Pros & Cons of boiler heating system?

stretchadFebruary 8, 2008

I'm in the market to buy a home and I've spotted a listing online for a 90 year old tudor with a boiler for heating (new one installed in 2001).

Can someone explain to me how a boiler works, what pros and cons it has? I am not at all familiar with older homes!

The house is 1800 square feet, if that has any bearing.

Thank you!

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The boiler heats water to probably 180 F. Some older systems, I believe, passively circulated water to radiators. I could be wrong about that.

The hydronic systems that I have seen use small pumps to circulate hot water to radiators that typically cover the baseboards on outside walls. Some older systems use a higher profile radiator that sits below the windows rather than low along the baseboards. They dont look much different, to the average Joe, than steam radiators. Some people feel that the radiators are unsightly. I have seen sheet metal-covered baseboard heaters and more rarely cast-iron in some older systems.

The average hydronic system is quieter because you donÂt have air blowing around. They also yield more even heat. They may have more inertia because the pipes need to warm up. I think that negligible. and with timer thermostats it practically becomes irrelevant. Hydronic systems are pretty easy to break down into zones so you can control individual areas in the home differently. As an example, my sister has a three-bedroom home in Broome County NY. She has four zones including one that handles the basement. You can save money by heating only the area you are in.

Hydronic heat can also be installed under floors to eliminate the radiators and you have nice warm floors in the winter. Boilers can be the basis of a sort of hybrid system where the hot water is circulated where it is needed and the common radiator is replaced by a blower and a more compact water to air heat exchanger. You can have these and the more common radiators in the same home. In fact, in kitchens kick-space heaters are very commonly installed.

A boiler can supply hot water to the home as well, but it must be set up for that purpose and not mix the hot water for taps with the heating water.

Some disadvantages of hydronic include the time required to clean radiators. If you want AC, you have to install a duct system so expense for a separate heating system is higher, much higher. Sharing a duct system with heating and AC is not without its problems, however. It seems to be difficult to get them both to work well, especially in two or more level dwellings.

Some advantages to forced air aside from economy are that with forced-air heat you can easily install a whole house humidifier or dehumidifier depending on what you need. You can install air cleaners and heat-exchanging ventilators more easily. I think, however, that the former are over-rated.

One problem I have with forced air, since I cook a lot, I donÂt like the forced air competing with the kitchen ventilation system in keeping grease, smoke, steam and odors out of the rest of the house. Forced air can seem drafty to some. The most modern systems have returns in every room, but the older systems might have one in the house or maybe two. The doors are usually undercut to provide return air. You can install jump ducts in the walls to fix that. If there is not a return in each room, it is more difficult to zone the system.

If I had the choice between identical houses with hydronic or forces air heat, I would choose the former.

    Bookmark   February 8, 2008 at 7:45PM
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It is a good steady heat...but.....compared to forced air furnaces,the efficiencies are not bad,but not great is good that the boiler has been upgraded,but it might only be 80% efficient.forced air furnaces can be 80% up to 95%,so every dollar you spend for fuel,on a 95 pecent furnace,only 5 percent goes out the flue pipe.there ae some money saving devices sucha s a beckett heat manager that is supposed to save you 10% on fuel costs.You could also get an outdoor reset controller that will adjust the water temp from the boiler based on outside air temp.example-outdoor temp is 20 degrees,boiler water temp-180-190 degrees,if temp goes up to 50 degrees,boiler temp would go down to 115-125 degrees,thus saving fuel costs

    Bookmark   February 8, 2008 at 8:09PM
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I realize the above example was just that, an example, but if someone uses an outdoor reset module to jack up the water temperature to 180°F on a 20° day, they shouldn't have bothered with the module. In my 1,350 sq ft home with hydronic heat, the module doesn't push the boiler to 180° until it hits -20° outside.

The purpose of the Outdoor Reset Module is to program the water temperature of the boiler so that it can match the heat loss of the house. Your area has a "design day" setting, so you would need to find that out. Ours is -20°. My boiler will start responding to the thermostats at 70° outdoor temperature. The boiler water will be at a minimum, such as 120°, for my system design. As the outdoor temperature gets cooler, the water temperature climbs. In my case, peaking at 180° set point when it's -20° outside.

Hydronic heat is slower to react than forced air. For example, if it's 65° indoors and you want to go up to 69°, it will take some time. Hydronic heat, in my opinion, is ideal because it's a more even, constant heat. It radiates. It doesn't induce any drafts in the home. And because it radiates, you're heating the contents of the room rather than the air, which is an insulator. When the hydronic system turns off, the heat gradually fades away, unlike forced air which is an immediate loss of heat being introduced into the home.

Hydronic can be set up for in-floor heat, which is very economical because the water has to be below 100°. Takes less energy to heat to 100° than it does to get to 180°, eh?

Forced air has the ability to spread dust, pollen, mold, dander and odor. With hydronic heat, you may need to open a window once in a while or run your bathroom fans on a timer to draw in some fresh air.

An advantage of forced air is that it is more resistant to cold damage. If a hydronic system fails and the pipes freeze, the ice that formed in the pipe can burst the copper pipe.

Because hydronic heat is slower to react, it is not recommended to use a programmable thermostat with it. You'll come out ahead if you just leave the thermostat at a constant setting. Depending on the installation quality, it can be quieter. There are no filters to change. If given regular maintenance, it can last at least 20 years, as long as 50 or more.

If I were shopping for a home, having experienced what I have with my current (first) home, I'd shy away from a forced air system.

    Bookmark   February 8, 2008 at 9:40PM
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"You could also get an outdoor reset controller that will adjust the water temp from the boiler based on outside air temp.example-outdoor temp is 20 degrees,boiler water temp-180-190 degrees,if temp goes up to 50 degrees,boiler temp would go down to 115-125 degrees,thus saving fuel costs" What type of boiler do you have? With a CI boiler bringing water back that cool is going to cold shock your boiler and you could end up with some kind of ugly mess in your asement some day.

    Bookmark   February 8, 2008 at 10:55PM
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A modern simple (no fancy gadgets) steel horizontal tube boiler will be 85% efficient. A modern simple furnace will be less efficient.

    Bookmark   February 9, 2008 at 6:36AM
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A boiler can provide heat in two different ways...

The first, as described, is via hot water.

Hot water systems can be configured in two ways, as well: forced circulation and gravity.

Gravity circulation worked on the principal that hot water rises, cold water falls. This was VERY common at one time as it didn't depend on electricity to move the water via pumps, and it worked very well with coal boilers, which had a constant fire in them.

Homes with gravity heating were zoned (if they were zoned) vertically. That means that instead of having the first floor and the second floor as different heating zones as is common today, the front rooms of the house (first and second floor) would be one zone, and the rear of the house would be a second zone.

That's how my Mom's house is set up. It was originally a coal-fired gravity hot water system, and when it was converted to oil the zoning was kept.

When electric became more reliable and oil became more common (really kicking off after WW II), system design was changed. Those systems won't work on gravity flow, but it's a better zoning system as you can control an entire floor more easily.

The other kind of heat that a boiler can provide is steam heat. I grew up in a home heated with big cast iron radiators and steam.

Steam systems are generally less efficient than hot water because it requires more fuel to take the water over to steam, but the surface temperature of the radiators is about 30 degrees more, so you tend to get more heat into the room more quickly.

Steam systems have a number of interesting quirks, though, and fewer and fewer people are around who know how to deal with them.

There are two main kinds of steam heating systems: one pipe and two pipe. One pipe systems are more common, most two pipe systems were installed after WW I.

To me, the pros of boiler heating is that it tends to be a much more comfortable heat, especially if the system uses baseboard units that wrap the exterior walls.

Radiators are nice, too. Those large thermal masses help maintain a nice heat level in the house over a long period of time, generally making you feel warmer and more comfortable even at lower temperatures. Plus, there's no breeze blowing over you when the system is running as there is with forced air heat.

In my opinion hot water or steam heat is really the only way to go in an older home. I've seen quite a few older homes converted to forced air heating, and unless a LOT of money is spent on insulation, new windows, and crack sealing to prevent drafts, those homes are never as comfortable as one with hot water or steam.

Boilers do tend to be a bit less efficient than forced air, but I think that in an older home the greater comfort of hot water/steam more than makes up for that.

    Bookmark   February 9, 2008 at 12:19PM
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I have a boiler system in my 1960 2 bedroom ranch. I love the way it warms the house, but my only problems/complaints are:

1.) When the heat starts up you can hear the copper fins "clicking" as the expand. This is because the previous owners have them all banged up and at some point I'll have to straighten them all up.

2.) You'll need a humidifier. My house gets extremely dry during winter months and we had to buy several small units and put them in the bedrooms. I wish i had a whole house unit to add humidity, but there is no way to do this using a hyrdonic system.

    Bookmark   February 9, 2008 at 7:00PM
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There is hope for you hydronic people

They work quite well-
(don't worry humidity travels quite well throughout the house from one central point)

Want state-of-the-art humidification for your radiator/baseboard heating system? Look no further.

The Aprilaire Models 350/360 Whole-House Humidifiers are specifically designed to bring all the benefits of patented Aprilaire humidification to homes with radiators or baseboard heat. The Models 350/360 are so effective and flexible, they work equally well with central heating and cooling systems.

    Bookmark   February 9, 2008 at 9:12PM
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Wow, momma didn't cook dinner tonight?

    Bookmark   February 9, 2008 at 10:37PM
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Had an hydronic system for 25 yrs and loved it, forced air now and its drafty.

We had a 2200 sq. ft. house with 6 zones, all baseboard. and the main bath was common to all the zones, ran with one pump the size of your fist.

    Bookmark   February 10, 2008 at 2:27AM
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Simply stated: With hot water heat, you'll always be warm and won't know the heat is ON. With warm air heat, you'll always be aware of the cycling and it's drafty.

    Bookmark   February 10, 2008 at 6:41AM
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If you'd like some basic and easy to understand information about various heating systems, including hot water and steam (you didn't mention if the system in the old house you're looking at was one or the other), you might check out the website at the link below. There's a ton of useful stuff there.

    Bookmark   February 10, 2008 at 3:11PM
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Low return temps on a cast iron boiler can be eliminated quite easily with proper primary/secondary piping design and thermostatic control valving.

    Bookmark   February 11, 2008 at 10:29AM
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"Because hydronic heat is slower to react, it is not recommended to use a programmable thermostat with it. You'll come out ahead if you just leave the thermostat at a constant setting."

This statement is false. The basic physics of heat transfer indicate that it is false. It is a commonly-propagated legend, but never-the-less, false. I do not believe that you can support it with reason or cite any reputable source.

    Bookmark   February 11, 2008 at 6:11PM
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In PA, a usual setback for hydronic heat is about 5 degrees, maybe slightly higher.

    Bookmark   February 11, 2008 at 7:00PM
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A grossly over-sized boiler may lead to inefficient short cycling, but I don't know if the constant higher set temp or the short cycling on recovery would use more fuel.

    Bookmark   February 11, 2008 at 7:27PM
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