Interesting old system

Jeff Perry_3

   Ran across an old system this past week that I have only seen once before, and my father had to remind me about it for me to even remember. It was a long time ago and I don't have that many brain cells left.

   Anyway, it's a 1 pipe gravity hot water system in an old 1850's house. Took me a while to realize what I was looking at but when I did a smile appeared on my face. It was originnally coal but sometime in the past someone installed an Iron Fireman half million BTU gas boiler.

   As houses are for this period you have a central stair and hall and a large room in each of the 4 corners. There's a 4" main that goes from the boiler all the way to the attic. Someone tapped the 4" cast elbow and installed the open expansion tank with the overflow going out to the eve of the roof. The main splits into 2 - 3" runs. One run goes one direction around the attic and splits off 2 - 2-1/2" drops going down each corner of the house. The other 3" run goes the other direction around to the other 2 corners of the house.

   As the 2-1/2" drop heads toward the basement it comes to a radiator. There's a 1-1/2" tee with a standard radiator valve and it immediately goes into the top of an old ornate 38" tall column rad. The return off the bottom of the radiator comes out and goes right back into the same 2-1/2" drop. It does this through 3 floors in all 4 corners. All these tie back together and go back to the boiler as a 4" return.

After removing a few radiators from an 1890's addition that is getting demolished and rebuilt we filled the system back up yesterday and got to witness this old living beast come back to life. (House has been empty for a few years). Except for one rad that apparently froze and broke sometime in the past, that we had to remove and cap off for now, this system took over like it had never been shut down. If you went outside you could hear the gas meter half way across the yard.

   We have to give these people quotes for various options and I think that if anyone else is quoting a boiler replacement and doesn't know what they are looking at and prices a new boiler with a circulator I think they're in trouble. I would have to believe that if you throw a circ on this system the water will no longer have a reason to go into the rads and will pass right by. I think it'll just stop heating. That would sure put you to scratching your head.

   We're either going to price repiping the 2-1/2" drops to include a return or more likely price a gravity boiler. We have already talked to Peerless and they say there's no reason we can't take a steam boiler with 3" tappings, install a hot water trim kit and not install a circulator.

Now, sizing this new boiler is another matter.

If anyone wants pics I'll take some early next week and post them.



Jeff Perry

Piedmont Radiant

Charlottesville, VA

tim smith

Re: one pipe down feed system

These are basically the first mono flow systems. We see these several times a year. You can pump them with a modern boiler, have to be careful not to overpump. You can also put either balance valves between the tees on the drops at the radiators or orifice the upper tee to get some pressure differential to cause flow if flow becomes a problem to radiators. You really don't have to repipe the returns usually.

Jeff Perry_3

It would seem to me

that if you're going to go through the trouble of dismantling the piping to install balancing valves or orifices you might as well repie it. If you simply remove the radiator returns from the main and plug the main and cut the main after picking up the bottom radiator supply and then plug it too. You can then connect the rad returns together with a new run of pipe. Once you get down to the place where you plugged the main at the last radiator you can connect this new run of return into the pipe that was already going to the boiler as the return. You would now have a true separate supply and return system.

Jeff

Charlie from wmass

You can do any thing you like with a boiler

Nothing wrong with pumping a gravity system and using a modcon boiler. You just need to pump it properly and utilize the outdoor reset feature well. constant slow circulation will drop condensate out of the boiler like mad. The peerless idea is nice and simple but the mod con will sip the fuel. The mass of the peerless is not going to be enough to keep the gravity working as it should. Variable circulators are a good idea here also. TRV's are another good choice.

Ironman

Tim's Right

And pumping it primary/secondary would allow you to install a mod/con which should really cut fuel consumption. I'd recommend doing a load calc. You'll probably come up with the load actually being less than half of what the current boiler size is. We just recently did one in Staunton that was about 1/3 of what the old boiler was. The customer was very pleased and said the house had never come close to heating as well as it does now.



Look at all the old rad valves; probably most of them are bad. If the customer's budget allows, you might want to consider putting TRV's on all of them and put the loop on constant circ with a Stratos or Alpha delta P pump. Of course, insulating the pipes would be a necessity, but really should be done anyway.



I would love to see some pics of this one or if you don't mind I'd like to see the job. I'm just over the mountain from you in Augusta Co.

Charlie from wmass

Great minds think alike

I guess I justed typed a bit faster. Happy Holidays guys

Ironman

Thanks Charlie

And Merry Christmas to you and all on "The Wall".

Mark Eatherton

Blending the old with the new....

What about this. Install a 6" steel pipe, capped on both ends with tappings at the same elevations as the old boiler had. Then, install 2 smaller tappings on the other side of the pipe in between the elevations of the system tappings sized to the new mod con heat source tappings. This way, the circulator will not have any effect on the gravity circulation side of the system, and the condenser gets the opportunity to work with a great differential and stays in the condensing mode most of the time. Adding a pump to a system designed for gravity is a bad idea. Trust me, I know this from first hand experience. The mains were hot, but the branches wouldn't flow very well if at all. It has a tendency to break up the stratification that the gravity fittings depend on for delivering heat and circulation.



Essentially, the 6" pipe would serve as the low loss header, except there is nothing but gravity working the load side of the system :-)



Think outside the pipe grasshopper :-)



And definitely get us some pictures.



ME

Jeff Perry_3

I like it.

Mark, I completely agree with you. If this were a 2 pipe gravity system I would be a lot more comfortable pumping this system. But one pipe?...... I don't think so. That water is going to want to go right by the rads and follow the main right back to the boiler. The modcon idea was on my mind but I think money will be an issue. It's nice that Viessmann has options all the way up to 370,000 input.

I like the idea of the 6" pipe. That's doable but if the money is there for a modcon, Viessmann has low loss header models rated at 35, 80, 119 and up to 189 GPM so that would be an option too.

One problem with the modcon will be venting. On top of that ceiling height in the basement may not allow us to install one anyway.

Thanks for your input mark.



Jeff Perry

Jeff Perry_3

Mass not an issue.

The mass of the Peerless is no less than the Iron Fireman that is in there now. And the tappings are actually larger on the Peerless than the Fireman so operating the Peerless would not be an issue. However, with a 1 pipe gravity setup I don't agree that we can throw a circ on this system and get away with it. Without repiping the returns there's no way we would chance it.

Thanks

Jeff

Jeff Perry_3

Like I mention

and Mark says below, we're not going to pump the system in its current configuration. We'll probably size any new biler by looking at the rads and adding about 25% to 30% piping losses. And there's no way we'll insulate the piping. Don't need to. With the addition of a foamed roof for insulation the piping will now be 90% in conditioned space. There will be a small amount of piping under the lowest floor of the house and it's inaccessible. The main riser is in a chase and the drops are exposed in each room.

All the valves actually work. Only one is missing a handle. We will be contacting Danfoss and talking to them about their valves and restrictions of their valves even in the full open position. I don't want to replace all the old valves with expensive 1-1/2" TRV's and find out the gravity flow will want to bypass. Plus the largest they make is 1-1/4" so we would have to do repiping anyway. They would not be a direct replacement. 



Jeff 

meplumber

Another Win for the Dead Dudes.

Aside from all of our attempts to make it better, we cannot ignore the simple elegance of the dead men.  They seem to show me something new, every time I think that I have seen it all.



I saw a completely original piping system last year in a house from the late 1870's.  Simply genious in its simplicity.



I learn something new everyday.



Good Luck and Happy Holidays fellow basement dwellers.

Steamhead

It can be done

as long as you use a SMALL circulator.



The idea is to mimic the gentle gravity flow. All the circ needs to do is get the water in and out of the boiler or primary loop. The system does the rest.



How much radiation is on that system?