Hoffmann Differential Regulator No. 0

Unknown

It stands AT the waterline of the boiler,(probably it has a water line marked on it, near the bottom third) and it operates when the boiler gets above about a HALF pound, or at about 10 ounces. It does need the check valves to work properly.

It has no moving parts.

When the steam pressure got high enough in the main that the condensate backed up in the loop, the loop shut the air vent, pressureized the dry return, and the equal pressure in the supply and return allowed the water to drop into the boiler. Then the loop returned to idle, with the steam inlet covered by water again, waiting till next time. By using a vaporstat, the thing rarely operates.

It is a beautiful thing.

Noel

Jamie Hall

Hoffman Differential Regulator No. 1

Help! I am restoring an old vapour steam system (and I have purchased the book -- never fear -- but it hasn't come yet) which I suspect was rather badly mis-plumbed when a new boiler was put in about 30 years ago. There is no Hartford Loop, nor are there check valves on the condensate return lines. One rather hopes that the boiler low water safety trip works, but I'd rather not bet this house on it. What there is, however, is a contraption entitled a Hoffman Differential Regulator No. 0. It is hooked up to the dry condensate return line (on one side)(which is above it) and to the wet condensate returns (on the other side)(there are two, at floor level well below it), and appears to be located above what I estimate was the water level in the original boiler; certainly well above the water level in the present boiler. It also has a connexion to the vapour supply header (on top), and a large diameter (2 1/2") vertical leg from the bottom about 2' down which is capped, but not connected to anything.

Do you anything about what the Dead Men intended this thing to do? Do you know how it was supposed to be hooked up? Do you know how to test it to find out if it will do what it was supposed to do, assuming it was hooked up right?

Or can you direct me to another source for more information?

Thanks
James C. Hall, PhD, PE
Mechanical Engineer

jchnhtfd@att.net

don_9

Try

Books and more,Dans has a book call lost art of steam heating,Its go's in great detail about This device.
Its has something about injecting steam into the dry return to turn a b dimension back to an a dimension to get the water back in the boiler.Where are you steam head?

Jamie Hall

thanks -- the book is on order. I thought that was probably what was intended... what worries me is that there are no checks nor is there a Hartford Loop anywhere in sight so if the wet condensate were to leak and the boiler low water cutoff and feed weren't working things might go boom. Am I paranoid? Steam cutoff is at 16 oz, on at 4 oz.

don_9

Paranoid

No I don't think so.Even I a simple force air man know how
important a hartford loop is.Sound like to me you had every right to be concern."murphy law"

Unknown

Most of it is still there

And the good news? It just sits there and does nothing as long as the steam pressure etays below 1 PSI {if it is 30" above the waterline} which is probably relative to the waterline on the previous boiler. It had check valves on the returns below when it was put in, I think.

What's it do? It fills with water when the steam pressure gets too high for the water to slide back into the boiler on it's own. When it gets full, steam shoots the water back into the boiler from the line fed from the header.

This is from memory, my books are at work. I'll look it up when I get time today and see what I left out.

Noel

Steamhead

Where are you located, Jamie?

I see by the spellings of "Vapour" and "Connexion" that you might be outside the USA. These are proper British English spellings but in the States we spell them "Vapor" and "Connection". Which brings me to your Hoffman "Differential Regulator"- I am positive it's the same thing as the device we know and love as the "Differential Loop".

Noel described its primary function very well so I won't repeat it. But an old Hoffman ad tells me its secondary function was to maintain a difference in pressure between the steam mains and the dry returns, so no matter how high the boiler pressure got, steam would flow into the radiator when you opened the shutoff valve.

I've never heard that Hoffman exported their equipment, but many other American heating suppliers did so it wouldn't surprise me that Hoffman did too. You may have brought a new dimension to the Wall- I'd love to hear where this "Differential Regulator" is located!

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Jamie Hall

Thanks guys!

You are all fabulous! Now to get the thing replumbed the way it should be -- and, I expect, unclogged. Oh well...

Edward A. Carey

Your vapor system

Jamie,

You commented that your LWCO may be of concern. When you are working on the pipes for your system, you should disassemble and thoroughly clean that LWCO, testing it after it is cleaned, to assure it works.

One of the most common mis-conceptions is that LWCO failures destroy boilers. LWCO control save boilers.
However, LWCO controls that are not taken apart and "properly" cleaned each year, and "properly" flushed on a regular basis thereafter, destroy boilers.

Please refer to the manufacturer's spec for your particular LWCO, for service of the control. If you can't find it, get the name and M/N of the product and stop back here. You will get all of the information you need to keep that LWCO safe & operational.

Regards,
Edward A. Carey