Oil Burner, Radiators getting hot

shandi235

hey all, I have an oil boiler that's around >30 years old. No water heater. The issues I am having with it lately is the steam radiators are filling with steam when the shower is on any longer than about 8 minutes.

I'm a novice when it comes to these things, what information do you need from me? I've seen a few other threads so I went downstairs and took as many photos as I could, let me know if you need more

Jamie Hall

The grey box labelled "Honeywell" at the bottom and with a small temperature dial at the top (third to last picture) is the aquastat. It should be wired in parallel with the thermostat to the burner control. What is intended is that it should keep the boiler warm, to make your hot water, but it should turn the boiler off before it gets to steam temperature unless the house thermostat is calling for heat.

That's not happening.

Which suggests that it may not be working properly. They can be replaced…

mattmia2

Or the probe for the aquastat is above the water line. what is the level on the sight glass?

mattmia2

Open the manual fill valve until the water line is about in the middle of the sight glass and see if the problem goes away.

the schedule an oil burner tech to clean and adjust the burner.

Robert O'Brien

It is amazing how improperly piped jobs will work just fine and yet other jobs with the slightest piping error will be a nightmare.

shandi235

Thanks, I will go and try to fill it up, I have noticed that in the past that the water level seems to drop to about where you see it now in the photos. If the water probe is in fact above where the sight glass level is indicating, could my auto-feed be the issue? Is it not filling the tank enough?

EdTheHeaterMan

There is one thing that may be happening. If the hot water is not exiting at the bottom of the tankless coil, that the water temperature near the aquastat sensor may be cooler even though the boiler is steaming.

To test this, turn on a hot water tap in the house somewhere and see it the top is hot or cold. It should be cold. Also I did not see a mixing valve on your hot water piping, It may be there but hidden behind something. If you do not have a mixing valve then you should have one added. even if the cold is piped into the bottom and the hot is coming out of the top. under the right conditions, someone could get burned from opening a hot water tap or shower valve.

Here is a diagram of how a mixing valve might be connected to your boiler. There are several types to look for on your system. If you don't see something like this with three. pipes going to it then you may not have one. Then you should get one installed by a plumber.

shandi235

Thanks guys for more insights, I went downstairs and started to feel the pipes.

Here's an updated photo that shows the entire pipe configuration around the Aquastat

I felt the pipes, and color coded it, the top pipe coming down is cold water feeding from the main, however once it hits that top elbow it's HOT. I used my thermometer and it was about 110F, the hot pipe coming out of the bottom was around 140 F

Is this normal that the hot water is… backfeeding?

EDIT: What is this? What function does this provide?

EdTheHeaterMan

That hand operated valve is someone's attempt at providing a mixing valve. That is not acceptable. There are times when the home is being heated, that the water in the boiler gets to be 215° around that hot water coil. If you are not using the hot water, that water in that coil will get very close to boiling temperature. At other times that same water can be only 140°F. so you need a valve that will AUTOMATICALLY adjust the handle in real time as the boiler goes thru the lower temperature hot water only or full on steam heating… and anything in between. I would ask the plumber that puts in a manual valve "Who is going to be there to adjust the valve as the call for heat changes from hour to hour?" YOU NEED A MIXING VALVE!

shandi235

dang ok, I'll talk to a plumber who has done work for me on other projects to put in a proper mixing valve.

Interesting to note that we just gave the children a bath and used more hot water than normal, on purpose, the furnace did not call for water, did not kick on and obviously did not cause the radiators to heat up.

Is there a way that I can adjust the minimum fill for the furnace? It seems as that might the issue, there just isn't enough water in there in the first place. I also noticed that our hot water pressure seemed a bit better. Is this problem actually the auto-feed?

EDIT: I googled the auto feed part number, it says to replace that unit every 10 years, and change the filter every year. I've been in this house 6 years, I didn't even know that thing had a filter in it. This house was a rental unit before we purchased it. I'm gonna go out on a limb and say this auto-feeder is at LEAST 20 years old, if not older. I think first thing is to bring the auto-feeder into the 21st century.

mattmia2

You should really be checking it once a week or so and keeping it about half way up the gauge glass along with blowing down the lwco. When it is steaming and there is condensate out in the system when it drops to the level where the feeder fills, once the condensate returns to the boiler the level will be higher so it probably keeps the level high enough during the heating season.

If the level drops significantly when it is just doing water heating you need to look for a leak in the returns. Some water will evaporate through the vents but if it falls from the center to where it is now in a couple weeks and it hasn't been steaming there is a leak somewhere. If it fell that much over the summer, especially if it was just where the auto feeder put it, that could just be evaporation.

shandi235

Good morning! I had to search for what blow down meant. I did that this morning, I drained out of the black unit that's infront of the boiler, I am assuming that's the low water cutoff. I slowly opened and shut the valve until the water ran clear.

While I was doing this the sight glass kept getting lower and lower. The boiler never called for water.

I also noticed that my auto feed is connected to the loop but it seems like it's connected into my steam pipe loop. The pipe coming into the top of the aquastat is being fed off my main cold water line in the house.

Is this correct?

shandi235

A little more context. I have stem radiators, no water heater

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1813215#Comment_1813215

yes

EdTheHeaterMan

OK, this is interesting.   You have a steam boiler that has been neglected for years.  You might want to look into finding a good steam boiler person. Use the "Find A Contractor" link above. to see if there are any contractors in your area.  Not all plumbers are knowledgeable on how steam systems work.

To be clear about your hot water system, and all the rest of the steam boiler parts that make the radiators hot.  Domestic Hot Water (DHW) in your home comes from a tankless coil that is inside your boiler that water is separate from the steam system.  The Low Water CutOff (LWCO) has nothing to do with DHW.  Think of it like this.  You have a barrel of hot water, then you put your garden hose in the barrel.  Then you run cold water through the hose.  Then the cold water absorbs the heat from the barrel, and the water comes out the other end of the hose hotter than when it went in.  The water in the barrel did not change.  It only let off some of the heat.  

Now if the barrel water lets off too much heat, the oil burner under the barrel will come on to heat up the water in the barrel.  So the water feeder to the barrel when the burner operates, and the water level in the barrel have little to do with the DHW.  All those factors are independent of the DHW.  All those other components need to just keep the water in the barrel at the proper level and proper temperature so the garden hose always has hot water available.  Sometimes the burner will operate in the summer when the boiler temperature drops, even if you are not using DHW.  Other times the boiler temperature is hot enough that the burner does not operate even when you are using DHW.  The two systems are independent of each other.  

It sounds like you flushed the LWCO and the water level in the boiler gauge glass dropped, and you expected the water feed to turn on to put the water back in that you flushed out. That sounds reasonable. But you may not have taken enough water out to activate the water feeder. You may also have a defective feeder. I think it is time to get a Pro that knows his stuff to make a house call.

Can you post some photos of your boiler?

shandi235

I can, my first post has lots of photos, do you need more?

shandi235

Hey all! Here's an update.

Got the boiler cleaned out today, professional came out and descaled the coil, now the hot water works perfectly. He also showed me how to make sure the sight glass has enough water to enure my coil is fully submerged. Hot water problem fixed, radiator do not go off when I need hot water, cuz it's already hot enough!

Now for the update: When he opened the stack to get down in there to clean out the soot on the furnace block…. he found a massive crack at the top of the block. I'm losing steam, that's where my water is going. Ironically enough after he did the thermal tests my furnace is 80% efficient, which he said was actually really good.

So now I'm in the market to move on from oil, I already have gas lines in the house and when we brought the gas in from the street we plumbed the entire basement with fittings for the eventuality that the boiler would die, and we'd move away from oil.