Vaporstat Time?

The traps on the radiators are one part of the equation but the way the mains connect to the returns is the other part. If there is a trap for condensate than the vaportstat would likely not do too much, it would increase the thermal efficiency slightly by lowering the steam temp a little but it may also increase standby losses by cycling the boiler on and off.

On the other hand if it will prevent steam from pushing through a water seal from the main to the return then it will have a big benefit.

Measuring your actual pressure now(on a long cycle with a low pressure gauge) will give you an idea of if you are building pressure for the vaporstat to control in the first place.

You already bought it…use it.

I have never seen a pressure gauge rated for that high of a pressure bounce like that on a pig tail, they usually don't move at all. What does the gauge glass look like?

That's terrible.

has it been skimmed since the repipe?

ok you said flushing which is why I asked.

Is there ever any oil sheen seen exiting the boiler? That’s the only reason to skim.

Do be aware all that fresh water will increase rust formation

The 3/4" plugged tapping should have been fitted for skimming.

Somewhere up there there is a comment on a pressure gauge bouncing. Some installations will, depending very much on just where the gauge is tapped into the boiler. This is particularly true if the tap is below the water line. The cause is turbulence in the water, not so much pressure variations — not really surging.

Are you up for a glass boiler, @ethicalpaul ?!

When one is playing with pounds, it shouldn't be a problem. Where the problem can arise, at least in my experience, is when one is using a vapourstat, especially the mercury ones, which are very sensitive to pressure variation (they are meant to be, folks!), and when one is close to the cutout pressure, as even a slight bounce may cause a false trip.

Snubbers are available which cure that — but be aware that they can and do clog, which is a worse problem. My own suggestion, which I use, is to place the vapourstat on the header, or at the very least on a tap high in the steam chest should you be so lucky as to have one. Problem solved…

Back to your original question. I didn't watch the video but I see that you have a 0-3psi gauge. What is your normal operating pressure? Do you cycle on pressure often?

If your radiators are toasty hot at 0.5psi of steam, then yes a vaporstat is definitely worth it. If your boiler is extremely oversized you'll be cycling on pressure a lot with a vaporstat, which isn't the end of the world. If your radiators need 1psi+ to get hot a vaporstat may not be the best idea….yet. With a two-pipe system you should definitely have low pressure steam and higher pressures to get things hot indicates other problems with the system.

I have a 45 year old Peerless boiler. Single pipe, counterflow. About 50% oversized. My radiators get plenty hot at 0.5psi. I added a vaporstat to cut out at about 14 ounces of pressure with a 10oz differential. Its a sweet spot between cycling too much due to being oversized and keeping the pressure low.

The system works great and the pressuretrol is now a backup safety device. The less pressure my 45 year old boiler has to see, the better!

It sounds like your boiler is sized correctly. I'd 100% use it, you already have it and it will allow you to use your pressuretrol as a secondary safety. I'd start with a 8oz cut-out and see how thing work.

If your radiators are screaming hot at 8oz there is no need to keep firing at 100% until the thermostat is satisfied.

It looks like the manufacture's recommended cleaning method is on pages 19 and 20 of the manual, Section 4: Maintenance (Steam Boiler Cleaning Instructions).

https://archive.org/details/manualzilla-id-6979130/mode/2up

Was the oil washed off of the inside of the new pipe before it was installed ?

Absolutely, but do it by skimming, and daily is not required. Then once the oil is out you can strive to minimize the introduction of fresh water.