Does anyone make a mod con natural gas steam boiler?

nicholas bonham-carter

maybe the flue gases before leaving the basement could make some hot water or heat a hot water loop and use up the last bit of heat? you would have to have perfectly clean combustion so as not to plug the little passages of the heat exchanger.
nbc

Diciocco

Does anyone make a mod con natural gas steam boiler?

I have a one-pipe steam system, with a natural gas-fired CI boiler that needs replacing. Is there such a thing as a mod con boiler for steam heat that is natural gas powered? If not, what is the most energy efficient replacement option for me, apart from switching to hot water? Thank you.

Brad White_198

Condensing and Steam are

in the practical and elemental sense, mutually exclusive.

ModCons (modulating condensing boilers) are typically hot water and operate below the dewpoint of flue gasses, typically with water less than 140 degrees F. on the supply side and 120 degrees F. on the return side.

Steam boilers operate, obviously, at least at 212 degrees F. at sea level, just to get off the ground. This will not allow any condensation of flue gasses short of initial warm-up.

Accept that your best gas-fired steam efficiency will be in the low 80's at best. Some of the newer 3-pass oil boilers can get to 87% but are not rated for gas operation. Gas typically is a few percentage points lower in efficiency than oil anyway.

JohnNY

No

A boiler won't make steam and condense at the same time.

The most efficient gas-steam boiler runs at about 80-82%.

I prefer Burnham, but just pick one. I doesn't much matter.





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Brad White_198

I like

your answer better.

Steamhead (in transit)

The most efficient gas-fired residential steamer I know of

is the Smith G-8. This is a wet-base cast-iron boiler that is available from the factory with either oil or powered gas burners. Its thermal efficiency on gas is roughly 6% better than the usual atmospheric gas boiler.

Here's a shot of a G-8 we recently installed. Do you know how much radiation you have, in order to properly size the replacement boiler?

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joe lambert_2

Vacuum

Theoretically, what about a vacuum return system using lots of vacuum, now the steam temp can be lower and maybe you can get some condensing.

The Steam Whisperer (Formerly Boilerpro)

Modulating....Yes, Condensing....Not yet

I believe Power Flame now as a modulating gas burner(model X4M)for small boilers.....from 90,000 to about 400,000.....that works with standard modulating pressure controls or thermostats. You would have to talk to them to see what boilers it has been tested on. Eventually, a condensing steamer could be built by using the cold intake air to cool the exhaust gases.....something done on large installations with the addition of economizers on the exhaust. Dunkirk did this on there Quantum leap hot water boiler. It uses a primary condensing heat exchanger and then they added a secondary heat exhanger to use the heat from the exhaust to preheat the intake air. On mine the exhaust typically runs about 15 to 20F cooler than the return water. Whether a condensing design would be feasible economically, I don't know.

Boilerpro

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Brad White_198

Not theoretical

but true. That is why I qualified my response as, "in the practical and elemental sense".

Some days though, I wish vacuum steam would make a wider comeback.

Steamhead (in transit)

Maybe

you, Boilerpro, Noel, Mad Dog, myself and maybe some others should research that.........

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The Steam Whisperer (Formerly Boilerpro)

I already have a call into my Power Flame Rep

To see what boilers they've tested the X4-M burner on.

Boilerpro

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CC.Rob_10

latent heat collection?

When Dice-K pitches, there are often ads on the billboard behind home plate (the computer generated stuff) from Japanese companies.

Last night, there was an ad for the "Z boiler" from Miura.

http://www.miuraz.co.jp/en/boiler/0101.html

Says they have a latent heat recovery system for their steam boilers.

Not modulating, but perhaps condensing or recovering heat in some other manner? I don't know squat about steam, but I do watch the Sox....

Brad White_198

At their very core...

All steam boilers are "condensing boilers" and cannot work without that principle.

(I have yet to sell this to a fortune cookie company though. Imagine if some of Dan's Rules made it to the Golden Dragon at check-time?)

Unknown

Condensing or Evaporating?

I think of steam boilers as the inverse of a condensing boiler, in a way...

Noel

Brad White_198

It starts

with evaporation but ends with condensing, Sensei.

Unknown

We have al;ready had those

they were called "heat reclaimers" we service people really loved them as we cleaned all the soot they made in the boiler and flue. They were however a step toward what we have today which is the condensing concept that pulls the latent heat from condensate.