My wife and I are looking to purchase a home in the very near future. Currently the home we are in contract to purchase has baseboard hot water heat and no Central A/C (so no ductwork). One of the reasons that we are drawn to baseboard heat is due to the fact that with forced air, the dry air produced tends to give more bloody noses, etc. That said, I have been researching GeoThermal heating and cooling since I would like to install Central A/C in the new home. From everything I have read, GeoThermal is a forced air solution. Are there any remedies to bring that humidity up in the air so that the harsh dry air isn't forced through the house? Luckily the new house is approx. 1/2 acre in lot size so we should be able to do a horizontal closed loop. Any considerations I should have when looking at the technology and having contractors come out and survey the property? With the type of investment I want to make sure I do it right the first time. Thanks in advance!

http://welserver.com/WEL0664/

The only way to make this work with baseboard heat is to put one of the high temperature heatpumps in. Usually, baseboard requires high supply temperature ino the radiantors, something a regular hydronic heatpump make hot water cannot do. So you can have radiant heat via baseboard, and that heatpump can then go into A/C mode, sending chilled water to hydronic air coils, providing A/C. You can also make your all your domestic hot water with the heatpump. Link to an example above.

Where are you located, how big is your house, when was it built?

It is a fallacy that forced air is any drier than baseboards. There is no drying mechanism associated with either blowing air across a hot coil or letting it naturally convect through hot baseboards.

Any combustion appliance (furnace, boiler, water heater, woodstove or fireplace) whose combustion air is sourced from indoors will cause drying during winter weather since replacement air comes from outdoors where humidity is lower than indoors pretty much whenever weather is near or below freezing. Likewise drying may similarly occur from duct leaks if ducts are in unconditioned spaces (again, makeup air comes from dry outdoors) but don't be so eager to "shoot the messenger" that carries the heat to your rooms.

Absent those exceptions, baseboards and ductwork totally within the conditioned envelope act identically upon indoor air - adding sensible heat only. Put another way, neither system incorporates any manner of dehumidification while operating in heating mode. For drying to occur, air must be cooled to below its dewpoint or be in contact with a dessicant, neither of which happens in baseboards or ductwork with a heating coil.

Psychrometric class dismissed...good night all.

Are there any remedies to bring that humidity up in the air so that the harsh dry air isn't forced through the house?

Humidity is constantly added to the air inside a house by showers, cooking, plants and human respiration. The only way for the air to become "dry" inside the home is through leakage, where the moisture laden air escapes and is replaced with dryer air from the outside. Sealing and insulating properly can fix that.

Depending on where you are located, a good fix for a ductless home can be a "ductless" heat pump, which will get you air conditioning, too.

I agree, take a good look at ductless air to air heat pumps before going with geo.

I'm sure that there are many ducted systems that are unbalanced, causing increased air infiltration and dryer air. But the answer is to balance them (each room equal to outdoor pressure), not to consider ducted systems drying.

Also note that a humidifier is far less expensive and more effective (for dryness) than a geo upgrade.

Many ducted systems contribute to dryness whether "balanced" or not. Nat gas, propane and fuel oil equipment often takes combustion air from home which has to be replaced by outside air encouraging infiltration.

What's the fuel source and boiler type/size on the existing heating system, and where is this house located?

Scope it out, get a 3rd party "Manual-J" heat load calculation from a reputable energy consultant, along with recommendations for how to reduce the load cost-effectively relative to budgetary geothermal costs, and see where it lives. Only AFTER you know the size of the load and the room-by-room loads can you make rational decisions about heating equipment. Even if it costs you a grand to have an energy nerd measure it all up and calculate it for you, it'll save more than that in upfront geothermal costs, and you'll be able to better vet the proposals from contractors. The number of 4-6 ton systems out there serving 2-3 ton loads are many, an egregious but common situation, as is the number of 5 ton loads that could have been cost-effectively been brought down under 3 tons, reducing the size and complexity of the geo supporting that load. A ton of load reduction buys more comfort and has a longer lifecycle than the "extra" ton of geo to support the load, and the operating cost of that ton of reduced load is zero, unlike the additional ton of geo.

Geothermal systems can have hydronic output, but rarely is there enough baseboard to be able to run at temperatures where geothermal is really efficient. In some instance adding radiation can fix that at a reasonable cost, in others not. The air temps of air-delivery geo is on the tepid side, not the scorched-air you may be thinking of with 78% efficiency fossil burner furnaces. Rather than being roasted while sitting in the output stream, it's usually a bit of wind-chill, and locating the registers where they won't blow directly on humans is an important factor for keeping comfort levels high during the heating season. (It's not rocket science to get it right, and comfort levels are high when you do.)

As others have noted, no heating system inherently removes or adds moisture from/to the air, except by unintentional outdoor air infiltration drives. One powerful infiltration drive comes from air-handler induced room-to-room pressure differences, making leaks to the outdoors a part of the return path. Seal up the house, seal up the ducts, and providing legitimate return paths can reduce that to a very low level though, and air-sealing the house is strongly recommended even for houses heated with baseboards.

The notion that the combustion air volumes are sufficient to make a significant contribution to drying is ridiculous. It may be measurable with careful instrumentation and sophisticated methods, but it's the least of it- orders of magnitude behind other common infiltration drives, (even for atmospheric-drafted boilers.) If combustion air volumes were the largest (or only) factor, you'd never experience dry air. And sealed combustion direct-vented boilers & furnaces have ZERO infiltration drive (none!) The remedy for dry air in winter is to reduce the ventilation/infiltration rate: Air-seal the house sufficiently and even leaky ducts have a miniscule effect on unintentional ventilation/infiltration, provided that the ducts are all fully inside the pressure boundary of your house.

Depending on the location and the actual heat load ductless air source heat pumps can approach the efficiency of geothermal, usually for a fraction of the upfront cost (even after subsidies are factored in.) The cost of geo varies a lot with region as well as site/design particulars, and there is some inherent design risk, as every system is pretty much a custom system. Ductless air source systems are essentially a "system in a can", the engineering is done, and the primary issues for the installer is to size and locate the head(s) correctly. Unlike geo, ductless is point-source (or multi-point-source), heating, it directly heats only the space where the interior head or cassette is located, and there may be room-to-room temperature balance issues to factor in (either with more heads, or supplemental heating/cooling), but many mid-sized homes can be heated comfortably and efficiently with 2-3 ductless heads and a modest amount of auxilliary resistance heating (panel or cove radiators, electric baseboards if you must.) They are far better suited to homes with relatively open floor plans, and total heat loads under 35,000 BTU/hr (Under 30K is even better.)

Unlike geothermal, the output temps of ductless systems are always above human body temp, and while mounting the head where it blows directly on your kitchen table may create other issues, wind-chill isn't one of them. Locating them where natural convection can let provide substantial heat to adjacent areas/rooms is key to getting the most out of them. Also, unlike ducted air delivery, ductless system don't create room to room pressure differences to drive infiltration- the air is drawn from one side of the ductless head and blown out the other, all within the same room. If your outside design temps are much colder than -20C/-4F your ductless options narrow, but there are at least two manufacturers with model lines designed for operation at or below -25C/-13F. (Mitsubishi MSZ-FExxNA series, or Fujitsu AOU-xxRLS2H series.)

In areas with high summertime or shoulder season outdoor dew points Daikin's Quaternity mini-splits are are capable of dehumidifying to a user adjusted setpoint, in either heating or cooling mode. They're on the pricey side (still much cheaper than geo in most cases), but they're about as cushy as it gets in the ductless air-to-air heating/cooling world.

In some houses you'd never be able to go ductless at reasonable comfort and cost, and geo might be the best option, but don't get locked into the notion that it's the best or only option too early in the game- it's a big ticket item with many factors to consider. Even 3-4 head 3-ton ductless systems are typically under $12KUSD, installed. In my neighborhood that would barely buy the hardware for geo of equal output, let alone the all-important custom design, and the installation + dirt-work. A well designed geo system would beat pretty-good ductless by about 25-30% on raw seasonal efficiency in my climate (central MA), but even with 20 cent electricity it wouldn't cover the difference in upfront cost within the lifespan of the equipment, and spending the difference on rooftop solar can sometimes EXCEED the difference in annual electricity use. (As solar prices continue to crash, this is becoming the case more often, especially in places where solar is heavily subsidized.)

Here's a 13 month picture of what happens with indoor humidity for a 3400 SF home in the Dallas climate.  It shows a 30 day rolling average that stays between 37 - 47 % RH, and a 24 hour rolling average that stays between 31 and 52% RH.  Biggest influencer is outside weather.

http://www.welserver.com/perl/plot/WEL0043/Humidity.png

Hope this helps.

Best regards,

Bill

The outdoor dew points in Dallas TX at their extremes are rarely as low as the mid-winter averages in a US climate zone 5-8 locations, where wintertime air dryness can be a real issue in leaky or overventilated homes.

Pull up dew point charts for these, for comparisons's sake:

http://weatherspark.com/#!dashboard;a=TX/Dallas (average winter dewpoint about +34F)

http://weatherspark.com/#!dashboard;a=USA/NY/Rochester_%28Monroe_County%29 (average winter dew point around +17F)
 
http://weatherspark.com/#!dashboard;a=USA/ND/Minot (average winter dew point around +6F)
 
The dew point of comfortable healthy 70F/35% RH air is about +40F, so the average wintertime drying from ventilation in Dallas is substantially less than in Minot or Rochester.

No matter HOW much air-handler induced infiltration or general air leakage might be going on in the Dallas home it's unlikely to become overly dry, but that's not so for the much cooler locations, and ventilation rates would have to be more carefully controlled.

Posted By Dana1 on 31 May 2013 03:17 PM
The outdoor dew points in Dallas TX ...

Very educational, and much appreciated!

Best regards,

Bill

Check out this product:
http://www.smithsenvironmental.com/html/he.html

I don't know anyone who has tried it but it is basically a hydronic baseboard heater for low temp applications like geo and solar. If anyone has any insight I would love to hear about it.

200 btu/hr/ft @100F is pretty good if it is correct.

We used the smith product quite a bit, works well, about twice as much output than regular baseboard.