Steam Oil fired boiler comes on with thermostat all the way down

Leo

One thing to keep in mind,

It seems this unit has been in service and I assume trouble free for many years. Someone put the aquastat on for a reason. It may be best to let the sleeping dog sleep. All too often these units get brushed out and vacumed in the spring then shut off for the summer. The moisture builds up during the summer then everything loosens and falls inside. Now the oil tech and oil in general get blamed when it is not their fault.

Leo

Bobby the Plumber

steam, oil fired boiler turns on by itself & thermostat is down

My steam, oil fired boiler turns on by itself & thermostat is set as low as it can go (approx 50 degrees) and house temperature is approx 70 degrees. I know with zone valves I'm supposed to set heat anticipator to match thermostat. I have no zone valves here. Is there something similar on an oil fired burner?? This is a small residential home. Is my thermostat bad? It seems to work well in winter. It's in the summer when I've turned the thermostat all the way down & it still comes on that bugs me. I've been turning it off @ the switch by the boiler. But as we get closer to the heating season I find I'm having to go outside, around the house & into the basement to to flick the switch so it can turn on as the air get chilled in the evening and as the day gets warmer, I have to make the trek again to turn off the switch so it won't come on by itself @ inopportune times. So much for automatic operation. Any feedback is welcome.
P.S. I'm a plumber who works on other peoples but can't do my own. I suspect it's related to the mysterious oil burner I freely admit I know nothing about.

JOHN_103

do you have or did you have a tankless coil on here at one time? maybe theres an aquastat thats mantaining temp.

Leo

It is probably an aquastat maintaining temperature to keep the boiler from plugging. There are some boilers more prone than others to plugging when left cold and the service call in the fall out weighs the cost of oil used to maintain a low temp. Not to mention the aggravation.

Leo

Unknown

I agree with John and Leo

The easy way to see if the thermostat is the problem is to disconnect one wire from it and see if the burner still kicks on . But if you have a coil on the boiler for hot water I'd guess its the aquastat is bad or set too high or the well it sits in is crudded up .

bob young

dom. h.w.

but if he is shutting the power switch and he has a coil & aquastat would he get no domestic hot water ? i am sure he would notice that . must be a defective thermostat i would say.

Leo

He can have an aquastat without a coil to maintain a low level in the boiler. In his post he never said the house overheated.

Leo

Unknown

Yeah , I've seen a bunch

of steamers without a coil or with an abandoned coil , with a still functioning aquastat to maintain temp .

Bobby the Plumber

I do have an aquastat but I have a seperate elec. water heater.

You might be onto something there. There is an aquastat set to 100 degrees on it, wired to the control box on the oil burner. It looks like what might have been a tankless coil although I don't see a place where the cold & hot water lines would have entered & exited. I don't need that now as I have a seperate electric water heater for the domestic water. Is there any other possible reason for an aquastat on a steam boiler? (I can't think of one) Should I just remove it from under the screw terminals on the boiler oil burner control box?

Unknown

It could be the only thing

that's keeping the boiler sections and/or rubber gaskets from leaking , depending on how old the boiler is and what shape . You can check to see if it's the aquastat control that's giving you the problem by removing one wire from a terminal . If that's the probelm , I'd change out the aquastat and well and keep some heat in the boiler till you get a new one .

Leo

If your boiler has an aquastat set at 100 then it is there to keep the boiler warm. For the price of oil it is cheap compared to the can of worms opened if the boiler cools off. It can happen to any boiler but if you have a Weil Mclean or a Peerless JOT you are asking for problems if you cool iot down. I work on these all the time and have nothing to gain by advising you of this.

Leo

Bobby the Plumber

Interesting. I guess you must be right. I've never heard of that. So it sounds like you all recommend keeping it in there & letting it run occasionally. That oil is not getting any cheaper but I guess it's a lot cheaper that getting a new boiler. I may tempt fate and see what happens if I eliminate it just because it bugs me to hear that thing run when the thermostat's not calling for hear. (I don't think it gets that cold). It's an HB Smith for the record if that matters. I going to guess 20 years old but I could be off by a few decades. Thanks for the advice.

scott75

what would happen if the boiler cooled off? I have a steam system without an aquastat that only kicks on with a call from the thermostat. I don't have any trouble.

Leo

If this is the HB Smith FD (?) 12, a small blue unit they leaked and most are gone KEEP IT WARM. If it is one of the other models they get scaled up which in turn soots up. My complaint is most people "WON'T LISTEN" let them be cold and call on a Sunday night for no heat. The cost of the service call far out weighs the money saved on oil. Given you are a plumber if you can clean it yourself then you may be ahead of the game. For another person that asked I have seen Peerless JOT boilers get so crudded up they begin to get back pressure over the fire that can't be relieved. This is not a good situation. Not knowing you I could care less if you buy oil or not but as a professional I don't want to see you haveing service problems. As a side note Timmie Mcelwain has also said on gas systems since standing pilots were eliminated they are seeing a detrimental effect.

Leo

Unknown

More than likely

nothing will happen . It's the boilers that have maintained constant temperature then become cold starting that we see things leak . Just about every old hot water boiler we work on will leak at the gaskets if you have to drain it down and fill it back up with cold water , or if it sits cold for a prolonged time . Funny thing is , once it heats back up the gaskets stop leaking ( most of the time ) .

Unknown

Bobby

I'm not familiar with the HB Smith , do you know how the sections are put together ? Yep , you can eliminate the aquastat , just keep an eye on the boiler and make sure the coil gasket don't leak . It doesn't take much time for water to corrode the coil plate and the cast iron .

Bobby the Plumber

Boy, you guys are giving me a lot of food for thought. I'm not real big on maintaining my stuff even though I recommend it to all my clients. (At least they're paying me to do it.) I did have a lot of problems last year with it not firing properly but I hired an oil burner guy to fix it and after 3-4 times I think he got it right. At least it doesn't cut off and the flame sounds more or less correct now. I guess I should get some gadget that analyzes something in the flue thet will tell me something else. Do you revcommend any particular brand & model to do that? Of course I wouldn't know what to do after that so I guess I need some training on that subject. I don't think Dan's classes include oil burners @ least not the ones I went to years ago.

Bobby

Big Ed

Penny Wise

Leo set you right,I know he seen enough screwed up boilers in the start of the heatng season from home owners shutting off their boilers.Wore out a few soot swords too over the years.


I Just want to add that that warm boiler in the basement helps keeps it dry.Did you notice how damp it gets when you shut it down? It may be cheaper to run then a deumidifier....