There is little I like better during dog days of summer than a road trip to North Carolina mountains – above 3000′ life is sooo much more comfy outdoors, even in summer.

Up there I see a heckuva lot of Mitsubishi H2 ‘hyperheat’ minisplits and also Fujitsu Halcyon minisplits. I noticed the same on a recent road trip around New Brunswick and Newfoundland – testament to cold weather heat pumps.

@Curt
Wow ! Could $1700 have covered enough air sealing to get to -50 Pascals???

That and it runs counter to the enlightened trend to remove fossil fuels from residences whenever feasible.

I get that 45*F water flowing through a coil in an air handler is an excellent way to cool and dehumidify indoor air…with the possible added benefit of modulating that water temperature a bit either way to intelligently respond to latent load.

I’m a huge fan of heat pump storage electric water heaters, in part because they mesh well with my warm climate operating area. The Rinnai tankless propane fired water heaters are big down here, but I dislike them for their use of fossil fuel (especially in homes off the natural gas grid – pricey propane). There is also the ‘moral hazard’ often reported by parents of teens – the capability of so-called ‘endless hot water’ returns the unanticipated and undesired outcome of teens taking virtually eternal showers!

I have had multiple teens do that, but in the case of a tank storage water heater, the showering does end when the tank runs out – a feature I have come to value even though occasionally inconvenient.

I repeatedly make the case for at least some sort of redundancy – an uncooled home is effectively unlivable during summer anywhere along the gulf and southeast Atlantic coasts, and gone are the days when nearly all repair components (or at least non-OEM alternatives) of even the most complex heat pump systems were continually locally stocked.

Today’s high end variable capacity systems nearly all require proprietary controls / components often not available same day (or even same week)

Don’t confuse hydronics with radiant panel heating or cooling. Hydronics is a distribution medium and control strategy. Heat transport in an air system is strictly a matter of displacing the air in the room and moving it past the single heat exchanger at the source and delivered at a constant temperature. With hydronics we typically hold the design water flow through the terminal device at a constant and then vary the heat output to the device and room by varying the delivery water temperature to something roughly proportional to the load or the application.

Chilled water de-humidification and/or air cooling is done with ~45°f chilled water. The hydronic system adds capacitance to the system and buffers the compressor by not directly subjecting it to the near instantaneous changes that occur in an air system operation. In a DOAS system the incoming ventilation air is subjected to the cold coil after the ERV has recovered conditioning energy in the exhaust air.
Radiant panels, operating well above the dewpoint and close to the room temperature are very effective at removing sensible gains from an otherwise conditioned, (de-humidified) space. Often these sensible gains can make up the larger fraction of the total conditioning load. Radiant panels return warm water back to the compressor increasing it’s performance. Again, with hydronics we can vary the delivery temperature depending on the application.

* fun facts to know and tell -it takes ~120,000 btu/hr to heat ~3.5 gpm of instantaneously water over an 80° temperature rise.

It’s just circa 1999 insulated flex duct. Something about the choice in material used for the exterior skin. That’s all I know.

While I agree that in-floor radiant heat is a premium solution with many advantages, the limitation posed by a cooling system unable to address latent load (i.e. dehumidify) seems a disqualifying factor throughout all but the driest desert climates. My understanding is that climate change is reducing the area / regions able to be solely sensibly cooled.

I’m not sure I completely buy into heat transfer vs mass transfer…hydronic systems substitute pumping water through a system of pipes vs blowing air through a network of ducts. I would think that the only system able to lay claim to being purely heat transfer would be electric resistance.

In some cases, follow-me zoning will result in over-conditioning in other rooms, but in other cases it may result in under-conditioning in the unoccupied rooms. It depends on zone loads relative to the delivered heating/cooling to each zone.

With much respect, I must point out how crude air based heating and cooling systems are with respect to control over heat/cool delivery. With hydronic delivery systems, because we practice heat transfer and not mass transfer, and because of the high energy density of water, it’s quite easy and natural to subdivide a single piece of equipment into several zones using low voltage zone valves and variable speed deltaP circulators. We zone spaces differently depending on how they are used and/or the extent to which they experience different thermal exposure. The heating water temperature is generally regulated by outdoor reset control according to outdoor air temp. Lowering the water temperature to be appropriate to the instantaneous load helps eliminate cycling.

Typically, Living, Kitchen, Dining, and Great rooms are zoned together as they usually all share common space. Bedrooms and bathrooms are zoned separately from bedrooms, especially with radiant as everyone likes to “sleep cold”, and it is a feature to have warm floors in the bathroom at 2 am, ;-). Especially the a master bed and bath. Guest bedrooms are turned down most of the time as is the garage, which we often include as a part of the heated area.
Domestic hot water is treated as another zone taken from the same equipment and often given priority over other heating zones so that the dhw load is recovered quickly or instantaneously. When using panel radiators as terminal equipment we are free to use non-electric Thermostatic Radiator Valves, (TRV) which turn each radiator into its own heating zone.
Of course one can “zone” air handlers as well, which can. carry chilled water for cooling. However, I have learned that, to the extent to which cooling is really dehumidification, zoning is less important and can be counterproductive to comfort. As you know, vapor pressure is real pressure and moisture moves through the air from one dry zone to another which can create “clammyness” where the air is cold and wet.
Sensible cooling with radiant panels can be zoned but such must operate with water temperatures well above the dew point.
Thanks for listening.
Dale