Toilet Exhaust thru an ERV with a rotating wheel??
Toilet Exhaust thru an ERV with a rotating wheel??
(OP)
Hello,
I haven't been here in a while. I have an application where I'm currently exhausting 525 CFM @ .75 ESP from public restrooms and a janitor's closet through a energy recovery ventilator (ERV) with a static plate total heat exchanger (RenewAire). I'm bringing in 250 CFM @ .75 to 1.0 ESP of fresh outside air, via the same ERV, to ceiling cassettes in a VRF system. The 250 CFM of OA is not my total fresh make-up air. I also have a packaged RTU providing the necessary make-up for the 525 exhaust air for positive pressurization. Both airstreams are separated via the current ERV. My issue is the ERV is only (1) speed, unless I go with ECM motors. I don't want to go that route.
I'm thinking about switching to a ERV with a totol energy recovery wheel for this application.
My question: Am I allowed to use a wheel, since the airstreams (exhaust and incoming outside air) will not be totally separate like a static plate total heat exchanger?? Does the code allow this configuration, if the wheel has purging capability??
Thanks for any info/advice that you may give,
Michael333
I haven't been here in a while. I have an application where I'm currently exhausting 525 CFM @ .75 ESP from public restrooms and a janitor's closet through a energy recovery ventilator (ERV) with a static plate total heat exchanger (RenewAire). I'm bringing in 250 CFM @ .75 to 1.0 ESP of fresh outside air, via the same ERV, to ceiling cassettes in a VRF system. The 250 CFM of OA is not my total fresh make-up air. I also have a packaged RTU providing the necessary make-up for the 525 exhaust air for positive pressurization. Both airstreams are separated via the current ERV. My issue is the ERV is only (1) speed, unless I go with ECM motors. I don't want to go that route.
I'm thinking about switching to a ERV with a totol energy recovery wheel for this application.
My question: Am I allowed to use a wheel, since the airstreams (exhaust and incoming outside air) will not be totally separate like a static plate total heat exchanger?? Does the code allow this configuration, if the wheel has purging capability??
Thanks for any info/advice that you may give,
Michael333





RE: Toilet Exhaust thru an ERV with a rotating wheel??
Hazardous exhaust
Explosive/flammable exhaust
Smoke control systems
Kitchen hoods
Clothes dryer exhausts
However, if this is a hospital (I doubt it), there are different requirements that are more involved. In general though, bathroom and janitor room exhaust is acceptable through a wheel. Consult your local codes though.
RE: Toilet Exhaust thru an ERV with a rotating wheel??
Not sure what separation a total or sensible wheel gives you. And as I'm answering this from my so called smart phone I apologoze for any typs. SI equals SO. Crap in equals crap out.
Also. U sure u have enough air to warrant cost of ERV?
RE: Toilet Exhaust thru an ERV with a rotating wheel??
RE: Toilet Exhaust thru an ERV with a rotating wheel??
Ultimately, this is your call. If you are concerned about it, go with the plate setup.
RE: Toilet Exhaust thru an ERV with a rotating wheel??
From what you’ve posted, it does not seem that your ERU optimizes ventilating air as it only recovers heat for about 40% of it, where the remaining 60% of the ventilating air still comes through the RTU. The ERU makeup air should supply 110 or so percent of the exhaust and the RTU can be set to full recirculation (as if it were a fan coil unit). This would depend on your system configuration.
RE: Toilet Exhaust thru an ERV with a rotating wheel??
For toilet exhaust systems I have successfully used heat recovery wheels with 3A molecular coating in lieu of the more common desiccant materials. Also ensure the fans and pressures in the AHU are designed so that any leakage will leak from the clean air stream into the dirty air stream to eliminate contamination.
These systems only transfers small water molecules (which are < 3A in size) and not any other contaminnents (which are > 3A in size). These systems are also used and approved for use in labs and fume cupboards.
Below is an extract of the marketing from Semco
http://www.semcohvac.com/104
•3Å Molecular Sieve Desiccant Coating
◦The EXCLU-SIEVE wheel utilizes a 3Å molecular sieve desiccant coating to limit the risk of desiccant cross-contamination which would otherwise cause a portion of the exhaust air pollutants to be transferred, along with the water vapor, to the fresh air stream. The 3Å molecular sieve material utilized by SEMCO was developed specifically for “selective adsorption” and has been successfully used for decades by the petrochemical industry. Other desiccants like silica gel and oxidized aluminum cannot provide selective adsorption. Molecular sieves are structurally stable, chemically inert and have a strong affinity for water vapor. This strong affinity for water vapor produces the high rate of adsorption which provides superior latent transfer performance.
RE: Toilet Exhaust thru an ERV with a rotating wheel??
RE: Toilet Exhaust thru an ERV with a rotating wheel??
1- your exhaust is 575 cfm, is it total building exhaust?
2- ERV exhaust 575 cfm and bring in 250 cfm to VRF system, the difference is 50%, is it right?
3- your building exhaust 575 cfm, RTU and ERV bring in 575+250= 825 cfm of OA, is it right?
4- you are dealing with 575 cfm what benifet of changing equipments ( ERV OR weel) for such amount