Burner Limit Switch Problem

Maybe you could mount the limit switches off the the side, on standoffs, or some such way to get them farther from the heat; and then attach extension arms to the registers to reach the relocated switches.

Thanks.

One of the problems we faced in doing so is that there is no space.

The limit switch is close to the burner wall.

Plan B: Put some thermal insulation in the space between the limit switches and the mounting surface.

You could try using an optical limit switch with remote-mount (fiber optic cables transferring light to and from the electronic switch unit) option. Let the mechanism break the light beam to verify position. Remote mounting solves the heat problem.

As for dust, use a purge air nozzle near the fiber optic lenses to keep them clear of particulates.

The "flame safeguard system" and "combustion controls" are components that are shipped with the "conventional boiler package" hence for liability sake, this is problem that should be corrected by the manufacturer of the boiler or burner. I would put it on them to correct the problem at there expense and expertise.

GA

Safety first. Do not re-invent it.

On the other hand, just for the sake of giving ideas: a flexible steel cable link, that will move with the air register as it opens or close, could be used to actuate a remote switch. this will allow you to get rid of the space problem near the boiler wall (as you said).

Suggest it but get the maker/supplier to approve it.

Like Tornado mentioned you can wrap the limit switches in insulation and install some vortex coolers to cool the inside and / or outside of the instrument bodies.

I have seen in some cases where a small box with the sides and back filled with thermal insulation is placed around the limit switch with cut outs for the limit switch arm to go through.

Another option would be a static pressure switch (mounted remotely) sensing pressure of the fan discharge.