Flooding boiler and spurting radiators

jbaskin

Hello,

I just moved into an old house with an oil boiler. We got new air valves for all the radiators and got the boiler serviced. It heats just fine, except that once the steam pressure hits about 1-2 psig, two things start happening:

1. two of the radiators start spurting water from their air valves (on the 2nd floor only -- 1st and 3rd are ok!) I also hear a gurgling sound in these radiators -- but no water hammer
2. the water level drops enough for the automatic feeder to kick in, so the boiler ends up with a too-high water level after heating stops.

When we first moved in the boiler water was very dirty with rust, I flushed it out but we are still getting more rust (from the pipes I assume) when running the boiler so I blow down the boiler regularly (1-2 days). Maybe these radiators are just full of sludge?

The Internet suggests that spurting water from air valves is usually a sign of bad valves but these are brand new! I am wondering if we are getting very wet steam, but then why is it only these 2 radiators and not the ones on the floor below? I was also worried that the radiators were pitched incorrectly but I checked with a level and they look fine.

Photos of the boiler below. Thanks in advance!

Zipper13

I'm still very new to understanding my own steam heating system, but I think a lot of people here will suggest that the piping is questionable and could suck some water out of the boiler into the mains triggering the autofill? You will definitely be asked for more pictures of the near boiler piping.

Jamie Hall

Well... I'm sure you are getting wet steam; there is no way to avoid it with that header arrangement. Furthermore -- I can't see in the picture, but is there an equalizer on that header? Can you add a couple of more pictures -- three more -- of the other three sides of the boiler?

Second, the pressure should not go over 2 psi. In fact, it really shouldn't go over 1.5, and it looks as though the pressuretrol is set properly for that, though it's hard to see. But... is the pressuretrol seeing boiler pressure? It might not be a bad idea to take it off and make sure that the pigtail is clear -- and that the opening from the pigtail into the boiler is also clear.

I would temporarily disable the automatic feeder -- having verified that the boiler will shut off if the water level goes too low. Then figure out where the water is going when the boiler fires up and fix the problem.

You should not need to blow the boiler down -- never mind drain it -- more than once or twice a season, although that type of low water control does need to be blown down perhaps once a week. Adding fresh water to a boiler unless really needed isn't a good idea.

On the radiators which are spitting water -- check and make sure that they have some pitch towards the inlet valve and that the inlet valve is fully open.

I think there's more work that will need to be done here...

jbaskin

Thanks! Here are some more pictures including a close-up of the pressuretrol with the cover off. The differential was set to 2, so it should only have cut out at 2.5 psi, I just reset it to 1 as you can see which should hopefully help.

(I believe the pipe on the back of the boiler is an equalizer?)

Jamie Hall

Setting the differential to 1 should help. Maybe a lot.

And yes, that pipe on the back of the boiler is the equalizer. Not, mind you, that header is piped correctly --but at least it does have an equalizer (the header is piped riser/steam main/riser/ equalizer; it should be riser/riser/steam main/equalizer)(and it is kind of low) so that, at least, is not the cause of the disappearing water. The piping sequence on the header does pretty well guarantee wet steam, though.

Since you are getting a gurgling in those two radiators -- and only those two -- but no hammer, the very first thing I would check would be that the inlet valves are fully open.

jbaskin

OK that makes a lot of sense, I don't think the water drops low enough to trip the feeder at 1.5psi so fingers crossed.

Re the radiators, I don't think it's the inlet valves because they are both all the way open (I triple-checked) and brand new. I do get a bit of water hammer but only at the very end of the cycle...

Thanks again!

Fred

Take the Pressuretrol off of that pigtail (looped pipe) and make sure the pigtail is not clogged. If it is clogged, the Pressuretrol can't see the system pressure and it may be running high enough that water (condensate) can't get back to the boiler while the boiler is running.

EBEBRATT-Ed

Contrary to popular beleif you should not be building steam pressure in most cases. Also, check and see if the service technician can install a smaller nozzle in your burner and still retain good oil combustion Your wasting fuel if your building pressure on a residential job. T.oo much pressure will cause burner short cycling, unstable water line and waterlogged air vents. Also check the pitch on all your piping

First step, measure all your radiation installed in the house and add up the total and get your total installed radiation in EDR or square foot of steam (same thing)

once you get this total multiply it by 233x 1.33 then multiply it by 1.25 (boiler efficiency) then divide this total by 140,000 (btu/gallon of fuel oil)= nozzle size

Equation: total installed EDR x 233 x 1.33 x 1.25/140000=gph rate of oil you need to burn.

Example: 500EDR x 233 x 1.33 x 1.25/140000=1.38 gallons/hour nozzle size. In this example your technician would adjust nozzle size and oil pressure to fire approximately 1.38 gph and check combustion with instruments.

Your near boiler piping is far less than ideal. Firing at the correct rate may help to calm things down.

jbaskin

OK now I have my pressuretrol set right and things are better.

One thing I noticed: when the pressuretrol turns off the boiler, the LWCO loses power too (the green light goes out) which doesn't happen when the thermostat turns the boiler off. Is this normal, or is something miswired?

Jamie Hall

Well, it's one way to wire it. But yes, the thermostat control can be separate.

JUGHNE

On the back of the boiler is there a return pipe coming up out of the dirt? Then there is another smaller pipe connected to that, is that from your water feeder, and it looks like there is a check valve there.
Another picture would clear up what is what.

jbaskin

Good eyes -- sitting underneath a pile of coal ash (!) is what could be a check valve:

Among other things it might be time to clean out the cellar.

JUGHNE

Those check valves were used for safety before the Hartford Loop was introduced. Some hung around after that apparently.

It was meant to keep the water from draining out the bottom of the boiler is the wet return pipe leaked. The HL requires the boiler water to jump up out of the boiler to be lost.
And we also now have LWCO' s to shut down the fire.

If you have slow water return to the boiler this may be the main suspect/culprit. The flapper has to open by gravity flowing water and then not very far. This is possiblily a catcher of sludge and blocking the return water.

IIWM, I would dig more dirt out from under the union that is just before the boiler on that pipe (I am assuming dirt floor there). This will give you a drain for the nasties that might come out of that return pipe. I would crack the union open....2 wrenches.....and drain the water down into the ground.
Then a hose on the drain fitting of the wet return would lower the water level even more.....it too could go into the ground if that works.
Then the top square plug of the check valve could come out.
There is a flapper inside held in place by the small bolt head screw on the side. Just remove the flapper and close up.

An impact driver with the proper square head socket may make this easier. Other wise use 2 wrenches.

You could back wash thru the drain fitting and maybe flush some crude out of the wet return. A push of water and drain several times might produce some blockages being removed or at loosened up. This junk will end up in your boiler bottom eventually and need drained out.

Please let us know how this goes.

Also is that a 90 elbow or tee between the check valve and boiler.....could be under ground return pipe also?? Dig a little more up....could be another check valve if a pipe there.

jbaskin

I have a boiler mechanic coming Wednesday so I'll try and get a quote for flushing the wet return and taking out the check valve, but I have a feeling this is a project that will wait for spring. We'll see!

jbaskin

And it's an elbow, nothing going underground.