Convert boiler to direct vent.

Snowmelt

I’m converting a boiler to direct vent with a fan. Supply house told me if I put the fan close to an outside wall I can use smoke pipe, when I get out side or on other side of fan I can use stainless steel? Would that be the correct way of doing this?

Robert O'Brien

Powervent not direct vent.

STEVEusaPA

Which boiler, which kind of fan.

Snowmelt

Weil McLain 140,000 btu chimney vented, changing to power vented, the boiler less then ten years old and there building an addition and want to remove the chimney.

Note... I was called from someone doing the plumbing to just put the boiler direct fan on the unit and run it outside the house. Not to try to upsell them anything.

Jamie Hall

Oil or gas? And is that boiler listed to be used with a power vent? If not... don't do it.

Snowmelt

I’m not sure I think they want to convert it. It’s a gas CGA

Jamie Hall

I don't see anything in the manuals for the CGAs which provides for power venting... I'd contact Weil-McLain to see if they have any comments. Otherwise... you may be experimenting on your own.

Steve Minnich

I agree with Jamie.

STEAM DOCTOR

I think that field control makes a conversion kit. Will probably void manufacturer warranty

Snowmelt

I think the boiler is past it’s warrantee, my supply house says they do make a fan in a can for this?

EBEBRATT-Ed

@Snowmelt

Has nothing to do with the boiler age, warranty or what the supply house says.

Gas appliances are listed to be vented a certain way. I would call Weil McLain directly and ask

Just tryin to keep you out of trouble

Steve Minnich

“Fan in a can” brings in combustion air for the appliance.

mikeg2015

I think field control does make kits, which most importantly have pressure switches to verify fan operation just like an other induced draft appliance.

But I think you’ll need a barometric damper and combustion analysis to fine tube the airflow to get it back to specs.

Ultimately, the boiler doesn’t care what happens to the flue gases. Just so that the fuel air ratio is correct and secondary air is adequate to prevent condensation in single wall pipe while also not wasting too much energy. You will mainly end up with excess secondary air and waste energy sucking air out of the house. No different than having a really tall chimney.

jumper

If the appliance comes with hood you require permission from utility and provincial safety to remove it.

Steamhead

jumper said:

If the appliance comes with hood you require permission from utility and provincial safety to remove it.

In the case of the Field and Tjernlund power venter kits, the existing draft hood or barometric damper stays in place. The combustion appliance itself is not modified.

John Mills_5

Those normally mount at the outside wall. Outside the house is a hood like a big dryer vent. You run b-vent to the power ventor. They also show a barometric i the horizontal run. We've used them on 80% furnaces but not atmospheric draft boilers.

Snowmelt

I’m going to find out the hard way, that’s what I will be doing Friday