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Re: What does "Wet Steam" mean to you?
If this were a purely scientific discussion @ethicalpaul, my vote would be different. I would vote #4: All residential steam is WET steam because it is at the saturation temperature of water. For steam to be really "DRY" it must be superheated at least one degree above the saturation temperature. At that point there can be not water in the steam. As long as the steam is at the saturation temperature, then it can contain some water vapor or actual liquid water condensate.
But I stand by my answer in this forum because we refer to wet steam as any steam that also entrains water as a result of the boiling process or as a result of the velocity of the steam traveling thru the piping system that reaches the main piping that is well above the water line of the boiler.
Wet steam in this context is relative the the industry. You can see wet steam in the videos you post and the video of the Weil McLain boiler with the glass piping.
When your system is in normal operation, there may be a little condensation on the glass pipe sections but you don't see that water moving up into the main piping. When you do some of those tests you do then the water surges past the glass pipe.
So WET steam in our world is actual water surging into the main. while saturated steam is considered Less that Wet Steam. (but not really Dry Steam)
That's my story and I'm sticking to it!
Re: Outside of combustion chamber red hot
Who was able to have the knowhow to install a brand new burner, but not have the knowhow to see what was 6 inches away from their face? Consider yourself lucky.
HVACNUT
Re: Outside of combustion chamber red hot
In order to help in the removal of the front door, start putting penetrating oil on these 4 nuts that hold the front door in place. On a boiler that old, they are probably rusted on there pretty good. You may need heat from a torch to free them up.
I agree with @EBEBRATT-Ed about the combustion chamber never being vacuum cleaned properly. and the NEW Boiler pitch. The replacement boiler for your home will have the same burner that you just purchased. It will also have about the same fuel consumption as the P68 boiler you now have. No big change in the way Weil McLain builds them today v. 1980 except for a hinge to open that combustion chamber area for cleaning. With a new chamber and a proper vacuum cleaning, you will have a boiler that is as efficient as a new one.
Re: Long-term project to update old hydronic -- let's start with the Mercoid switch!
The pressure of the expansion tank has to be set with no pressure on the system. even te 10ft of water above it really should be removed when setting the pressure of the airside of the tank. it should be set to whatever the cold fill pressure of your system will be. to measure the system pressure, you need a gauge on the water side. the air pressure in the tank may not exactly be the system pressure and you are loosing an not insignificant amount of your precharge every time you test the pressure.
You should get a pressure gayge with or adapted to hose thread and test the system pressure at one of the drains.
the outdoor temp is only part of the heat loss. some factor for increased infiltration due to wind is also added so unless you have whatever wind speed was used you don't have the design conditions. the infiltration is just a guess unless you've done a blower door test to measure it.
mattmia2
Re: Long-term project to update old hydronic -- let's start with the Mercoid switch!
On a final note, I will admit that I really like having that nice, WARM, radiator next to me in the morning, and not sure how I will feel about a much cooler one (even if it keeps the house at the desired temperature). :)
Then you'll probably be pretty unhappy with a heat pump.
I'm also thinking your expansion tank is too small. Those gravity systems have a LOT of water.
Re: Long-term project to update old hydronic -- let's start with the Mercoid switch!
If it has a relief valve. I see what may be the discharge pipe for it. At 30psig it may be riding the relief valve because the precharge is wrong in the expansion tank or it is too small. Might be a higher pressure boiler too, I don't see a pressure rating on the ratings plate.
It is an old boiler but the savings in fuel from a new boiler will take decades to pay for the replacement. Looks like the mercoid aquastat has asbestos wiring in it but typically mercury switches will last forever in an application like that. The only application I know of where they have problems is in traffic light and flasher controls where they rock back and forth with a crank and clock motor and eventually after flexing once a minute or 2 for the better part of a century the wires eventually break.
The way to figure out if it will work at lower temps is to measure your radiators and figure out the EDR and convert that to output at different average water temps and compare that to a heat loss calculation. I bet under most conditions they don't get very hot before the heat call ends now but you should still keep the aquastat at 160+ or so.
mattmia2
Re: Long-term project to update old hydronic -- let's start with the Mercoid switch!
If that pressure gauge is correct, the water pressure in your system is too high. 30 psig should trip the pressure relief valve and put water on your floor. This is especially notable since the temperature gauge shows the boiler was cold when the photo was taken; water expands when heated and that will raise the pressure.
You may have a faulty or undersized expansion tank. Old gravity systems have a much larger water volume than more modern systems with fin tube or panel radiators, and the expansion tank size is based on the water volume.
you may also have a leaking pressure reducing (automatic water feeder) valve and/or a faulty pressure relief valve which is a critical safety device.
From what I can see on the rating plate, that boiler was oil fired when installed, and given the ratings for steam and water it burned up to 3 gallons of oil per hour. It is probably not the original boiler from 1925 but dates perhaps to the 1940s or 50s. This must be a large house!
bburd
Re: Long-term project to update old hydronic -- let's start with the Mercoid switch!
Two very different groups of actions here.
As you note, the number one priority if tightening up the house. That will determine how much fuel you use — although a newer boiler will, of course, make a difference too. But the envelope is the biggy.
The boiler… well, you probably need a new one. Until you do that, though, there isn't much point in worrying about the control. The old Mercoid may be out of adjustment — but it is reliable. You do want to worry about return temperature with the old boiler, though. They were never intended to condense, and so you want to make sure the return temperatures get above 140 for most of each heating cycle.
Re: What does "Wet Steam" mean to you?
My expectation would be that very wet steam would, after all the vents are closed, lead to higher pressure and eventually burner cycling. If there isn’t a proper header there could be cycling on the low water cutoff. Assuming all the pipes are pitched properly and the radiation is oversized for the house, I’m guessing you’d never know it was happening, except for the problems with vents getting debris in them. Just a guess.
Matt_67
Re: What does "Wet Steam" mean to you?
To measure create a simplified one pipe one radiator system. Put a drip right before the radiator inlet. Counterflow from boiler to radiator. Measure temperature at radiator (ideally multiple temperature sensors top, bottom, near and far). Configure boiler nbp to create driest and wettest steam. Run boiler for X amount of time. Over that time measuretotal condensate collected and measure area under each temperature sensor curve plotted as temperature vs time. Compare results for wettest steam config vs driest. Repeat 3 times each in randomized order.
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