Help with a new (to me!) oil fired steam system

merikus

Hello everyone!

I purchased a beautiful old house yesterday that came with a beautiful old oil fired steam heating system. When our offer was accepted on the home, I immediately purchased “We Got Steam Heat!”, “Greening Steam”, and “The Lost Art of Steam Heating Revisited.” I wanted to make sure I was ready to care for this house and this system. The only thing I’ve been able to figure out myself so far is these pipes really need insulation! But there are a few things that are really odd to me here. I hope you all will be able to help me with one of more of these questions. 

My first question is regarding what seems to be short cycling of my boiler during what is effectively summer weather here right now. Every few hours, I hear the boiler cycle on for approximately 60 seconds before it cycles off. Of course the initial thought would be that this is warming our DHW, but we have an electric DHW tank. This tank is linked to the boiler, and what the previous owner told me was I should toggle a switch (photo attached) to turn on a pump to allow the water to circulate from the boiler to the HW tank in the winter months to save on electricity.

My theory (but I really don’t know what I’m talking about here!) is that the DHW tank’s call for heat is somehow linked to the boiler—and it’s own internal electric system. So the tank calls heat, that fires up the boiler, also fires the internal electric system, it reaches temperature very quickly and the call shuts off, thus cycling the boiler in about a minute. 

I think that is supported by the photo below. The “Summer/Winter” switch appears to be wired to the thermostat for the hot water tank, which is in turn wired to the controller for the oil burner. I would think this summer/winter switch would kill that connection somehow, as it is between the DHW thermostat and the oil controller. But clearly I’m wrong here since the boiler is turning on for no reason and something odd is going on here! Here’s the wiring of that system which I think supports my hypothesis, but I don’t know what to do about it:

My second question is regarding the overall setup of the system. When I look at the radiators it appears to be a one pipe system, but when I then look at the piping in the basement it almost has qualities of a two pipe system! I’ve attached a picture as an example. Off the riser I have three main steam runs going north, south, and east. At the end of each of these runs where the pipe should elbow up, there is instead a T and the T goes (on one side) up to the radiator and (on the other side) down to a smaller pipe that heads to the return. (I’ve pictured the east run, which will make sense why in the sentence after the photo.)

This east run photo here is the only one that has a vent on the steam pipe itself—none of the other steam runs do. However, I have vents on all three of these small return pipes.



They are all also covered in white gunk, as is the main vent at the end of the east run. Is this even the right kind of vent, and are they properly placed? 

Even odder is whatever is going on at the end of the south run which makes no sense to me (pictured—what’s up with that loop?). 

I’m also trying to figure out what all these things are on my boiler. 

I think the one on the top is the pressuretrol. The one on the middle is the most confusing to me. 

I think it has something to do with my thermostat (the brown wire leading off of it connects to the main oil controller and to a brown wire headed in to the my house, and my guess is that it’s the thermostat). But why does it have a dial, and why is that dial set to about 190? 

On the bottom is the burner controller I think. 

Is there a way to set this so it ignores the hot water call during the summer? Also, any way to run a C wire off this thing so I can install an Ecobee thermostat?

My next question is far less of a big deal than the other ones, but all of my radiators have these marble tops. The previous owner said he put them in because it “keeps the air from going up” (we have 10 foot ceilings!), but my thinking is that all they’re doing is messing up convection. I’m thinking of taking them off. Thoughts?

Finally, how do you find someone who really understands this stuff? The guy who has worked on the boiler forever (he installed the thing)—I can’t tell if he understands steam or not. I’m worried that this boiler has been short cycling for years due to this DHW issue and hasn’t been addressed—also worried that the main vents seem sort of odd and that hasn’t been addressed. Are there questions I could ask to sort of gauge if he’s a steam guy? And if not, how do you find a real steam guy?

Thank you all!

JUGHNE

Try "Find a Contractor" at the top of the page.

Where are you located?

merikus

We are located in Vermont. 

Jamie Hall

merikus said:

We are located in Vermont. 

Oh. Steam folks seem to be a bit thin on the ground up there. Not sure why. However, never fear, there are other ways to go.

The domestic hot water -- that control with the temperature dial in the picture is an aquastat, and it is telling the boiler to maintain a certain minimum (and shut off at a certain maximum) temperature. You are going to need to do some pipe tracing and wire tracing to figure out how to safely disable that system -- which will most likely end the short cycling problem.

How do the pipes run from you cold water supply (are you on a well, by the way?) to the electric water heater? I'm thinking they probably run through the plate with the aquastat on it -- in one side, out the other; that plate is probably a domestic hot water coil in the boiler itself. If so, there's no harm to leaving it just like that. Now find out where the wires from the aquastat go. They are probably connected in parallel with the house thermostat and eventually to the burner control, but you will have to verify that. If they are -- and you want to run that hot water coil in the winter -- simply place a switch in either wire from the aquastat to where it ties in with the house thermostat, and then turn it off to stop the aquastat from firing the oil burner. That should do it. If not, come back with as complete a wiring diagram as you can for the whole thing and we'll try to figure out what does what.

The piping dropping down and then going along -- the smaller, lower, horizontal high level pipes are condensate and air returns. It may have been done that way to avoid having wet returns cluttering up the basement floor. In any event, it's a perfectly good way to pipe things. That siad, those vents you noted near the boiler are functioning as main vents -- and are woefully undersized for the job. Both you and your system will be a lot happier if you replace them with bigger ones -- I'd suggest Gorton #1 or #2s.

I have no clue as to what the trombone hanging from the ceiling is meant to do. However, it probably does no harm.

The Carlin ProX box is the burner control, and a good one. It has some very handy features -- however, if the previous folks didn't leave the manual for it, it's hard to use them. Downloading this: https://carlincombustion.com/wp-content/uploads/MN70200B-062819-Instructions-web.pdf
will solve that problem!

You are right -- the highest square blue-grey box is the pressuretrol, and -- for a wonder -- it looks as though it's probably set reasonably.

The insulation on top of the radiators is quite unnecessary... but insulation on the steam pipes would be a very good idea indeed.

JUGHNE

That "trombone"/ return bend looks like it has a rad vent on the top. Maybe a pipe heater for basement heat?

mattmia2

My guess is that the pump for the dhw heating from the boiler is connected to that switch and the aquastat only keeps the boiler hot all the time. For summer shutdown i think they were turning off power to both the boiler and that switch to the pump. The pump is probably 240 v and powered off the water heater circuit.

merikus

Thank you for the very detailed reply! 

Based on your comment I took a more detailed look at how the system relates to the aquastat. The aquastat on the boiler doesn’t have anything going through it—the only thing it has is what looks like a pipe (or perhaps a probe?) going into the boiler itself. 

It also has a brown wire coming out of it which is spliced with my regular thermostat wire and the spliced together wire then goes into T1 & T2 on the Carlin controller. 

The controller also seems to be wired to the pressuresol, the main cutoff switch, and whatever this thing is:

I did a little pipe tracing as well. My well water comes off the pressure tank and then heads to a water softener. After it comes off the water softener, it heads to a T, one side of the T which goes to the electric hot water tank an the other side which goes to that McDonnell thing above. The side that heads to the McDonnell pump then heads into the boiler here (you’re seeing the backside of the McDonnell pump right above the yellow cutoff level, water flows down through that to the really big pipe that also takes in the condensate back into the boiler):

There are two additional pipes (aside from the main steam pipe) that come off the boiler itself:

The one on the left heads to this circulator pump and then into the electric hot water tank:

And the one on the right also heads to the hot water tank, but comes in on the bottom:

I’m wondering if the one on the right is a feed in bringing water out of the DHW tank to the coil, and the one on the left is a feed out, taking water out of the coil to the DHW tank  

Now, following the wiring, the main power comes in through this emergency switch:

And then heads to this thing:

Two wires come off the main power. One goes to the circulator pump switch and then through that to the electric hot water aquastat:

The other wire heads down to the main oil controller and then up to the pressuretrol and over to the pump I indicated earlier. 

If I’m starting to understand this correctly, water comes into the DHW coil from the DHW tank  when that water is too cold, it’s firing the boiler, but it’s cutting off real quick, which makes me wonder if the LO or DIFF on the boiler aquastat is set wrong (how would I check that?). The water then flows out of the coil to the DHW electric tank—but that’s not being circulated in the summer because the circulator pump is off.

Anyway, it seems that the logical thing would be to either figure out if the LO or DIFF on the boiler aquastat is set wrong, or, wire a switch between the aquastat and the spliced aquastat/thermostat line. In the summer I’d switch the aquastat off, and in the winter switch it on. I also am going to replace all the air vents with Gordon #2s (the three at the returns for sure—should I also replace the one on the east steam run? And I think there might be one on the trombone, should I even try to get at that? It’s in a super awkward place over an old cistern).

Thanks a million, this is very helpful and really getting me to think critically about this system!

merikus

JUGHNE, that’s a real interesting point! I thought that was a vent on the trombone, but it doesn’t look like any vent I’ve seen in books. That would make sense as it is in a more utilized part of the basement. 

merikus

mattmia2, I was actually asking myself “why is this boiler even powered on in the summer?” But part of the problem here is the power for the electric DHW is served by the same power line as the boiler, so if I shut that switch down I’d lose hot water. 

I can’t help but wondering if there’s a way to shut down the aquastat on the boiler or shutdown the boiler as a whole for the summer, but I simply don’t know enough to know what to do there. I also heard it’s good to run your boiler every once in awhile in the summer? But maybe I’m wrong on that too. 

merikus

A small update. The boiler aquastat is a Honeywell L4006A with the temp set at 190 and the DIFF at 5. 

My electric hot water aquastat seems to be set at 140:

It seems to me I should be able to set the boiler aquastat to 140 and it should fix this problem...but I’m not doing so because on the other hand all I can think is that if the boiler aquastat was really set at 190 and the electric DHW was really set at 140 the boiler should be running all the time!

Unless I’m not thinking about this right and in actuality this aquastat at the top of the DHW electric tank is actually the circulator aquastat in this wiring diagram, and the DHW electric aquastat is elsewhere?

mattmia2

i see another aquastat in the top of the water eater, that controls the pump. the aquastat on the boiler fires the boiler whenever the temp of the boiler drops regardless of if there is a hot water call, it keeps the boiler always hot. that is why it only runs a couple minutes, it is just heating the boiler itself if the pump isn't running.

does that white romex that feeds power to the electric water heater connect back in to the boiler power somewhere? I would be surprised if it did.

merikus

mattmia2, you are right! I was reading the wiring wrong. The romex does not go back to the boiler, it goes to the circuit breaker box. 

Do you suggest I power down the boiler in the summer, then? I feel like I read somewhere you should run your boiler a bit every once and awhile if it is powered off. If that’s true, how often should I power it up and run it?

Thank you for that insight! You likely saved my boiler from all that short cycling!

Jamie Hall

Keep in mind that the boiler will fire if, and only if, the two terminals marked T1 and T2 (the left two) in the control are connected to each other. The job of the thermostat -- and, in your case, the aquastat connected to the boiler -- is to make that connection. The boiler is cycling quickly because that boiler aquastat is set with a 5 degree differential -- and without the pump running to the water heater, the burner is going to make up that differential very very quickly. If you want the boiler to heat your domestic hot water, even in the summer, I'd set the boiler aquastat to 140 with a 20 degree differential -- and leave it there. It will be plenty hot in the winter. If you don't want the boiler to run in the summer -- just depend on the electrics -- install a switch in one of the wires from that aquastat to where it is spliced to the thermostat wires, and turn it off.

Now -- regardless of where the aquastat is set -- to have the boiler heat the water in the hot water tank, you need to have that pump turn on when the tank calls for hot water, and at the same time enable the boiler aquastat to call for heat in the boiler, if needed. To do that you are going to need an aquastat in the hot water heater -- and you are going to need to have that aquastat control the pump and also a relay to close the circuit from the boiler aquastat to the thermostat wires (that switch I mentioned). I see no sign of such a relay, so you'll have to add it.

This is not wired anything like the Diagram 5 you posted. Sorry...

The McDonell Milller things are a low water cutoff and low water signal to the automatic feeder. I think based on what I see that all of that -- and the pressuretrol -- are on the 120 volt circuit to the burner control, but I'd have to check to be sure.

merikus

Thanks, Jamie, that makes a lot of sense. I now see that I was misunderstanding the entire setup. I think I just want to rely on the electric in the summer. Is there a specific switch you would recommend for this use case? I’ve never done any work like that before. 

mattmia2

Jamie Hall said:

Now -- regardless of where the aquastat is set -- to have the boiler heat the water in the hot water tank, you need to have that pump turn on when the tank calls for hot water, and at the same time enable the boiler aquastat to call for heat in the boiler, if needed. To do that you are going to need an aquastat in the hot water heater -- and you are going to need to have that aquastat control the pump and also a relay to close the circuit from the boiler aquastat to the thermostat wires (that switch I mentioned). I see no sign of such a relay, so you'll have to add it.

the aquastat on the water heater is 120v. It turns on the pump and moves water from the water heater and through the tankless coil in the boiler to heat it.

Jamie Hall

No specific switch -- being a somewhat tidy soul, I'd probably use an ordinary light switch in an ordinary wall box... and probably a plastic box from the dreaded big box store at that.

merikus

Thanks, Jamie! I’ll do that. The outpouring of help here has been amazing!