New Build

Northernmax

I am looking for some guidance on a new build in Zone 6, North Central Ontario.

Construction:
House is 2100sqft per level (Finished basement and main floor) plus 950sqft of garage. Construction is tight with ICF basement, Closed cell Spray foamed rim joists and exterior walls @R24, Vented vaulted ceilings @R40 Foam and vented attic @R12 Foam plus R50 Cellulose. Basement slab is 4" with R11 insulation, 1/2 tubing spaced @9" o/c and main floor is 1.5" concrete, 1/2 tubing spaced @6" o/c over pour and R19 in joist space. Entire house including garage is to have radiant UHF, forced air will be required for back-up/supplemental. Great room (18x18) has a large number of south facings windows and 18' vaulted ceilings, two bedrooms also have 15' vaulted ceilings. House has 3 full baths (Master bath has 96 gallon whirlpool and rain shower) and 2 powder rooms.

Heat Load Calculations:
House: HTG Load-56,966 BTU
Ceiling Load-31,826 BTU
HTG AVG cfm-1407
CLG AVG cfm-1200
Garage: HTG Load-10,693 BTU
Ceiling Load-20,816 BTU
HTG AVG cfm-198
CLG AVG cfm-706

Question:
Wholesaler has recommended a Viessmann Vitocrossal 300 CU3A (35) 25-126 MBH, Vitocell 300-V (79 gallon) indirect and AirflowPLUS AH2A-354 series air handler. Main floor, basement and garage to each have a Vitotrol 300 Remote. Our mechanical contractor while supporting the choice of Viessmann has no experience with this model and limited understanding of the controls for this type of application. My questions/concerns are:

-Is this the right set up for us?
-What would be the best way to handle the zoning requirements? (This boiler was recommended to limit short-cycling)
-Is an air handler the best choice, or should a separate propane furnace be installed?

Thanks in advance.

kcopp

What does your installer suggest? What is he most familiar w/?
He is the one who has to work on this...

Why do FHA as supplemental? Panel radiation or a kickspace heater would be simpler.

Brewbeer

The heat loss seems high for the insulation characteristics you described. Do you have a lot of windows?

pecmsg

A nice read:
http://www.icynene.com/sites/default/files/US content uploads/builders/ProperDesignHVACSystems.pdf

Mark Eatherton

By my estimates, your heating loads are somewhat high for a high performance home. My math say around 24 btu's/sq ft/hr, which in my mind seems somewhat high. Who's heat loss program was used? What infiltration factors (Air changes per hour) was used in the calculations? Once we get those numbers squared away, we can start talking physical plant.

ME

Northernmax

Thanks All,

In response:
Load calculations were performed using Wrightsoft by a P.Eng. (I now that doesn't make them right). Glazing ratio is 19.44% and inflation ratio used was .31 Heating and .07 Cooling, Light local shielding. Design winter db/Outside-15F/Inside 72F, Summer db/Outside 84F/Inside 75F.
House has one gas Fireplace, Commercial range hood, 1 Bathroom fan (110 cfm Master Bath) and 2 HRV's( House and Garage)
FHA backup has been specified for the AC, Mini splits are not an option for the better half.

SWEI

Northernmax said:

FHA backup has been specified for the AC, Mini splits are not an option for the better half.

Can I ask why?

Modern mini-splits come in a number of different indoor unit form factors. The mini-duct type can often be used quite discreetly to feed multiple smaller rooms, and the 4-way ceiling cassettes work great for larger (family room / great room) applications. Either can be installed in a joist space, which allows for freedom of placement simply not possible with conventional AHU designs.

Brewbeer

@Northernmax did the P.Eng. make all the measurements in each room of the surface areas of the windows, doors, walls, and various types of ceilings, and use the correct R-factor for each surface? The heat loss is only as good as the measurements that went in to it.

Northernmax

@SWEI. It's the look of the wall mount units, and the fact that we cannot find a multi zoned unit (To prevent multiple outdoor units) with any capability below about -15C. That's a hard sell when we just had 3 straight days below -30C. The FHA provides both AC and reliable supplemental heat, but perhaps we could be persuaded.
@Brewbeer. We received what, in my limited experience appears to be a fairly detailed report that seems to accurately reflect the site conditions as provided by the architect.

SWEI

A couple of experienced airside designers clued me in to the fact that single splits are really the performance leaders. Having two, three, or even four small, quiet condensers outside a building turns out to be a non-issue on most jobs.

Once you get into commercial-scale VRF/VRV with 3-pipe heads and multiple VFD compressors in the outdoor units, the balance shifts the other way.

Northernmax

We have some time to sort out the AC and supplemental side, any opinions on the Hydronic/control side?