Hartford loop

Jim Pompetti

A few weeks ago , I inspected a Steam System , On my report I said that the Hartford Loop was missing . Today I was called by the Code Enforcer , and told that THE LOOP was NOT code . It was not necessary ,I asked him if felt ,that if the loop was not there, it would be a safe install . Also the the relief valve was horizontal , I SAID it should be installed vertical . Because that what the instruction say . Help me!!!

Magnehelic

LWCO Took It's Place

Jim,

     I totally agree with you HOWEVER when the hartford loop was designed and implemented, it was to protect the boiler from a low water situation (on a rolling river) and there were no "low water cutoff" mechanical safeties at the time.  In our jurisdiction (and in every one I've ever heard of) there are TWO LWCO's required.......one being manual reset.  These safeties effectively take the place of the hartford loop.

Cheers!!

Don

Jim Pompetti

Only

one LWCO installed

Magnehelic

That wouldn't fly around here

at all.......although on hydronic boilers they do allow us to use a flow switch (as long as it is manual reset) in place of the lwco........on a condensing boiler anyway.



Don

SWEI

took its place but...

Is it still a good idea?



I have precious little experience with steam systems, but the Hartford Loop sticks in my mind as one of so many old things I learn about and think, "Gee, that's a really clever and low tech way to solve the XX problem."



I've become a really big fan of low complexity safety systems with few dependencies.

Jamie Hall

Aren't local codes fun?

and wouldn't it be nice if they were a little more uniform?  Around here, a residential boiler only needs one LWCO and no Hartford Loop.  Which I regard as hopelessly unsafe.  Larger boilers -- such as the one in this ark I supervise -- require the two LWCO, one (lower) manual -- and no Hartford.



I like the Hartford... !



Bizarre.  But then I've always been a belt and braces type...

The Steam Whisperer (Formerly Boilerpro)

I wonder what the client's insurer has to say.....

I bet they want a hartford loop.

Alan (California Radiant) Forbes

It sounds

though the answer to Jim's question is that the Hartford Loop is NOT required by code, but is perhaps a good idea as a redundant, non-mechanical device to prevent dry-firing of the boiler. No?

furnacefigher15

Ask the code inspector

If he is willing to put his or his families life on that decision.



I would assume not.



Low water cut outs go bad, even the float style. Floats bind up on sediment. Most boilers don't get proper lwco maintenance and regular blow down making the trouble worse. The switches are also very easy to jumper, and that is exactly what an ignorant building maintenance guy would do.



I had that happen on a 3 million btu boiler here in town at a local GOVERNMENT RUN pool. The "chief building operator" jammed a screwdriver in the flow switch b/c it was keeping the boiler from running.



Low water cutouts are also now relying on micro switches instead of mercury which makes them even less reliable.



McDonald Miller, recommend replacement of all LWCO devices every 10 years.



I really don't understand the inspector on this one. If they don't know they should err on the side of safety.



ALL CODES DEFER TO INSTALLATION GUIDELINES SET BY THE MANUFACTURE, which in the case of the Hartford loop is set by an insurance regulation.



Have a lawyer write up a waiver of liability, and have the inspector sign it, and print so every one can read it.

Jean-David Beyer

Do they ever put a hartford loop on hot water boilers?

The supply and return come out of the top of my boiler, so this probably does not apply to my system. But I could have had my bioler mounted on the wall and plumbed out the bottom. In that case, since my radiant slab is beneath the boiler, all the water could run out if my slab sprung a leak. It so happens that the controller in the boiler can infer low water and shut the boiler off. They say some inspectors allow this. My installer did not take a chance and installed an M&M probe type LWCO.



But if I elected to take the water off the bottom, I suppose I could preven the water running out by running the supply and return pipes high enough over the boiler to ensure everything that should be wet would stay wet. This would sort-of be like a hartford loop on both the supply and return pipes. In this case, it would be simpler just to run the water in and out of the top, of course.



On my old boiler, though, which had no pressure relief valve and no LWCO, the water could have all run out. Luckily, it did not. There was a red double valve gizmo on the make up system by Bell and Gossett. One was a pressure reduction valve, and the other looked like a pressure relief valve. And it did weap when the old expansion tank (not diaphragm type) got full of water. But on the instruction sheet, it specifically said that valve was not the one required by the various codes for pressure relief.

furnacefigher15

Hartford loops

are for steam boilers, where there is a continual threat of running dry.

Jean-David Beyer

continual threat of running dry.

It seems to me there are two ways a steam boiler could run dry. 1.) a steam pipe could break or a vent valve could fall off, letting stem out as fast as it is genereated. After a little while, the boiler would run dry. A Hargford loop would not hel with this.



2.) a wet return could spring a leak and all the condensate would run out. Without a Hartford loop, the water from the boiler would go with it.



Now a hot water boiler should not ever experience #1. But #2 could, it seems to me, be just as likely to happen as with a steam boiler, depending on how that boiler is piped. For me, my boiler is on the ground floor and the main heating zone is buried in the slab beneath the boiler. So if there is a leak down there, away would go the water. In fact, all the water enters and leave my boiler by the top, so the only way it should lose water is if someone opened the drain valve. You may be able to make something fool proof, but you cannot make anything damned fool proof. So I would not need protection similar to what a Hartford provides, but my old boiler sure could have used it.