HI--LO HOW-TO

gerry gill

so i don't remember if the low fire was achieved thru energizing or de-energizing..really doesn't matter as far as the discussion goes tho..the high fire is set up as strictly OEM..set its vaporstat for the most you want..say 12 ounces..set the low fire vaporstat to either energize or de-energize (whichever is needed) at a specific amount of pressure..say 8 ounces..so this vaporstat then becomes the one doing all the work,as it goes about life activating and deactivating the low fire based upon pressure buildup and fall..much the way a coal boilers damper regulator would..the OEM vaporstat (high fire) just sits there as a limit control and may or may not ever activate..did that make sense to you? it hard to explain and much easier to show..

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nicholas bonham-carter

HI--LO HOW-TO

i am preparing soon to install [with pro help] a honeywell 1 1/4" dual stage gas valve on my 1,050,000 btu 1-pipe system now running at 3-12 oz. pressure.

if i have 2 vaporstats would the control wiring be as if there were 2 separate valves? then when setting the v-stats #1 would control the high side of the valve from 0-2 oz. and v-stat 2 would control the low side of the valve from 2[or some overlapping setting] to 12oz.

is there any worry about overlap where both hi and lo are being energized at the same time- would you then have 100% plus 75% gas flowing? when this is finished then i suppose that a new combustion test shoul be performed on both hi and low burns of my atmospheric burner. i like the look of the siemens controller described elsewhere but feel it does much mre than i need [also cost is a factor!]

the pajek Electronic Pressure Controller is also an object of elegant [ but not so simple] engineering. so for now i'll just rely on the modern vaporstat controller crap-shoot, if i can avoid over firing in the overlapping pressure range.--nbc

kevink1955

The 1" Honneywell valves I have seen excluding the igniton and flame proving wiring are 3 wire control. A common, a first stage and a second stage.

When in first stage the regulator outputs about 1.8"wc, when the second stage is powered the regulator output increses to 3.5"wc. Your BTU output will depend on the size of the orifice in your burner.

I have never tryed powering the second stage only but I do not think it will flow anything at all unless the first stage is also powered.

If your burner was designed for 3.5"wc as most seem to be your output will not change on HI Fire, the thing you will need to watch out for is proper combustion when in LOW FIRE.

The only way to set this up properly is with an analizer and someone who knows how to use it.

Mark Eatherton

I wouldn't do it....

Especially of it is an atmospheric boiler. The heat exchanger, heat exchanger surface and excess air are extremely specific. The problem is that there is no way to control the secondary air. If there were, they'd still be popular and as efficient as it can get. When the boiler is running on it's low burn setting, the thermal efficiency on the flame sucks. It will be running on low burn most of the time.

When is Burnham, or some other American steam boiler manufacturer going to come out with a variable power burner. It would be so simple to maintain the perfect fire..... The rest of the world is trying to get rid of small steam systems. District heating systems are another matter.

Maybe that's asking them to think too far outside the pipe :-)

If I were you, I'd wait on replacing the boiler, and when it gets REAL cold outside, sit next to the burner with a stop watch and see what percentage of an hour the boiler burner operates.

Clock the boiler in whatever way works for you for per hour input, and size your steam boiler to that, divided by .8 Don't ask, just do it....

You'll probably immediately realize a 30 % reduction in fuel consumption...

JMHPO

ME

nicholas bonham-carter

HI--LO HOW-TO

thanks as always for your replies.
i will now teach myself to use the combustion analyser i have borrowed and see how far off the hi burn would be from the low burn on the atmospheric burner and share the results here.
nbc

Steamhead (in transit)

Watch your stack temp

on low fire- it should not get below 325º or so to avoid condensation in the chimney.

ME, you're right about "the perfect fire"- we once hooked up a lo-hi-lo valve on a huge W-M LGB steamer that the original installer had ignored. Combustion test was OK, but the excess air on low fire was, as you say, higher than I like. Nevertheless, the owner reported his gas consumption dropped 40%!

In a few months we should have some comparison numbers on a Federal 175-HP Scotch-Marine with a 3:1 modulating gas PowerFlame that was all screwed up control-wise, combustion-tuning-wise etc. Watch the Wall for this.

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Steamhead (in transit)

Gerry, if memory serves

you wire the Vaporstat to break the 24-volt high-fire control circuit while leaving the low-fire circuit energized.

On power burners there's usually a set of leads or terminals for this control. Generally these are jumpered for high-fire-only; you remove the jumper to hook up the Vaporstat.

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