OK, a couple more \"dumb\" questions about my old gravity system

Al Roethlisberger

I apologize in advance for continuing to put you all through these 20 questions that probably seem pretty basic... but I think I've got it narrowed down to two final questions to confirm what I(and you all) think. That my system is an overhead gravity system, currently running in "reverse" after being converted to a closed circulator system about 15 years ago.

Well, I have the original blueprints, although over 80+ years, some of the legend and other notes are gone from the margins. So one still can't call this the Rosetta stone of my system.

But, there are still some clues. And this is where my final two really dumb sounding questions come into play, so bear with me.

Although on the blueprints, there are arrows on the piping diagram, believe it or not, there are a couple places where the arrows are in conflict on the same pipe. So I think that may have been an error on the part of the architect/engineer.

But...

1) There is one main line that runs from the boiler all the way to the attic, called the "main riser". Now, based upon this name, I would like to assume it means exactly what it is called, and if so, would have been the original supply side of the system. So question #1: Is it safe to interpret "main riser" as being the original "main supply riser" of the system?

2) There are several pipes labeled as "return" lines. I would like to assume these too mean exactly what they are called. So question #2: Is it safe to interpret lines labelled as "return" as lines that actually were intended to "return" the cooler water back to the boiler?


Now, if the answer is "yes" to both of these, then I indeed seem to have an overhead gravity hot water system, that has the radiator control valves on the output/return(bottom) side of the radiator, and is currently circulating backwards following its conversion to a closed circulating system around 1991.

If I can confirm this as seeming to sound reasonably correct from all of you, I would then like to describe again my current setup, and see if I can get some opinions on why they may have plumbed this backwards, and if it would be a good idea to make some changes now.

But I'll save that for another thread following your feedback on my two questions =)

Thanks!
Al

Timco

A question for you...how does it heat? Even? Noisy? short cycles? The riser is the riser, and the returns are the returns, but if it heats well, what is the objective here? If it ain't broke.....

Tim

Al Roethlisberger

It ain't broke, but I think it may be working too hard....

Hi Tim,

Reasonable questions.... let's see if I can answer them as directly as possible.

The system apparently has heated "well enough" over the last 15 years since the conversion for no one to feel enough pain to look into whether the system is currently engineered correctly. It was originally installed in 1929 as what I believe to be an overhead gravity system.

It seems to heat pretty evenly in its current configuration, and the cycles don't seem too short, but I really don't have anything to benchmark it against right now. I suppose once the weather becomes consistently cold(we are in Sanford, NC, near Raleigh), and we move upstairs out of the basement(renovations have us living down here) I can time the cycles and see how many times it cycles per hour. I do know that my new electronic thermostat has it defaulted to expecting cycling every 20-30 minutes. But again, I don't know if that is reasonable?? Also, my circulator pump only runs while the boiler is firing and I have one loop, no bypass of any kind, if that is helpful information.

But since purchasing the house in March of last year, this is our first Winter in the house, and I have been taking the time to investigate and learn about its current state.

This interest was driven by several observations:

1) Some radiators do not heat well(which could be from several causes such as a broken valve or air, which I am also investigating)

2) Past $500/mo heating bills in Jan/Feb (gas fired ca1991 80% eff boiler, 2 story 4000 sqft, 1929 house with about 65 windows, but well insulated for its time, even in walls and 12 inch thick brick on first story)

3) Obvious other oversights in the conversion such as no pressure relief valve, no system air vent, etc


So I am trying to learn enough about the system to help inform the heating folks around here, because none seem to have an boiler/steam expertise anymore beyond basic repair. For example none seem to have the expertise to know what a gravity system really was/did, and if it is currently circulating correctly.

What I'd like to do is learn how it should be configured, so I can make educated recommendations. Then I'd like to feel confident that the sytem is running as effectively and efficiently as possible, and right now a $500 heating bill and some of the other questions make me wonder if there may not be a little more of both that can be squeezed out of the system.

Plus, I like to solve "mysteries" and understand the systems of my house Prior to this, no previous owner I talked to, or local HVAC/mechanical folks had any clue how the system was supposed to work or be maintained.

Thanks in advance for any help and suggestions.

Cheers
Al

jim lockard

Pressure Relief Valve

No pressure relief valve??? Al thats your first priority, get a properly working pressure relief valve on that boiler. Air managment, constant circulation and balance can all come later. Right now defuse the bomb. Best Wishes J.Lockard

Al Roethlisberger

I gotcha, it is "on the ASAP list". Technically I do HAVE one, but it is a 150psi/210degree type you would typically find on a water heater. I need a 30 psi relief, and am trying to source one as the local big box doesn't carry those.

Al

jim lockard

ferguson enterprises

AL There is a Ferguson plumbing supply and a Ferguson heating and cooling outlet close by RAL. NC. Best Wishes J.Lockard

rob brown

reverse flow

al, #1, get the proper relief valve. #2 look at your pump,is the water flowing out the top of the boiler? not the lower tapping? then your not counterflow thru the boiler. reversing flow thru this type of system might help in balanceing. gravity systems would want to flow to top floors first where as pumped would favor shortest run.if not counterflow,and balance is not a problem, i would just insulate the heck out of that run thru the attic, and seriously consider a mod-con type boiler as a replacement when time comes as your system would be ideal for this type boiler. rob

Al Roethlisberger

Thanks, and some questions/observations.


Thanks Rob, I really appreciate the detailed thoughts.

I agree on the relief valve, and that is on my list ASAP.

When you say "mod-con" boiler, what do you mean? I suspect the "con" is "condensing", but not sure on the "mod" part

My boiler is currently a Dunkirk(rebadged as a Carrier) PWB-8D, 80%, Gas Fired, ca1991 vintage.


Regarding the flow, yes the flow through the boiler is correct as is not counterflowing.

Here's a question for you though. Can you expand on how a pumped system would find reversing the flow in a system like mine to help in "balancing" or favoring "shortest run"?

I ask for a couple reasons.

1) It seems to me that one would want the pump to work with the natural tendency for convection through the system(hot water to rise to the attic riser), not against it? This may be an incorrect assumption, but just something that comes to mind. Right now of course, it is pumping against what nature is trying to do.

2) "Shortest Run" .... to where? In several cases in my house, the shortest run to the radiator is actually up through the riser. In some cases it would be to the return. It just depends. I'd say it is a good 50/50 split.

3) My radiators are currently filling from the bottom, not the top as originally designed. I would think that filling from the bottom could cause some inefficiencies as the hot water would immediately rise to the top of the radiator in the first few coils right up to the top of the radiator, and out the now top "return". Apparently over time the rest of the radiator does indeed get warm, but I wonder if I lose some efficiency here as well.

Anyway, these are just some thoughts.

I've ordered several books from this site on the subject including Dan's book, so I'm sure that will help as well.

But I really have no local expertise here, even in Raleigh they seem to have no idea other than basic repair as all the old-timers are gone.

So I am just trying to understand why my system is plumbed in "reverse" now, and if that is the best way for its current configuration. If not, I'm happy to simply replumb from the boiler back into the old feed/return next Spring as that would be an easy task.

I've even toyed with building a simple diverter setup so that I could run it either way and time and measure the temperature results. Maybe if no one seems to really know the answer as to which way is best, maybe that is exactly what I'll do *shrug*

Thanks for all the help! Any other thoughts or experience in converting an overhead gravity system to a closed circulator system is much appreciated.

It would be great if by this time next year, I could feel confident that the system was correctly piped and controlled as efficiently/effectively as possible.

Cheers
Al

Al Roethlisberger

Thanks, I'll check out their Raleigh office.

> AL There is a Ferguson plumbing supply and a

> Ferguson heating and cooling outlet close by RAL.

> NC. Best Wishes J.Lockard




Thanks, unfortunately after going to their office here in Sanford, all they seem to have is plumbing supplies... but no expertise.

I'll give them a call Monday in their Raleigh office as well just to see if they may have some expertise there.

I had one "old timer"(although not really that old, maybe 50ish) come by last week. He was from New Jersey as of about 15 years ago, and had worked on many boiler systems. But although he could certainly do maintenance if needed, he didn't have any expertise in the types of systems themselves, etc. He didn't even know what an overhead gravity system was *sigh*

I have one other service, the only ones within about 30 mile radius with a boiler/steam license, coming over next week. An old timer here in town recommended them, so I'm hoping they will have some insight.

... we'll see.

Al

D107

Just keep in my mind the actual piping might not have been

done as per your drawings. Homeowner here. I have a 1924 house with original drawings. Heating wasn't shown, and other aspects, including plumbing, weren't always as per drawings.
4000 sq ft house $500 heating bills doesn't sound terrible for jan-feb though I know you're warmer than up here in ny. Perhaps that Ferguson supply house will be in touch with some good contractors.

Good luck,

David

Al Roethlisberger

> done as per your drawings. Homeowner here. I have

> a 1924 house with original drawings. Heating

> wasn't shown, and other aspects, including

> plumbing, weren't always as per drawings. 4000

> sq ft house $500 heating bills doesn't sound

> terrible for jan-feb though I know you're warmer

> than up here in ny. Perhaps that Ferguson supply

> house will be in touch with some good

> contractors.

>

> Good luck,

>

> David




Thanks David,

I agree on the inaccuracies of original drawings. We have several things in this house that deviated from the original plans during actual excecution.

However, so far, it looks like the heating pipe plan looks to be very accurate, which is good news. But yes, I would not be surprised if we found some deviations under close inspection.

I'm hoping I can show that to the guys that come over, and see a light bulb go off over their heads

We'll see.

Cheers
Al

rob brown

gravity

al, the "mod" means modulating,as in the burner ramps up or down to match load. if you look at the top of this page, click on heating q&a. there is a whole section on gravity systems that will answer all those questions better than i could. good luck, rob

Al Roethlisberger

Thanks for the clarification on "mod" Rob

I have read Dan's excerpts for the gravity systems, but unfortunately it still leaves questions about whether a "reversed" flow once it is converted to a closed circulator system aren't clear. I've ordered the book, so hopefully that will help.

But if there is anyone with experience/knowledge on the best ways these overhead gravity systems were converted, that is what I am looking for... to validate the current setup I've got, or to confirm if it needs to really circulate in its original direction.

Thanks again!
Al