Hoffmann Differential Loop newb

GW

I looked at a job yesterday, big ole boiler needs to go. It's has the Hoffmann Differential Loop. It does have a patch on it, one of those 'clam shell' clamps; would one still leave the Loop?

The water line is the highest i've ever seen on a residential boiler. There are loop seals--two mains and the loop seals are about the same height. I didn't measure the height but I'm guessing 4' or so. I'm guessing the water line is 5'.

How many inches above the loop seals might I want the new water line? Basement seems plenty tall.

I could go back and get more notes if anyone can help me make this less scary. And thank you for those that PM me here and there when i have steam questions. I am good with one pipe but never dealt with two pipe much. I told the older gent that I haven't done a two pipe with the Loop, and he is fine with that fact. he said he was (is) a PE.

Thanks, Gary

New England SteamWorks

Keep The Loop. Just watch Point W. Here you are:



More info, especially on crossover traps. For those you need @Sailah, aka Peter The Great.

Danny Scully

@GW, with a modern Vaporstat, in theory, the loop isn't needed. I only say this because you're suggesting there is or may have been a leak in the differential loop. If the leak isn't repairable, then again, in theory, a Vaporstat is all you need. I do love these original devices, however, and if you could keep it, that would be great too. You would still need a Vaporstat though.

GW

Thanks NESW, it's got the crossover traps. Are new traps hard to come by? I was reading a post on that.

What am i looking for at Point W? I'm guessing the Loop stays in place.

The loop seals will be above the new boiler's water line---I need to lower the loop seals i take it.

Gary

GW

Danny Scully said:

@GW, with a modern Vaporstat, in theory, the loop isn't needed. I only say this because you're suggesting there is or may have been a leak in the differential loop. If the leak isn't repairable, then again, in theory, a Vaporstat is all you need. I do love these original devices, however, and if you could keep it, that would be great too. You would still need a Vaporstat though.

Danny, I thought if the loop goes there's a bunch or re-do'ing going on. One could take the loop out and not get into too much trouble?

Yes, a new vaporstat is easy enough.

The leak looks like it's been holding well.

GW

GW

well it was up and down

Sailah

New England SteamWorks said:

Keep The Loop. Just watch Point W. Here you are:



More info, especially on crossover traps. For those you need @Sailah, aka Peter The Great.

Lol, I told my wife she needs to start referring to me like that....

It's cold in the barn with this weather!

New England SteamWorks

That's better:

Steamhead

The air vent on that Loop is way too small. We generally use at least one Gorton #2 on these systems. Remember, that's the only air vent in the entire system, and it does get steam if the Loop operates.

Jamie Hall

Beautiful. As has been said, keep the loop. And do put a much larger vent on it -- that old vent was OK with a slow firing coal boiler, but not with a modern boiler.

Don't put ANY vents anywhere else on the system. If there are any, remove them.

Also as has been said, you will need a vapourstat. The loop will trip at somewhere around 10 to 12 ounces, and you don't want it to do that if you can help it.

The crossover traps are just like radiator traps. Sometimes bigger. They are essential! Barnes & Jones can get you replacement innards (or whole traps) if they aren't functioning.

One of the beauties of the system is that with the loop operating, the pressure differential at a trap never goes over that 10 to 12 ounces -- and traps tend to last forever.

GW

Thanks Jamie so the new boiler would have a water line of about 24". The two Loop Seals are about 48". The old water line is out 60", very tall beast.

Do I get some ugly cement blocks or chop the seals and lower them. If I lower the loop seals I can add ball valves and a way to flush out the wet return mains which run along the floor, I'm guessing 40 foot each. Maybe 50

There is a rad with an air vent. Oddly, that rads trap is set up sending the return pipe into the wall.....not down into the floor. I am guessing the trap doesn't work when it is sideways.

The house is a little packed, putting it nicely. The owner says there is one other radiator with an air vent as well, which I haven't seen yet.

I sent off and initial quote, homeowner seems good to go. I said I need to go back to get more notes, information.

Danny Scully

You'll want to build a false waterline @GW.

GW

Don't worry about the goop in the wet mains ?

Danny Scully

No @GW, you should still address that. I guess now that I'm thinking it through a little further, lowering the loop seals is probably the same amount of work as adding a false waterline.

GW

Cool, huh? I could drop a new radiator return into the wet return in the basement i guess.

Jamie Hall

Were it mine I'd drop the loop seals (and anything horizontals) to well below the new water line -- look all over the place! And add nice drains or at least Ts to flush them.

I like that return going into the wall... sigh. Oh well. If you do drop the return directly into a wet return rather than a dry, then you would need a vent on that return line somewhere above the water line.

ChrisJ

MMM, dirty toilet brush touching hot radiator.

That must smell nice.

Jamie Hall

That should have been anything horizontal which was below the old waterline! I sometimes (often?) type faster than I think...

GW

Yes Jamie i knew what you meant.

The horz wet ret is pretty close to the floor, I'm guessing a foot or so.

I'll plan on lowering the loops seals and installing a means to flush with a hose.

When I go back I'll get more notes.

Sailah

We make left hand right hand traps so the angle pattern isn't laying on its side like that.

GW

Peter what's the model?

Thanks, Gary

JUGHNE

Is that an air vent on the lower part of the rad near the trap, in that picture?

So Chris, how do you know the potty brush is dirty???

Sailah

GW said:

Peter what's the model?

Thanks, Gary

Hi Gary,

Sorry for delay. That would be a 122RH (Right Hand), 1/2 x 1/2 NPT

Attached pic

Peter

GW

Peter thanks, that's a pretty looking valve

in my case, the orig installer just took a normal trap and spun it sideways, I presume that's not gonna vent well? Hence, the added air vent?

You think i could get that valve installed in place of the 'normal' trap that's there now?

Sailah

Well I can't speak in absolutes based on a picture but I can say that a normal trap won't work well because the element is sideways in condensate 100% of the time. So if anything it's probably venting too much and won't close. Ie blowing by.

This is the correct trap for that configuration, right hand, but it's up to you to get the pipes aligned to where it will fit. Might take some moving of pipe to fit, not very good access I will admit.

GW

Yes Ok i will cover that in my details if this guy pulls the trigger

Is that you in the B&J Youtube videos?

Sailah

Why do I look different than you expected?

Yes that's me, unless you are seeing Danny in the videos. He's been there for 39 years and I'm turning 40 this March!

GW

I can't see you, just you shirt sleeves and watch

Hmmmm the full post didn't go in

Anyway I was saying it sounds like a voice of a 40 year old and not a voice of a guy that's been there 39 years

Sailah

Yep that's me. I have face for radio

New England SteamWorks

GW said:

Is that you in the B&J Youtube videos?

What videos? Do share!

Sailah

New England SteamWorks said:

GW said:

Is that you in the B&J Youtube videos?

What videos? Do share!

This was probably my favorite. Remember when that radiator exploded last year? I decided to turn on the steam in our lab and see how long I could stay in there. It just got really humid haha.

https://youtu.be/X-ffmWA1fH0