Anyone Convert from Hot Air Heating to Hot Water or Steam Heat?

lovetogardenJanuary 17, 2012

This is my first winter in a house with hot air and I can't take it any more. I feel like I'm living in the Sahara Desert. My sinuses, which have never given me trouble before are killing me now and I seem to have a constant case of laryngitis. My throat is constantly raw. I have humidifiers going in every room in the house but it doesn't seem to make any difference in how dry the house it. On top of that this heat can't be regulated. You either freeze or boil. I'm seriously considering selling this house, though would hate to since this is the house of my dreams. I was wondering if it would be possible to convert this house to hot water heat, or steam heat (my ideal)or even baseboard. and how much work and money that would entail? The present furnace is a newer (only 2 years old) high efficiency model. Any info would be appreciated. Thanks

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As a rule furnaces can't be converted into boilers (what's needed for heating fluids for hot water or steam heat). So you need a new boiler. (Furnaces heat air, but boilers heat water.) You also would have to install a complete circulation system to move the water or steam around the house.

And right now you have an air duct system that probably also functions in warm weather as your A/C system. If you removed it enitrely, you'd have to figure something else out (room A/c or mini-splits) if you feel you needed cooling in the summer.

Are you new to the area as well as to the house? Sometimes it takes a while to acclimate to markedly different outdoor temps. If you're cold, get up and get outside and move around - you'll feel warmer doing it and then feel warmer indoors afterward. Plus it is often much more humid outside than in. I'm in northern NY and I still sleeping in a room with an open window, despite below 0F outside temps, because the outdoor air feels better to me. Our heat is even dryer than forced hot air: woodstoves.

I agree forced hot air is not the most agreeable source of heat in a cold climate, but many people like if for the dual capacity in the summer.

Perhaps you should have a heating company come out and see if they can balance the thermostats and make suggestions for increasing the humidity. It's also possible that yhe duvct work needs cleaning and dust or particulates may be the source of your respiratory distress, rather than simply the dryness.

Since this is the Old House Forum, perhaps you have an ancient house (like I do) which is very leaky causing your furnace to work more than necessary to compensate. Some work tightening up the house might make a difference.

If you are considering a new heating system, and it is technically feasible, do look into a hydronic radiant under floor system. They are the best, most comfortable, type of heating around.

I would install one in my house if it was technically possible but, alas, it is not!

Have you measured the Rh of the room with an hygrometer? For a given amount of water vapor in the air, the measurable humidity can vary depending on the temps. Warmer temps can keep more moisture in suspension in the air. Too much moisture in cold rooms will result in damaging condensation on your windows, or worse, migration into the wall cavities if you don't have vapor retarders on the warm side of your wall assembly.


    Bookmark   January 17, 2012 at 2:25PM
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The furnace is 2 years old. When I had the company that put in the furnace service it this past fall they vacuumed out all the vents too. So it's not a question of dust blowing around. The problem is the air is so dry - even my skin is burning off my face - regardless of how much moisturizer I use or how many humidifiers I have going. I really hate this heat. I couldn't do radiant heat because that would mean ripping up the floors. My house was built in 1921 and is pretty solid and tight. I never feel any drafts here - almost wish I would. This house had been completely renovated right down to the studs with new windows and doors too. I just can't deal with the dryness that's why I was wondering if I could change this to a different type system. I also live in the upstate NY area so I'm used to the cold weather too. But, I consider it a problem if I have to go outside in order to get relief.

    Bookmark   January 17, 2012 at 3:28PM
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You might look into having a humidifier added to the furnace itself -- it will add moisture to the heated air and humidify the whole house. We added one to our system in Colorado, where the air is dry to begin with, and it made a huge difference. Our skin wasn't as dry, our sinuses didn't quit on us, and our furniture didn't crack. The humidifier we had could be adjusted to maintain the ideal humidity for the temperature.

    Bookmark   January 17, 2012 at 9:56PM
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THere's all sorts of myths being circulated here. Here's a lot of assumptions going on here. Furnaces don't dry out a house unless they are not direct vent. Older natural draft furnaces do draw in air form the outside into the home, but not in large quantities.

Small humidifier are a joke. Most can only do 1 gallon per day. A good whole house model is good for 12+ gallons per day. You problem with dryness is air leaks, and stack effect (heat rise drawing outside air in from the lower floors). Radiant heat doesn't not prevent this.

Next, you're biggest problem sounds like a poor installation including an oversized furnace. Next, if it's installed in a attic, air leaks in ductwork can cause more outside air to get drawn in. Then poorly designed ductwork isn't distributing heat evenly.

It would be cheaper to fix your current system and upgrade it. You'd be amazed and how good central air and a furnace can work when installed correctly.

In our home, the PO's hired a contractor that did a crappy installation. But a few tweaks and modifications to the ductwork and it's like a whole new system despite both furnaces being oversized.

Don't give up. Find a good contractor that can do a load calculation and duct sizing and evaluate your system. Maybe you need something as simple as a better thermostat or relocating the thermostat.

Boiler systems had a lot of advantages, but they are much more expensive (that's why they disappeared in modern homes), require more maintenance in general, can last longer, but have more components. They also require an engineer or a very competent installer to design and layout.

You will likely still have a dry home afterwards.

That being said, I'm considering going to a hydronic loop off my domestic hot water heater when I replace the heater and then later replace my upstairs furnace. I only need about 30k BTU's of heating, so even the smallest furnace is oversized. With a 2 speed circulator pump, I could get nice even heat all the time.

    Bookmark   January 17, 2012 at 10:58PM
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In addition to the other suggestions, consider wearing more layers and turning your thermostat down quite a bit. If you have it set to 68 or 70 and no supplemental humidification, of course you're going to dessicate your face and airways. I'm not saying a lower temperature will fix everything (for that, consider the other posters suggestions), but if you want a quick fix, turning the heat down will help. you could try 58 or 60 for starters.

My neighbors keep their house quite frigid (low 40s, I'm not kidding) and none of them have had any respiratory illness since they started the practice years ago. I'm not recommending you go that low, but it's an impressive anecdote. They started this when their kids were teens, and I offered the kids warm showers, but they said it was fine, they didn't mind. I keep thinking I should try it, but I like my creature comforts. We keep our house between 55 and 65 (higher for company).

Also make sure your air filter is changed regularly, and consider getting an air cleaner for your bedroom. There are many nice models out there; Honeywell 17000 would be a start. I remember the first time we ran one in our bedroom; I woke up feeling like I'd been breathing mountain air all night--in a good way.

    Bookmark   January 18, 2012 at 8:59AM
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Winter air is not able to hold as much moisture as summer air in northern climates so the best remedy is a hot air furnace with a humidifier and more sophisticated controls that reduce the temperature and air speed when less heat is needed.

Hire a good HVAC designer to replace the furnace with a better one and try to keep the existing duct system.

    Bookmark   January 18, 2012 at 10:14AM
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The most common system in my area is a boiler that feeds two air handlers that are located in the basement and attic spaces in order to reduce ducting. You might consider a boiler and one air handler in the basement using the existing ducts. The air handler would have a 2 speed fan and controls that use the outside air temperature to determine how to keep the air at the lowest velocity.

This system can also have baseboard heating units on another circulator pump.

The air handler can also have a cooling coil with a remote compressor/condenser unit outside.

    Bookmark   January 18, 2012 at 2:19PM
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I am confused by your suggestion of a boiler that coordinates with air handlers. Did you mean a furnace?

@ the OP:
You certainly can change to another kind of system, but understand that it will be require a complete, possibly very expensive, change: new boiler (to replace your newish furnace as furnaces don't heat water or steam, only air) plus extensive pipe system for the hot water and steam to travel all around the house in (need to open walls to install the pipe - have it in the open as was done early on); radiators of some kind (cast-iron, baseboard, etc.) along with wiring for thermostats (though that may be resuable from the current system.) Plus if you remove the airducts, you'll need to address the A/C issue somehow, though here in upstate it's less critical. I have no A/C and need none as the summers are cool enough.

Depending on how you heat your domestic hot water a change may involve your hot water supply, too.

If you are sure your house is well-insulated and tight then you might try a humidifier either as part of your ducting system, or even just in the room you sleep in. Unless you have really powerful exhaust fans (kitchen and baths) that are exhausting indoor air, humidity added to the air, furnishings, etc, will stay in the house.

Which brings up a question: Is your furnace drawing its combustion air from the house or a dedicated outdoor-connected air intake system? Our woodstoves are connected to outside air intakes specifically to prevent them from using indoor air (in our case this is to preserve warmed air). A question to ask your HVAC service is how your furnace intake is ducted. If it's drawing combustion air through the house (from leaky places in the wall assemblies and around doors and windows - you wouldn't feel it as drafts, necessarily, though you might), then it would feel much, much dryer than otherwise.

BTW radiant underfloor heating doesn't require tearing up the floors in most cases. The system is installed from below so if you have access to a cellar and are willing to have the ceilings of the first floor opened to access the underside of the second floor, you're good to go. Unless you don't have a cellar or have elaborate plaster ceiling, the installation is not too onerous. It avoids a lot of issues with moving the hot water or steam around to radiators all over the house.

The key with any heating system is the competance and skill of the designers and installers. The Capital Region seems to be well-supplied with skilled HVAC companies.

Good luck!


    Bookmark   January 18, 2012 at 3:07PM
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Hi everyone, thanks for your suggestions. Looks like there is really not much I can do about this situation. I've already contacted a realtor and am looking for another property.

    Bookmark   January 18, 2012 at 5:25PM
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The whole house humidifier can be added to your existing furnace. My parents added one when they replaced their forced air furnace and have been very happy with it.

    Bookmark   January 18, 2012 at 6:58PM
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badgergrrl, thank you so much. Tomorrow I'm going to call the company that put this unit in and have them do that. Thanks so much again.

    Bookmark   January 18, 2012 at 9:04PM
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A furnace heats air directly in a metal box above the firebox and that hot dry air is ducted to the conditioned spaces.

In a hydro-air system, a boiler heats water that is pumped to an air-handler where it passes through a copper coil and heats the air that passed through it and is ducted to the conditioned space. This system is more expensive than a furnace but it runs more continuously at lower fan speeds and the air is not as hot or as dry.

I would think it would be more practical to replace the furnace with a hydro-air system than to tear the house up installing a forced hot water baseboard system.

What you need to do is to contact a reliable HVAC designer.

Here is a link that might be useful: Why Hydro Air?

    Bookmark   January 18, 2012 at 9:10PM
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A typical lowest-initial-cost forced hot-air furnace system is designed for the worst case heating condition (coldest day) and therefore during the rest of the year it heats air to a high temperature and delivers it to the conditioned spaces with a high-speed fan until the thermostat is satisfied and turns the system off.

More expensive systems have multi-speed fans, computer controls, and outdoor thermostats that allow the system to anticipate the need for heat and to run more continuously at lower temperatures and slower fan speeds. In addition, the use of a boiler and an air-handler (fan-coil unit) allows the air to retain more of its moisture content which means less needs to be added in very cold weather.

It should not be necessary to sell your house in order to get a comfortable HVAC system but it will cost more than a basic furnace system.

    Bookmark   January 19, 2012 at 10:59AM
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Hi Guys, badgergirl recommended a whole house humidifier. I contacted the people who put this furnace in (it's only 2 years old)and they said it can be done on my model and they put them in all the time. They also told me I will feel an immediate difference. They're coming next week and I can't wait. Thanks again.

    Bookmark   January 19, 2012 at 2:36PM
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Furnace mounted humidifiers can correct the dry air problem caused by hot air furnaces but they can also introduce other problems. Discuss with your installer the potential for bacterial growth of the several types of systems, the mineral content of your tap water, and the required maintenance schedule.

    Bookmark   January 19, 2012 at 6:25PM
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Folks, folks, furnaces don't "dry" out the air anymore than any other heating appliance. Especially if they are newer direct vent units.
Furnaces don't remove water from the air, they only raise the temperature. Lower efficiency furnaces do draw combustion air from inside the home, but so do most boilers. and domestic water heaters. Dry air comes from air leaks to the outside or poor quality ductwork installations that leaks air into a vented attic, or force air out leaks around windows and doors when they run.

Forced air systems...any heating system should not be designed for the coldest day. They get designed for design conditions in your area. Its' usually a 97-98% temperature. Meaning only 2-3% of the heating hours during heating season are colder. Most system sadly get oversized...including boilers.

As for a furnace being hotter. Well, that's a matter of design. A furnace usually has a temp rise of 50-60F. You can easily design a hot water hydronic air handler to have a temp rise of 60F. Actually, they can be much much hotter if you want since a boiler can supply 180F water temps. You can have 160F air temps if you want. Temps that would damage the heat exchangers of most furnaces.

    Bookmark   January 21, 2012 at 8:58PM
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Moving air has the added feature of being able to evaporate more water. The air movement in and of itself imparts the effect of a sirocco.
Central humidifiers attached to hot air systems have to be controlled for lime scale buildup in hard water regions and the possibility of bacteria and mold growth within the unit.

    Bookmark   January 21, 2012 at 11:16PM
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Motorguy, thanks for the information, but having lived before with steam heat, hot water heat, coal heat, and wood heat, I have to say that without a doubt, hot air heat is by far the driest. Now, it might be true what you say about insulation as I do live in an older home, but it was renovated down to the studs with all new insulation, a new roof, and new windows and doors. I don't feel drafts anywhere in this house. Even the attic and basement doesn't feel drafty. The furnace is a 2 year old high efficiency with all new galvanized ductwork. The air returns are in the house. There's several on each floor to account for central ac, which I don't have now but plan to get in the spring. What I do know for certain is that I find it very dry in this house, I am constantly getting shocked, I am constantly sick, and even my cactus plants are suffering. It's even too dry for them. I know it's not in my head.

    Bookmark   January 21, 2012 at 11:45PM
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However the burners of a forced hot air furnace are sized, that is what heats the air whenever the thermostat calls for heat and if the fan is single speed, that is the speed at which the air will move until the thermostat is satisfied. This kind of inexpensive unsophisticated system tends to heat the house unevenly and hotter than necessary air moving at a greater speed than necessary tends to have a surface drying effect on anything that contains moisture like you and your plants.

A multi-stage, variable speed furnace (or hydro-air) system will not raise the humidity as much as a humidifier but it will help a lot and it is more energy efficient and requires less maintenance.

    Bookmark   January 22, 2012 at 8:43AM
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You've probably never been in a home with properly sized ductwork. Don't feel bad, it's estimated that as much as 3/4 of the heating and cooling systems in the US are oversized. 2 stage and modulating furnaces are better, but I've lived in a home with both, and both can be very comfortable and the single stage equipment doesn't make it feel more dry that I can tell.

BUt you are correct, multistage cna reduce the sense of dryness you might get with a less than ideal system. THe RH of hot air is lower than cooler air, but cool air can make things feel drafty. That's why radiant heat is popular. You essentially have very, very low air velocities and much of the heat energy is indirect infrared heat which make you feel warmer, similar to direct sunlight.

Keep in mind too, that unless you have an outdoor rest control for hte boiler or to sped up or slow the circulator, most hydronic air handlers are single stage for heating. So the heat is no different than a furnace. Worse, as you reduce BTU's to the coil, the airflow speed is usually ocnstant, so air temps get cooler.

My point being, that a properly designed and installed furnace won;t make it feel dry even if single stage. But yes, oversized furnaces and those with restricted airflow can. Vairble capacity will always make the system more comfortable, but it will cost more. Radiant heat overall is superior, but the installed cost is much, much higher. That's why it fell out of favor. Same reason drywall took over the market and plaster disapeared. ITs' primarily a matter of cost. It's also why stone and brick homes aren't built anymore and concrete homes are the minority.

    Bookmark   January 22, 2012 at 10:00AM
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Historically, drywall was cheaper than plaster but that was not enough for it to overtake plaster in homeowner acceptance. What did that was the labor shortage during WWII but I assume cost would have caused it to happen eventually. In my area taped drywall has never been fully accepted because the installers offer veneer plaster for the same price.

I assumed the OP's furnace was oversized but the systems that go into my designs are not. I recently used three of the Matrix systems by NTI.

Here is a link that might be useful: Matrix

    Bookmark   January 23, 2012 at 6:38AM
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Forced air heat takes the air in the envelope and heats a fraction of it hotter than desired.
This drops the relative humidity (%RH) of the air.
Warm air can hold more moisture, and if it is heated without adding moisture the %RH drops.

This small fraction of hotter air is then ducted to the envelope and distributed.

It has the same absolute moisture level, but the %RH is lower.

Any heating of colder air drops the %RH.

Since the delivered air is rarely that uniformly mixed any warmer spots continue to exhibit a lower %RH.
Hydronic heat does not discharge as high a temperature as forced air heat and while once the entire envelope is heated uniformly the %RH would the same.

Steam heat with use of vents is one system that actually adds some moisture to the envelope, but only until the thermostatic vents heat up and close off.
If there is significant release the vent is defective.

Hydronic and steam, heat users have used pans of water on top of the radiators or even long narrow pans 'inside' the radiator elements so they do not show as badly to increase humidity for a very long time.

In very cold areas ANY heating of the air during heating season can result in very low %RH that requires humidification for comfort.

    Bookmark   January 23, 2012 at 10:38AM
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It's interesting to read what the differences are in the heated air being put out by a forced warm air system vs. hydronic or steam systems. I always thought that the only way a hot water based heating system could be less dry than a furnace is if there were a substantial leak somewhere. I've had good results with a whole house humidifier installed on the furnace, but if the blower doesn't run much, you don't get that much humidification. I have a furnace and two wood stoves, and between the kettles on the stoves and the houseplants, my humidity stays at a comfortable level, considering it's winter. I also keep the thermostat at no higher than 62, often lower. I'm very uncomfortable when visiting homes or businesses where the heat it jacked up to 70 or 72 degrees. I can tolerate it for an hour, and then have to leave because I start to feel like I'm being smothered. I guess it's all what you're used to.

    Bookmark   January 23, 2012 at 5:06PM
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Saypoint, I'm an old buzzard that needs to keep the heat at 68 or I feel like I'm freezing. The only time I put the heat lower than that is at night - 65. I like to sleep in a cooler temp.

    Bookmark   January 23, 2012 at 8:24PM
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Anyone have experience with whole-house masonry heaters - how do they affect humidity levels, and general comfort?

    Bookmark   January 29, 2012 at 5:54PM
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"It's interesting to read what the differences are in the heated air being put out by a forced warm air system vs. hydronic or steam systems."

Less heating of more air can be more comfortable, but the hotter air is easier to humidify.

If the air mixes completely it does not matter much, but even that is a rather rare occurrence.

Heating systems have always been deigned based on some percentile of the average coldest temperature.
The available unit sizes then further introduce 'granularity' in the system capacity.

If you need 80,000 BTU/hr and the systems come in 25,000 BTU/hr increments do you want to be chilly on 'design days' or go with a larger than required unit?

The falling cost of electronic controls has helped.
It has allowed for reset thermostats (they sense the outside temperature and adjust input) and the use of variable output heaters (staged burners).
It does make for a more complicated system though, and that cost money and decreases reliability.

Early multiple capacity cooling condensers went so far as to have two separate compressors to allow changes in cooling capacity.

It is not as much of a problem in large structures that use multiple heat sources.
You just do not turn all the sources on for low demand, instant staging.

    Bookmark   January 30, 2012 at 11:13AM
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lovetogarden, has the humidifier been installed? How are things?

    Bookmark   February 4, 2012 at 2:43PM
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vgnrts, nope I haven't got it yet. I called up several places and the prices are out of my range. One place I called told me about $350.00 to $400.00. When the guy got here it suddenly was $600.00.I went online and the highest price for a top of the line unit was $249.00. Most are in the $150.00 range. From the videos on Youtube most say it takes under an hour to install. I can't see the discrepancy between what the unit cost and the labor costs. I'm considering purchasing a unit myself and hiring someone to install it. It will probably cost a lot less that way than to buy it though a heating contractor. I'll keep everyone update, though I don't think I'll be doing it this year since the weather has been so good here I don't need to keep my heat up, which is what makes the house dry.

    Bookmark   February 4, 2012 at 3:44PM
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The online prices probably don't include installation. Don't believe any price that isn't in writing with an adequate specification covering materials and installation.

    Bookmark   February 4, 2012 at 4:33PM
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