Loop seal vapor

keith123

As for the supply valves on these systems, is it important to use an adjustable orifice equivalent? What type of supply valves were used on these? 

Thank you 

keith123

Also this system has check valves at each rad return in the basement. Someone added air vents to the rads, I assume the rad traps are beat, plus had no main vents on the system. I have some theories on why the swing check valves were installed 

EBEBRATT-Ed

If you have the system shown above you don't need any air vents it vents through the open return pipe.

I have some doubt that that system has not been mickey moused by someone probably several times since it was installed.

To make it work as originally installed you have to keep the pressure very low weather with a vapor stat, oarifice's or both.

keith123

My thoughts exactly. No swing checks in the original design either. I’ll be taking those out, replacing rad traps and adding main vents. Thanks for the validation. It’s good to have co-signers 

keith123

I’ll have to remove a supply valve (at least one with a wood handle) and look inside 

Steamhead

keith123 said:

I’ll have to remove a supply valve (at least one with a wood handle) and look inside 

What make are the original valves and traps?

gerry gill

you can use standard everyday inlet valves provided you have actual traps and not water seals. In its current configuration, do you have low inlets to the radiators as shown in the picture? if so you could also have an issue with the condensate actually draining back the supply instead of the return. A laser line level would let you know that. Hopefully there are eccentric bushings in the radiators outlet to lower the trap.

keith123

Thank you 

Jamie Hall

Any brand name or other markings on those traps? Quite possible they are rebuildable... if we can figure out what they are.

I doubt very much that the valves need anything more than repacking the stems, although it is possible that they might need new washers. Which may or may not be simple -- the bonnet should unscreew. Note: Should unscrew...

keith123

If you look at the diagram from Lost Art, the return valve is designed to be a thermostatic valve, not a trap. Now I’m not sure if the existing trap is in fact a trap, or a thermostatic valve. Being that someone added vents to the rads and check valves on the return piping in the basement, I’m rethinking my approach here. 

All the return piping in the basement is NOT connected to the supply main, but has its own “return” main. 

Therefor, I do not believe the swing check to be necessary. 

The return mains had zero main vents, which is why the vents on the rads were added at some point. 

To return this system to its original design with modern equipment, there’s two loops seals left. I’ll replace with F&T’s. I’ll add main vents on the return main after the F&T’s.  I’ll keep the supply valves as to not reinvent the wheel. As for the rad “traps” not sure if TRV’s or traps are more appropriate. Haven’t decided yet. 

keith123

It makes sense to keep the existing supply valves, because if this is where “two-pipe” steam started, why would they start with implementing varied orifice valves when they used “standard” supply coming from a one-pipe steam world? 

The TRV’s are whats in question now. 

I believe the check were installed after the chimney vent was removed. It’s easy to tell because of all unions installed on both sides of the checks 

Jamie Hall

Do NOT replace the loop seals with F&Ts. Wrong device for the application. A loop seal is a very very simple arrangement, and will work reliably. Forever. All you need to do is keep the pressure down where it belongs. No more than 8 ounces per square inch.

I'm not sure what you mean by "thermostatic valve". A thermostatic steam trap -- which is what it certainly looks like you have there -- has a thermostatic element in it which closes when steam hits it. Otherwise it is open, to allow air to pass, and it will open to allow condensate to pass.

If you reax the Lost Art carefully on the subject of vapour systems, which is what you have there, you will note that the steam mains are connected to the dry returns via crossover traps -- these are, in general, exactly the same as the traps (your thermostatic valves) on the radiators -- and they have to be there, and functioning.

The dry returns are then connected together -- usually near the boiler -- and provided with a main -- and the only -- vent. For modern systems, it may be better to use a cluster of vents in that location.

In general -- though not absolutely always -- there were also wet returns at or near floor level which collected condensate via drips from the steam mains and the dry returns.

The radiator vents don't belong. The check valves don't belong. one or all of your radiator traps -- your thermostatic valves -- may be malfunctioning. The crossover traps may be missing. The master vent cluster on the dry returns may be missing.

The pressure is probably way too high.

You have work to do -- but remember that a vapour system has two pipes to each radiator, but isn't really quite the same as a two pipe steam system and try to bring it back to where it belongs.

keith123

Do NOT replace the loop seals with F&Ts. Wrong device for the application. A loop seal is a very very simple arrangement, and will work reliably. Forever. All you need to do is keep the pressure down where it belongs. No more than 8 ounces per square inch.

this system had 4 loop seals. Two of them have been previously replaced by someone else with F&T’s

I'm not sure what you mean by "thermostatic valve". A thermostatic steam trap -- which is what it certainly looks like you have there -- has a thermostatic element in it which closes when steam hits it. Otherwise it is open, to allow air to pass, and it will open to allow condensate to pass.

As for thermostatic return valve I’m referring to the “diagram” from Lost Art. 

If you reax the Lost Art carefully on the subject of vapour systems, which is what you have there, you will note that the steam mains are connected to the dry returns via crossover traps -- these are, in general, exactly the same as the traps (your thermostatic valves) on the radiators -- and they have to be there, and functioning.

This system has zero cross-over traps. It’s exactly as the “diagram” shows. 

Supply mains to each rad. All rad returns are to a separate return main. 

The dry returns are then connected together -- usually near the boiler -- and provided with a main -- and the only -- vent. For modern systems, it may be better to use a cluster of vents in that location.

I performed this already. 

In general -- though not absolutely always -- there were also wet returns at or near floor level which collected condensate via drips from the steam mains and the dry returns.

The wet return is right at the boiler

The radiator vents don't belong. The check valves don't belong. one or all of your radiator traps -- your thermostatic valves -- may be malfunctioning. The crossover traps may be missing. The master vent cluster on the dry returns may be missing.

I’m planning on removing the check valves and rad vents already. I’m curious since the original arrangement had “thermostatic return valves” if that’s what they used to name steam traps, or did they mean something closer to a modern TRV. I’m guessing the former. 

As for the supply valve, it makes sense to me to keep them and perhaps repack them if need be. 

The pressure is probably way too high.

I did install a vaporstat

You have work to do -- but remember that a vapour system has two pipes to each radiator, but isn't really quite the same as a two pipe steam system and try to bring it back to where it belongs.

Thank you for your thorough response !! 

keith123

At what point if any is it appropriate to change the existing (one-pipe) supply valves with multi orifice valves. The industry changed for a reason when it comes to this. 

Jamie Hall

keith123 said:

At what point if any is it appropriate to change the existing (one-pipe) supply valves with multi orifice valves. The industry changed for a reason when it comes to this. 

In my humble opinion (oh well, maybe not so humble...) the multi-orifice valves are very nice. Also, if you have functioning traps (valves, whatever you want to call them) and keep the pressure down where it belongs, you don't need them.

Which, I think, is why the industry sort of shifted. The orifice valves -- or elegant valves like the Hoffmans -- are needed when there are not traps or when static widgets are used. Then you really do need to regulate the flow of steam to the radiator quite precisely. But with a functioning trap on the outlet? You don't. The regulation becomes one of changing the heat output, and any decent globe valve will do that quite nicely.

Steamhead

This could also be a variation of the Tudor system- go here for more:

https://heatinghelp.com/heating-museum/european-heating-systems-circa-1907/

keith123

Thank you so much !! So for the supply valves, the take-away is, with no trap, you need multi orifice. With a trap, you can use a plain supply valve, unless you want to vary your output, in which case there’s no harm in using a MO valve or globe valve. 

I just learned today that one rad has two supply valves. So this might also be one of the first two pipe systems that has been converted over the years. Just one straggler remains. 

Steamhead

How about a pic of the rad with 2 valves?

EBEBRATT-Ed

They took the loop seals out and replaced them with F & Ts because they ran the pressure too high

dopey27177

Do not replace the loop seals in the system, they are non mechanical steam traps.

This system is an upgrade from the two pipe system that used vent valves on each radiator, that system operated on 1 pipe steam rules.

This system must operate under 8" of steam pressure, the lower operating pressure the better because you have an open to the air air vent pipe and you do not want steam to be released to the atmosphere.

Jake

keith123

I’ll be back on the job next week. Being as this system has had “upgrades” on some levels and “downgrades” over the years, I feel the best approach because half the loop seals are gone, is to replace the others with F&T’s because the system has two already, remove the swing checks, replace the rad traps, remove the rad vents, and add a venting manifold with a vaporstat at the end of the return main. 

Jamie Hall

Um... well, if it were mine to do I'd replace the existing F&Ts with loop seals rather than the other way around -- but that's me. Vapourstat on the boiler, of course -- although they sometimes are happier on the header, if there is a place to put one...

keith123

Thank you Jamie. Because I like to experiment and try things out, I will remove one of the loop seals to see if it’s clogged. Although, this will probably prove itself to be pointless, I will at least have seen for myself that it is not clogged. If it is, the F&T’s will go in. If not, I will remove the existing F&T’s and replace with new loop seals. 

Thank you for your insight as most of my experience is with one pipe steam. 

JUGHNE

Are those air vents and the vaporstat on the same pipe?
If so what does the vaporstat control?

keith123

The vaporstat controls the boiler at the point of the systems lowest pressure. It’s wired in series with the pressuretrol on the boiler, operating the pressuretrol as a secondary high  limit. On this job I swapped the CG with a reg LWCO, because I only want the thermostat turning the boiler off. I hate those CG’s 

jumper

If there's thermostatic valves on returns why do you need adjustable inlet valve?
And how is air eliminated with loop seals?

JUGHNE

So the V-stat would not sense pressure until the air vents closed, indicating that the steam had made it to the end of the main?
Somewhat like an EOM temp sensor might do?
This seems like a good simple design.
(I am assuming this is another system in the picture)

Yes, air elimination with loop seals?
If a loop seal on each radiator then it would become a vented 2 pipe system, with rad vent?

Loop seal would be good for EOM going to return. Steam main air vented thru radiators to dry return, controlled by traps or orifice inlet of some type.

Jamie Hall

Well... now the description of the location of the vapourstat has me really worried about the whole job.

The vapourstat belongs on the boiler. At the location of the highest pressure. And if it's a vapour system, it must be set at no more than 8 ounces cutout.

If it's located at the end of the return, as I think you imply, it should never see any pressure at all if the system is operating properly. In fact, the whole return system should never be more than an ounce or two above atmospheric, if that.

I think rather than going over the whole thing here, may I recommend reading -- again, if necessary -- the entire discussion on vapour steam systems in The Lost Art?

keith123

Well... now the description of the location of the vapourstat has me really worried about the whole job.

The pictures I posted is from a one pipe steam system. 

The vapourstat belongs on the boiler. At the location of the highest pressure. And if it's a vapour system, it must be set at no more than 8 ounces cutout.

If the air out, steam up, water back cycle is operating as it should, there’s no issue with it on the return. We just may have a difference of opinion here. 

If it's located at the end of the return, as I think you imply, it should never see any pressure at all if the system is operating properly. In fact, the whole return system should never be more than an ounce or two above atmospheric, if that.
 

The results my jobs get speak for themselves. I don’t claim to know everything. I’m always looking to learn. Based on results, I do this with confidence because your above statement is the exact reason I install it there. 

I only want the thermostat operating the boiler.  

I think rather than going over the whole thing here, may I recommend reading -- again, if necessary -- the entire discussion on vapour steam systems in The Lost Art?

keith123

So the V-stat would not sense pressure until the air vents closed, indicating that the steam had made it to the end of the main?
Somewhat like an EOM temp sensor might do?
This seems like a good simple design.
(I am assuming this is another system in the picture)

You’re correct. This not from the loop seal two-pipe system this post is about. 

Yes, air elimination with loop seals?
If a loop seal on each radiator then it would become a vented 2 pipe system, with rad vent?

The loop seals are located at the end of the steam supply mains. No loop seal on radiators 

Loop seal would be good for EOM going to return. Steam main air vented thru radiators to dry return, controlled by traps or orifice inlet of some type.

dopey27177

You are forgetting that a loop seal is equalized by its connection to the dry return.
There is no loop seal required at the radiator unless it is for a special reason.

See Attached

Taken from my book Steam the perfect fluid for heating and some of the problems.

Jake