Why a ductless split isn’t the right selection, for your Cottage HVAC Design
Are you considering a ductless split or mini-split for your cottage or tiny home? While the strong advantages they offer such as; the potential for cost savings on equipment and installation, the advertised simplified installation, and a readily available fuel source that fits the needs of your small, isolated, or remote project, you might want to think again.
In the realm of high-performance HVAC, “Mini-splits” are said to be all the rage. A quick stop by the big box store might find you a unit on the shelf , pack it away in your truck and haul it off to the cottage. You and your buddy are done by lunch. Time to fish. The cottage HVAC is complete. So we’re all comfortable now? Maybe not, and you're not done with that inspector either.
What’s a mini-split heat pump? The language around its technology is often found to be perplexing, due to its inconsistent application. The term "mini-split" initially referred to a split system heat pump (and in most cases referred to an air conditioner) with a capacity that was lower than most standard systems. In that sense, a mini-split is exactly what it sounds like: a small heat pump configured as a split system. This century's improvements in the numerous methods and technologies employed (by the manufacturers of these systems) can make keeping up with tech and configurations perplexing. Let’s take a closer look. “Mini-splits” are traditionally either fixed-capacity compressor type, or an inverter-driven variable-capacity compressor. As a result, a mini-split could simply be a smaller version of a standard heat pump or, it could be a smaller, variable-capacity heat pump (these are less common). Most times these conditioning work horses are powered by electricity making them ideal source for all but the most isolated cottages. While the term “small heat pump” has historically been associated with “min-splits”, recent times and technologies have seen their capacities rocket up to 48,000 BTU/HR. Ontario HVAC Designers are more frequently seeing HVAC designs using these systems rejected to varying concerns. Those concerns include face velocities, wall coverage of exterior faces and operating temperatures and are leading to the outright rejection of their use (in some Ontario Municipalities) for HVAC Permit Drawing. These systems can be split down further in their configurations to include; ductless splits (indoor unit attached through wall to the outdoor unit), and multi-splits (outdoor unit connected to indoor unit, with a ducted distribution system to multiple “heads” or registers). For systems intended for northern climates (such as Muskoka or elsewhere in Cottage Country, you’ll find colder operating temperatures that may not support the units continuous year round use. Units must be equipped with a defrost to control condensation and the season’s freezing temperatures to prevent equipment failures in the harshest of conditions. Operating temperatures must support use in your intended region, or your year round heating source is likely to go seasonal. If you are seriously considering using a mini-split in Ontario be advised Saltzberry Design recommends that: Mini-splits should ideally only be used as secondary heating and cooling, or in spaces intended for seasonal use only and that the areas that they serve are thermally partitioned from the home. Unless operated seasonally, your cottage needs fulltime conditioning (heat). In most cases they won’t serve as primary heat source as heating capacities can’t be met, or ideal distribution may not be achieved. Nor does code allow for multiple variable use heating equipment to be considered when meeting the heating load. These include such things as gas/propane fireplaces or wood stoves. That they may suit residential HVAC designs with very simple distribution needs, serving homes with small HVAC loads (as determined by Heat loss gain calculations). Consideration must be given to the local jurisdiction’s Examiners, Inspectors and CBO’s acceptance of proposed equipment before commencement of the HVAC Design. This should be obtained in writing (however they may reconsider without notice even if you do. See minister’s ruling on such) Ductless splits may need more ductwork than you accounted for. Most of Ontario’s new homes require an HRV as prescribed by SB-12 and documented by a Mechanical Ventilation Design Summary (MVDS). Without a central furnace to connect to, the HRV will more than likely require to be fully ducted and designed as a Standalone Mechanical Ventilation Design System. The OBC and HRAI Digest prescribe the area’s to which fresh air may be introduced and must be removed from. Also architectural consideration to r-values and SB-12 Compliance must be taken into account, to meet electrical heating requirements. Trips to the cottage should be about the time spent there. Not about re-inspections, emails and hold ups on HVAC Permits. So if you're planning on building a cottage, get working with our Residential HVAC Designer’s on your cottage HVAC Plans today! www.bcinhvac2day.ca
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