Loosing pressure Adding Water

Paulvar1

My NEW (installed the day after New years, its now March 01) steam boiler on a 2 pipe open system cuts out at exactly 2 pounds of pressure and fires back in at about 1/2 pound of pressure. BUT when I watch the pressure gauge the pressure falls very quickly. It may only take 20 seconds to go from 2 pounds to one half pound and turn back on again. The system has added 10 gallons of water since installation. There is no leaks in the wet return lying on top of the cement floor. I see that one radiator has a slight crack at the top on the vent-rite side: it sweats a little then stops. There are also 4 radiator shut-off valves that also sweat for a little while (until everything gets hot) I have never replaced the vents and I have been here 30 years, but they seem to work ok. Is this the cause of my pressure loss and reason that I have added so much fresh water ? Is this the reason that my former boiler died after only 18 years ? ( I replaced the first Boiler I had when I bought the house, it had an installation tag indicating it was 48 years old and it worked great until the day it died, my fault for not blowing down the cutoff, the shut down failed, and not manually adding water as I was supposed to, I was young then and didn't know better). The Victorian style house was built in 1884.

SteamingatMohawk

How much water did the old boiler use? Did the situation change with the new one? All leaks should be fixed as much as possible.

ethicalpaul

I feel like you are making an incorrect connection in your mind between the steam pressure and the water usage of your boiler. They aren't really connected that way. There can be relationships between them, but not as I see your case.

The fact is that when the boiler stops firing, the pressure will drop very quickly. This is because the steam in the system condenses very quickly to water which takes up much less volume than steam. This is happening constantly during a heating cycle, and when the boiler stops making new steam, the pressure drop is very quick, just as you are observing. This is completely normal and expected.

Also I get the idea from your question that you feel steam pressure is a desirable thing. It is not, especially in many two pipe systems. The fact that your brand new boiler sees 2psi tells me that the installer did not size the new boiler to your radiation, resulting in you having paid for a larger boiler than you need, burning more fuel than you need, and cycling more than you need.

Jamie Hall

The pressure loss rate is perfectly normal. To give you a comparison, the system Cedric powers drops from cutout (6 ounces) to cutin (2 ounces) in about 10 seconds.

The water use is a little high, but not indicative of a major leak. Most likely it is from that crack and the leaking valves. The latter you may be able to fix by just tightening the packing nut or at worst repacking them. The crack... um. You might be able to get away with getting it really thoroughly clean and using JB Weld on it, but I wouldn't want to guarantee that -- and it may look pretty horrible.

18 years is not an unusually short life for a boiler. Not a particularly long one, either.

KC_Jones

You say 2 pipe, but then mention vents. If you have true 2 pipe, you shouldn't have vents and you should be running at ounces of pressure. Honestly I think they should all be running at ounces unless the boiler is oversized or the venting is messed up. Can you post a picture of a typical radiator to confirm what system you have?

10 gallons in 2 months I would consider excessive, and could have contributed to the 18 year life span of the previous boiler. Unless your system is huge, I'd say 1 gallon per month would be normal.

AdmiralYoda

I'll comment on the "small" leak and the potential water loss. I was filling up my 38 year old boiler once a week, probably 5 gallons during peak heating season. I had a radiator with a small leak between the sections due to a bad push nipple.

The radiator normally wouldn't hiss unless it was under pressure but even then it was minor. Maybe a few drops of water here and there but not much.

I replaced the push nipple and no more leak....and no more adding water to the boiler. I was convinced my boiler had a steam leak above the water line but it turns out a minor crack can lose a lot of water!

Jamie Hall

My point on leaks exactly, @AdmiralYoda

Paulvar1

SteamingatMohawk said:

How much water did the old boiler use? Did the situation change with the new one? All leaks should be fixed as much as possible.

I really dont know how much the old boiler used. It was an automatic water feeder with no meter like my current system has.

Paulvar1

KC_Jones said:

You say 2 pipe, but then mention vents. If you have true 2 pipe, you shouldn't have vents and you should be running at ounces of pressure. Honestly I think they should all be running at ounces unless the boiler is oversized or the venting is messed up. Can you post a picture of a typical radiator to confirm what system you have?

10 gallons in 2 months I would consider excessive, and could have contributed to the 18 year life span of the previous boiler. Unless your system is huge, I'd say 1 gallon per month would be normal.

KC_Jones said:

You say 2 pipe, but then mention vents. If you have true 2 pipe, you shouldn't have vents and you should be running at ounces of pressure. Honestly I think they should all be running at ounces unless the boiler is oversized or the venting is messed up. Can you post a picture of a typical radiator to confirm what system you have?

10 gallons in 2 months I would consider excessive, and could have contributed to the 18 year life span of the previous boiler. Unless your system is huge, I'd say 1 gallon per month would be normal.

The radiators have a supply side of 1 1/2 inch pipe and a return side of 1" pipe both at the bottom of the radiator. They all have vent-rite vents on the return side. It is known as a 2 pipe open system (Dan Halohan mentioned this in a video as did all the different plumbers (4) that ever came to my home). The radiators are 39" long x 44" tall x 10" deep. All the return pipes go to a wet return on the basement floor and the supply comes from headers off the boiler

JUGHNE

Have you compared the connected EDR to the nameplate on your new boiler?
Are your supply pipes insulated?