Security Seal Facebook Twitter GooglePlus Pinterest Newsletter Sign-up
The Wall
Mike Kusiak

Mike Kusiak

Joined on January 21, 2007

Last Post on February 14, 2014

Contact User

Recent Posts

1 2 3 4 5 ... 28 »

Replacing tubes

@ February 14, 2014 9:58 PM in Kenawee Smokeless Firebox No. 111

One problem with replacing tubes a few at a time is eventually you have the situation where the boiler has a combination of new tubes,40 year old tubes, and all ages in between. This virtually guarantees that you will be replacing a few tubes each year.

We have three large Scotch Marine boilers with 80 tubes each, built in 1981. We had a similar problem with a few tubes failing each year during the heating season, and doing emergency repairs and replacements. Finally we decided that it made more sense to do a complete retube on each boiler.

Actually it was quite cost effective to do this as a complete retube cost about the same as 3 or 4 years of plugging leaking tubes on an emergency basis and piecemeal replacements. Since the complete retube of each boiler, staggered over the past several years, there have been no tube problems at all. Sine all the tubes in each boiler are new and the same age, we can expect minimal failures for many years to come.

Something you may want to consider if you are replacing tubes on a continual basis.


@ February 13, 2014 11:39 AM in Two pipe Steam with no traps

Its really hard to tell from the photos, but it appears that the riser from the boiler is piped directly into the two  mains without a header or equalizer?

If this is true, then it will be very difficult for any carried over water to return to the boiler.

A closer shot of the boiler showing the riser and near piping would be helpful.

Water level

@ February 13, 2014 10:55 AM in low water level?

According to the manual, the water line should be 49" from the floor. You might take a tape measure and confirm the sight glass water level agrees with this.

Pump Algorithm

@ February 6, 2014 10:32 PM in How, exactly does

Harvey, your analysis makes a lot of sense. It really appears that the pump control algorithm is optimized for operation with TRV's.

The way I read it, the algorithm is trying to maintain the TRV's in the center of their modulating range, regardless of the required heat load. By determining the maximum and minimum pressure differentials and then setting the curve at a point in the middle, the TRV's control range is optimized for any given load condition.

This makes a lot of sense for operation with constant temp water, but with ODR there really seems to be no benefit. If the ODR curve is set up correctly, the TRV,s will be operating almost fully open at all times. Since there will be no pressure changes, the algorithm will set the pump at a fixed point on its curve and it will remain there.
So while the algorithm will work with ODR, there will be no benefit over using a regular "dumb" pump.


@ January 26, 2014 2:19 PM in Please confirm rad types

Well, if you did have someone with a combustion analyzer come in and check the present boiler, you could get an idea of the efficiency, and how much of that 198K BTU is actually making it to the steam. At least you would have a better idea of how much you are wasting in fuel with the present boiler and how much you might save.

Considering that its a converted coal boiler, my guess would be around 60% efficiency compared to the 80-85% you might get with a modern replacement.

Error in original calculation

@ January 25, 2014 2:02 PM in Most efficient steam system on the planet?

Yes, there is a factor of two error in your earlier gas calculation.

If you consume 2 cu ft in 36.8 seconds, then you use 1 cu ft in 18.4 sec. Then dividing 3600 by 18.4 gives you cu ft / hour or 195.7 cubic feet per hour.

At 1020 BTU/cu ft, you have 195.7 x 1020, or a firing rate of 199,600 BTU per hour

Thermostat location?

@ January 13, 2014 8:37 PM in Outside temp dramatically impacts thermostat settings

Where do you have the thermostat installed?

Is it an area that accurately indicates the average temperature of the building, and not installed on an outside wall which would be unduly affected by outside temperature?

Rated boiler input

@ December 31, 2013 9:21 PM in Over Fired Boiler Revisited

Looking back at your original post, it seems that your boiler was rated at 360,000 BTU input, so I am assuming the 260,000 rating above is a typo?

Why not try dialing back the input to the rated 360K ? This is what the boiler was designed to run and would be in the middle of the extremes of over and under firing you mentioned. It would certainly run more efficiently at rated input than it is now, being overfired at 450K. You are wasting a lot of gas running it this way.

Refrigerator insulation

@ December 23, 2013 11:02 AM in Pipe Insulating off Mains to Radiators

Asbestos cardboard usually looks much whiter than the normal paper kind, but for use as refrigerator insulation it could be a blend?

The reason I was suggesting it might be asbestos is that due to condensation, the refrigerator insulation typically gets moist and I would think that the organic paper would get soggy and rot in that application. 

Aircell Asbestos Insulation

@ December 23, 2013 9:49 AM in Pipe Insulating off Mains to Radiators

As far as I know, cellulose based cardboard was never used for steam pipe insulation. What the photo in the link shows is aircell asbestos pipe  insulation, which is made of almost pure asbestos fiber. This is actually corrugated asbestos "paper," which is made like cardboard but substitutes asbestos fiber and a binder for the usual wood pulp fibers.

And Chris, I would also assume that the insulation in your monitor tops is also asbestos rather than organic cardboard. Asbestos insulation was used in all sorts of consumer products in the 20's and 30's, from toasters and irons to stoves and radio cabinets.

You can confirm pretty easily by hitting a piece of it with a blowtorch flame. If it burns and chars then it is organic paper. If the flame won't touch it, then it is certainly asbestos.

Optimum efficiency

@ December 21, 2013 1:37 PM in High Boiler BTU

A cast iron atmospheric steam boiler is usually designed to operate at or near its maximum efficiency at its nameplate input rate. If you are overfiring, the combustion efficiency is reduced and you may be generating additional CO because there is not enough excess air available to burn all the fuel cleanly. The stack temperature will also be higher and more heat will be lost up the chimney.

Usually replacement gas valves are set at the factory for a manifold pressure of 3.5 inches of water, which is pretty much the standard for atmospheric gas burners. If your burner was designed for a lower pressure and the gas valve was not reset, then that may be the cause of overfiring.

Another possibility is that someone felt that the boiler was not generating enough steam at its rated input, and deliberately increased the gas pressure. This is definitely not a good idea.

How does your boiler steam output seem to match your radiation? Do you cycle on pressure at  the end of a thermostat cycle, or can the thermostat be satisfied before the pressuretrol limit is reached?

In any case, if you actually are overfiring by as much as you suspect, you are definitely wasting fuel over what you would be using at rated input.


@ December 21, 2013 8:20 AM in High Boiler BTU

It sounds like your boiler is being overfired, comparing  the original specs to the measured gas useage.

The original specs were based on the burners themselves, their configuration and the number and size of the cast iron sections of the boiler. The original firing rate was determined by the gas orifices in the burners and the manifold gas pressure, not the gas train valves, etc.

If the orifices were not changed, it seems that the manifold pressure may have been set too high in the Robertshaw replacement valve, which is resulting in the overfiring condition. Typically, setting the manifold pressure to 3.5 inches WC results in the nominal BTU input rating being met. The only real way to tell is to have someone with a manometer check the manifold pressure and see if it has been set too high.

It is not a good idea to throttle the input valve to reduce the firing because you are reducing the gas pressure before the electric gas valve's pressure regulator, which will result in unreliable operation. The valve may not open and close properly and the flame size will vary will gas line pressure changes.

The only proper way to set the manifold pressure is by the regulator adjustment on the gas valve, and this should only be done by someone who knows what they are doing and with the proper equipment.

You might post your question in the Gas Heating section as Tim McElwain has extensive experience with older gas boilers and can give you all the info you need to know.

Heat timer controls

@ December 13, 2013 6:27 PM in Need advice for "rule book" for residents

There are two versions of the EPU control. The standard model is equipped with a 60 minute cycle timer motor and is normally used with cast iron radiators. The model recommended for convectors has a 30 minute cycle.

I am not sure if the 30 minute timer motor is available separately as a replacement part to do the conversion, or you have to send the complete control back to heat timer for conversion. The last time I checked the 30 minute EPU control was still available new as a special order.

If you don't have the heat sensor installed at the furthest radiator or return to determine when steam has reached the last radiator, you will definitely have trouble maintaining uniform indoor temperatures. This might be the first thing to check.


@ December 13, 2013 10:02 AM in An exercise in PH readings - paper VS electronic

I have  a feeling the dye has very little effect on the paper's accuracy, as the color seems very weak. You could try putting a strip of plain paper into the treated boiler water and see if it stains the paper significantly.

I have used the PH test paper to check car antifreeze which is sometimes dyed either green or red and the readings do not seem to be be significantly different with either color.


@ December 13, 2013 9:46 AM in An exercise in PH readings - paper VS electronic

Yes, but which test gives the accurate reading? I don't think that you can automatically assume that the electronic meter's reading is accurate and the test paper is wrong. Both methods seem to give the same reading with calibrated test solutions

Without some other means of testing to confirm the actual PH reading of the boiler water, all you really know is that the readings don't agree.

Is it worth it?

@ December 10, 2013 9:01 PM in Boiler oversized

While your boiler is slightly oversized, I don't think it is a good idea to do what you seem to be proposing. Are you planning on removing one burner but not removing the corresponding cast iron boiler section?

If you do this, the section without the burner will be at a different temperature than the remaining ones, resulting in cyclical mechanical stresses. In addition, cool excess air will still flow through that section with no burner, reducing efficiency.

A better idea might be to downfire the burners 10% by either changing orifices or reducing manifold pressure. It is also easily reversible in the case if you add the additional radiator and need extra output. This is a simple procedure, but should be done by someone with a combustion analyzer to insure safe and efficient operation.

Prssure differential

@ December 9, 2013 8:59 PM in Single Pipe Vacuum

With a vacuum in the system you will certainly have a pressure differential as soon as the boiler begins to generate steam.

 As boiling begins, the point of lowest pressure will be the radiators, and the steam will travel to them to try and equalize pressure. As the steam condenses, It will maintain the lowered pressure until the radiators gradually reach the atmospheric pressure boiling point. Then with positive pressure in the system, any air will vent until the vents close and pressure will rise until the cutout pressure is reached or the thermostat is satisfied.

So at all times during the heating cycle there is a pressure differential. It just may begin at below atmospheric pressure, but the absolute pressure is always positive and highest at the boiler when it is producing steam.

B to A conversion

@ December 9, 2013 10:24 AM in modify L408B Vaporstat to "break" on pressure?

Looking at the photos of the A and B model, the only difference appears to be that the position of the mercury switch capsule is reversed end for end. So perhaps it is possible to convert?


@ December 9, 2013 9:56 AM in modify L408B Vaporstat to "break" on pressure?

Also, keep your eye out for the L608A model. This is the same as the L408A, but has a mercury switch with both NO and NC contacts (SPDT). A number of these have sold on Ebay recently for less than $100


@ December 9, 2013 8:36 AM in modify L408B Vaporstat to "break" on pressure?

Keep an eye on Ebay, as they do turn up occasionally. You can enter a search and they will email you when one becomes available for sale.

I would not use anything but a mercury switch with a millivolt system. With such a low voltage, high current circuit, contact resistance becomes critical. With the typical dry contacts of a microswitch, any oxidation can increase the resistance to a point where the system may become unreliable.

Stick with what you have until you can find a proper mercury switch control

Spiral spokes

@ December 7, 2013 8:20 AM in Frog Tape and IR Thermometers

I have wondered about his myself. Aside from the artistic aspect, the only thing that I could think of is that the curved spokes allow for a little "give," or flexibility compared to a straight spoke.

When the wheel is cast, there may be unequal contraction as the metal cools, causing stresses to be placed on the spokes. With the curved spokes, the stress may be reduced because they are more flexible in the same way as swing joints in piping, which allow for expansion and contraction.

Check the chimney

@ December 5, 2013 5:33 PM in High Humidity/Boiler Leak?

There may be more than just steam escaping into your basement. You also may be getting combustion gasses backing up into the basement if the chimney flue is clogged. This could be contributing to your humidity problem as the combustion exhaust gas contains a large amount of water vapor.

This could be a very dangerous situation and it makes sense to check the chimney
1 2 3 4 5 ... 28 »