Residential Steam Boiler Replacement

Kevin Kennedy

Sorry this is a long post, includes some background. My goal is to choose the right contractor to update my steam heating system.

I recently decided it was time to replace the ancient gas fired National/U.S. Radiator steam boiler (150K input, 120K output, 375 sqft) in our house. I recently purchased Dan Holohan's book "We Got Steam Heat" in order to understand better how to choose the right contractor and perhaps the right equipment as well. Any contractor hired will have to do an EDR analysis as part of the bid.

Since we purchased the house we have insulated it, going from nothing in the walls to R13, increased attic insulation from R19 to R44 - and replaced all of the windows on the second floor with low e thermopane windows. We plan to replace most of the windows on the ground floor this fall. We have generally tightened up the house where possible.

Normally we heat the house to the low 60's during the day and to no more than 68 in the evenings. The thermostat is programmed to just three set points and spends about 16 hours a day at the lowest setting. (~60) This does appear to save us some money - unfortunately the steam lines are all stone cold as is the boiler, and it takes a long time to get up steam with some minor clanking/clinking along the way. Working pressure is under 1psi typical. (I'd have to check the pressuretrol which IIRC is the subtractive type.)

We have single pipe steam, (w/Hartford loop, no condensate pump) and have decided that conversion to hot water is not an option. Based on reading Steam Heat, and some web research I have some concerns I need to discuss with the contractor.

Issues:
1. The header is only 20" from the boiler water line.
2. There are no vents in the mains - and no evidence that there ever were. There are two mains with several risers off of each. The end of each main is connected to a condensate return.
3. The wet condensate returns are vented quite near the boiler.
4. I have insulated most of the mains, but have not insulate d much of the returns, and some risers to ground floor radiators need to be insulated.
5. The system generally needs much less than a quart of water a week, however I do have just one radiator that will leak under some circumstances.

My concerns are venting, and the radiator as I expect the issue with the header will be sorted out with the new boiler installation.

I'll admit after reading and studying literature on the net I have developed a preference for the Dunkirk Plymouth II or the Trane which I suspect to be a rebadged Dunkirk. I have looked at literature from Burnham, Utica, and Weil McLain as well - their use of stainless steel burners turns me off - perhaps mistakenly. Any unit purchased would have PID, and automatic boiler feed - probably a Hydrolevel VXT. It has been suggested that adding a float type mechanical low water cutoff is not unreasonable even with the standard probe type already installed on the boiler. Piping will be iron and fittings cast iron. (No copper)

I don't expect this to come particularly cheap, but I expect to be in this house for a very long time to come.

What should I expect in a contractor and how do I tell whether the person knows what they're doing? (I know to ask to see the manufacturers installation instructions and to insist as part of a contract that they be followed.)

Kevin Kennedy

I determined the approximate EDR of my home heating system as 260 sq ft.. I think it might be possible to downsize the boiler significantly.

Looking at the installation guide for the Dunkirk PSB-4D shows the recommended configuration with the vents in the condensate lines near the boiler pretty much as is currently the case in our system.

Another question, one of the mains is fed from the side of the header furthest from the equalizer - is this an issue? (They're separate, i.e. not bullheaded at the header, the mains are fed from the ends of the header.) Obviously this is not recommended, but what problems could it cause assuming the steam is dry enough? (See above post.)

Our current system is a millivolt system and uses no power other than that generated by the system thermocouple. While power failures are quite infrequent here they do occur in the winter when we would most need heat. Anyone heard of a 24V backup power source?

Any thoughts?

Steamhead (in transit)

Check out the Smith G8 series

this is a wet-base boiler that is available from the factory with either oil or gas burners and for steam or hot-water. This way, if your gas utility gets too greedy, you can switch fuels without having to buy another boiler. It's also a bit more efficient since the flame is almost completely surrounded by water-backed cast iron. We'll be installing the 6-section version soon in a house near mine, watch for pics sometime in the next few weeks.

The 3-section G8 unit would be plenty for a system with 260 square feet EDR.

http://www.smithboiler.com/html/g8.asp

If Burnham offered their MegaSteam boiler with a gas burner, that would be the boiler to get.

You say the "wet" returns are vented near the boiler? Do these returns run above the boiler waterline or below it?

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ScottMP

Kevin

What is your cocern with Stainless Steel burner tubes ?

Thats a plus in my book ??

Scott

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