Does anyone make 1 1/2 inch radiator orifice plates?

The Steam Whisperer

I have an upcoming project that has quite a few huge radiators that were originally one pipe steam and were converted to two pipe. It looks like the radiators were sized to the old SBI standards so they are double the size needed originally and the structure has since been insulated. We're cutting down the radiation capacity by about half with orifices as part of replacing the boiler and dealing with the radaitor traps.

gerry gill

I would make my own. I always have.

The Steam Whisperer

Yes, I've done it before, it just takes some time. I was hoping to save some time. I probably need to make a dozen or so.

EBEBRATT-Ed

@The Steam Whisperer (Formerly Boilerpro)

Suppose a metal fabricator with a plasma cutter could rip them out for you.

retiredguy

Why not just reduce the size of the existing radiators?

mikeg2015

+1 on plasm cutter. You’d be surprised how cheap it is. Could easily make a range of sizes too.

PMJ

2 pipe with large radiators...now there is a beautiful thing. PWM anyone? With that there is no such thing as too much radiation. Far easier and more effective than fiddling with hardware.

The Steam Whisperer

PMJ, This is a steam system which we are replacing the boiler and downsizing the radiation by using orifice plates. Current EDR is about 1800 and we are dropping it to 995 EDR. The savings by cutting the boiler size by nearly half will easily pay for orifice upgrade, elimination of the radiator traps, new zone valves and probably cleaning and rebuilding the drip traps and cleaning the wet returns. Elimination of the traps alone will just about pay for all the design and work related to installing the orifice plates. We will also be going from 2- 3 inch and 1- 2 inch zone valve down to 2-1 1/4 inch and 1- 1 inch, another huge savings in equipment cost. Of course, the ongoing maintenance costs and future repair costs will probably be cut about in half too.

Retired Guy, Its a lot cheaper and easier to just properly size and slide an orifice plate in than remove and replace 100 EDR rads. We are resizing about 25 radiators for about the cost of putting in 2 to 3 new ones. And keeping the big radiators also means we can get rid of the radiator traps too, since steam will never make it to the return line with properly sized plates.

PMJ

Sounds like a lot of work. You didn't read me to say replace any rads I hope. I was saying no hardware work at all except replacing the boiler which I assume is necessary. PWM doesn't care how big that is either except if it truly isn't big enough.

I just make a plug once in a while thinking someone might try some downsizing with a simple PWM control instead. That's what I did with my 2 pipe system with many oversized rads that never get close to full (which means traps aren't needed either).

Don't get me wrong - I understand that an orifice will effectively downsize. The pressure drop across it restricting the flow will allow tripping a pressure control on the supply side without blasting the place with heat first. But PWM allows for 2 pipe operation with no pressure at all or certainly not enough to do any control with. No restrictions is more efficient too.

My point is with PWM the size of the rads doesn't make any difference - again unless they aren't big enough.

The Steam Whisperer

However, we have 1800 EDR and are putting in a boiler with 995 EDR, Will PWM make that work?

PMJ

Yes. The unused EDR beyond the fill makes no difference.

The Steam Whisperer

So the steam won't favor the closest rads over the end of the system when the system is filling very slowly since the boiler capacity is grossly undersized? I can see this working with boiler sized to the EDR not problem, but at 1/2 the EDR I see problems.

PMJ

All systems must fill approximately evenly to work right. You said this is 2 pipe right? Choke off inlet valves some on close in rads if they fill too fast. If close in ones fill too fast a bigger boiler matched to the total EDR won't make them fill slower relative to the others anyway.

Or, as I have said many times, I see no advantage to sizing the boiler to the small end. Seems to me everything gets more critical the smaller you go with the boiler. The velocity of the steam goes up in the header as the boiler size goes down to get the same job done moving you closer to wet steam and hammer. With PWM you set the net EDR capacity of whatever boiler you have with the %on %off setting of the cycles. If the control won't let a given boiler run more than 50% of the total elapsed time then voila its capacity is 1/2 what the plate says or any other % you desire. So run a bigger boiler a smaller % of the time with lower velocity drier steam when it is running. Is there any efficiency loss at 3CPH vs 1CPH? From now over 25 years experience I can say absolutely not. Is there too much wear and tear on the controls or the boiler. Um, no, I say also from the same amount of experience.

Ok, I can't resist. In two pipe you can go even a step further and pretty much eliminate reliance on valves altogether by letting the system go into natural vacuum between cycles. You then end up with the system in vacuum 80+% of the total time and coldest areas with the highest condensation rates determines where most of the steam goes, not the valves.

The Steam Whisperer

The most obvious problem with running the larger boiler is that it is 3 times more expensive to install than just putting in orifice plates. In the case of the structure I am working with that is using atmospheric boilers, using a boiler sized to the radiation will yield a boiler running about 55% seasonal efficiency. Going to a boiler sized close the heat loss will bring that efficiency up to about 72%. These efficiencies are based on long tested efficiency curves of equipment and I been able to predict fuel
savings quite accurately with them when changing boilers. And the plates allow you to get rid of the traps. What we've seen is if you fill the steam mains too slow, the steam is going to favor the easiest path which is the close rads. Once those rads start filling with steam, they condense, creating a vacuum and pulling in the steam even faster. This does not work well at all with a boiler undersized to the radiation. The larger boiler will be able to get steam quickly to the far ends of the system since it can overcome the strong vacuum that occurs in the radiators close to the boiler.
As to the velocity in the header, its not going to change much between 1 ounce and 3 ounces. In fact the orifices will allow the boiler to build pressure faster, cutting down velocities slightly.

I agree that PWM will work fine if the boiler is sized to the radiation, but with a boiler greatly undersized to the radiation, you are asking for trouble. We've seen it happen even with high pressure drop orifices installed...the steam favors certain mains and radiators over others.
As I said in this particular system, the savings in installed cost of the smaller boiler is going to cover the cost of the orifices,, other system trap testing and probably repairs and still have money left over. And the fuel usage should be about 20% less too.

PMJ

I always argue for the bigger boiler because I think there will be less problems. You have it as given that a boiler matched to the existing EDR is a non-starter because it will be by your numbers some 30% less efficient - no matter how you control it. I don't agree. But it does help explain why controls rarely ever get any consideration and haven't changed in decades. The idea that big boilers are bad is hard wired here. So, they get smaller and smaller with more intricate headers required to get the steam to come out dry.

Hardware continues to be the only possible solution to all issues. What I don't get is that at the end of the day the hardware is one size. And if I have learned one thing in all these years it is that one size does not fit all demands. The only thing that has a chance to be flexible and responsive to changing demand in a meaningful way is the control. Why is that the control gets no consideration in the mass market - not even for a moment? The original coal burner controls were more sophisticated and actually responded to demand for goodness sake. With the control technology available today I am embarrassed for steam.

Also, with your "grossly undersized" boiler you are comparing to a very large quantity of EDR at the remote ends of radiators which never see any steam at all and so can't affect steam flow in any way. I was asked if I thought a much smaller boiler would work and I still do - even though I don't recommend it. If close in radiators in a 2 pipe system really fill to much too fast....close the valves some.

Also, this is where things like Mouat traps and others were genius. The first radiators to start condensing automatically slow down with no moving parts letting the others catch up.

The Steam Whisperer

The numbers regarding efficiency of atmospheric boilers are not my numbers but those published from the 1950's forward (National Bureau of Standards) and I have numerous projects which have shown that the numbers are correct. From stage fired multiple atmospheric boiler hot water systems to steam systems where we have cut the boiler firing rates when installing new equipment. Probably our greatest success recently was a formerly vacuum pump system ( vacuum had been off for a number of years) we converted to orifices and then down fired the large power burner boiler to about 1/2 its former capacity ( it was also over sized for the radiation). These initial steps reduced the fuel usage 40%. We later fixed the drip traps in the basement and then allowed the system to vent properly into a new condensate pump tank since the former dry returns became wet when the vacuum pump was shut off. The final step was to set up the burner to modulate off of the outdoor temperature and another reduction in peak input. IIRC we went from 2,500 to 1300 mbh to 850 mbh currently on the burner. We haven't reviewed the fuel usage yet since these final 2 improvements were made, but I expect some additional fuel savings. The system is now even quieter than before.


I agree about the need for better control and that its easy to do. The orifice concept is the springboard I use for providing outdoor reset for many systems. With the orifices helping to make sure steam is distributed evenly through the system ( on some systems we have to prime the system with higher boiler input and then back it off once all the radiators are getting steam), we allow the burner capacity to directly track the outdoor temperatures. The radiators get more or less full of steam as the heating needs change, with the boiler almost never cycling. Systems run nearly silently since there is almost no expansion and contraction noises from the piping and the radiators are constantly warm. I've had a property maintenance person put a video monitor on the boiler on one of these systems and he said he never saw the boiler cycle off for over 6 weeks. Of course this was not an atmospheric, but a modulating power burner.

While the hardware in this case is one size, the "boiler size" is varied and the pressure in the system is varied according to outdoor temperature. Pretty much the same as with coal... the fire never goes out.
I also have a number of systems that are naturally induced vacuum and when the system operation mimics how the coal boiler was operated, they hold vacuum almost continuously throughout the day. The owners of these systems are generally using single input boilers with a slight setback at night. The first long cycle in the morning largely fills the system with steam and then when the boiler shuts off and the system cools some, N 8 to 10 inch vacuum is formed which goes up and down some as the boiler cycles on and off throughout the day. These systems also generally have orifices and "undersized" boiler, or full sized boilers without orifices. The full size boilers and systems may have some advantage here, since they can probably generate a greater initial vacuum, but with the boiler twice as big and the installation cost much higher, the bigger boiler probably isn't worth it.

I also have a system that is running much like you said. A two pipe system with an undersized boiler. It took a lot of tweaking by the homeowner to get it to balance well. We use the orifices to provide that balance.

PMJ

My comments are about residential systems. At the commercial level there actually has been significant control development. I run modulating gas burners at work - one on a 6MM btu/hr low pressure steam boiler.

My opinion is that a fairly oversized to the heat loss residential boiler cycling in natural vacuum will outperform a continuously running modulating boiler. So significant is the amount of both steam production and steam delivery with the burner off and flue closed that I don't see it being challenged. The flue big enough for full fire draws more through the boiler than necessary at low fire. The time with the flue closed in vacuum is especially productive. The bigger the boiler, the longer the off periods, the deeper the vacuum.

Steam still has significant interest and development at the commercial level. Residential steam, however, is being left to die. So no business will be investing in a residential control now. So from that perspective I guess I understand everyone just riding the same horse till it drops for good. I am disappointed though as so much more was possible with just a little control work.

Last season my PWM duty cycle varied itself based on the demand using only two inputs - a temperature sensor and pressure sensor - both on a very remote rad fron the boiler. Every burn runs until both steam and any pressure over atmospheric is seen at that location plus a fixed but changable time. At that point the burner shuts off. Every rad has a partial fill at that point. From there the system sinks into vacuum. If the call for heat is still in place when the temp sensor goes back below 140F a new fire begins. This time because of the vacuum the temp sensor will see steam well before the vacuum is gone so the burn goes until the pressure sensor just goes positive. In colder weather the steam condenses faster so the wait periods get shorter. The vacuum pulled is deeper though so the burns get a little longer to kill the vacuum. In this way the run/wait percentages change themselves with the demand. The colder it gets the longer the calls go on - hours sometimes. Performance wise both comfort and efficiency it will run away from a single speed boiler of any size with standard controls with standard stops - tsat and vaporstat and of course no vacuum.

The Steam Whisperer

It would be interesting to see which actually uses less fuel....the larger boiler running with a natural vacuum or a modulating burner running nearly continuously. If both boiler are power burners ( low stand by losses) I imagine the larger boiler will win. What probably would work best is a larger modulating power burner boiler that runs a long cycle periodically to reestablish vacuum in the system and then modulate under continuous vacuum the rest of the time. With atmospherics the standby losses are just so great, that the typical boiler sized to the radiation is about double the heat loss, which really kills efficiency. Of course if you are running vacuum, that cuts the stand by losses some, but the boiler still only gets down to about 195F under typical vacuum levels.

With that most recent orifice system I was talking about, I think our next thing to try is put check valves on the condensate tank outlet and see if it can generate some vacuum.

PMJ

I get the standby loss thing if the boiler is somewhere other than the structure it is heating. It seems to me that my boiler mostly warms the basement and floors above and so mostly it isn't lost.

I also get how big commercial boilers with long stack purge cycles on every startup might suffer efficiency wise with many cycles. But in my case with full boil only seconds from new fire in the deepest part of the vacuum I'm not seeing where the losses are.

Long ago I considered modulated fire and 2 stage valves. But watching natural vacuum at work eliminated those things from consideration. In residential 2 pipe I will put natural vacuum cycling up against anything.

jumper

Funny how things go around. I think that long ago Domestic Pump pushed vacuum to lengthen cycle. In those days business used coal so the boiler operator could throttle the fire appropriately?

jumper

Returning to OP's original question, somebody must make washers in USA? Can't they supply discs without holes? Then it's only a matter of figuring out what size hole to drill.

The Steam Whisperer

Tunstall makes up to 1 1/4 inch and the can stamp the hole sizes you give them. We've put in probably over 1000 of them. However, 1 1/2 and 2 are hard to come by. Just about everyone has stopped making 2 inch supply valves. It seem the only ones you can get are the cheap ones.