Do I have a 1 pipe Vapor System?

CKNJ

Hello again. I have been doing some detective work on my 1909 foursquare and need some help from the pros here. Here is what I have found so far. I was having an issue with the second floor heating up to 75 while the first floor would be 68. So, I installed Vent Rite #1's on all radiators. I have it in balance (sort of) with all 1st floor radiators set at 7 and second floor set at 2.

Now, here is what a cycle is like. Boiler comes on, mains are vented in less than 3 minutes (I have big mouths on the main). The first floor radiators get hot and the valves shut off, second floor radiators just starting to heat up. But the boiler (currently has a Pressuretrol) will now build up 1.5 lbs of pressure and stay that way until thermostat trips. To me that seems like an immense waste of steam and fuel. Which got me thinking. If it were a vapor system, wouldn't it heat more evenly with a vaporstat instead of what it is doing now?

Here is what I have observed and found:
- I believe the house had Vent Rite #11 throughout. I replace 2 of these on the second floor and 2 on the first floor and they were old. I thought it odd that the same vent would be used on both 1st and 2nd floors.
- My system has a 2" main and a dry return. Aren't dry returns usually found on Vapor? I believe I read that on the Wall also.
- The main vents are located at the ends of the dry returns by original design. This seemed a little odd to me, but again, I remember reading that was a Vapor trait as well.
- I measured the EDR and it is matched almost exactly to the boiler. this was the first place I started (with Dan's Book in hand).

I am thinking of putting a Vaporstat on the boiler (with the pressuretrol) to see if that makes a difference. But before i do that, if anyone has run across such a system any help would be appreciated as I believe I am wasting a lot of fuel here. Also, what settings would I use on the Vaporstat?

Fred

No, you don't have a vapor system. You have standard radiator vents and no vapor system could work with vents that open as soon steam drops away from any vents. You would also have some type of vacuum vents on the Mains/Dry returns. I don't know if there is a successful one pipe vapor system, even with some induced vacuum from a pump. What I suspect is happening is that you are closing enough radiator vents to cause the pressure to build to 1.5 PSI before the Tstat is satisfied (essentially over-sizing your boiler). That amount of pressure is not really a problem but it will likely go higher and cause the Pressuretrol to shut the burners off when the outside temps get cold enough for the boiler to need to run longer (some level of short cycling). I think the question is where is your thermostat located relative to the radiator, windows, is it on an outside wall? Do you have an open staircase that is acting like a "chimney" drawing warm air up the stairs? Is the temp actually 68 in all the rooms on the first floor or does it vary? Have you checked other rooms with thermometer? Is there a lot of traffic in and out of the house with exterior doors open often and is the thermostat in the path of that cooler air?
Many, many one pipe systems have dry returns, including mine. Your vents are probably on the dry return because that was the most convenient place to locate them. Those returns don't need to be vented but it is OK to do so if that's where you can place the vents. The best location is somewhere immediately after the last radiator run-out.

JUGHNE

How do we define a "vapor" system?

Fred

JUGHNE said:

How do we define a "vapor" system?

I assumed (maybe wrongfully so) the OP was asking if his system was designed to go into a vacuum and stay there for an extended period between cycles. Steam is a vapor so technically we all have a "vapor" system.

New England SteamWorks

CKNJ said:

I have it in balance (sort of) with all 1st floor radiators set at 7 and second floor set at 2.

Hopefully, the above is a typo. But if not, set the first floor vents to 2 and the 2nd floor vents to 7.

Unless you enjoy fine-tuning your boiler and are in to this stuff, not sure you really need a vaporstat.

CKNJ

Thank you for the responses. My real question was would I be best served to install a vaporstat that will operate the system at a much lower pressure and possibly provide better heating distribution?
But to answer some questions:
- Thermostat is on an inside wall, in living room across from the 2 radiators that serve that room. Same spot since 1909.
- I have checked each room temp with a thermometer for accuracy.
- The above was not a typo. 1st floor is set to 7. Otherwise the second floor bedrooms will rise to 75 degrees even if they are set at 2. Each bedroom has a 3 column, 5 section radiator. (room sizes are roughly 12x14 each).
- No traffic except for me in the house and I am at work all day.
- Remember I checked the EDR and it is matched almost exactly to the boiler. I even used Dan's other method for sizing a boiler in his book. The resulting calculation is spot on to the MBH of the boiler. So it is not oversized.

I only bought the house in June of this year so I really don't have previous operating knowledge.

New England SteamWorks

The pressuretrol or Vaporstat is really a safety device. If the boiler is piped correctly, sized correctly, and the system vented correctly, you should not build much pressure at all. You are sized correctly, and you vent the mains in 3 minutes, so that is all set. So confirm if you did indeed switch the radiators vents around on 1st and 2nd floors, and maybe some pics of your boiler piping.

BobC

What is the boilers sq ft of steam rating and what is the connected radiations EDR rating?

If the Boiler is oversized by an appreciable amount you will build pressure. Assuming the venting is adequate replacing the pressuretrol with a vaporstat will just cause short cycling.

Bob

CKNJ

Bob:

The boilers rating is 375 SF, connected EDR is 350 SF. I believe that is good.

One other thing I discovered is the radiator layout. the way the radiators were placed, they are ALL almost equal distance from the main. Yes, that includes the risers to the second floor. 1st floor radiators are set far away from main on outside walls of the house. Thus gives the runs the same distance to the radiators as the 2nd floor radiators (yes, I did measure). This tells me that at least in theory, steam would reach all radiators at the same time if they were all vented at the same rate. That would explain why the previous owner had the same vents on practically all radiators.

Another note. NONE of the pipes in the basement were insulated. So over the summer I insulated all the lines in the basement. And that is when the train went off the tracks. LOL. I think I might have changed the dynamics of the system when I insulated.

This is really baffling me as everything seems to be set up correctly but it is almost working in reverse of what is should be with regard to vent settings on 1st and 2nd floor. Its as if steam is hitting 2nd floor faster than 1st, but they are all tapped off the same main. If it were one radiator I would see a problem, but all on each floor behave exactly the same.

Fred

You didn't say if you have an open staircase or not. That isa huge factor in making the second floor several degrees warmer than the first floor. I had that issue and it took me a couple heating seasons to get the radiator vents adjusted so that both floors are within a degree or so apart. The thing I learned is that I had to make the vent adjustments during the coldest part of the season to get the first and second floor temps balanced. What that meant was that during the shoulder season, my second floor is about 2 degrees cooler than the first floor but I'm fine with that. As I said earlier, an open staircase can and will act like a chimney and draw the warm air up from the first floor, causing the boiler to run a little longer to satisfy the first floor. In the process, the second floor gets too warm. Coupled with that, I also found a fairly large hole behind the thermostat where the wires came into the thermostat. That hole was allowing cool air to updraft from the basement and/or down from the attic cooling the back of the tstat causing it to call for heat longer and more often. If you have that situation, stuff insulation in that hole.

DanHolohan

By definition, a vapor system is one that never goes above 8 oz. pressure. It doesn't necessarily have to go into a vacuum to be a vapor system.

CKNJ

Fred: Not exactly an open staircase but you can feel the warm air in lower part of it from the 1st floor, then gets cooler at the top 1/3 of the stairs. Like the warm air is just hanging out there. The "service stairs" from the kitchen don't exhibit this behavior. Hole for the thermostat wires is sealed with insulation as well so no temp changes.

Dan: Thank you for the definition. I got the idea about this after reading some 1910 and 1911 engineering journals and they talked about Vapor on one pipe systems (no vacuum). Yeah, I own an old house and have no life anymore.

DanHolohan

Owned by da house. I get that.

CKNJ

Alright guys, I think mystery of upside down heating has been solved (I hope). I decided to start at the basics again. My thermostat is a Honeywell T87 with adjustable anticipator (this will become important in a moment). The anticipator was set at 1.2 and it still was. But I noticed some black along the edge with the setting numbers on it like if you had a lit match next to it. On closer examination, the piece the anticipator arm connects to (not sure of name) was blackened and sagged at the higher end of the scale. It looked like you took a match to it.

I went out and got a new thermostat this afternoon. Just a plain Honeywell CT30. Well guess what? Complete change in the system behavior. The bad news is now I have to readjust ALL those Vent Rites I put on the system.

So I will ask one more thing from the Wallies. What settings should I start with on the Vent Rite #1's for 1st and 2nd floor?
Also, many thanks to all for your assistance here.

Fred

Here are the venting rates of the Vent-rite #1's at 1, 2 and 3 ounces of operating pressure. I would start out in the middle range, around 3 or 4 and adjust up or down as needed.
Ventrite #1 Setting 1 Off Off Off
Ventrite #1 Setting 2 0.033 0.020 0.021
Ventrite #1 Setting 3 0.025 0.036 0.046
Ventrite #1 Setting 4 0.030 0.053 0.066
Ventrite #1 Setting 5 0.045 0.071 0.091
Ventrite #1 Setting 6 0.056 0.091 0.116
Ventrite #1 Setting 7 0.070 0.108 0.133
Ventrite #1 Setting 8 0.083 0.125 0.158

CKNJ

Thank you Fred. You know, I would have never thought to look inside the thermostat if not for that mark. In the few hours since new thermostat, the change is amazing. 2nd floor is 65 degrees and 1st floor is 68. I am going to set all vents at 4 and go from there.

Fred

Good deal. Sounds like you are well on your way!