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Jamie Hall

Jamie Hall

Joined on September 16, 2002

Last Post on April 18, 2014

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@ 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.

There are a number of considerations...

@ March 5, 2014 9:48 PM in System piping

but one of the more important is going to be to make sure that you don't change the level of the boiler water line when you install the new boiler.  That may take some thought!

Can you make a diagram of the existing system piping?  It would help understand it better...

The only thing that is surprising

@ March 5, 2014 9:34 PM in Skyrocketing Electric Rates

about the higher rates is that they are surprising.  They shouldn't be; the companies are very clear, although in very fine print, that they can raise the rates at will after the introductory period.

The people to get mad at are the politicians who sold the public a bill of goods on how "consumer choice" was going to save big bucks.

I wrote a whole paper, years ago, on the phenomenon of natural monopolies and how they should be treated (electric power is one; so is natural gas.  Cable television.  Telephone used to be, but isn't any more.  etc.).  It's an interesting topic.

In some situations

@ March 5, 2014 8:43 PM in copper in 2 pipe steam

it is possible to get rather severe electrolytic corrosion as a result of having both copper and iron piping in electrical contact -- say through a threaded joint.  It appears that it is very uncommon, but if one really wanted to be very certain that the problem wouldn't happen, one would use dielectric unions to make the joint.

Which are a nuisance.

But one could search "dielectric union" here on the Wall and get some more thoughts on the subject.

I hate to be skeptical, but I very much doubt the theory of "copper ions" attacking the boiler tubing -- for two reasons.  First, the concentration of dissolved copper ions in the boiler water will be very low, unless the water is very acid (very low pH).  Second, if this really were a problem, the feed piping in most situations is also copper -- and the problem would be common.  I've not heard of someone suggesting that having the feed piping to a boiler be copper is a problem...

Schvenzlerman asked

@ March 5, 2014 8:36 PM in Why not a cut in of zero?

what I meant by the possibility of a vapourstat being set too low and locking out the boiler.

What it is is this.  As the pressure drops, the diaphragm in the vapourstat relaxes.  At a certain point, it relaxes enough so that the switch flips from off to on, allowing the boiler to fire if the other controls say "go".

If the cutin is set too low, it is possible for the pressure being sensed by the diaphragm to never drop low enough for the diaphragm to relax enough to flip the switch -- and if that happens, the boiler can't run.  Hence the term "lockout".

Problem is, it won't do it every time.

If  vapourstats were perfectly repeatable, then this would not be a problem -- but they aren't.  There are small mechanical friction losses involved, as well as other sources of small variations in the pressure both at which the vapourstat will cut out and the pressure at which it will cut in (and, yes, it is possible to build them to minimize that problem; the old mercury switch ones were much better in that regard.  You don't want to pay what it would cost to build one with significantly better precision today, though).

End result?  Don't set that cut in too low.  If you really want to skate at the edge, you probably will be alright with a cutin of an ounce or two.  If you want to be more certain, best not to have the cutin much less than half the cutout.


@ March 5, 2014 4:21 PM in Carlin Gas Conversion or new oil tank?

That's an understatement and a half!

Probably at this point

@ March 5, 2014 4:19 PM in Short cycling

more of a difference of opinion, since I don't think anyone has done a study on it.

I think I'm right (naturally!), and I think my point of view has a good deal of logic associated with it.  But I'm not going to make a Federal case out of it!

There's short cycling and short cycling

@ March 5, 2014 2:37 PM in Short cycling

and we really should have two different terms.  At least...

What you want to avoid is a situation where the pressure starts to rise noticeably -- above a few ounces -- before all the radiation is filled with steam.  Good main venting will avoid that problem.

On the other hand, once the radiation is completely filled with steam, but the thermostat is still calling, you don't want the pressure to rise further  -- so the pressuretrol or vapourstat kicks in and shuts off the burner -- but you still need heat.  So, within reason, the shorter the off period (within the capabilities of the burner) the better.  Why?  Because that way the boiler never has a chance to cool down and therefore you don't lose any energy bringing the kettle up to a boil again.  It would be better, perhaps, to refer to this short cycling -- which is matching the boiler output to the capacity of the radiation -- as modulating, but that term has been used to refer to variable firing rate, rather than on/off firing.

So -- "short cycling" near the beginning of the cycle is not good.  "Short cycling" near the end of a cycle is not a problem and is expected unless you should be so lucky that your boiler exactly matches your radiation.

And furthermore...

@ March 5, 2014 2:29 PM in Why not a cut in of zero?

What you don't want is to get into a situation where the pressure does NOT drop to what the vapourstat thinks is zero.  It could happen, and that would effectively lock out the boiler.

Slightly more direct...

@ March 5, 2014 2:28 PM in HELP with new steam boiler


1)    Do I need to add any EDR for the piping?
No.. But you need to insulate the piping.

2)    Someone told me that gas boilers give off less heat per BTU
(compared with oil) and therefore if I currently have 177,000btu oil
boiler, I should get at least 200,000btu gas.   Is there any merit to
No.  Size by EDR, not BTU

3)    Bottom line: what size gas boiler should I get?
Match the EDR as closely as you can.  A bit over is a little better than under.

4)    Does the boiler size have anything to do with the size of the house or EXCLUSIVELY the EDR of the radiators?
No.  Exclusively EDR of the radiators is correct.

In two pipe steam

@ March 5, 2014 10:52 AM in question on dry returns

it is not only the mains which need to be vented, when you think about it.  It is also the dry returns.  Why?  If they are not vented, then air can't get out of the radiators, no matter how good your main venting is.

A fully looped steam main is very difficult to vent properly.  As you note, unless you are very fortunate indeed you will get air trapped somewhere in the loop.  For this reason, fully looped steam mains are just a little unusual.  Looped dry returns, on the other hand, are no problem -- since steam is never supposed to get into them in the first place.

Your first post refers to the dry returns.  As has been said, there is no problem if they connect above the water line near the boiler.

Later posts refer to the steam mains themselves.  If they connect above the water line, there is a problem.

It needs to be perfectly, unambiguously  clear what we are talking about.

That steam release valve

@ March 5, 2014 10:44 AM in Steam boiler banging, hissing and water noise

is a safety valve.  It is set at 15 psi.  There are two possibilities as to why it started leaking: either it has failed -- which is unlikely -- or the boiler managed to get to 15 psi.  Either way, that valve must be replaced.

Part two: there is the possibility that the boiler managed to get to 15 psi.  That means that either the pigtail to the pressuretrol is blocked or partially blocked, or the pressuretrol has been bypassed or failed.  This must be investigated and fixed if fixing is needed.

Both of these items are urgent; having them attended to yesterday morning is none too soon.  There are safety implications here...

OK.  We got that far.

The boiler piping is incorrect, and you are getting wet steam -- almost without a doubt.  It is possible that this is not causing a problem, but I wouldn't bet on it; it depends very much on whether there is a drip on that steam main before it heads upstairs.

The particular radiator which is banging... water hammer.  Several possibilities.  Trace out the piping, and make sure that every foot of any near-horizontal pipe is pitched to drain, either back to the boiler or to a drip.  No sags, no dips.  Make sure that the radiator is pitched back to the inlet (I'm assuming here that we are talking one pipe steam!).  Make sure that the valve on the inlet is fully open.

That will do for starters, anyway...

What bustof and Snowmelt

@ March 4, 2014 8:32 PM in Pressure keeps tripping relief valve

are getting at, Thedra, is that your boiler is connected to your domestic water supply in at least one, and possibly two, ways.  One way is the boiler fill line -- the water supply for when, if ever, you have to refill the system.  That line is commonly connected to the system through a pressure reducing valve, the purpose of which is to reduce the domestic water pressure in your house to whatever the boiler is supposed to run at (ask your plumber -- could be around 15 to 20 psi).  That pressure reducing valve can, over time, decide to leak, and very very slowly allow the domestic water to push its way into the boiler, which will raise the pressure in the boiler.

The quickest way to check that is to get the pressure in your boiler back down to where it is supposed to be, and then find the shutoff valve leading to that pressure reducing valve leading to the boiler -- and shut it off.  Then keep an eye on the boiler pressure.  It should hold pretty steady.  If it does, that pressure reducing valve is your problem.

Now... it may be that you aren't set up that way, and that the only way to add water to your system should you ever need to is with a manual feed and shut off.  It's possible that that is leaking a little.

A second way in which water can get into your boiler and mess things up is if your boiler also provides your domestic hot water.  If it does, there will be a coil in the boiler with domestic water in it.  If that coil develops a pinhole leak again you get domestic water in the boiler and the pressure goes up.  The way to check that, if you have that setup, is to isolate that domestic hot water coil and see if the pressure is steady.

There is yet another possibility: that expansion tank may have become waterlogged or the diaphragm may have failed.  You would see that if the pressure went up when the system was hot, but dropped again when the system cooled off.  If that's what you are seeing, the expansion tank is your problem.

Copper -- it depends

@ March 4, 2014 9:47 AM in copper in 2 pipe steam

The problem with copper is two fold: first, it expands much more than iron as it heats up.  Second, the soldered joints have no inherent give in them.  So...

Copper in the near boiler piping (the risers, header(s), equaliser, etc.) is a very poor idea; it expands so much more than the boiler that it puts a good deal of stress on things, and in time can damage the boiler or develop leaks at the joints.

However, although it is better to use iron elsewhere inn the system, copper can -- in my view, anyway -- be left in place if it is there, provided that it is hung or mounted in a way that it is free to expand.  Because it is expanding, it may be noisy.

I'd be more interested in the main which doesn't sound as though it is sucking air when it shuts down.  Does it have a main vent?  And, if so, is it working?  Or is your system setup with a single main vent and crossover traps -- and if so, are they working properly?


@ March 3, 2014 1:34 PM in Pressure Questions

that should do -- try it just a smidge above 0.5

Don't freak -- it's not that bad

@ March 3, 2014 12:11 PM in Pressure Questions

If you have an additive pressuretrol, you should be able to safely dial the cutin down to 0.7 without having it fall apart.  Then your differential -- set at 1 as it is -- will give  you a cutout of 1.7 -- still higher than ideal, but much better than what you have now.

Almost certainly

@ March 3, 2014 9:18 AM in Pressure Questions

the cutout pressure is too high.  I'm not quite sure what the numbers for cutout and cutin you cite are saying; the cutout must be higher than the cutin, so it makes me wonder if one of those two numbers is a differential rather than an actual pressure.

It is possible to set a pressuretrol lower, although iit needs to be done with care to avoid having the thing come apart on you.  Try to set it so the cutout is 1.5, and the cutin around 0.5.  Depending on the particular pressuretrol,, this may be a main dial setting of 0.5 and a differential of 1.0 (that would be called an additive pressuretrol) or it might be a main dial of 1.5 and a differential of 1.0 (that would be a subtractive pressuretrol).

The 0 to 15 gauge is there for the insurance and code folks, and I'm not surprised it doesn't show much.  They usually don't.  You could add a 0 to 3 psi gauge on the same pigtail as the pressuretrol, though, which would show something.

If the pressuretrol never shuts your system off, even on a very long run, either you boiler is very closely matched to your system or the pressuretrol isn't working...

The combination

@ March 2, 2014 6:04 PM in Unequal circulators in series

can work, but figuring out just what each pump is doing and creating the combined flow vs. head curve is a little tricky.  What needs to be done is to add the heads for each pump at the same flow rate across the performance curve.  That will give you the combined head.

A caution, however (I haven't looked at the pump curves): if one pump's maximum flow  at low heads is significantly different from the other's, and the system operates in that range, you will have trouble.  The one with the lower maximum flow must be downstream, as there will be a significant headloss across that pump (which will be acting as a turbine and overspeeding) which could (probably would) cause cavitation in the other pump -- and may cause problems with the motor as well.


@ March 2, 2014 5:54 PM in Knocking and hammering

Squick and draining is all very fine, but it isn't going to solve the problem.

Which sounds like water hammer, which is caused by water (usually condensate) getting stuck in steam mains (or, occasionally, returns) where it shouldn't be.

It would help if we knew if this were one pipe or two pipe steam, but while you are getting that information, here are some starters.

First, check the pressure on the boiler.  Regardless of whether it's one pipe or two pipe or vapour, it should never go over 2 psi, and 1.5 psi is better if you can persuade the pressuretrol to go that low (not all of them will).  If it's vapour, it will need to be much lower still -- but we'll get to that later.  While you're at it, make sure that the pressuretrol is actually working to shut off the system.  It wouldn't hurt to take the pigtail off the boiler and clean it, and the opening in the boiler, out so that it is free.

Then, start working your way from the boiler outwards.  What you are looking for is all steam pipes must pitch so that condensate which forms in them can make its way back to the boiler.  In some one pipe systems the pipes pitch back to the boiler; in others, and in almost all two pipe systems, they will pitch away from the boiler and eventually find a "drip" down to a wet return, and then back to the boiler.  Runouts to individual risers or radiators must all pitch back to the steam main.  It's not just end to end; check every foot of every pipe for sags and dips.

You might also take and send along a few pictures of the near boiler piping.  Some installations are such that that piping can cause "wet" steam -- steam with a lot of water droplets in it -- which doesn't help at all.

Anyway.  There are some things to start on.  When you can, get back and tell us more details about the system.
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