steam traps and putting in a new boiler

1908

I have a 105 year old steam radiator system. The 65 year old gas boiler needs to be replaced. The system is a blend of one and two pipes. 4 of the radiators are still with dry returns with what looks to be Dunham thermostatic steam traps (page 252 of the Lost Art of Steam Heating). The other 9 radiators are converted to a one pipe system. EDR is about 600 sq. feet of radiator capacity. Steam pressure has been less than one pound.

With a new boiler installation, do you keep the old steam traps on the 4 radiators? Do you allow the pressure to be between 2 and 4 lbs (recommended by installer)? We have a newly installed vent at the end of the dry return, no main line vents. The new boiler may be a Crown Bermuda BS1241.

Thanks for your ideas.

JStar

Steam

Can the one-pipe radiators be converted back to two-pipe? That would be ideal for comfort and efficiency.



Any installer who recommends 4 psi of pressure should be shown the one-way door out of the house. ESPECIALLY with two-pipe systems. You probably need 8 OUNCES or less.

nicholas bonham-carter

Pressure recommendations

I am sure he meant ounces of pressure, and not pounds. Those old traps may not work with pounds of pressure.

Now for the most important advice: make sure the new boiler has been properly sized. This means calculating their radiation total (EDR), expressed in square feet . Then you look at the prospective boilers EDR totals in square feet, and find a match, which may even be another brand. The old boiler may have been incorrectly sized, and this will make sure the right size is installed.

Somewhere on this site is a video showing the importance of proper piping of the new boiler, and the installation manual will have instructions that must be followed(put it in the contract). Any plumber who might say "I've been doing it this way for X years" . He needs to read the instructions and follow them, as far as pipe sizes go.

Along with your old Cadillac system, you should have a low-pressure gauge (0-3 psi), along side the useless code required 0-30 psi. Put on a 0-16 ounce vaporstat to keep the pressure in check.

Are you burning gas or oil? You may want to consider a "wet-base" boiler, such as Smith or Burnham Megasteam (oil only). These give a few more percentage points of combustion efficiency, although with a bit more noise.

Ask your installer to make sure the venting is generous. You may be very surprised how much less fuel you burn this winter if this is all done right!--NBC

Jamie Hall

While converting back to two pipe

might be ideal, it isn't necessary.  Nor is replacing the traps (unless they aren't working).  Do make sure that all the pipes are pitched correctly, though.



Steam pressure is critical.  It should never -- ever -- in a residential system be above a pound and a half, and it is very likely that it will work best at about 8 ounces cutout.  For that you will need a vapourstat on the new boiler.  Your man who recommended 2 to 4 pounds is either mistaken -- as NBC hoped -- or just plain wrong.



Boiler size is critical, as noted.  So is near boiler piping.  So is making sure that the new boiler is installed so that its working water line is within an inch either way of the water line on the old boiler; this may require raising the new boiler on a pedestal.

1908

1908

Thank you all for your comments. It is difficult to find someone here in Eastern Washington who is familiar with the intricacies of residential low pressure steam heat. So many people have converted to hot water systems instead. 

I was able to watch the video regarding the near piping for the steam boiler. A talking picture is so much easier to understand.

Another question - my current piping coming out of the boiler is 3 1/2 inches diameter and there are two of them. Is this a problem going to the solo standard 2 inch pipe from the new boiler to the 3 1/2 inch main lines?

Jamie Hall

Check and double check

that boiler size.  Three and a half inch mains are pretty big.



However.



If the near boiler piping is done correctly, in careful accordance with the manufacturer's instructions, then going from the header into the large diameter mains shouldn't be a problem.  I would suggest, though, that you may get better results if you come vertically off the header at header size (double check those manufacturer's instructions for that size!  And it would be better if the header were a size or two larger than the riser, even if the manufacturer doesn't call for it) and increase to the main size in the vertical leg, rather than increasing in the horizontal once you get up there.



As to the eastern Washington problem.  Indeed, there are large parts of the country where people who really understand steam are pretty thin on the ground.  However, if you will purchase the set of books (Lost Art of Steam Heating etc.) they will give you a good knowledge of steam heat (it really isn't all that complicated -- simpler than hot water, by a long shot) and if you have a good, honest workman plumber, who knows how to thread pipe and is willing to learn something new, you and he (0r she!) can work together to get a steam heating system which really works beautifully.



Oh yes -- and don't either you or your plumber be afraid to post questions on the Wall.  The best in the business read it, and are more than willing to help out.