Steam pressure gauge problem

Dan Nibbelink

I'm not sure exactly what you mean by "flush the boiler regularly". Drain all of the water from the boiler and refill? Doesn't this add oxygenated water which is a "bad" thing? Is regularly once a month or once a year? I do open the valve on the bottom of the waterlevel control once a week or so.

Dan Nibbelink

Steam Pressure Gauge problem

1920 Dunham Home Heating System, page 252 in The Lost Art of Steam Heating. Two pipe system. The pressure gage has been reading 5 to 7 psi. I seem to remember that previous winters that it was reading 3 or 4. So I adjusted the pressuretrol from 2 psi to 1 psi. Now the gage is reading 6 psi. The gage is built into the front of the boiler which is 1920 vintage, so it's possible that it is not reading correctly.

Discovered that the pressuretrol was stuck. It had been mounted without a pigtail or any kind of snubber. Cleaned it up so that is was no longer stuck and installed a pigtail. Also T-ed off after the pigtail and added a pressure gauge (0-15 psi). Pressuretrol set for 1/2 psi and 1-1/2 differential. See pictures.

Now the problem: the old gauge is still reading 6 psi when the boiler is fired. It goes to zero when the boiler is cold. The new gauge DOES NOT MOVE! Nada, zero. I removed the pigtail, pressuretrol and gauge from the boiler and blew into the pigtail and got a reading of 1-2 psi, so it seems to work. And I get heat to my radiators. I stuck a coat hanger thru the hole where the pressuretrol is mounted and could feel the pipes inside, and got the wire wet. If I take apart a steam trap while the boilers is hot I get a very small flow of steam/air.

So I am confused. Is it possible that my system is working with very low pressure and that the old gauge is failing? What would be the failure mode? Or is the new gauge?defective? What do I do next?

Paul Fredricks_2

OK

I would imagine the new gauge is reading correctly. The flex is probably all used up in the old gauge. You could leave it place just for old times sake. Good move installing the pigtail. Make sure you flush the boiler regularly.

Bernard Smith

Your gauge is too high anyway. (0-15) You should have a 0-5. Steam should only operate at about 2psi. Your system is probably well vented so pressure doesnt build up. I don't think you have anything to worry about. Pressuretrol is fine, just not reaching pressure due to venting. Are all your rad vents shutting off when steam hits them? If not, you'll never build pressure- kind of a bad thing because boiler doesnt get a chance to breathe. Check all those vents

Dan Nibbelink

gauge range and vents

The 0-15 was the lowest range offered by the outfit I bought the gauge from. I'll get a 0-5.
This is a two pipe system, so no radiator vents. The end of line vents quit venting about the time that the radiators are hot. No known venting otherwise. The weather has been mild the last week or so. Perhaps the boiler doen't run long enough to build real pressure.

Unknown

Bernard

I believe it is code to have a pressure gauge on the boiler that measures 2 times higher than the relief valve setting . Nothing is to stop anyone from adding another lower range gauge along with the high range one .

Dan , it could be that the boiler is running a long time with no pressure buildup . We installed a steamer last week that ran a good hour with 0 on the gauge all that time .

John H.

Gauge

If you have a 2 pipe trap system could it be a vapor system and the oridginal gauge be showing ounces of vapor instead of psi.

DanHolohan

I agree.

The only way to build pressure is to fill the system with steam and then add more steam. These systems were designed to run at very low pressure (often less than 1 psi), which probably won't register on these gauges. If the radiators are getting hot, and the distribution is good, I wouldn't spend any time watching the gauge.

Bernard Smith

does't this take your pressuretrol out uf play? isn't boiler supposed to cycle rather than run until tstat tells it to shut off?

DanHolohan

It's all relative. Consider a vaporstat, for instance. Its highest setting would be 16 ounces. Typically, you'd set one of those to cut-in at 4 ounces and out at 12 ounces. There aren't many gauges that could see that low a pressure, yet the system is still able to cycle on pressure.

Long Beach Ed

Wanna have some fun????

Take a big wrench and try digging that old guage out from all that asbestos. Hahahaha. Just kidding.

Be careful meddling with an old boiler like this. Many times the pipes have warn very thin at the threads. Here comes Hercules with his 40" wrench and breaks it off at the boiler. Forget about it.

Dan is right on with this. Many a well designed system never built up any measurable pressure. In fact, many of them would satisfy a thermostat long before the radiators were fully heated and the vents closed. So don't sweat the guage.

Just treat that old snowman with respect.

Long Beach Ed

oil-2-4-6-gas

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get that pressuretrol out of there that control is not sensitive enough for your system or most any residential steam system for that matter they do not shutoff at the pressures you set it for - buy a vaporstat i have a new old stock 1 sealed in the original box--check online for a gage in the lower range or go back to your supplier and have them order 1 --do not remove the 1 on the boiler -that is asbestos surrounding it --as for code and any inspectors --with the old gage still in place (-which needs to be 50% higher than the rating of the boiler) you are covered --

Dan Nibbelink

Is the old gauge

"broken", or is it reading ounces/sqin?
At 7 oz/sqin it makes sense - just under 1/2 psi.
Full scale is 30 units, which would be just under 2 psi.