A hot water boiler operates at a lower temperature than a furnace and the controls keep the fan speed as low as possible instead of cycling on and off. The cost of operation is lower and the comfort level is much better than with a furnace.

The system is also easier to zone (multiple thermostats) and additional zones can be added. The only system that might be as comfortable is radiant in floor heat but if AC is needed hydro-air is best

I had a hydro-air system in New York. It was very nice. It was a new build. I don't believe it was exorbitantly expensive to install versus force hot air. The coils do have to be filled with a specialized fluid, not water. I think it's more efficient.

I've also had radiant floor heat and hot water radiators (not steam). They were all wonderful. You didn't dry out.

JDS - does that mean air is consistently blowing lightly out of the vents? Because that alone already sounds better. As opposed to forced hot air which blows hard on and off

homechef, how did you feel the hydroair compared to hot water radiators? Any difference in comfort and dryness?

I think I've heard the specialized fluid prevents the pipes from freezing, but I could be mistaken...

Yes, the system's computer uses a variable speed fan and an outdoor sensor to keep the air flowing slowly instead of cycling on and off.

The only more comfortable system is in-floor radiant heating but if you want AC, hydro-air is the best IMO.

Heating lines from the indoor boiler carry plain water and are not exposed to the outdoors. AC Lines from the outdoor compressor/condenser are freon and do not freeze but the outdoor unit can freeze if it malfunctions.

A heat pump might be an option but its difficult to be specific without knowing your climate.

There is no substitute to snuggling up to a hot water radiator. You can put your shoes, coats and anything else that needs drying. We were able to attach a hot water floor system for the renovated kitchen because we had the boiler. It was a nice solution.

Anyhow, to answer your question, I don't exactly remember. I have sold the house. But, that is a good thing. I don't remember there being any issue with the system. It provided consistent heat. I didn't notice excessive drying of my skin or nose, either.

One thing that we did run into was the half-asxxd builder that built the house tested the system with water for leaks. That's okay. But, he never purged the system and installed the special fluid. I awoke one Saturday morning to a frozen system. It wouldn't have frozen with the fluid. I found the cans of fluid behind the boiler in the basement. I was so pissed. I was in the attic in a blizzard with an extension cord and blow dryer frantically trying to melt the ice crystals before the supply lines burst.

Moral of story, make sure you have the special fluid installed. The system worked great when it was configured with the right fluid.

Boiler pipes should not need special fluid to avoid freezing; all pipes and equipment should be in conditioned spaces. When any part of a system is in an attic, the attic should be insulated at the rafters so the attic will be part of the conditioned space of the house. That will not only prevent freezing, it will lower your energy expenses.

Like I said, I had an axxxxxe of a builder.

Your experiences with uncomfortable forced-air systems are probably based on inefficient homes that did not benefit from this type of service. Most older systems have only one or two fan speeds blowing into poorly designed ductwork. The systems are also usually serving older, building envelopes with crappy windows, pathetic insulation and horrendous air leakage.

Springtime Builders - Yes, yes and yes. Everything your saying is true. Our current house that has the terrible forced air system has falling insulation, leaky windows and one fan speed - HIGH.

So your making me feel better about our new build being more comfortable.

If an HVAC company is certified with EnergyStar, would they be a good company to use? Or would an independent mechanical engineer be best. (Not sure where to find one of those who does HVAC planning for residential homes?)

homechef - I agree - the fact that you don't remember the system is a very good thing. The hot air furnace I have now is so bad I wanted to originally go full on radiators for the entire house in this new build.

I'm so sorry to hear about what happened with your installation - that's terrible! We'll definitely ask about what kind of fluid should go in the pipes - and in general, how to prevent freezing pipes.

JDS - very reassuring to hear that the fan speed is low. In my current house - in the winter it feels like a fan is blowing on me whenever the system cycles on.

Full radiant is too expensive for us as well as radiators in the whole home - so I'm starting to get excited about HydroAir as a real possibility.

We're in the northeast, so how would that work with a heat pump?

Another question about HydroAir. If we wanted radiant heat let's say in the master bath and kitchen could that come off the same boiler that runs to the HydroAir coils?

Could we even have radiators in just one room and HydroAir in the others?

A hot water boiler can supply anything that uses hot water since it can have multiple small circulators that respond to dedicated thermostats but any space not served by ducts from the air-handler will not have air conditioning and i don't know of a way to design that system to serve some rooms with cool air and others with warm and cool air.

I guess if you wanted radiators in a separately controlled zone of the house they could be on their own circulator and thermostat for hot water heat and the hydro-air ducted system could still serve that zone for heating and cooling. Then you could choose what form of heat you wanted from the two thermostats. Perhaps this could be automated but thats beyond my knowledge.

I suggest that you be careful to not unnecessarily complicate an already expensive, sophisticated, efficient, and computer controlled HVAC system with less sophisticated partial systems and configurations.

For the money you would pay for a redundant system you could probably afford in-floor radiant heat with a ducted ac system.

If you don't like hot air blowing on you, I can't see what difference it makes how that air is heated. You still have hot dry air blowing over bare skin, which I also find unpleasant. I've personally experienced traditional forced air, with floor registers, the split system, and the Unico system, and the unpleasant, unnatural sensation is much the same. (Somehow it's not like standing outdoors in a warm breeze, which feels fine to me. I suppose the difference is the sun on one's skin.)

If you don't need air conditioning, look at some form of true radiant heat, not convection. I'm going with hard wired electric baseboard heating. There's very little equipment needed, and no moving parts. Not much maintenance or noise. You can zone it by the room. So overall, the total cost of ownership over the whole life of the product (not just installation and energy) should be pretty good.

Personally, I would prefer to put all that money into one system, which can only be heat pump based. The cooling system is the heating system. The electric radiant mentioned by JDS makes sense for small areas compared to an entire home.

Ground Source Heat Pump would be nice, but they have questionable simple paybacks for efficient building envelopes. Lots of high performance builders are using mini-splits in cold climates as the main heat source but it takes a very efficient envelope and comes with the challenges of aesthetics and distribution.

The industry is beginning to adopt variable speed technology (used in mini-splits) for traditional ducted systems. I would look into Carrier's new variable speed compressors infinity or greenspeed. Many HVAC companies are offering variable speed air-handlers, which should solve your blowing air concerns, but it's the variable speed compressors (outdoor unit) that's efficient for cold climates.