Pics of old gravity h.w. Comments?

Climate Creator

was wondering if there were any comments to be had. My two concerns are, that I am wondering why they split the returns and how it will affect my Biasi P/S piping, anything to watch out for here? And also looks like there is NO expansion tank here so they must be using the rads? I know there are somethings to watch for on those bottom piped rads, and my spirovent and auto feed set a little higher might take care of any air problems? Anything on this to look for? All comments are welcome or course, the good the bad and the ugly, I will as always post the finished product for final review! ;)

Thanks,

Rich

Constantin

Current unit looks like a fire hazard

Pink house insulation will begin to decompose at 475, start to burn around 500 deg F. A former colleague of mine found that out the hard way at work (he had himself a lab fire). There is a reason that appliance-grade fiberglass (the yellow stuff) costs more... the binder is different (in either case the SO2 fibers won't usually burn).

As for the rest of the system, I'm sorry but I have no clue. I did notice what looks like asbestos insulation hanging around the pipes above though. Be careful and best of luck!

Climate Creator

Yes

That pink insulation was just sitting there to "protect" the oil line that used weep according to the HO. That unit is no longer there.



Thanks,
Rich

Constantin

Allow me to be dense

I'm just a HO, but the most obvious reason that I can see for the split return piping (to the bottom of the back, right?) appears to be the chimney flue in the middle.

The return going into the boiler certainly does not look bigger than the pipes attached to it... thus the two pipes reaching it in tandem doesn't explain it either.

One thing that does come to mind is that these two long loops could be meant as a means to prevent thermosiphoning if some radiators in one part of the house have been turned off or down, right?

As for the expansion tank, have you read this amusing article by Dan on expansion-tankless gravity systems?

With the help of a proper pump, expansion tank, and boiler, I would think you should be able to join the two circuits higher up. Siphoning (if it's even an issue after adding the pump) can always be addressed with check valves...

Paul Mitchell

A couple quick things

Check the attic for an old expansion tank. If not one there then it is the radiators. P/S piping good idea. But if you change the system from the standard gravity piping, first supply is first return and make it a reverse loop, first supply is last return then it will heat much more evenly. If you dont then the house might heat uneven. Hope this helps.

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Steamhead

CC, that's probably not the original boiler

From what I see, I suspect that the original was a round coal-fired unit that had two outlet tappings. On this type of boiler, the flow mains went straight to the top of the boiler instead of being joined together. There are still many of these round units in service, and most of them waste lots of fuel.

The original expansion tank was probably in a top-floor room or attic. If there is no tank currently in use, the feed valve is probably shot from over-use, as is the safety valve. Look for evidence of over-pressurizing (leaks, etc), I had one of these reaching 60 pounds recently, so I added a tank and a new dual valve unit.

If you go P/S, you might consider a separate circulator for each pair of flow & return mains. Size your secondary circs from the chart at:

http://www.heatinghelp.com/newsletter.cfm?Id=125

This will mimic the gentle gravity flow at what would have been its maximum rate, which will help keep the system balanced.

If you install an indirect on this system, it should be the first set of take-offs from the primary loop. This will make sure it gets the hottest water.

Looking forward to the "after" pics.

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Climate Creator

Thanks

But I am not quite sure what you mean.on my p/s loop I will pipe the indirect first supply then return the house supp and ret then back into the boiler. It will be piped exactly as my last p/s boiler found here

http://forums.invision.net/Thread.cfm?CFApp=2&&Message_ID=82368&_#Message82368

So if you see anything there feel free.

Thanks,
CC

Climate Creator

Thanks

I did see that article before, it has been useful thanks for taking the time to put it together and also to post here on my query. I found that tank, its gone now. also what about that rule that your supposed to divide the pipe size in half then drop one size when connecting to old gravity any merit there? Also I posted the link to a previous job I did, and this one is going to be a carbon copy. So if you see anything there that concerns you please feel free to tell me. (I can't wait to post the finished pics either!!!)

http://forums.invision.net/Thread.cfm?CFApp=2&&Message_ID=82368&_#Message82368

Thanks SH,
CC

Steamhead

That divide-and-drop rule

was probably a way of reducing the circ's capacity before the current crop of small circs came out. If a small flow rate is called for, I prefer using a small circ- it costs less and uses less power.

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