Mod-Con Intake Pipe Question

Glenn Harrison_2

and I will keep this anonymous since I was e-mailed privately.

The intake pipe is not direct connected so that in the event of a breach of the HX the leaking fumes will not suffocate the burner, and the leaking fumes will not fill the cabinet, and eventually leak into the house, or words to that effect.

I had thought of the other suggestions, except for the debris collector, which is a good thought to, but HX safety had not crossed my mind.

Glenn Harrison_2

I had a customer...

ask me a question today that I don't know the answer to.

Why are manufacturers of Mod-Con's, such as Weil McLain, Buderus, Munchkin for example tha I know of, dump the intake air into the cabinet where it can cool off the HX, instead of direct coupling the intake pipe to the burner? I'm sure there is a legitimate answer, my customer and I are wondering what the design is behind this.

Mitch_4

because

as I understand it...pre heating the combustion air can result in imporoved efficiency. (so long as the jacket seal is intact)

J.C.A._3

It promotes....

The main function....Condensing.

Cooler intake temps. Make the boilers further CONDENSE the exhaust factors in the process. That helps raise the efficiencies of the "package". Chris

Mike T., Swampeast MO

I'll give two different reasons:

1) Convenience and design economy. If the air inlet was ducted through to the blower, not only would it likely hinder service access, but it would require more parts and assembly.

2) Efficiency. To somewhat pre-heat the combustion air via its contact with the interior portions of the flue and/or any secondary heat exchanger. (Some mod-cons use a secondary HX in the flue.) As long as the outer jacket surrounding the inlet air is very well sealed--some are quite leaky--the cool air plus the fact that it's being drawn into the burner will eliminate convective heat transfer between the primary HX jacket and the combustion chamber (or outer) jacket. If the boiler is installed in unconditioned space this [might] increase efficiency by a tiny amount.

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A concentric flue would [appear] to be the best way to increase efficiency by recovering "free" energy from the exhaust when the boiler does not use a secondary HX.

jp_2

#3

how about #3.

a debris collector?

any debris coming in on the intake will fall to the bottom of the enclosure instead of being sucked into the combustion chamber?

Mike T., Swampeast MO

Very good thought!

Derheatmeister

Yes jp ,I've serviced a Viessmann that had a lot of little Bug's in the bottom of the cabinet ,something in the gas , or exhaust attracts them into the intake then they die in the cabinet...

Glenn Sossin_2

Glenn E Sossin

I've also been told, by Triangle Tube, that in the Prestige, the intake air is used to cool the electronic circuitry

Derheatmeister

Glenn, Which i am not so sure if that is a good idea especially when you direct sidewall vent on the wind laden( prevaling winds)side of the bld. In our Dry environment, Dry snow enters into cabinet hits electronics on blower and well you can guess the rest.I think a shield may be in need ,or a tee on the exhaust. Heatmeister.