How often do you add water to an oil boiler? (steam heat)

CoachBoilermaker · September 12

I saw a few comments about adding water:

I always let mine boil the water and heat the radiators for a while after adding water.

"heat up your boiler after adding water at the end of the season (to avoid having the same water line all year)"

I was told to drain from low water valve each week, until water is clear (few seconds of draining) and then refill the sight glass to half.

Am I supposed to do more? Is there an annual drain and fill? What exactly is supposed to be done?

Jamie Hall · September 12

Generally speaking, what you are doing is just fine. It's not a bad idea to blow down a boiler from one of the drains — not the low water cutoff which is what you are using (I hope) for the weekly bit) once per season, but… it's not the end of the world if you don't.

AdmiralYoda · September 12

Keep doing exactly what you are doing. It isn't great to add cold make-up water to a screaming hot boiler since the hot metal might not like the cold water.

When I blow-down my boiler I usually lower the thermostat and let the boiler cool a bit then drain the crud out of the LWCO and maybe a little out of the boiler drain just incase there is some sludge, there usually isn't. I then fill it up to about the 2/3rd line on the site glass and then turn the thermostat back up to temp.

It will boil the water and drive off any free oxygen. Free oxygen can contribute to increased corrossion.

My boiler is old and the water will get cloudy and eventually dirty after a month or two. I drain and fill the boiler usually twice per year. Some people don't. I let it cool down before I drain and fill it and then run it hard for a bit to give it a good boil.

Some people's domestic water doesn't play nice with the metal in boilers. Low pH, chlorine, other stuff….my domestic supply is great so it works out fine.

SuperTech · September 12

Are you referring to a steam boiler? It would depend on if you have a float style low water cutoff. On a hot water boiler I usually only drain a little water once a year to check and recharge the expansion tank.

CoachBoilermaker · September 12

https://forum.heatinghelp.com/discussion/comment/1810284#Comment_1810284

Thanks. I'll ask the tech what he does, the next time he's doing a service

CoachBoilermaker · September 12

https://forum.heatinghelp.com/discussion/comment/1810286#Comment_1810286

Not sure what I have. Here is a video of the main sections.

https://tinyurl.com/3frutcpb

Big Ed_4 · September 12

How tight is your system , I had them down to 5 gallon a year on a small system .. Good working air vents and no leaks are needed tighten them up… Mud indicates steam leaks …

ethicalpaul · September 13

I wouldn’t drain weekly. (Edit!! Except you have a float style low water cutoff that does need to be drained weekly to flush it out—see post below)

The problem with it is you are trying to keep it clean, but by introducing fresh water you are increasing the corrosion and the “mud” (rust) being produced, ironically adding to the dirt problem,

once per year drain just enough till it runs clear, and keep your ph at 11 which will also minimize corrosion and resulting dirty water

Something like that

Note That your subject line is different than the question you asked (adding vs draining)

Add as little as possible by ensuring no water or steam leaks.

CoachBoilermaker · September 14

https://forum.heatinghelp.com/discussion/comment/1810325#Comment_1810325

Confused.

Let's agree on terminology

A) Adding means drain a few seconds and refill sight glass.

B) Empty and refill means fully draining the boiler.

I was told to do "A" every 1-2 weeks. I think clean water has lower boiling point.

I have never done "B", but maybe the annual tech does that?

CoachBoilermaker · September 14

https://forum.heatinghelp.com/discussion/comment/1810285#Comment_1810285

Let's agree on terminology

A) Adding means drain a few seconds and refill sight glass. (blowdown)

B) Empty and refill means fully draining the boiler.

How often are you doing "A"?

You are doing "B" twice a year.

ethicalpaul · September 14

Your “A” is not my definition of “adding”. “Adding” is adding water, for example, when the water level is low for whatever reason.

In your video I see you have an old float-style low water cutoff (LWCO) so I have to correct my earlier reply. You have to drain a little from this (what you called “valve #1 in your video) every week. The manufacturer documents exactly how.

Also that LWCO I believe is supposed to be replaced every 10 years. Consult the manufacturer documentation.

Otherwise:

I say drain a little from the lowest drain once per year to clear any mud.

I say never perform drain completely and refill. There’s no point.

CoachBoilermaker · September 15

Ok, so I will keep doing the same.

Each week, drain a few seconds and refill sight glass.

Never a full drain and refill

JUGHNE · September 15

Your valve "A" is the low water cut off, a very critical safety device on the boiler, AKA the LWCO.

It is probably the only LWCO on the boiler.

You should put a bucket under it while the boiler is firing, open the valve, be prepared for hot water/steam.

Keep it open until the burner shut down……there is a electrical switch inside that will shut the burner off in the event your water level gets too low……very important that this functions correctly.

Not only are you testing the switch operation, which depends upon a float inside of the iron housing, but you should be flushing the crud/sludge out of the housing. If this builds up the float may not drop as needed and the boiler could run out of water and dry fire……not good.

These are fairly easy to take apart and clean, requires only one gasket. If you have someone do that, they also could extend the drain pipe so you could have a bucket on the floor to catch the water.

You should "blow down" the LWCO every 1-2 weeks…..while the burner is on.

AdmiralYoda · September 16

@ethicalpaul Why never completely drain and refill? If I simply do blowdowns to clear the float type LWCO and add a bit of water to top it off and periodically add a little water to make up for lost steam…my water will be pretty murky by the end of the season.

Murky enough that it will cause some surging. So I completely drain and refill at the beginning of the season and somewhere in the middle to keep the water relatively clean.

Fun fact. I have been using Rectorseal 8-way for the past 5-ish years to get the pH up to 9-10 to prevent corrosion. Perhaps the 8-way is just slowly cleaning the junk out of the drip leg and boiler over time? If I recall though the water still got nasty, perhaps even nastier prior to using the 8-way.

SuperTech · September 16

Fresh, oxygen rich water causes rust and corrosion, this leads to boiler failure. This is probably part of the reason why your boiler water gets so nasty and causes surging. Piping issues and dirty condensate return problems can be another cause.

ethicalpaul · September 16

Note I did say:

once per year drain just enough till it runs clear, and keep your ph at 11 which will also minimize corrosion and resulting dirty water

The reason why never to drain and refill is to minimize needless fresh water introduction. If you drain the whole thing and refill it, you are likely creating more brown water.

Yes, the 8-way could definitely be removing rust and/or scale from the interior of the boiler. It does contain ingredients that are supposed to do that. I would say try to let that stuff settle out a little bit, then drain some water to flush some out periodically. Just not all the water.

CoachBoilermaker · September 18

Ok, I now understand the difference between draining the Weekly Blow down of LWCO to clean out the float (versus a total boiler drain, which seems optional/debatable)

8:00 mark

https://youtu.be/9KutfrNrmNE?si=f5CMj5hwcCsZV0Qp&t=500

How often do you add water to an oil boiler? (steam heat)

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