Acoustics of GSHPs for Hotel Guest Rooms

[Allgreatmen]

I'm looking at the possibility of using ground-coupled, vertical stack water source heat pumps to provide htg/clg for the guest rooms in a new 450 room hotel (12 floors) in the Pacific Northwest.

Based on the Geotech report and our analysis the economics look pretty good relative to the other option (straight 4-pipe fan coil) being considered. (That said, if anybody has solid cost data for what it takes to bore and install a vertical-type ground coupled piping system ($/foot perhaps?) on the scale being considered here, I'd appreciate that.)

My question, however, is regarding the acoustics of these heat pumps, since they'd be located within feet of sleeping hotel guests. Does anybody have any nightmare stories to share, and what to do to avoid them? This project is a 3- to 4-star hotel, so sound similar to what most hotel PTACs make as they cycle isn't good enough. Are there any design/install details I would need to pay particular attention to in order to avoid problems?

 

[walkes]

We are designing a similar system (boiler-tower loop though). The keys to the acoustic aspects would be to ensure you have an acoustic panel on the return and a lined discharge plenum, with the unit mounted in a drywall enclosure per manufacturers recommendations.

I recently stayed at a hotel in Baltimore where they used the stackable heat pumps and I found them to be very quiet, much more than any PTAC.

 

[GMcD]

Geothermal well drilling: I'm in slightly northern Pacific NW and we use a budget # of $10.00 per foot for drilling costs, and $5.00 per foot for the pipe and grout as a starting point, so a nominal 250 foot hole will cost $3,750.00 per hole as a budget #. Costs can vary greatly depending on soil conditions, whether the well has to be cased or not, and quantity of holes. The more holes you need drilled, the cheaper the cost per hole. The deeper you drill, the higher the cost per hole.

The key with any geo-exchange system is to minimize the heating/cooling loads first, so you minimize the amount of geo-exchange system. The other important thing to check is the seasonal energy balance- you don't want to extract more heat out of the ground than you put back in and vice versa, depending on the soil conductivity factor.

I bet the hotel is a high rise concrete building....it would be an ideal radiant slab system application (heating and cooling from radiant slab ceiling and floor) and an energy recovery ventilator for the bathroom exhaust and corridor make-up.....

 

[Allgreatmen]

Thanks for the information guys.

As for the radiant slab option, I'm hesitant because it is a requirement of the Owner that hotel occupants can choose whether they want heat or cool anytime of year. So, we have to anticipate somebody might want cooling in winter or heat in summer, and certainly a mix of both at the same time would not be unusual in the Pacific NW climate during milder days. So, zoning would need to be at an individual room level in a 4 pipe configuration.