purpose of a hartford??

jpf321

i was discussing the hartford with Uncle Al the other day .. of course I thought I knew it was there because if there is a catastrophic failure on the return, the water doesn't poor out of the boiler .. and he said,  "yeah, but if you keep making steam, the water's sure going to leave the boiler (out the top) .. "



OK .. so now we introduce an auto-feed, so now, when the water leaves the boiler (out the top), it is made up automatically right?? well aren't most autofeeds piped into the hartford? I guess it now really depends on which leg of the hartford you are feeding, as one leg is presumably open pipe somewhere.



and what about those systems without an auto-feed?



so without opening a can of worms .. doesn't the hartford just buy a bit more time, and with these low water capacity boilers .. the time bought is probably not long.



at the end of the day, the hartford doesn't seem to have much real purpose .. and it's much more important to focus on the correctly operation LWCO ..



FYI, according to recent reading of the deadman books, the hartford looped used to be known as "the underwriters loop" .. and it's unclear when it became the hartford nor if it was after named the "Hartford Insurance Company" itself or simply Hartford, CT where insurance companies seemed to all be located at the time.

Jamie Hall

Hartfords...

The Hartford loop was named after the Hartford Steam Boiler Insurance Company -- I asked a chap who used to work there who used to work with me years ago.  They got tired of dry fired boilers blowing up or burning things down or both, for some reason.



And if, as you note, the autofeeder is piped into the return before the Hartford, as most are these days, when the autofeeder kicks in because of a leak in the returns, it will just make the flood worse; a somewhat dubious proposition and I can certainly see where your curiousity is coming from!



I really don't think it was intended for relatively slow leaks, but for a genuinely broken return -- which would, without it, drain the boiler in a matter of minutes.  But you are quite right -- if the burner doesn't shut off (or if, in the bad old days, someone didn't close the dampers or pull the fire) you are only buying time, as the water boils off at the rate of about a gallon every 6,000 BTU or so.  Doesn't give you all that long...



However... the low water cutoff(s) should kill the burner before you get too far in drying out the boiler.  Which is why I have two of them, in series!  So, as you say, pay attention to those LWCOs!

jpf321

well without ....

specifically enunciating it, it sounds like you are in agreement that the hartford really doesn't serve much purpose except buy a bit of time perhaps .. but that time may be short lived. We are all in agreement that the hartford is a necessary and critical component of a steam system, but we are perhaps forgetting that there are 2 ways for water to leave the boiler .. and the hartford only "saves you" from the bottom exit. however in time, all the water will eventually leave by way of the top exit .. unless you have a working LWCO .. in which case, you didn't need a hartford anyway.



of course everyone that has a steam boiler requires a proper loop be it a hartford or a gifford (with the purpose of the gifford to simply "decouple" the boiler water from the return water) .. but it's just something that came up in conversation the other day so I wanted to toss it out there. and, i know this loop is required because it's in all the I&O manuals :-)



i have to say that the loop came in handy last night when I was working on my returns .. since the water stayed put right in the boiler and I only had to drain my returns .. maybe that's it main purpose .. i'll have to do some more reading .. i'll let you know if i find anything interesting.

Dave in QCA

Not as important as it was with coal... but....

JPF, your points are well taken.  But, consider that there is more was that a boiler can empty itself suddenly, that a leaky pipe.  For example, if someone has a set up with a king valve, decides to close it and start the boiler.  As the boiler builds pressure, it will push water out the return, but only down as far as the hartford loop connection.  And of course, there is that original scenario, a return pipe breaks, or suddenly bursts, and the boiler quickly pours the water out on the floor.  In the early part of the old coal burning days, there were no LWCO devices, and it was also difficult, if not impossible to quickly shut down a coal fire.

So, with redundant LWCO devices, is a Hartford loop really necessary?  Probably not nearly as much as it was in the past, but, I would not want to see what happens to a very hot, firing, cast iron boiler, that suddenly empties itself, even if LWCO does shut off the burner.  It may not fire dry, but that iron has a lot of residual heat.  I know my boiler continues to boil for a few minutes after the burner shuts off, so I'm not sure just how hot that iron is.  But I would assume it is hotter than 212.  I guess another thing to think about is the potential hazard of 20 - 50 gallons of boiling water suddenly running accros the basement floor.

Take a look at the following link, page 3, 1st drawing.   http://www.bellgossett.com/literature/files/7250.pdf

This was published by Hoffman Specialty in 1999.  According to them, you will notice that the only place a Hartford loop is used, is where there is a wet return.  Dry returns just drop to the boiler inlet, and the water line profides the seal to prevent backflow.

JPF, I have pondered your question myself, and it seems to me that there may be a number of cases where it may not be important at all, but "code says" ya gotta.   It's too bad that code doesn't accurately describe "near boiler piping"!! 

jpf321

well here ya go ...

From Dan himself ..

http://www.masterplumbers.com/plumbviews/2001/hartford.asp



In the first paragraph quoted below Dan mentions that the Hartford "bought time" .. agreed .. and it bought them alot of time presuming there was a fire tender standing there adding coal or wood .. and more time based on the huge water capacity (relatively speaking) of the old boilers.



But in the 2nd paragraph quoted below, the loop is called a 'backup for LWCO' .. which I think we now see it technically incorrect .. if you keep the fire on, and the LWCO fails, the water will eventually leave the boiler .. and with the size of today's boilers, this could happen in 1-3cycles (assuming a cut-pipe "suddenly" empties the boiler,  but it really depends on how bad a leak you have) .. and I'm not sure there are many non-wallies that are checking their basements for 15gal floods every 3cycles. if Jamie's figure is correct .. 1gal/6000btus .. then 10gals in 60,000btus .. or about 30mins of 1gph oil firing.



quoting ..

"Here's how the Hartford Loop works. If a return line breaks, water can only back out of the boiler to the point where the wet return line connects into the equalizer. The Loop works like a siphon that runs out of water. The point where the Loop connects to the equalizer is higher than the boiler's crown sheet, and that's what provides the safety. Since the water couldn't instantly vanish from the boiler, it bought the Dead Men some time to notice the problem and save that wood- or coal-fired boiler. The piping arrangement wasn't fail-safe, but it was a vast improvement over the old way of returning condensate directly into the bottom of the boiler.



Should you use a Hartford Loop nowadays? I sure think so! Your low-water cutoff should protect the boiler against a sudden loss of water, but if you have a gravity-return system, a Hartford Loop is the cheapest insurance you can buy to back up that low-water cutoff should a return rupture and water suddenly leave the boiler. Low-water cutoffs are great, but believe it or not, there are a few out there that don't get blown-down once a week. Really!"

jpf321

fyi ..

the I&O for my S/F TR-30 Steam lists my water content as 6.9gals....the hartford with a failed LWCO isn't buying much time



page 9: http://www.slantfin.com/documents/771.pdf

jpf321

thanks Dave ...

thanks for your input .. i'm headed off to blowdown my LWCO now :-) and perhaps work on adding my probe LWCO as a backup.

and be thankful that my LWCO line is set above minimum safe water level :-)

Dave in QCA

good points all around

My comment with the 20-50 gallons comes from my own boiler, that has 44 gallons setting there.

Good research JPF.  All points well taken.  Hartford not as critical as it once was, but still perhaps a small thread of added safety.  In the case of your boiler... a VERY small thread.

Polycarp

re-pipe

Now you have me all worried that I should repipe my feed to be on the boiler side of the loop.  Of course that means that I have to finally switch the feed to hot water since I won't be getting the water mixing in the return.



Thanks a lot. 

World Plumber

Remember

You need to remember that when the  Hartford loop was first introduced when coal was king. There was no quick way to shut the boiler down.  Where as without the Hartford loop a break in the return would empty the boiler and dry fire it before  the fire could be extinguished. Today the LWCO can shut the burner down. But the loop also plays a big role in how the system works. As well as a backup if the LWCO fails. Remember we are supposed to be checking the boiler each day!!!

jpf321

got it..but also remember

if the lwco fails without a return leak..the hartford isn't going to help

Dave in QCA

new thread, LWCO maintenance free

Gonna start a new thread on the subject of LWCO and maintenance free adaptation

Charlie from wmass

Safety devices

are only there to help prevent total disasters in most cases. Nothing is fool proof. You are better to have one than to not have one. LWCO are known to fail, especially when not maintained. we still use them. Why because it is better to have them then not have them. If a steam boiler or any boiler or furnace was maintained and watched over as it should be we would need no safety equipment. BUT they are not. Lots of forms of protection have a failure rate, yet we still use them. A little protection is far better than none.

Dave in QCA

A little protection is far better than none. ...

I great deal of wisdom in that statement.  Not only does it apply to boilers, it most certainly applies to just about every hazard that a person might be exposed to.