Heat recovery wheel and DPS 1

[saeedplc]

Hi dear Experts,

I have seen a differential pressure switch across a heat recovery wheel in some AHUs.
Could you please let me know the function of the DPS and how it should be adjusted.

Regards,

 

[HVAC-Novice]

typically it is used to indicate a frozen wheel.
Measure dp at full flow and set it a bit above that.

 

[saeedplc]

Thank you for the reply,

Can it also be an indicative of the wheel blockage by dust or etc?

 

[HVAC-Novice]

Yes. But typically there are filters upstream on both streams.
Even with perfect filters, they have a finite life. If you don't have filters, those ERV are the most expensive filter you could have bought.

some are designed to be cleared with water or other cleaner. You have to disassemble the wheel and take outside. I can't imagine cleaning it inside the AHU. Not sure how well the desiccant then works, or how effective cleaning is. Look at the thickness of the wheel, and the very thin "tubes". Looks really easy to clog up.