What is an over fire draft?

 

The draft in the firebox. On residential you typically check it right above the fire through the peep hole. There is typically a little notch in the steel cover of the peep hole. On commercial boilers typically it is taken from the back of the boiler if there is no port on the front.

 

I have a older Bacharach kit to check overfire, and what not.

 

Are you using the old big draft gauge that you can sit down on something, zero it out and then take the reading? Or the Draftrite gauge?

I am mainly wondering if I use a digital manometer with a hose and a steel tube if that will ruin the manometer.

 

On the residential oil furnaces I have tested, I use the Dwyer 460 draft gauge. The same gauge I use for measuring draft in the flue of all Cat I appliances.

It is small, simple to use, and accurate.

 

Thanks I do mostly commercial with some residential. But I do not see why that would not work. Did that metal tube come with it or did you buy or make it? I would get a longer plastic tube, would like to be able to see it when measuring from back of the boiler.

 

Yeah that draft gauge is what I was talking about. They do not make them anymore.

 

A quick search of the internet shows most place are saying it is discontinued, but seems it can still be found.

The small metal piece came with it.

Maybe contact Dwyer and see what they may be selling now in a "like" instrument.

 

An micro-manometer works well for draft if you want to get all fancy about it.

Otherwise the simple 760 works, and so does a magnehelic gauge with a low enough range.