Richardson System venting

Fizz

The Richardson System literature is quite specific for requiring a vent on each circuit's air return main and not venting 2 or more with a single vent. I've wondered why, when many systems are vented with a single vent where more than one ARM is connected. Anybody know a practical reason?

Danny Scully

Well @Fizz, how would it vent otherwise?

nicholas bonham-carter

If you had one long return, connected above the waterline to a very short return, then the steam would race through the short pipe, arrive at the vent, and close it before the long return was fully vented.
Other systems have crossover traps between the return and its connection to the main air vent to prevent this.—NBC

Fizz

That's just it, my system(Richadson), only has one vent above boiler for 2 Air returns, apparently this was the original set-up, over 100yrs ago. My system works fairly well, though the shorter side heats quicker and somewhat bettr, vent doesn't close til heat cycle ends, then into vacuum(vent is vacuum). Would it be advantageous to add vent to long side, as there is no room on shorter side. To do so would involve dropping return before common pipe.

Fizz

Piping is origninal to installation in 1917.

Danny Scully

Come on now @Fizz, where are the pics?!

New England SteamWorks

Does this help?

Jamie Hall

The Richardson is a little odd in that it does require a separate vent for each loop's dry return. Many systems had only one, for all. However, please please be aware that the return line is for air and water only, never steam. It is not a steam main! There should be no danger of steam "racing through the short pipe and closing the vent..." -- steam should never have access to the short pipe.

That said, kindly also note that the Richardson system had a very specific outlet fitting for each radiator, which ensured that steam could not get into the return line. Further examination of their literature shows that the intended maximum pressure in the system is 5 ounces per square inch. Ounces. Pressure over that will surely blow the water seal in the outlets -- and then you will have steam in the returns, and the system will operate poorly, if at all.

So. Bottom line. Make sure you have the proper fittings on the radiator outlets; if not, they must be replaced with traps. Also make sure that your vapourstat is set at a 5 to 6 ounce cutout; the cutin can be around 1 ounce. You will need a low pressure gauge to verify these pressures!

PMJ

Note the only (vacuum) vents are miles from the boiler - air must travel through everything to get out......once. No vents on the steam main anywhere. Works fine with a cycling burner too - really.

Fizz

Have a copy of Richardson Vapor System, which is explicit in having a vent for each loop, as Jamie noted. Probably moot point as system has been in vacuum past 2 yrs with very favorable results. Between cycles(have t-stat on hot water setting of 3cph), gauge reads between 4-10hg/in vacuum and when running never gets to positive reading. Here is picture of piping where air returns are tied together. Note vent shown is prior to putting in vacuum vent.

PMJ

@Fizz,

Your reading may never go much positive but no air can leave at all unless you exceed atmospheric by something. Unless your system is perfectly sealed then some air leaks back in every cycle. So unless you pump that air out you will lose a little ground steam fill-wise every cycle if you don't remove the air that leaked back in. It is only a little bit but some time slightly above atmospheric each burn is required with natural vacuum.

Fizz

PMJ, perhaps my gauge isn't completely accurate, but overall, heat is comfortable and bills consistent.

PMJ

@Fizz,

I am quite sure it is comfortable. I was just pointing out the basics for others really who may wish to try this. Barely positive pressure is required at the header to push air out at the very far end of a system. For me 2 inches water or so and for a minute or two out of a 20 minute cycle(6-7 minute burn/13-14 minute wait).

Jamie Hall

Check your pressure, @Jim_R . The tech. may have "adjusted" it.

Fizz

That's about same burn times for me also.

Jamie Hall

Oh NO!!!! I hope he didn't replace the mercury vapourstat, or if he did he left it there for you. Those things are absolutely bulletproof and completely reliable -- and worth a small fortune on e-Bay.

Granted, they do have to be levelled correctly -- it helps to have a low pressure gauge to do that -- but...

Oh dear.