low water content boiler

Gary Usa

hiya guys,hope you are all keeping safe and well.may i ask an opinion if i may with regards to heat,by this question i mean being able to heat water up within a boiler as quick as possible and as effecient .the bearing in this matter comes to me within the field of low water contect boilers,may i ask is their a reason why they are not seen more here,where a large cast iron boiler weighing around 250LBS plus ,where as a low water content boiler can produce the same amount of heat be quarter of the size,hung on the wall cheaper to purchase does not suffer so much to cold shock,heats the water up considerebly quicker,was just wondering is their a reason why they are not used more please,thought a low water contect boiler would be an ideal application to radiant heat,and seeing their are low water content boilers now in oil and gas and condensing too.

thanks guys sorry it just has me curiuos,

take care

all the best

gary usa

John@Reliable

Gary,

Welcome to the USA. We want it BIG ,we grow up with them big so if it was good for them it's good for me!I really think this is how marketing people think,but they have gotten a little smaller here over the years.Will be a other 20 years before we catch up to the rest of the world.

hr

Properly applied

low mass boilers work very well. Since you have "motorhead" tendancys think of it this way. A low mass boiler is like an engine without a flywheel. or a very small flywheel. Ever ride a true motocross motorcycle. They rev up and down very quickly, unlike a popping johnny John Deere tractor.

If you distribution system is in harmony with that type of power source, all will be fine. Snowmelts are excellent application, long steady unchanging loads, for the most part. Batch hot water generation, pool heaters, etc.

The challange for non modulating low mass is a multi, small zoned system. Multi zoned radiant low temp is a classic example. Anytime you have a distribution system that presents these type of loads low mass need some "outside help" In my opinion.

Two stage firing helps, reset controls help, buffer tanks help in those cases.

Life expectency is another issue. Waterside maintenance is very critical. Flow rates and water quality. Also the thin copper fins used on many low mass will in time deterioate. The by products of combustion eventually take their toll. Run em cold for extended periods and the HX's will start to plug. Can't say I have ever seen a 30 year old copper tube boiler (in use) Plenty of 30 plus year old cast are pictured here on a regular basis.

Apply em, install em, and care for them properly and you will see a 15 year life without a problem. Mis applied, count on a 5 year or less life. Once again just my opinion for what it's worth

hot rod

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Bill Clinton

+ 2cents

I agree with hot rod except that I have seen numerous low-mass copper boilers in service for 40+ years and still going strong.

Like hot rod says, multiple zones and low temperatures are death on copper boilers. The twin problems are low flow rates and condensation. Even with care, condensation tends to happen on start-up The reason those older boilers lasted so long was their relatively low combustion efficiency, often around 75%. Low combustion efficiency allows the products of combustion to remain pretty hot and out of the condensing range. Our current mania for efficiency, however has combustion efficiencies hovering around 87% on a hot boiler; even higher on cold startup. With conditions like that, condensation is agonna happen.

Copper boilers are the most vulnerable to condensation damage, but I have to believe its happening in cold-start cast iron boilers too; just slower to make itself known.

I don't even wanta get into whats happening to sheet metal flues with aluminum liners, but it's real ugly.

The demand for efficiency is not going to go away. The solution seems to be to design boilers for condensation and use plastic or stainless steel vent material. There is still a lot of grief to be endured before these technologies are "plug and play", and I'm not sure I'm happy about it, but that's the future.

Bill

hr

Stainless steel vent

material looks to be the material of choice these days. Wisely so I feel. Seems like all brands of induced draft boilers now require stainless.

This will solve the vent material problems associated with long condensing mode runs. We still need to be concerned with the boiler Hx itself. Cast iron takes a lot more abuse but the "iron" material also has limitations. Unless it's made in Germany

Pipe and protect your installations with this in mind.

hot rod

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Steve Eayrs

oil-fired condensing boilers?

You mentioned you know of oil-fired condensing boilers on the market. The only thing I have seen are either not a true condensing boiler, or some proto-type unit that usually lasts for a few years, before the acid in condensing oil gasses, eats away the stainless steel flue, the boiler, or both.
Gas has done quite well w/ condensing boilers, but as far as I know not oil. If you know of one that actually work, I would like to know what it is.

And would like to add that I agree with all the others comment on this so far.
thanks, Steve

Steve