Pressure

Steamhead (in transit)

doesn't come back and bite you! Converting steam to hot-water is an iffy proposition. One problem is the drastic increase in operating pressure- this will do a great job of finding weak points in radiators and piping. Coupled with the increased danger of frozen pipes, especially in outside walls, makes it even less attractive. And these things don't necessarily happen right away. My company does not recommend or perform such conversions and will not touch a system someone else has converted.

Now as to your efforts to make the Vapor systems work better....

Ultra-low pressure is key, as you've discovered ("very pleasant calmness"- I like it!). Since steam is a gas, it can be compressed. This is great when you want to run a locomotive. But if all you need to do is fill pipes and radiators with steam, you don't need to compress it. The boiler doesn't have to make as much steam to fill the system if you run at ounce pressures, thereby not compressing the steam. This increases the system's efficiency.

The usual cheap pressure cutout that comes with boilers cannot accurately limit the pressure to ounce levels. Sometimes if you crank these things down too far, they don't close when the pressure falls, as you've seen. The control you want is the Honeywell L408J1009 Vaporstat, which cannot be set higher than 16 ounces. I suggest getting a gauge that reads 0-30 OUNCES or so, to accurately monitor the actual system pressure. The usual 0-30 pound gauge must remain to satisfy Code.

With a Vaporstat installed, if you then have trouble getting steam to some parts of the building, you generally have bad traps or vents. These are easily fixed.

You would cure short-cycling by reducing the firing rate somewhat. If these boilers are big enough that they could be fitted with "low-high-low" burners, you could set up the low fire to effectively shed the pickup factor and just simmer along until the thermostat or ODR was satisfied. We have one customer who saved 40% on his gas consumption this way.

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chelini

pressure

Greetings to All, I have a question conserning a small apt project I have been reciently doing repair work at. The complex involves 8 small(14 unit) buildings which are heated with newer and some old steam boilers, around 1 mil btu input. Since I have been there most of the complaints are conserning noise (of course)and I usually find a bad trap or vent causing problems. What I don't like about this project is they are all on average operating at around 4 to 5 psi. I don't do a lot of steam but it seem to me if I could get the pressuer down alot of my problems will go away. All these boilers are operating with one pa404 and one L604 pressure controler. I have tried to get these pressure controlers to operate at lower pressures and then in the middle of the night I get the NO HEAT call and have to go to the project and turn up the control so the boiler will go back on.
Now I hope I am about to answer my own question. Today I went back to the no heat call(from last night2am) and removed pa404 controler and replaced it with a L608 VAPORstat. I set the controller at 14 OZ with 4 OZ dif. The boiler started cycling at around 1 psi, the building seemed to aquire a very pleasent calmness to it and the place just "felt better" if you know what I mean.
Am I on the right track? Do I have another no heat call comming? Should I do the rest of the project like this?
You guys have helped me out befor and it really means alot to me THANKS
Jim

Jamie Hall

It does sound

as though you are very much on the right track there. Maybe some of the experts will chime in -- I'm just a knuckle-dragging building superintendent...

chelini

Still wondering

if what I did was correct. I had a no heat call there last night in another building, cloggeg vent. While I was there I stopped by the building where I instaled the vaporstat. The building was heating fine and quite. I did however notice that the boiler seemed to be short cycling somewhat. I hope somebody who knows what there doing chimnes in here. Could it be that I have to run 3 or 4 psi just to keep the boiler from short cycling? Could I put a time delay on the gas valve maybe to creat a longer cycle? Thanks for any help here.
Jim

Phil_17

short cycling boiler

when i got a new boiler 1,050,000 and reduced the pressure below 1 psi everyone noticed an immediate improvement in heat quality. before we were either roasted or frozen [had other problems as well].at low pressures everything seems much better.
we also wonder what to do about the short cycling.i have investigated installing a "hi-fire-low-fire" setup to keep the flame on low from 4 oz. to cut-out at 12 oz.but it does seem expensive.
you may have the opportunity of cross connection of your boiler systems so that when the combined total pressure of your 8 boilers reaches 5 oz. 3 or 4 boilers cut out leaving 4 or 5 remaining boilers to keep the system at its sweetest pressure.-nbc

chelini

nbc, Thanks for replying. These are eight separate building unconnected. There used to be one centeral plant but that was done away with many years ago. There is actually nine buildings. Last year I converted the "ninth" building from steam (two pipe) to hot water with two condensing boilers beacause the steam boiler was in need of replacement. The condo asso. agreed to replace the old (falling apart single pane) windows but still haven't done it so I don't know if they are saving money or not.
thanks again
jim

chelini

Steamhead

Thanks for your reply I respect your vast experance and was hopeing for your reply.
As for the ninth building the idea only occured to me beacause of the configeration and pipe layout of the building. These are large condo/apt units approx 14 per building. The basement/boiler room level is more or less completley open and all the piping is exposed. There is a supply and return that goes all around the basement and each raditor in the building is piped to those two mains on tees. I repiped the smaller return with two inch copper, replaced each raditor valve and removed the steam traps. It is working good. I only had one raditor leak and a few leaks in the orignal piping. I used two 250 Prestige boilers. I wouldn't have done it either if the piping wasn't so cut and dry. Is my customer going to save money? Yes lots of it espically if they get rid of the 75 yr old windows. Did I make money? Yep. Would I do it again? I don't know. This job is approaching 100k. And without A/C being part of the deal I don't think it was worth it.But then we are talking complete rehab... very complex indeed.
As for the boiler I did instal the L408( I think I said L608 in the orignal post statement by mistake)and I think it really is going to be great improvement to the building/buildings. An example would be the OT call the other night with the clogged vent, bet those calls will be greatly reduced as with the noise complaints. The only problem is the short cycling. These are atmosferick(spell) boilers. I am going down there tommrow with a water column and see if I can cut down on the gas flow but other than that I don't know. Is it possible that these boilers will only run efishent(is there a spell check on this fourm?) at the higher pressure?
Thanks Again
Jim