Historic small hotel

I've found your postings here to be very helpful, so I thought I might run a few questions by you all about a proposed ground-source installation at a National Register property in east-central Kansas. Thanks in advance for your patience.

I'll post the data I have below, but to sketch the background: This is part of a total rehab of a 4,000-square-foot limestone hotel. 2 stories, L-shaped, on a SW corner. Public rooms downstairs, 7 sleeping rooms up.

As building is on the Register, we will be repairing the single-pane double-hung windows and adding wooden storms, but won't be replacing windows. Stone exterior walls likewise will be uninsulated, though they'll be repointed. The roofing is new, TPO over 1.5-inch insulation. But still, not the greatest envelope ... No LEED certification for us!

We have a basement under the E half and a (small) mechanical space on the 2nd floor.

Because sleeping-room space is at a premium and I've been told that individual console units are less efficient -- and I fear all that plumbing in the ceilings -- we're headed toward a zoned two-stage system to serve the 2nd floor. My worry there is the shoulder seasons, when the N side wants heat and the S wants cooling. Someone is out of luck. (But we can always supply space heaters ...)

My other concern is room-to-room noise transmission via ducts. I don't want that undermining our sound-deadening efforts elsewhere.

The simplicity of operation and maintenance of this proposal, though, is very appealing.

We have the place completely open to the bones at this point, so we can do what we need to do, $$ allowing. But I need to get it right.

We'll be adding a commercial kitchen to this space, which the contractor figures will require another ton of capacity and a commercial makeup air unit for 1,500 CFM. But these are the numbers we're working with for now.

I feel confident in the contractor -- they have been the most responsive over the couple of years that I've been pursuing this, and locals have had good luck with them. I just need to be sure this direction is the best before I present it to the owner and his money people. I'm no HVAC guy, but I am coordinating the whole show.

Any guidance/opinions are welcome.

The numbers I have (via the contractor and Elite Rhvac Manual J & D software, 8th Ed.):

Daily temperature range: Medium
Lat: 39 degrees
Elev. 0
Winter outdoor dry bulb: 3. Wet bulb: 2.24 Rel. humidity: 80% Indoor dry bulb: 70
Summer outdoor d. bulb: 95 Wet bulb: 75 Rel. humidity: 40% Indoor dry bulb: 75
Total building supply CFM: 4,037
Square ft. of room area: 5,404
Volume of conditioned space : 48,636
Square feet per ton: 611
Total heating required, inc. ventilation air: 163,636 Btuh
Total sensible gain: 88,818 Btuh (84%)
Total latent gain: 17,385 Btuh (16%)
Total cooling required: 106,203 Btuh
8.85 tons (based on sensible plus latent)

This is divided into 2 systems, one upstairs, one down.

The equipment proposed:
10 tons total from 2 units of GeoComfort Serenity GXT060, variable speed, 2-stage compressor, with DSH for ground-floor unit
Dual-pump flow center for loop
8-zone system with stats, control board and motorized dampers for 2nd floor
20kW electric strips for backup
Loop system of 1.25 pipe for loop field, 0.75 for vertical loop field (U-tube, polyethylene SDR-11)

Loop info:
Average rock
Bore depth: 150
Total bore required: 1,487
Min. loop temp: 30 F
Max. loop temp: 100 F
Average heating loop temp: 48.6
Average cooling loop temp: 75
Deep earth temp: 56
Annual temp swing: 26
Phase shift: 32 days
Soil conductivity: 1.4 Btu/hr.-ft.-F
Soil diffusivity: 0.04 ft2/hr
Pipe conductivity: 0.226 Btu/hr.-ft.-F

Thanks again!

-- Andy

 

I'd have less fear of plumbing in the ceilings than I would of trying to work out the minimum airflow requirements of an 8 zone air system. Don't get me wrong - my last job had 5 zones spread across two systems and my own house has 4 zones off one system. I understand and like zoning, but I know it has its limits.

Every hotel I've stayed in in the past 22.5 years of corporate travel (Free at last on 1Jan11 Yay!) has had plumbing in the ceiling...big pipes with fragile fixtures...fire sprinklers.

I sympathize with issues of historic architecture, but if historic architecture also means historic quaint (i.e uncomfortable) heating and cooling, you won't get many repeat customers.

If compressor consoles put you off maybe a 4 pipe hydronic system would work. Use geo to maintain tanks of hot and cold water (wouldn't need the hot in July nor the cold in January) but during shoulder seasons a room occupant could get either delivered via an individual thermostat without the duct issues.

You'll need to decide on whether to circulate hot water. and given the high hot water use in a hotel supporting a restaurant, I'd try to find a way to utilize DSH on both units - maybe a buffer tank on each floor.

Just some thoughts, hope they help - sounds like a neat project, wish I was in on it.

 

Thanks for the response, Curtis. Particularly regarding the challenge of an 8-zone system working right. Upstairs DSH makes sense too; we're kicking around notion of circulating hot water vs. individual room tankless units -- but I think with geo, tankless seems like unnecessary expense.

Our primary concern is that people be comfortable. (Actually, I think No. 1 is that they pay their room bills, but close behind that is their comfort.)

It's not the pipes in the ceiling that bother me, it's access. But that could be arranged, I imagine. We'll already have to sprinkle the place.

Can you explain how a four-pipe system delivers Btu to the room? What appliance/fitting is in the room, for instance? What sort/size of tankage would we be looking at accommodating?

Thanks again.

-- Andy Badeker

 

Of course individual consoles are less efficient especially since guests often look for large temp swings. 8 zones will be less efficient as well as you run a 5 ton compressor to cool or heat 1 room.
Geo consoles are available as are hydronic consoles for system curt described.
Frankly that's the way I would see this built.
If you are running a 5 ton unit you still need 1200 CFM for 1st stage thats a lot of fan noise in one room (if the others aren't calling). I would not be a fan of the system described.
Good Luck,
Joe

 

Thanks, Joe. I hadn't thought of the 1200 CFM problem. That would be unacceptable, I think. (Although the fan noise could cover up the reality of our location on a state highway.)

If we reverse course and consider consoles, does one manufacturer stand out for its performance and/or appearance of its units? (The owner is an interior designer, so sleek/unobtrusive is desirable.) Something that could be semi-recessed would be a plus.

I'm assuming hydronic consoles would be smaller/cheaper than geo consoles, which would contain individual compressors. Am I wrong?

Thanks for your insights.

-- Andy

 

Not wrong that hydronic consoles are cheaper, but it means you have to buy a water to water geo. You'll have to get a bid to see which is cheaper net.
You can find console units on any manufacturers web site in with the commercial equipment but the appearence is similar to the Amanas seen in 75% of the hotel rooms you've been in.
Joe