Huba Differential pressure switch

dave2 · Jul 6, 2012

My local landlord has just had a new hob fitted in his pub kitchen.

The gas installer left the above switch in a plastic bag and told him to get a sparky in to wire it up.

No diagrams/info and no idea.

Above the hob is a big commercial duct with a fan. The hob cannot be operated unless the fan is working. When the fan operates it opens a gas valve allowing gas to the hob.

I believe the above switch is an extra precaution in case the fan operates but the fumes are not exhausted.

Has anyone fitted one of these and where are they situated.

Here is a link to the Huba site. The switch is a 604. 9010032.

Dave2

Andy™ · Jul 6, 2012

no idea on that particular switch, but there is usually a hole in the duct with a small hose which attaches to the switch. switch is usually wired NO

kme · Jul 6, 2012

Having power to the extraction system is one thing; but, similar to the flue pressure switch on a boiler; you can sometimes need a more positive response that there is actually a suction event occuring - which is where your differential switch comes in (as Andy says)

It would normally be insinuated into the gas solenoid wiring - it will actually ensure there IS airflow before opening the gas valve - does that help?

dave2 · Jul 6, 2012

Thanks Andy

The switch has 2 tube inlets and there is a length of mini plastic tubing.

Does one tube go into the duct and the other outside?

oldtimespark · Jul 6, 2012

Hi Dave2 here is a link to a pdf which I think explans it better than I would.

Bacon · Jul 7, 2012

Have fitted those types before,not the best but do the job.

They should be wired back to a control box with 2 dials on it on for extraction (fan speed hi and low.settings)And the other for drawing air in(fan speed hi and low.settings)

If the kitchen has a vent above the gas hob the fan will be behind that and sometimes there would be a fan in the duct in the centre of the kitchen above the ceiling with a fan there and a

P/Switch connected to that.

But i have fitted these recently in a large kitchen.

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