Bringing a 2-pipe pumped-return steam heating system back in service

PEvans

My first post. I have been lurking for a while and have read a couple of Dan H's books. I just bought this house, with a steam heating system and a hot water heating system, both oil.

I am told the steam heating system has not run in years. I'm going to be optimistic and guess the prior owners gave up on what were fixable problems.

The house is in Maine and I did not find any HeatingHelp.com contractors "near me." I am hopeful to find someone local who is knowledgeable but not optimistic at all.

I have a zillion questions for the Wall and can give you lots of details about the system, its components, near-boiler piping, distribution piping, and radiator inventory. I listed a few below.

My first question is where to start? Should I test individual components, or connect the water and new fuel and see what happens?

Right now the raw makeup water connection (copper) is separated. Should I re-plumb it with threaded steel? DHW was taken off this boiler some time in the past and there is an oil-fired HWH right there. Should I take boiler makeup water from the HWH?




________________
Boiler: US Radiator Corp Capitol Model 25
Feedwater Control: Model 47-2
Pressuretrol: Honeywell Type P404B1---4
Burner: RW Beckett SF/Honeywell R8184G control/Marathon motor/Franceformer ignition transformer/Suntec Model J fuel unit
Condensate System: Hoffman Watchman Model WC-8-20-B
2 zone valves with Honeywell M644A controllers
4 steam mains depending on how you count

Steamhead

Pictures!

PEvans

I have lots of pix. What would be most useful to see first?

Steamhead

Boiler, piping around boiler, return pump, some radiators...............

dopey27177

As to installing or using a condensate pump it depends on what type of system you have. If yoy have a two pipe system are there steam traps installed or water loop seals

If it is a one pipe system are there steam traps installed or do you have an extension the the steam main that drops to the floor with a vent valve 12" behind the the vertical drop.

If you have a wet return the use of a pump may not be needed.

Pictures will be helpful.

Jake

PEvans

Boiler:




Feedwater control:




Burner (sorry, the ignitor transformer is open, covering the nameplate):




Steam Header (this looks like a drop type and the loops are not very high above the waterline; note mains come off in the middle; you can see one of the zone valves; that line coming off the right main goes to what I called the equalizer below):




Steam Header Condensate Drain:




Condensate Manifold:




Condensate Unit:




Equalizer? This comes off the top of the right steam main and drops down to return to the boiler. The condensate is pumped into it just below the water line.




Steam Header steam trap:




Steam Main #1 steam trap (note no strainer):




Steam Main #2 steam trap:




Condensate vent (I think - note, that valve is closed):




Add-on jacketed wet loop (not used):




I don't have any radiator pix at the moment. They are a mix of cast iron tube, thin tube (water type), and cast iron baseboard. Basically all have Hoffman 17C traps.

PEvans

dopey27177 said:

As to installing or using a condensate pump it depends on what type of system you have. If yoy have a two pipe system are there steam traps installed or water loop seals

If it is a one pipe system are there steam traps installed or do you have an extension the the steam main that drops to the floor with a vent valve 12" behind the the vertical drop.

If you have a wet return the use of a pump may not be needed.

Pictures will be helpful.

Jake

I have wondered if the system really requires the condensate pump. However, based on my understanding of Dan's books I am going to guess that there is not enough height difference between the steam header and the waterline to get by without it. It is a two-pipe system and there are lots of steam traps. All but one of the returns are above the waterline.

JUGHNE

I would "flood" the boiler, that is to fill it up to the header...you can feel when it gets cold. Just use the copper water connection for this.

But first, IIWM, I would be sure the boiler drain works. Probably plugged but you can back flush it with a double female end hose (washer hose). Get it to flow and be sure it can drain and shut completely off.

Flooding the boiler will let you know if there are any holes in the cast iron.
If the floor or the burner chamber gets wet then probably bad news is coming.

I would let it sit for hours full of water.
Then drain down...good chance of sludge inside.

How had they heated the house without it?
Was there a chance of freeze up.
With steam all water should drain back down to the basement pump.
Some F&T traps will hold water but if in the basement they should be OK.

PEvans

That is a reasonable first step. There is a drain valve at the very base of the boiler under the fill valve. Is that the boiler drain? Or should I be looking for something at the base of the condensate return piping?

They abandoned this section of the house with the heater not working, so there is a theoretical chance of some freeze damage. The cold water piping had frozen and popped some connections which we are going through and fixing. I believe all of the F&T traps are in the basement piping.

JUGHNE

The lowest point of the boiler would have the drain.
The condensate piping is isolated from the boiler by the cond pump.
There would be only one connection from the pump to the boiler....usually.

Hopefully the boiler was drained before freezing, some basements won't freeze if any heat in the house at all and the wind doesn't blow thru the basement.

But the water heater was down there and I assume they were using it, so it is still intact?

PEvans

There are low point drains all over the place on the condensate side. Is the boiler drain you are referring to the one visible in the lower left of my first photo if you zoom in a bit, with a hose attached to it? That looks to me like the overall low point and might be where they drained the system.

I can pretty easily attach a washer hose to that and run water in from the pressure tank for a bit, then see if it drains. That would be progress!

I don't think the prior occupants were using the WH either; there is another WH in the house. I'm going to get some more fuel oil and have the WH restarted, or at least attempt it, as part of the water system reboot for this part of the house, so I'll find out.

PEvans

Actually I take that back. All the condensate drains are in fact on the other side of the pump.

Jersey2

I thought I was the only one with an antique heating system. I guess there are a lot of old systems out there.

JUGHNE

The drain where the hose is connected looks like the boiler drain, it is also where the fresh water is added so that boiler opening may be open.

You may be able to turn the water on for the feeder, there is usually a bypass valve for quick fill. You could get some water flow and then see if the drain will drain water thru it.

PEvans

I connected the feedwater and tested the boiler drain. It flows well and is pretty clear, actually. I filled the boiler to where the condensate manifold drain was flowing. The steam header is the lowest input and it feels cold so I think the boiler is full to the steam header. The sight glass did not fill, I don't know if that is to be expected.

No leaks over several hours, and the places where I drained water are drying out. I'll check again in the morning.

Steamhead

PEvans said:

The sight glass did not fill, I don't know if that is to be expected.

It should have filled. The glass and/or fittings that hold the glass are probably plugged.

Jamie Hall

I haven't really been following this one... sorry.

The sight glass should show the water level in the boiler as it is filling or draining. If, however, the boiler is full above the sight glass it can be remarkably hard to tell if there is water in it or not. If you can't see the water level when draining or filling, though, it may be that either the valves (if any) to it are closed -- or the openings from it into the boiler are plugged. Which wouldn't surprise me one little bit.

On the condensate pump. If this is a true two pipe system, both the dry returns and the steam mains must be high enough above the water level in the boiler. But "high enough" is a function of the maximum pressure the system is allowed to run at. If this is not just a plain vanilla two pipe, but a vapour system, remember that vapour systems are designed to run at only a few ounces, and if you have a reliable pressure control with a cutout of perhaps 6 to 8 OUNCES of pressure, 28 inches clearance above the water line is ample.

PEvans

Steamhead said:

PEvans said:

The sight glass did not fill, I don't know if that is to be expected.

It should have filled. The glass and/or fittings that hold the glass are probably plugged.

I stood there and watched as I filled the boiler and never saw water in the glass. If you look in the first picture you can seen little valves at the top and bottom of the sight glass. Perhaps these are closed or clogged. They don't move.

PEvans

Jamie Hall said:

I haven't really been following this one... sorry.

The sight glass should show the water level in the boiler as it is filling or draining. If, however, the boiler is full above the sight glass it can be remarkably hard to tell if there is water in it or not. If you can't see the water level when draining or filling, though, it may be that either the valves (if any) to it are closed -- or the openings from it into the boiler are plugged. Which wouldn't surprise me one little bit.

On the condensate pump. If this is a true two pipe system, both the dry returns and the steam mains must be high enough above the water level in the boiler. But "high enough" is a function of the maximum pressure the system is allowed to run at. If this is not just a plain vanilla two pipe, but a vapour system, remember that vapour systems are designed to run at only a few ounces, and if you have a reliable pressure control with a cutout of perhaps 6 to 8 OUNCES of pressure, 28 inches clearance above the water line is ample.

There seems to be relatively little elevation difference relative to the water line in the near-boiler piping. I can give you the measurements if that helps. How would I know if this is a vapor system? I saw that chapter in the book but it wasn't clear.

The pressuretrol is not a high-precision device.

PEvans

The valves to the sight glass were closed. I opened them and filled the boiler to just over the top of the sight glass, so it is above the normal water line.

Two of the F&T traps near the boiler leak a little, one at its fitting and the other via its gasket. The boiler pressurized as I raised the water level, and the main relief finally opened at about 15 psi on the gauge. I had opened what I thought was the vent on the condensate system, so maybe there is another vent and it is trapping air.


Edit: I guess it is possible that most or all of the radiator supply valves are closed, so air can't pass through the system.

JUGHNE

The fact that you have zone valves may be one reason why you have a condensate return pump.

The zone valves turn your "A" dimension into a "B" dimension as you no longer have the steam pressure on the return, when the zone valves close, to push water into the boiler.
This is mentioned more so in the LAOSH...Dan book.

If the drop header is cold then it would fill the boiler, also if you pressurized it up to where the relief valve opened then the entire boiler would be pumped up to 15 PSI.

Water should not flow from the boiler to the condensate pump, there is a check valve to prevent that...it may be stuck in either position.

This is not an absolute test for leak checking. When boiler fires and steam is produced things can change. But most likely you are OK. IMO.

Jamie Hall

Argh... well at least you know the pressure relief valve works...

And you know that if there is a check valve on the condensate pump that it's closed...

15 psi is 33 feet of head.

Let's consider a two pipe steam system. There has to be a way, somewhere, somehow, for condensate to make it back to the boiler or -- in your case -- the condensate receiver. If you managed to get 33 feet of head on there and didn't have water coming out of the condensate tank, there are valves on there somewhere which are closed or all the F&Ts are frozen shut -- and the radiators all closed.

Not to say it isn't possible to flood a steam system -- I've done it, by accident -- but with an open vent on the condensate tank, it shouldn't be possible.

There has to be another valve on there somewhere. Or valves.

I might add (sadly...) that if the main vents weren't toast before, they are now. Most main vents won't take that much pressure.

Would it be possible to draw a diagram of the system? With some elevations from the boiler water line? That would help me visualise what is going on here, because as some folks might say, something just ain't right.

PEvans

I will post a diagram.

FWIW, note that I did get water flowing out of the open condensate manifold drain before I closed it. So water is getting back to the condensate system.

About the "main vents." Venting for a two-pipe system with a condensate pump is unclear to me. There are not vents per se that I recognize on the steam mains. There is that tall pipe rising out of the condensate system that you can see in one of the pictures. Is that the only "main vent?"

PEvans

It occurs to me that the zone valves might be closed, and the corresponding hand-operated steam main valves might also be closed. Wouldn't that mean the air in the near-steam piping has nowhere to go if the steam manifold drain is closed and the condensate vent is blocked by a check valve?


Edit: I feel like I should be able to figure this out, but is there a way to hot-wire the zone valves to force them to open if they should be open for this boiler fill test? I looked at the schematic and even made a 25VAC test rig, but it did not seem to work.

PEvans

The hand valves on the steam mains are too stuck to move without tools, and I can't tell for sure if they are open or closed.

Water is definitely getting up into the steam distribution system. Several (most) radiators leaked quite a bit through their stem nuts. Some were actually very loose. Lots of water dripping in to the rooms below and the basement, etc... I should have checked these ahead of time, but I was not planning on getting water up into the distribution system, and even the tight ones leaked a little.

Edit: I guess hydrostatic testing of a residential steam distribution system isn't a normal thing, but there it is. :-\

Jamie Hall

" I guess hydrostatic testing of a residential steam distribution system isn't a normal thing, but there it is. :-\"

Well, no... considering that a residential steam system should never go over 2 psi...

Probably no real harm done, except, as I noted, to vents and thermostatic traps -- which are, likely as not, shot anyway and in any event needed to be tested (but not that way!).

Figuring out a steam system from scratch isn't really all that hard, but it is by no means a cut and paste job either. As Dan has been heard to say, there really are only three considerations: the air has to be able to get out of the system somewhere; the steam has to be able to move in; and any condensate has to be able to find its way back to the boiler (or if there is a condensate receiver, the receiver) -- all of that taking place with very little pressure or by gravity.

There are two things which make it hard. First, there are any number of ways to accomplish all of that and, second, in many systems it isn't unusual for work to have been done on the system after it was installed -- even just a new boiler -- and the individual doing that work may not have really understood how the system was intended to work and as a result messed up something critical without meaning to. This can make figuring out how it was supposed to work and getting it back to that condition a real exercise in creative thinking.

The approach I like is to study the system just as it is -- all of it -- and make, as a first pass, the assumption that all the widgets are working as they are supposed to. Then take some time to think about how what you see is going to accomplish the three objectives.

You mention that you have manual and zone valves on the steam mains. These are sometimes needed -- but they can cause a lot of unintended mischief. First off, they really have to be full port, straight through valves -- either gates or ball type. Reduced port can cause odd problems (saturated steam doesn't like to be squeezed and then re-expanded), and globe valves are a catastrophe. And they must be either fully open or fully closed.

Where they can cause unintended mischief is that air and condensate has to be able to get out of the steam main -- on both sides of the valve -- whether the valve is open or closed. If the steam mains are parallel flow, there must, therefore, be a way for condensate to leave on the upstream side of the valve. If they are counterflow, there must be a way on the downstream side. It's not a bad idea for there to be both. Whether parallel or counter, there must be a main vent (or crossover trap) on the upstream side, as well as one at the distant end on the downstream side.. It may seem counterintuitive, but on a true two pipe system (the dry return really is a dry return, and not an extension of a steam main) there is no need for there to be valves on either the dry return(s) or any wet return(s). In fact, it's better -- and much simpler -- if there aren't any.

Again, on a true pipe system, the dry return(s) much be adequately vented to the atmosphere. Indeed, in some older systems, that venting is simply an open pipe! On newer systems, and some oddities which were meant to go into a vacuum, adequate main venting is needed. This can be done with a vent or cluster of vents on the dry returns before they join to drop to the wet return, usually near the boiler.

The air gets out the radiators through their traps (if they have traps -- some vapour systems don't) and into the dry returns.

The air also has to get out of the steam mains, however, if the heating is to be fast and even. There really are only two approaches to that: main vents on the steam mains at their distant ends or crossover traps to the dry returns. The former is obvious; that latter may not be -- but is simple enough: a thermostatic trap, often a radiator trap like all the others, is connected to the steam main at its inlet (usually a riser, a 90. and a short horizontal) and the outlet connected to the parallel dry return.

Condensate is slightly trickier. Most of the condensate will show up in the dry returns, coming from the radiators. Provided there is enough elevation difference between the dry returns and the boiler water line (28 inches for each psi of maximum operating pressure) this can be taken care of by simple vertical drips from any low points in the dry returns to a wet return. This also works, of course, if the wet returns go into a condensate receiver. There will, however, always be some condensate in the steam mains as well. Again, if there is enough elevation difference simple vertical drips will suffice if the wet returns are connected directly to the boiler. If the wet returns go into a condensate receiver (which has to be vented to the atmosphere), however, this won't work, and each drip from a steam main will have to have a F&T trap on it.

In either case, if there is no handy wet return at a low point in a steam main, a water seal -- simply a loop vertically down and then back up to the matching dry return) will work, provided two things: the dry return must be at a slightly lower elevation than the steam main, and the water seal must be deep enough ((here's that 28 inches again...) so that steam can't blow its way through into the dry return. And, of course, somewhere at a lower elevation on the dry return there has to be a drip back to the boiler...

What happens if our steam main is less than that famous 28 inches above the water line? Oddly enough, nothing. At least with regard to the steam main (assuming, of course, that it is at least somewhat above the water line), provided it is counterflow. But what about the dry returns? They are, inherently, at atmospheric pressure. Thus they will have to go into a condensate receiver. Otherwise the boiler pressure will force water up into them and the whole system comes to a halt. You can't fix this with a F&T trap or a check valve! While that may keep boiler water from backing up into the return, condensate still can't stack up enough to get back to the boiler.

I'm going to stop at this point -- I hope some of these remarks may be useful, and not too confusing. More later, and clarification of more answers if neede!

PEvans

Jamie Hall said:

Figuring out a steam system from scratch isn't really all that hard, but it is by no means a cut and paste job either. As Dan has been heard to say, there really are only three considerations: the air has to be able to get out of the system somewhere; the steam has to be able to move in; and any condensate has to be able to find its way back to the boiler (or if there is a condensate receiver, the receiver) -- all of that taking place with very little pressure or by gravity.

There are two things which make it hard. First, there are any number of ways to accomplish all of that and, second, in many systems it isn't unusual for work to have been done on the system after it was installed -- even just a new boiler -- and the individual doing that work may not have really understood how the system was intended to work and as a result messed up something critical without meaning to. This can make figuring out how it was supposed to work and getting it back to that condition a real exercise in creative thinking.

The approach I like is to study the system just as it is -- all of it -- and make, as a first pass, the assumption that all the widgets are working as they are supposed to. Then take some time to think about how what you see is going to accomplish the three objectives.

Perfect.

Jamie Hall said:

You mention that you have manual and zone valves on the steam mains. These are sometimes needed -- but they can cause a lot of unintended mischief. First off, they really have to be full port, straight through valves -- either gates or ball type. Reduced port can cause odd problems (saturated steam doesn't like to be squeezed and then re-expanded), and globe valves are a catastrophe. And they must be either fully open or fully closed.

I will post pix of the automated valves and the manual valves.

I think this is a second-order topic. Dan is no fan of zone valves and his book suggests that these days you can replace the zone valves with individual valves on each radiator. I would be fine with that.

Jamie Hall said:

Where they can cause unintended mischief is that air and condensate has to be able to get out of the steam main -- on both sides of the valve -- whether the valve is open or closed. If the steam mains are parallel flow, there must, therefore, be a way for condensate to leave on the upstream side of the valve. If they are counterflow, there must be a way on the downstream side. It's not a bad idea for there to be both. Whether parallel or counter, there must be a main vent (or crossover trap) on the upstream side, as well as one at the distant end on the downstream side.. It may seem counterintuitive, but on a true two pipe system (the dry return really is a dry return, and not an extension of a steam main) there is no need for there to be valves on either the dry return(s) or any wet return(s). In fact, it's better -- and much simpler -- if there aren't any.

So I am pretty sure my returns are counter flow to use your terms. The mains serve radiators in branches and the returns collect via separate branches. I have one wet return (drops below the water line) and the rest are dry. I don't see any evidence of vents on the mains out away from the boiler or on the condensate lines.

The "Steam Header" (4th picture) above shows what might be what you call a crossover trap. Basically a line that rises out of the steam main and continues through a trap to the condensate. This is on only one steam main. Also the steam main itself definitely has a condensate path to the condensate header.

Jamie Hall said:

Again, on a true pipe system, the dry return(s) much be adequately vented to the atmosphere. Indeed, in some older systems, that venting is simply an open pipe! On newer systems, and some oddities which were meant to go into a vacuum, adequate main venting is needed. This can be done with a vent or cluster of vents on the dry returns before they join to drop to the wet return, usually near the boiler.

The air gets out the radiators through their traps (if they have traps -- some vapour systems don't) and into the dry returns.

The air also has to get out of the steam mains, however, if the heating is to be fast and even. There really are only two approaches to that: main vents on the steam mains at their distant ends or crossover traps to the dry returns. The former is obvious; that latter may not be -- but is simple enough: a thermostatic trap, often a radiator trap like all the others, is connected to the steam main at its inlet (usually a riser, a 90. and a short horizontal) and the outlet connected to the parallel dry return.

Again, I don't see any vents on the condensate returns. The one possibility is a tall pipe rising from the condensate receiver. All of the radiators have traps.

Jamie Hall said:

Condensate is slightly trickier. Most of the condensate will show up in the dry returns, coming from the radiators. Provided there is enough elevation difference between the dry returns and the boiler water line (28 inches for each psi of maximum operating pressure) this can be taken care of by simple vertical drips from any low points in the dry returns to a wet return. This also works, of course, if the wet returns go into a condensate receiver. There will, however, always be some condensate in the steam mains as well. Again, if there is enough elevation difference simple vertical drips will suffice if the wet returns are connected directly to the boiler. If the wet returns go into a condensate receiver (which has to be vented to the atmosphere), however, this won't work, and each drip from a steam main will have to have a F&T trap on it.

In either case, if there is no handy wet return at a low point in a steam main, a water seal -- simply a loop vertically down and then back up to the matching dry return) will work, provided two things: the dry return must be at a slightly lower elevation than the steam main, and the water seal must be deep enough ((here's that 28 inches again...) so that steam can't blow its way through into the dry return. And, of course, somewhere at a lower elevation on the dry return there has to be a drip back to the boiler...

All I can say is there are mainly dry returns (with no vents) returning to a condensate receiver, and there is not a lot of elevation difference. There is one wet return. And all of this seem very intentional.

Jamie Hall said:

What happens if our steam main is less than that famous 28 inches above the water line? Oddly enough, nothing. At least with regard to the steam main (assuming, of course, that it is at least somewhat above the water line), provided it is counterflow. But what about the dry returns? They are, inherently, at atmospheric pressure. Thus they will have to go into a condensate receiver. Otherwise the boiler pressure will force water up into them and the whole system comes to a halt. You can't fix this with a F&T trap or a check valve! While that may keep boiler water from backing up into the return, condensate still can't stack up enough to get back to the boiler.

I think maybe this is the way my system was designed. They are trying to overcome either a lack of elevation or the zone valves with the condensate receiver.

Jamie Hall

Quite possible that it was designed with a condensate receiver and pump. Sometimes necessary -- particularly with limited headroom. Two thoughts until tomorrow: first, please make sure that it's wired as a boiler feed pump, and not a condensate return pump. A boiler feed pump is controlled by the low water sensor(s) on the boiler, and feeds whenever the boiler needs water -- but only when it needs water. Makeup water is fed to the condensate receiver, not the boiler, and is controlled by low water in the condensate receiver thank, not the boiler. You will save yourself a lot of heartache if it's set up that way -- or, if it isn't, if you redo it that way.

The condensate receiver tank will need an overflow.

Second, analyzing how the system is intended to work isn't much different -- if you remember that the condensate receiver (and hence any wet returns and the dry returns) are at atmospheric pressure at all times because of the vent on the condensate tank. The only real factor there is that any drips from steam mains will have to be trapped.

Oh. Three thoughts. It's time to begin to figure out how the system is actually vented. The dry returns can vent through the condensate receiver vent, assuming that they come in above the normal water level or at worst only an inch or two below it. However, the steam mains won't be vented unless there are crossover traps at the ends (and just upstream of the zone valves) or they actually have main vents at those locations. They aren't absolutely mandatory -- the system will work without them -- but it will be significantly faster and much more even if they are present. F&T traps are NOT a suitable replacement for main vents!

PEvans

Yesterday tightened all leaking fill valves, etc. which seemed to stop the leaks. Then I opened the boiler drain to get the the water and pressure out of the system. It was down to a few psig when my wife had something more important for me to do so I closed the boiler drain. Over the next few hours the system re-pressurized and sprung a new leak in one radiator. To my eyes it did not look like a valve leak (they were all dry), perhaps it could be between the sections of the radiator, however unlikely that is, or maybe in the piping.

Anyway, water dripping from the living room ceiling made the steam system the top priority again. I re-opened the boiler drain, and drained water until the eventually the gauge showed zero psig. The sight glass was still full, so I kept draining. Eventually the gauge showed a few pounds of vacuum. I opened the boiler relief a few times to relieve the vacuum, though the drain flow was reasonably strong considering that valve is now probably full of crud. So again, what is venting and what is not is a mystery to me.

Poking around, I did find that the inlet isolation valve for the steam receiver had been and was closed. So that vent was not open to the rest of the system.

I let the boiler drain overnight, and this morning the sight glass was empty. I figured I would refill the boiler until the waterline is visible. However, I heard water trickling into the steam header even though the sight glass was still empty. I opened the condensate receiver inlet valve and some water came out of the vent. So I drained everything down until that stopped and that is where the system sits at the moment.

Edit: After some time the present water level is now visible in the sight glass.

Like I said, the venting is still a mystery to me. In addition, the sight glass does not appear to be a responsive indicator of the boiler water level. It seems likely that not all of the F&T traps are opening and sending water to the condensate manifold, just given their age, but at least some must be.

I will post the requested diagram.

PEvans

Upon further thought, tell me if I'm wrong:

Maybe my experience is entirely related to the closed condensate receiver isolation valve. If I had begun to fill the boiler with that valve open and the receiver vent open (it was), I would only have gotten as far as the height of the condensate receiver vent in terms of water level and pressure, irrespective of what the boiler sight glass was showing me.

Further, perhaps the entire system is vented from that condensate receiver vent. The one steam main that has a wet return has what looks like a crossover trap, and the other steam main, with only a dry return, vents through the condensate receiver.

(I know, I know, a diagram of the near-boiler piping would help.)

JUGHNE

The only connection between the boiler and cond pump would be the 3/4" fill line which has a check valve. The check valve should keep the water of the boiler from flowing into the cond tank. It may be stuck open or leaking back.

If you flooded the entire system then the return water would flow back to the cond pump, provided the traps are not stuck shut.

So apparently your system is fairly water tight.

With a cond pump/tank and F&T traps and rad traps the cond tank could possibly be the only air vent.

The valve on the vent pipe should not be there...it may have been added when steam was coming out of it (indicating bad traps), at which point there would be almost no heat distribution.

Steam header usually would not have a F&T, the drip from it would go to the equalizer which would put that drip water into the boiler.

Your heat exchanger from steam to HW would probably have a F&T and possibly be lower than the pump manifold. It could use the steam pressure to lift the cond water up to the manifold. (possibly requiring higher pressure than needed for heating).

Can you back up for pictures showing all the piping floor to ceiling, several angles?

Also cobwebs reduce the view.

Jamie Hall

I'm going to go out on a limb a little and, agreeing with @JUGHNE , say that the condensate tank vent is the only vent on the system. Which is fine, but it does mean that you have to be sure that all the dry returns can get there.

You say that the steam main with only a dry return vents through the condensate receivers/ How? That should not be. A steam main must be separated from a dry return by a crossover trap. Otherwise when you get steam up you'll get steam in the dry return -- and the system will work poorly, if at all.

Do something to get the sight glass working. It should respond quickly and freely to any change in boiler water level. That really is a fairly urgent priority, and may mean taking things apart so you can clear the connections to the boiler (I word from experience: if you take the glass out -- which you will need to -- have a new glass and o-rings available. It's fragile...).

It is highly unlikely that the system was meant to hold any level of vacuum at all. Therefore... something or somethings are suck shut. Or there is a closed valve or valves. I have found, however, that sometimes thermostatic traps will stick shut if overpressured, and yours have been with the high water levels.

PEvans

The gauge glass drain cock opens easily and drains. However, the gauge glass does not drain with only the water cock open, suggesting that the lower port is at least partially blocked. So I will have to take it apart.

That is probably lesson #2. #1 is if the condensate receiver isolation valve is open and the vent is open, you can't inadvertently flood the steam distribution system. #2 is if the gauge glass isn't filling in that condition, the glass probably isn't reading reliably - you may be over-filling and not know it or you may be draining and not know it.

FWIW I am also finding that the boiler keeps refilling on its own. I suspect the radiator traps are reluctantly giving up their water, and I will have to replace the innards of many of the traps.

Jamie Hall

""FWIW I am also finding that the boiler keeps refilling on its own. I suspect the radiator traps are reluctantly giving up their water, and I will have to replace the innards of many of the traps."

That wouldn't surprise me one little bit. Fortunately, it's not expensive to do that -- and with the proper wrench it usually isn't even all that difficult.

PEvans

Jamie Hall said:

... with the proper wrench it usually isn't even all that difficult.

What is the proper wrench? I'm always up for more tools.

Jamie Hall

PEvans said:

Jamie Hall said:

... with the proper wrench it usually isn't even all that difficult.

What is the proper wrench? I'm always up for more tools.

Ideally a six point socket of the right size. Don't need one rated for an impact wrench! A big crescent wrench will do, but one needs to be extraordinarily careful with it. There really isn't all that much to grip, and the caps aren't all that sturdy so it's all too easy to round them off. A pipe wrench is very much the WRONG tool!

PEvans

Thank you. I'll look for one.

JUGHNE

As close a fit as possible, if it slips the edges are gone and then the pipe wrench or plyers are needed and make a mess of things.

A 1/2" battery impact driver is the best shot.


What brand of valves and traps on your rads?
Any more pictures?

I can't see how you get more water in the boiler by any traps releasing water, that water would end up in the condensate pump. Assuming it is not energized, that tank would just overflow.

PEvans

JUGHNE said:

What brand of valves and traps on your rads?

The valves are marked "H" (brown handles) and what looks like a Greek letter delta (black handles). One is marked "Kennedy" and one has a pointer handle, maybe a variable orifice.

The traps are nearly all Hoffman 17C, there is one Barnes & Jones 12

JUGHNE said:

I can't see how you get more water in the boiler by any traps releasing water, that water would end up in the condensate pump. Assuming it is not energized, that tank would just overflow.

I think this is what was happening.

PEvans

Here is a diagram of the near-boiler piping. Hopefully you can read it.

The elevations are based on the outside of the pipes measured from the underside of the floor. I measured to the top of the pipes for steam pipes and to the bottom of the pipes for condensate pipes.

Of note:

- the two steam risers come up as high as -18 1/2 inches, then drop down to the steam header at -33 1/2
- the steam header has its own condensate drain, but it goes to the condensate manifold, not directly back to the boiler
- Steam Main #1 has this funny loop that goes to what looks like an equalizer of sorts in that it is where the condensate receiver pump connects and it rises the full height of and returns to the boiler. FWIW this is the main with a wet return.



I did not include the hot water loop since that is for a greenhouse and may not be used right away (if ever).

I'm sure there are mistakes and missing details. I can provide photos as needed.

PEvans

Like I said above, I found that the gauge glass water cock was blocked, so the glass wasn't reading properly. I got the gauge glass out, but can't get the gauge valves out to clear the ports without damaging the valves -- there isn't room with the very close connections to the 47-2 feedwater fill valve. So unfortunately I will have to put in a new gauge glass set to continue testing this system, unless someone has a better suggestion.

This is the water cock, turned 90 degrees. You can see the y-shaped fitting that connects to the feedwater valve doesn't allow room for the water cock handle. If I get a replacement that sits further out there is only 4 inches at most to clear the water supply piping.