old boiler ressurection

Turbo Dave

Hi all. I've been approached to restore central heat to an old house in TN. It has a very old coal-fired steam boiler converted to a Janitrol natural gas burner. The system was used until 2 years ago when the burner failed and a local gas company technician advised my customer replacement parts were unavailable. I have worked with hydronic heat in Alaska for many years, but have never even seen an old steam boiler before. My first inclination was to abandon the original boiler, hang a condensing gas boiler on the wall and convert the house to hot water from steam. Since then I have done quite a bit of research and it seems this original boiler can be made to operate with a replacement burner. This would be in keeping with the original historic nature of this home built in 1878.  I found that I can purchase a conversion burner from Heat Wise. I have a few questions:

1) How do I determine the input BTU required for this boiler?

2) Converting from an atmospheric burner to a flame-retention burner will change the flame throw into the combustion chamber. It's of course a giant chamber designed for coal. What potential problems can occur with the burner change I am proposing?

3) The new gas burner would have a much faster heating rate of the boiler water than the original coal. I am not sure any compensation was made in the rest of the system when the last conversion was done. What to look for here?

4) I am trying to get maximum efficiency out of the existing steam system. I already advised the customer the steam pipes in the crawl space should be insulated. I have installed Tekmar outdoor reset controls before and think adding a 269 steam control would greatly help even heating and optimize steam cycles. Would much benefit be realized with this giant old boiler?

5) I want to heat the domestic hot water AND a 1500 sq ft addition with an exchanger in the condensate piping. I have gathered I can use about 1/3rd of the boiler BTU capacity, but do not know how to determine what I've got to work with. Here are a couple of pictures. Thanks in advance for advice! Dave

Charlie from wmass

Don't waste your time or their money

Get a new steam boiler. slantifin and Smith both have power burner gas boilers. Weil, Smith, Burnham, Slant fin, Peerless, and a host of others have atmospheric vented gas boilers which will be much more efficient and reliable than the boiler you have now.

Charlie from wmass

The original installer even used galvanized piping

Check the rest of the system as it may also have less than ideal workmanship. If so It is one of the times I would say think of converting to forced hot water. I have seen systems that were beyond ressurection.

Turbo Dave

galvanized piping

I had dismissed using this boiler until very recently and didn't take notice of the galvanized piping. I will need to drive an hour to view the system again. I can see not all of the piping is galvanized from my pictures, but will need to crawl around under the house to inspect the rest. From what I have read since your post, anything but black pipe is unacceptable for steam and must be replaced. I am not sure of the age of the boiler or piping, but you've now got me wondering how many years black pipe could be used before many failures occur as well.  What other sub par steam practices should I look for? Bushings used instead of reducer/increaser, etc.  Sheer age is one reason I was not inclined to get this old boiler going, but this is the customer's preference at this point. 

Steamhead

This is a Hoffman Vapor System

I can see the Differential Loop to the left of the boiler. Vapor was the Cadillac of heating at the time this was put in, and is still one of the best out there.



The boiler is a dry-base, three-pass, all-fuel unit. I can't see the make but it looks like it might be American Radiator Co. If you can post the model information that will help. I wouldn't worry about that galvanized pipe, the zinc coating probably wore off the inside of the pipe years ago.



Since this is a dry-base boiler, it needs a proper firebox so the flame will not overheat the base. Pre-fabricated fireboxes are readily available. Also, the flueways of the boiler will need to be baffled for best efficiency. Without baffles, the heat will zoom through the flueways and up the chimney. This procedure was common when boilers were being converted from coal to oil, and will work just as well with a power gas burner like the HeatWise. It should only be done by a pro with combustion test equipment.



If this sounds like a lot, it is, and that's why we like to replace these older boilers. But if the boiler is in otherwise good shape and the burner is installed and tuned properly, it can work well.



The system itself might need some maintenance, such as trap repairs. Again, trap parts are readily available.



I wouldn't try to convert this system to hot-water. The drastically higher pressure- 12 pounds minimum, as opposed to 8 ounces maximum on Vapor- will do a great job of finding weak points and turning them into leaks. Also, the radiators might not be big enough to heat the house on hot-water. These are but two of the things that can and do go wrong, and that's why we don't do this type of conversion. And a condensing boiler wouldn't condense much of the time due to the higher water temps that might be needed- bye-bye, promised high efficiency.



I once went to Nashville to consult on what turned out to be a Marsh Vapor system. What part of the Volunteer State are you in?

Charlie from wmass

I want to make it clear

I am not suggesting a direct conversion of the current radiators to water. I am just concerned looking at the near boiler piping that the rest of the system may not be to full cadilac quality. Some dead men were not the best of trademen. Just been seeing a lot of that type of system lately. The type with laterals taken off the side. No swing joints, and no venting.

Turbo Dave

Volunteer state vapor

I greatly appreciate the response thus far.  I had already wondered about the increase in pressure, and warned the HO a conversion may not be possible,  but didn't realize the current system is supposed to be running on ounces rather than pounds! That likely means the existing pressuretrol should actually be a vaporstat. The additional of a proper firebox and flue baffles answers my question about the target area of the new burner. Some of my picture files are corrupted, so I am unable to positively verify boiler make today, but I am almost 100% sure I saw American Radiator or American Standard on the front of the boiler. That little metal plate is unreadable, but I may be able to lift a relief of the stamping to get a model #. Since your post I have looked around a lot at vapor system design and operation. Steam is new to me, I'm a hot water guy, but the materials and forum history are very quickly educating me. The HO report  no problems using this steam system prior to the burner failure, so it seems a good candidate to put back in service. I am just about exactly an hour from Nashville in Woodbury, the system is an hour from Nashville in Shelbyville.  A consult is exactly what I need on this job. 

Turbo Dave

quality installation

I appreciate your advice and, with some help, I will be able to determine the viability of the system. The existing boiler was in use until 2 years ago. The HO stated the house was extremely warm and they did not have problems with the system until the burner failed. They also were unaware they needed to drain off anything however. I'm amazed they didn't have more problems. I will be revisiting the home to take more pictures and see if I can identify the boiler at the same time. Maybe you will notice more issues that need to be addressed, but I'm hoping not many. Thanks again. 

Charlie from wmass

Dave I do think a new boiler will make for a nicer

and more efficient system. The owner will appreciate the quiet warmth steam can offer. I look forward to seeing the rest of the system.  If you have a vapour system you can have a wonderful system there.

Jamie Hall

Indeed...

that does look like a Hoffman Differential Loop over there.  So long as the rest of the system hasn't been knuckleheaded -- and if it was working well two years ago it probably hasn't been -- you have a wonderful system.  I have one -- as you can see from the signature line -- and I love it.



I suspect Charles is right -- a new boiler will be an improvement, though it may not be absolutely necessary.  The most important thing with a Hoffman system -- like any other vapour system -- is never to let the pressure get too high.  Mine is set at 6 ounces cutout, 2 ounces cut in, and that works well.  Anything much over that, and the the differential loop will do just what it is intended to do -- but which stops the system from heating at least briefly.  Vapourstat time.  Unless the existing control can get that low (some of the old ones could, but I can't see that one clearly enough to be able to tell).



Do insulate everything in sight.  It helps a lot.



The main thing the faster heating rate will do may be to require a bigger -- or more -- main vents.  I don't see one -- or them -- in the pictures, but they should be on the dry return very close to the differential loop.  In fact, for the differential loop to work properly, that's where they have to be.



If you do go for a new boiler, be absolutely sure the piping is right.  The differential loop needs its own steam feed from the header -- something which can be overlooked.

Steamhead

Shoot me an e-mail

to "steam dot head at verizon dot net". Include your phone number, let's see what we can come up with.