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Jamie Hall

Jamie Hall

Joined on September 16, 2002

Last Post on April 17, 2014

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@ March 12, 2014 10:13 PM in Help! Left water on filling boiler and now...

Mine is none too good -- I'm 72 -- but there are no bladders in a steam boiler, or anywhere else in a steam system for that matter.  That remark by your plumber does not inspire confidence...

However, it could very well be the pressuretrol.  It could also be the vents.  Enough water pressure to come out of a vent up in the house could very well have damaged any or all of them...

Keep us posted!

Not as you are leaving...

@ March 12, 2014 7:17 PM in water in tank

when you have just finished cleaning yourself up a bit and are getting in the truck...


@ March 12, 2014 7:10 PM in How to detect if there's oil in steam boiler water

when in the cycle does it "short cycle"?  It is, as Fred said, unusual for oil -- even a fair amount of the stuff -- to cause a problem with the pressuretrol.

You have a real problem...

@ March 12, 2014 7:07 PM in Help! Left water on filling boiler and now...

You don't know what your system is doing, and that could be quite dangerous.

However, I would ask one real fast question: what does that pressure gauge read when the system is more or less cool?  If it reads 0, or nearly so, and then scoots up to 10 when the boiler starts firing, it may be correct -- and that's not good, as the pressuretrol should shut things off long before then.

Bottom line on that: either the gauge is bad or the pressuretrol -- or, as has been suggested, the pigtail or the entrance to the pressuretrol is plugged.

I would be very hesitant to run the system at all until I could be reasonably sure that the pressuretrol was working the way it should.  The only real alternative I see for the time being is for you to assume that that gauge is correct (but check that 0!) and play pressuretrol yourself, turning the system off when the pressure rises and back on when it comes down again.  Again I say I don't recommend doing this; you'd be being a test pilot for an unknown configuration -- but it's the only thing I can think of until you can get a steam guy in there.

If you can keep the house above freezing in some other way WHICH IS SAFE, I'd do that instead.

Of course

@ March 12, 2014 11:34 AM in Boiler efficiency cycling vs continuous run

you all are quite correct -- so long as the pipes and the boiler itself are within the more or less heated envelope, the "loss" isn't actually a loss in terms of overall heating efficiency.  How much these heat transfers -- to avoid the term loss! -- contribute to the comfort of the house is another matter, and one completely dependent on the structure.  This is one of the many reasons why trying to pin down the "most efficient" way to operate a heating system is so darn difficult!

The only real total loss is the heat in the stack gas, and even then only to the extent that the stack is not part of the heated space.

Same thing is true, of course, of the water heater and the hot water pipes -- in any climate where heating is used much of the time, the "losses" from the water heater and the pipes isn't really a net loss.

As for the pumps and fans -- quite right there.  They do use a surprising amount of energy, which is conveniently overlooked by the folks (including the government boffins) pushing high efficiency hydronics, radiant, and particularly hot air.

All of which is why, although steam is sometimes given a bad rap (the best we can do without heat recovery heat exchangers on the stack gas being in the high 80s) the overall efficiency of pretty much any of the various heating systems is within a very small number of percentage points, provided they are all maintained equally well -- a rather big if.

I like to look at it this way...

@ March 11, 2014 12:42 PM in Boiler efficiency cycling vs continuous run

You need to deliver a certain number of BTUs to your heated space.  To minimize parasitic losses -- heat lost from the steam mains, lost by radiation from the boiler, etc. -- you'd like to do that in as short a time as possible.  However, the radiation can only deliver heat at a certain maximum rate -- so there is a minimum time which the radiation must be at steam temperature to do the job.  The problem arises when the boiler is delivering steam faster than the radiation can condense it.  Then you have to shut the boiler off long enough for the radiation to catch up -- but no longer.  Then run just long enough to fill all the radiation again, and so on.

The last thing you want is for the system to build pressure beyond what is needed to gett the steam to the radiators -- a pound or so at the very most in almost all cases (a few ounces for vapour systems!).  An ideal system would modulate the heat output of the burner to maintain just enough pressure to keep the steam moving; that's what the old coal burners did (but not very efficiently!) by varying the draught.  Instead, almost all residential systems modulate the heat output of the burner by turning it off and on -- and in most systems which are running well, the off time is limited by the burner itself!  Many power burners and oil burners have pre and post purge cycles, which are often plenty long for the pressure to drop to the point where the vapourstat or pressuretrol will cut back in.

It's not that intuitively obvious...

Sounds like

@ March 11, 2014 12:30 PM in Not enough heat with new boiler set at low pressure.

two unrelated problems.  First, as NBC says, your main venting needs to be checked.  If there is a big difference between when heat first appears at the first radiator and when it shows up at the last, that's a big part of your problem.  Get that fixed and then you can start adjusting the radiator venting -- but not before.

Second, you mention something about 10 minutes a cycle.  That's way too short for steam, and may indicate that your thermostat isn't set properly for steam heat.  If it's got a cycles per hour setting, make sure that that is set at 1 cycle per hour; most thermostats come from the store set at 6, which is wrong for steam.  If it's got an anticipator, try setting that so you get a longer heating cycle.  If the boiler doesn't run long enough, there's no way it can get heat to all the radiators before it quits.

I wouldn't recommend it, but...

@ March 11, 2014 12:26 PM in Converting one pipe steam to hot water!?

if the client is really interested, there are several things to consider.

First: will the radiators (particularly if it's two story, the ones on the first floor) take the pressure?  10 to 15 psi is a lot different from 10 to 15 ounces.

Second: Is there enough radiation?  This is particularly true if you are thinking of trying to run in a condensing mode.  That handout has the BTU per square foot figures for radiators; note that that temperature is the average of the inlet and outlet temperature, not the inlet temperature.

Third: you will have to run one new pipe to each radiator; you'd be well advised to run all new piping, as the odds of the steam piping being arranged for decent hydronic work are slim to none -- even if it doesn't leak.

That's for starters.

Your client will not save money.  She would be much farther ahead in that regard bringing the steam system back to operating as it should and, if necessary, installing a nice new gas fired boiler.

Exactly, Neil

@ March 11, 2014 8:59 AM in Boiler efficiency cycling vs continuous run

If the boiler is sized to exactly maintain the setpoint temperature difference -- say 70 inside, 0 outside -- and something happens to drop the inside temperature -- say someone sets the thermostat to 60 for a day -- the boiler cannot bring the temperature back to the setpoint.  Close, yes.  Give it enough time you might not see the difference.  But actually get there?  No.

Mark S has an excellent point on the efficiency loss from heating the steam pipes and radiation (not to mention the boiler and the water) after the burner has been off.  This is why I disagree with the theory of "let the latent heat do its work".  If you are dealing with the typically slightly oversize boiler, and are at the point where the thing is cycling on pressure, you want the off part of the cycle to be as short as possible, to minimize these losses.

A related question is the question of how many cycles per hour do you want to have.  That's really system dependent, but even in very cold weather most systems will have cooled enough in a half hour or so that there is no real additional loss in going out to an hour.

And yes, Mark, the thermodynamics involved is messy! 

In principle...

@ March 10, 2014 9:09 PM in Boiler efficiency cycling vs continuous run

you are basically correct.  A setback should save energy.  In practice, the amount saved is small enough to get buried in the noise, at least for reasonable setbacks on a daily basis (the actual energy used, all else being equal, should be related to the time weighted average of the upper and lower setbacks -- thus if you run 12 hours at 60, and 12 at 70, in principle you should see the same energy use as if you ran all the time at 65)(in practice, the whole thing is vastly more complicated -- if only because outdoor air temperatures aren't constant).

On the question of recovery, though... let us suppose, for the moment, that in fact the system is exactly sized to the heat loss at the design temperature, and that we are enquiring about steady state outdoor conditions (never happens, but what the heck) and recovery from a ten degree setback.  Now the rate of temperature rise will be proportional to the excess available heat, which in turn is proportional to the difference between our target indoor temperature and the current indoor temperature.

If we do a little mathematical magic with that -- which we needn't put down here, if only because I haven't any idea how to write the equations in a comment box! (hmm... come to think of it... the basic equation is dT/dt = K(Tdesign - T), where dT/dt is the rate of change of temperature with time, K is a constant depending on the structure, Tdesign is the design or target temperature and T is the actual temperature and time t) -- we find that the time required to reach the indoor design temperature is... infinite.  That is, we will never quite get there.

One of the minor beauties

@ March 10, 2014 8:53 PM in fuel cell

about fuel cells is that they don't produce much heat.  So the question might be asked, how are they proposing to supply heat to their HVAC?  Or is this in some southern clime?

There is a downside... a, those puppies don't come cheap and b, they do need fuel... and unless they are hydrogen cells, they don't do anything different environmentally than a good clean burning gas boiler or oil boiler (depending on the fuel).

If they want to go off grid, they'd be much better off (unless their heat loads are very small) to go with a natural gas (if available) or diesel co-gen system.

If their budget is anything like most churches, they'll be putting in a boiler, as Icesailor says!

But there's one in every crowd, I guess.

At the risk of sounding flip...

@ March 10, 2014 6:56 PM in Repiping options

whichever is going to result in the simplest installation with the correct pitches!

Well now...

@ March 10, 2014 5:58 PM in Boiler efficiency cycling vs continuous run

Depends a lot on what you really mean by cycling If we confine our remarks to the cycling which a steam boiler which is slightly oversize will do at the near the end of a long cycle, cycling off on pressure so that the radiation can catch up to the boiler, then the answer is yes, there is a small loss in efficiency.  Emphasis on small.  If the off period is short -- typically just long enough for the burner to shut down and restart, the loss is very small, as the boiler and the piping never really cool down at all.  If the off time gets longer, the efficiency starts to suffer, as it is  necessary to bring things back up to temperature.

At a guess,

@ March 9, 2014 6:02 PM in how to get rid of boiler solder smell?

the only way you will ever get rid of the smell is to drain and flush -- and drain and flush... rinse and repeat... until it goes away.

Which the leak won't, by the way.  It may have stopped for the moment, but it's odds on that it's going to open up again.

This can be done

@ March 9, 2014 6:00 PM in Steam distribution pipe removal options?

although it is likely to be a fairly major repipe.  By far the simplest way to manage it would be to relocate the main from about 2 feet in from the wall to as close to the wall as you can get it.  You would only gain a bit over a foot -- perhaps as much as 15 inches -- since the main, plus its insulation, is going to be at four and probably six inches or so in diameter, particularly allowing for fittings.  The problem, of course, is that not only does the main get relocated -- but you would have to redo the connections to each of the risers off the main, which would involve a good bit of pipe fitting.

None of it is that hard.  Just time consuming.

You could then, if you liked, encase the main in the top of some cabinets or something of the sort which were on the wall, perhaps.

Two things stand out...

@ March 9, 2014 3:33 PM in General Steam Heat optimization

although there is a third.

The first is "lots and lots of exhaust"... Ah... not good.  Is there any way to measure how much water the boiler is using?  It shouldn't use much -- some systems run as little as a gallon a year.  Lots and lots of exhaust sounds dismayingly like a leaking boiler.  Is this white smoke?

The second is the mix of cast iron radiators and baseboard.  Baseboard does not deliver anything like as much heat as cast iron radiators do, for a variety of reasons.  Did anyone do a heat loss calculation for the renovated second floor, to find out if there is enough radiation?  Better yet, to find out if the amount of radiation related to the heat loss is similar to the amount of radiation to the heat loss on the first floor?  If there is amount of radiation is smaller relative to the load -- more closely matched -- on the second floor, it just won't produce the heat needed since the first floor -- with an excess, perhaps of radiation -- heats up much faster and has the thermostat.

The third more minor thing is that the boiler comes on two or three times and hour.  Most steam systems work best if the thermostat is set up to come on once per hour, more or less (this is an adjustment in the thermostat).  You had an odd situation, though, with that baseboard -- which cools down much more rapidly than cast iron, and so might work better on two cycles per hour.

Then of course there are details... like the venting on the baseboards as related to the regular radiators, and the main venting, and insulating all the steam mains... and...

I might add that natural gas is just as good a fuel for steam as oil is -- and is usually less expensive (if you have access to it, of course!).

But the first big question is that lots and lots of exhaust.  Let's hear more about that.

Well, the diagram

@ March 8, 2014 9:32 PM in Is this fixable?

is a decent representation of at least one of many ways these things can be hooked up.  However, it does sound as though somewhere in the system there is (are) valves which shouldn't be open, or cross connections between zones.

I'm afraid that what you are going to have to do is start tracing pipes, very carefully.  Then, if you don't find something obvious, make a careful sketch of exactly what you have traced out and post that and we'll see what we can make of it.

That Weil-McClain does have

@ March 7, 2014 4:32 PM in wet steam /vent spitting

only one riser tapping; even larger ones may have only one.  But that doesn't prevent you from creating a drop header if you want to work on the boiler piping.  Up, over, down into one end of the header, then take your steam mains off the top of the header and, at the far end, your equaliser off the other end and down.


@ March 7, 2014 11:44 AM in Cleaning a boiler.

and it can be a very big if... the only real variation between summer and winter is going to be the temperature of the intake air (which is a minor variation) and the intensity of the overfire draught, which can make a fairly big difference -- but shouldn't be allowed to.  That is to say, there should be control dampers -- barometric and overfire draught -- on the stack, and these should keep the variation in overfire draught to a minimum.

Of course, if one does all one's adjustments with a cold boiler and a cold stack... rather than hanging around for the thing to warm up...

At least that's my feelings about it.

The most likely problem

@ March 7, 2014 11:34 AM in Water pouring out of main vent

by far is excessive pressure backing water out of the boiler into the return.

I've got to admit that I'm not super keen on the particular piping arrangement you have there -- I'd much rather see the end of the steam main drip independently to the wet return, and the dry return drip independently to the wet return; then you wouldn't need the F&T at all unless you are depending on the F&T to vent the steam main into the dry return and thence to the regular vents?

Anyway, the only way water can get pushed up to those vents is for the pressure in the boiler to push it there.  This suggests that the first thing you want to do is to make sure that the pressuretrol really is shutting off the boiler at 1.5 to 2.0 psi -- and double check how high those vents are above the normal water line (1 psi will raise the water in the return about 26 inches).  Take the pressuretrol off and make sure the pigtail is free of any obstruction, and that the entrance to the pressuretrol itself is clear as well.

The 0 to 30 psi gauge probably won't show anything useful at that pressure (you have to have it for insurance and code compliance); you might want to get a 0 to 3 psi gauge and mount it on the same pigtail as the pressuretrol to really see what is happening.

You really do need

@ March 6, 2014 4:01 PM in Need Help - New Gas Boiler for Steam System Problems

a steam pro. to come in and most likely redo that whole installation.  Try looking in the Find a Contractor tab on this site.  There are several firms in New York and New Jersey whom I know to be good -- Joe Starosielec of Thatcher Heating serves that area I think, and he's one of the best.  Or John Cataneo, at Gateway Plumbing.  And there are others of course -- those two just come to mind.

Not a project for the faint of heart...

@ March 5, 2014 9:52 PM in Boiler replacement?

but I can well understand your wanting to do as much of it as you can yourself.  If you can thread pipe, it is as much a matter of care and common sense -- and the ability to read and follow the boiler installation manual! -- as much as anything else.

There are some booby traps.  Such as make sure the water level in the new boiler matches that in the old (that's one of the more common ways of messing things up).

If the manual gives you size options, go for the bigger pipe!

Unless you are really happy and familiar with gas piping and gas burners, and have the necessary test equipment, though, I'd leave that part -- and adjusting the burner -- to a pro.
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