As the mains are warming up fast, the radiators haven't got steam all of the way across, yet.

When the mains are hot, the radiators warm up all the way across until every bit of steam gets used.

Too little, and one radiator won't heat.

Too much, and you'll build pressure.

I think it could be just right.

Can you shut off a couple radiators to see if it builds pressure? If it doesn't, I'd be looking at the chimney, too.

Noel

steve_6

t-stat rise

yes , when I first fired the boiler up. it went from 46 to 68 degrees with no rise in pressure in about a 2 hour period.

Big Ed

Very Clever

Gerry ,I thought your test was a very simple and clever . One to remember....

Boilerpro_3

To add to Noel's thoughts

Vapor systems are usually push/pull systems, as I understand them, not just push systems like steam. If your pull (ie. vacumn created by the chimney) is equal to your push, you won't see any pressure to speak of. What do you think?

Boilerpro

[Deleted User]

hi BP

yup, pretty much thats it..weve got alot of these Mouat systems around cleveland as they were a local company..they are quite tempermental systems..its very easy to blow steam right thru the mouat water seal..we like to find and eliminate the returns vent into the chimney and use main vents instead cause if we delicatly balance the radiators out for perfect running where the steam doesn't get to the mouat trap everything is fine, but you just know some homeowners gonna play with the valves..if they then blow steam thru, and the chimney vents still connected,they will keep taking on water..if there are main vents they will close and the short cycling boiler will get their attention..steve and me talked today about getting tunstall orifices to install in the valves so that the return vents to the chimney could stay..mouat systems are a real challenge but lots of fun..

Boilerpro_3

You know,

> yup, pretty much thats it..weve got alot of these

> Mouat systems around cleveland as they were a

> local company..they are quite tempermental

> systems..its very easy to blow steam right thru

> the mouat water seal..we like to find and

> eliminate the returns vent into the chimney and

> use main vents instead cause if we delicatly

> balance the radiators out for perfect running

> where the steam doesn't get to the mouat trap

> everything is fine, but you just know some

> homeowners gonna play with the valves..if they

> then blow steam thru, and the chimney vents still

> connected,they will keep taking on water..if

> there are main vents they will close and the

> short cycling boiler will get their

> attention..steve and me talked today about

> getting tunstall orifices to install in the

> valves so that the return vents to the chimney

> could stay..mouat systems are a real challenge

> but lots of fun..

Boilerpro_3

You know

It really is beginning to look like installing orifice plates in a system is a great way to upgrade the system. Orifice plates would allow radiation to be downsized to current loads, allowing smaller boilers with longer, more efficient burn times, and great system balance. Also, you could eliminate trap maintenance, which in my parts is nonexistant, if the radiator is big enough to handle the load at 80% full. Don't get a whole lot of steam around here, but more and more is coming my way. Maybe the next two pipe system I'm looking at I will propose plates to balance the system, use the now oversized piping system for vapor operation, and give them a much smaller boiler. I just can't help loving Vapor. It's what all steam systems should and I believe most could be.

Boilerpro

Unknown

I feel the same way.

Do a heat loss survey, control the steam pressure, and put the correct orifice at each radiator. What a way to go! It might even pick up the efficiency of the boiler a bit. It surely would require a smaller boiler.

Pity the next guy that measures the radiation for a replacement boiler....

Noel

Steamhead

You might also consider

finding the biggest thermostatic trap you can get, and installing it in the chimney vent line. That way steam won't blow into the chimney.

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steve_6

we also thought about

putting a strap on aqua stat connected to zone valve on that vent line

[Deleted User]

or an aquastat

controlling a maintenance required signal light..we could use a relay and wire it to ''self latch'' so that when the boiler stops and the aquastat opens it would stay lit cause the relay self latched itself...

steve_6

plugged the air vents

the system built pressure. looked up the chimney , no pipes in there. I did close down some radiators, didn't seem to affect it much. looks like the boiler is sized dead nuts on. thanks everyone for your help!!!!!!