Too much water in steam system

David Nadle

I only know about one heating system: my own. My hunch is that biggger buildings, colder climates, oversized boilers, might have more cutting out on pressure.

subetterly

Weil NcLain

We had a problem that I think was too much water in our system. The radiators were hissing steam and making way too much noise and the boiler was kicking on every 5 or 6 minutes. When I went to check it, the water sight tube was completely full. We drained two buckets of water from the yuck valve and the sight tube fluctuated but went right back to full. My husband then drained a lot of water out the bottom using a hose and the spigot on the bottom of the unit. The sight tube has stayed at half full for the last 4 days and things seem ok.

But one of our radiators on a separate line is not getting very hot and is banging slightly.

Our pressure reader is always on zero - what does that mean?

We have an automatic water feeder on the unit.

I changed all the release valves on the radiators and on the main pipes in the basement at the beginning of the heating system. The new ones seem like junk compared to the old beasts that I took off the radiators.

The problem seems relatively resolved for now but I would like to know what might be going on. What are the likely culprits for too much water in the sight tube? We seem to be going through fuel way too fast......

On a philosophical note - having a steam system is like having a child. You need to know what is going on with it at all times!

Susan

JohnG_3

Flooding

Not an expert, just a homeowner, but maybe your condensate is not returning to the boiler fast enough, causing your auto water feeder to flood your boiler. My parents have this problem and plan to replace a large portion of their return lines after the heating season is over. In the meantime, they turned off the auto water feeder and are blowing down and refilling the boiler just about every day.

As for your steam pressure gauge being stuck at zero, I have the same problem, plus my system is not cycling on pressure (pressuretrol not cutting out and in). I suspect my pigtail is clogged. When was the last time your system was cleaned and tested? It's been at least 10 years for me, way overdue.

mark ransley

Im not a pro but had something similar happen at the beginning of the year, the previous person looking after the boiler rarely draned the low water cutoff,the valve froze. When i filled it it would slowly get to the proper mark on the sight glass, I stopped filling it, then in about 5 seconds it would overfill. The boiler tech replaced the low water cutoff and found a nipple going to the boiler about clogged shut, so it got to a point then overfilled from the top. This was on a big old Kiwanee.

Jamie Hall

Pressure

Steam systems operate under very low pressure -- not seeing pressure on the gauge is quite normal; if the system is heating, it's working, don't worry about it!

JohnG_3

That may be true but

My system is heating but when it comes out of setbacks the boiler fires continuously for 45 minutes, never cycling on pressure. That suggests to me that the pressuretrol is not working properly. The 0-30 psi pressure gauge is too coarse to be useful.

Tom Hopkins

weil mclain

you said you had a automatic feed on your boiler. does the feeder have a time delay. if it does not i think what is happening is when the boiler shuts off on low water the feeder is filling the boiler to satisfy the low water cutoff

After Hours Burner Service

overfilling auto feeder

I am not an expert, but I have seen this problem often. I think the auto feeder is adding water before the condensate comes back, therefore when condensate is back boiler is now over full. I have seen this often when the auto feeder is not set properly for the type of low water cut-off in system , Weil Mclain website has a lot info on these problems. Good Luck

Phil_17

a common misconception

Coming out of setback there is no reason to expect your burner to cycle on pressure... Unless the boiler is significantly oversized for the connected load.

Every bit of the heat made by the burner is being distributed into the piping and radiators. You would only expect to see the system make pressure after the vents have all closed (and the radiators are all hot all the way across).

JohnG_3

Okay, but

Under what normal operating circumstances should the boiler cycle on pressure? I can't recall a single time my system has cycled on pressure in fifteen years of living in the house. I can hear the snap of the t-stat relay closing and opening, followed by the whoosh of the boiler firing up (or silence when it shuts down). There has always been a one-to-one correspondence between these events.

The pressuretrol takes on such prominence in Dan's writings but in my case it seems to be behaving like a short circuit.

David Nadle

What kind of t-stat?

John,

I've got a new boiler with a new Honeywell programmable tstat and a Vaporstat set at 12 oz. and the only time I cycle off on pressure is on very cold days. It's not much of an off cycle either. The system pressure drops to zero in about 1 minute, then the boiler comes back on. So it's not like a shutoff on pressure is saving me anything.

I think part of the reason is the tight swing of the modern tstat. An older tstat with a wider temp swing would have a longer on period and be more likely have all the vents shut. Tighter control of the room temp is better for comfort.

I'm thinking now that to save any fuel with the Vaporstat on my system I'd have to add some programmable logic to keep a minimum off time after a cut out on pressure and see if the hot radiators carry the house to the tstat set point.

If you want to see if the pressuretrol will cut out for you, try setting back the tstat a few degrees and let the house cool, then turn it back up. If the makeup runs long enough you should close all the vents and hit the cut out pressure.

JohnG_3

Thanks

Very good explanation, it explains a lot. Does that mean that those sinusoidal pressure curves in Dan's books are essentially a thing of the past?

Here is a comment I saw on another blog; it's a couple of years old:

The thermostat SHOULD turn the burner on and off in a properly operating steam system as a thermostat IS an operating control to turn the burner on and off, not a safety control as is a pressuretrol.

A finely-tuned steam system will have the pressure slowly come up to 1 psig, giving time for the air to leave through the vents, then maintain the pressure by balancing the fuel input with the radiation output; hopefuly, never reaching the pressuretrol cutoff setting.

Jon Held

Lots of questions

Lots of questions on this thread.

First let’s look at water return to the boiler. The very first thing I would do is make sure all of your radiators or convectors are slightly pitched back towards the steam shut off valve to allow condensate to flow back to the boiler. Make sure all shut off valves are fully open. Put a level on all of the accessible condensate lines that run back to the boiler and make sure that there is a constant pitch back to the unit so water can flow. I had a very similar issue where condensate would get trapped and she would run low on water and auto fill. Condensate would eventually return and then it would be overfilled. Finally, make sure your auto feeder is not leaking or water is not entering the boiler from another source like a tankless hot water coil with a pin hole in it.

Steam pressure should be as low as possible to move the steam as quickly as possible through the system. My pressuretrol is set to the lowest cut off differential (1) and the lowest cut in (.5). When recovering from a setback she will fire for a good 20 minutes or so before building up system pressure. I replaced my 30psi gauge with a 3psi gauge so I can monitor it correctly. It will cut off between 1.5 and 2 PSI. This also assumes that the radiator air vents are working properly and allowing air out and then close when steam hits them. I replaced all of mine with new Gorton valves a few weeks ago. The mains are each vented with a Gorton #2. A vaporstat is coming in the spring with some other tasty mods.

“A finely-tuned steam system will have the pressure slowly come up to 1 psig, giving time for the air to leave through the vents, then maintain the pressure by balancing the fuel input with the radiation output; hopefuly, never reaching the pressuretrol cutoff setting.”

I don’t buy that. If the thermostat is calling for heat and the boiler builds pressure because the system is properly closed and sealed and hot, then it MUST cut out on pressure. The boiler will then cycle on pressure alone until the thermostat is satisfied. I love the idea that someone posted regarding a timing circuit for the pressuretrol. I had the exact same idea and found several timing circuits that could work well.

Steam up; air out; water back. Words to live by. I don’t think I would live in a house without steam heat anymore.

Phil_17

Need a pro to resolve this...

"If the thermostat is calling for heat and the boiler builds pressure because the system is properly closed and sealed and hot, then it MUST cut out on pressure."

As I understand it, if the firing rate of the boiler has been properly matched to the EDR of the radiators (and pipes) then no, you should never make any pressure.

If the boiler is oversized for the connected load (arguably the typical case) then yes this will happen, but if the system has been carefully spec'd, designed, and installed you should never see any meaningful pressure at the boiler.

joe lambert_2

If the auto feeder is overfilling the boiler because the condensate takes too long to get back to the boiler than there is one option you can try. You can install a timer on the auto feeder that makes it wait a pre-determined amount of time before it will auto feed the boiler.

The steam system in my home never builds any pressure above a few ounces before the thermostat is satisfied and from what I read in Dans' books that's normal. Even with the old original coal fired snow man it never made more than a few ounces of pressure or went off on high pressure.