# 5 - Quiet: Why a hydronic heating system is quieter than forced air

This week's entry in the Heidronics blog is installment # 4 of the top 7 reasons why a hydronic heating system is a better choice than forced air — quiet operation.

Any well-designed, installed and maintained hydronic heating system will be virtually silent. This is true of hot water baseboard, in-floor radiant and even a steam heating system. If there's noise, your system's telling you it needs attention. These are not normal sounds.

A forced air furnace is inherently noisy compared to a hydronic system. Blower noise is the most common complaint. The mechanical whirring of the blower and the velocity noise of the air moving through ducts and across register grills are quite noticeable in most homes. Furnaces marketed as "high-performance" equipment are an attempt to minimize this noise by using variable speed blower motors that keep blower speeds as slow as possible — but the only way a furnace can match the silence of a hydronic system is when the furnace is off.

The ducts of a forced air heating system can also be noisy. The ducts will expand as they heat up and "balloon" as they're pressurized by the blower. This can create the popping or creaking sounds you've heard when the furnace starts up. At its worst, it can be like living in a tin can.

I've also seen forced air systems actually blow doors closed, move curtains and rattle blinds on windows.

Not convinced? Oh — there's more. Electronic air cleaners snap away. Humidifiers hum, hiss and rattle. Dampers shake. I think you get the idea.

Because a hydronic heating system uses a completely different distribution method, you don't get the "side effects" of hot air moving around your home. Water or steam move gently throughout your home via small tubing or piping. Water and steam can do their jobs silently, going unnoticed for months and years at a time.

The bottom line: Silence is golden, especially when it comes to your heating system!

Stay tuned  – next week's topic is cleanliness.

Heidronically yours,

Wayne

# 4 - Versatility: Why a hydronic heating system is more versatile than forced air

In previous blog posts I've talked about how a hydronic heating system is more comfortable, more efficient and more reliable than a forced air system. Today's topic is versatility and this is where hydronics really shines.

There's no more versatile means of heat production, distribution or delivery than hydronics. This may be a bold statement considering all of the heating system choices available today, but let me offer this list as proof positive.

Heat production:

• Traditional cast iron boiler (gas, propane, and oil fired)
• Condensing boiler (gas, propane, and oil fired)
• Modulating/condensing boiler (gas and propane fired)
• Electric boiler
• Tankless combi-boiler (gas, propane and electric)
• Traditional tank-type water heater
• Biofuel boiler (wood, pellets, coal and other solid fuels)
• Solar thermal
• Ground source heat pump (geothermal)

Heat distribution:

• Adaptable to existing steel piping (such as an old gravity heating system)
• Copper tubing
• Pex or pex-al-pex tubing (types of cross-linked polyethylene tubing)
• Series loop, direct return and indirect return systems
• Manifold header system (fed from common source point)
• Home-run system (individual delivery to rooms or emitters)
• Unlimited zoning (zone valves or thermostatic radiator valves)
• Mini-tube (ability to supply heat to remote areas or outbuildings)

 Heat delivery:

• Cast iron standing radiators
• Cast iron baseboard radiators
• Copper finned-tube baseboard radiation
• Steel panel radiators
• Aluminum radiant panels
• Towel radiators
• In-floor radiant heating (tube and plate staple-up, above-floor panels, thin-floor pour (gypsum overpour) and slab radiant (concrete)
• Radiant ceilings and walls
• Hydro-air
• Domestic hot water production
• Snowmelt (for driveways and walkways)
• Pool and hot-tub heating

Hydronics can provide all of this versatility from a single heat source. There's no need to have multiple fuel-burning appliances to perform all of your heating needs. That can simplify the fuel supply, electrical supply, and flue gas venting (chimney) requirements for the entire system. And fewer appliances means less maintenance.

These are just some of the many ways hydronics can be used to make our homes (and lives) more comfortable, efficient and convenient. (I'll go into more detail about some of them in future blog posts.)

Next week I'll write about why a well-designed hydronic system is so quiet, compared to forced air heating.

Hydronically yours,

Wayne

# 3 - Reliability: Why a hydronic heating system is more reliable than forced air

The reliability of your heating system is something you may take for granted – until it's not working. But  hydronics has a long history of reliable service – even when neglected.

The traditional workhorse of hydronics is the cast-iron boiler. You know – like the one in grandma's basement that's been feeding those big 'ol cast iron radiators you used to put your mittens on after coming inside from a sledding excursion. It you go down there today you may find that same boiler just purring along some 30, 40 or 50 years later. With its massive cast-iron heat exchanger sections, it may still be some time before a leak forces her replacement. (I'm still talking about the boiler here!)

Compare that to the sheet-metal heat exchanger of a forced air furnace and there's not much debate. The heat exchanger of any heating equipment goes through thousands of heat-up and cool-down cycles in its lifetime. Each of these cycles starts to fatigue the metal and bring the furnace one step closer to failure. Compare 1/8" (at most) of a furnace sheet-metal heat exchanger to a 1/2" (or more) of cast iron and you begin to see why grandma's old boiler is still kicking while her neighbor, Myrtle, has had the furnace guys replace a couple of "slip unders" in the same amount of time.

Now, I'm not going to tell you that grandma's 40-year-old boiler is as efficient as a modern replacement boiler, but then she's probably thinking, "If it ain't broke, don't fix it", and, with proper maintenance, that can be good strategy.

But another way a hydronic heating system has it all over forced air is in the reliability of its distribution system. Over time, a furnace duct system can develop leaks and build dust and contaminants that blow throughout your home. A hydronic heating system has a network of pipe or tubing that distributes the heat throughout your home with the same reliability and efficiency today as it did the day it was installed. (I've seen systems installed in the 1920's and even earlier, still moving water from the boiler to the radiators.) The pipes can last this long because, after a few days, all of the oxygen is "boiled" out of the distribution water and it no longer has the capability to corrode the piping's internal walls. And leaking pipes just cry out "fix me!" while a leaking duct can go on leaking energy for years.

Many hydronic system owners also choose to heat their domestic hot water (for showers, clothes washing, etc.) with an indirect water heater. (I'll discuss the many advantages of an indirect water heater in a future installment of Heidronics.) It uses the boiler's capacity to heat hot water for domestic use in a separate tank. Many of these have a lifetime warranty and will be the last water heater you'll ever buy. Compare that to the 12 year national average life span of a traditional gas hot water heater. Now that's reliability!

Even though I've seen plenty of older hydronic systems continue to work for years without regular maintenance it's been my experience that any system will work longer (and more reliably) with scheduled, thorough maintenance performed by a competent service technician.

If you're considering hydronics for your home, be sure to ask the designer and installer what provisions they've included in the design and installation to maximize your new system's reliability.

Next week I'll talk about how versatile a hydronics system is – and how that compares to what a forced air system can (and can't) do.

Hydronically yours,

Wayne

# 2 - Efficiency: Why a hydronic heating system is more efficient than forced air

When most people think about their heating system's efficiency they think of that yellow sticker on the side of their boiler that shows the annual fuel utilization efficiency (AFUE) rating issued by the U.S. Department of Energy. It's an attempt by the DOE to express fuel efficiency in annual or seasonal terms. Its accuracy has been debated by much smarter people than me, and could be the subject of a future installment of Heidronics. But for now, at least, I'll spare you the mundane details concerning lab analysis of combustion performance.

In my opinion, AFUE is a convenient, high-level measure of efficiency between "like" equipment — for instance, to compare one cast-iron mid-efficiency boiler to another, or one modulating-condensing boiler to another. In real-world terms, AFUE is not a fair way to compare different heat sources like a high-efficiency, condensing furnace to a condensing boiler. There are just too many differences in how these appliances are built, used and applied to make any kind of useful comparison.

What the AFUE ratings will tell you is how much of the fuel you've purchased is converted to useful energy, and how much is wasted up the chimney. A 90% efficient boiler will (theoretically) waste 10% of its energy, or 10 cents of every dollar, up the chimney. What the AFUE ratings don't (and can't) measure is how efficiently that useful energy is delivered to the rooms in your home.

When a boiler produces heat, it transfers that heat to water and delivers it through piping to the rooms in your home. Once in the room, the water's heat is delivered through a radiator or convector to heat the people, objects and air in the room. Water is a great conductor of heat and radiation is an excellent means to deliver that heat where it's needed. (You may recall that in last week's blog post, I discussed the various ways that hydronic systems make you feel comfortable.) Very little of the heat produced by your boiler is lost in the process of delivering it to your home.

When a forced air furnace produces heat, it transfers that heat to air and delivers it through ducts to the rooms in your home. Once in the room, the air needs to move through the room to heat the people and objects. This delivery system is ripe with opportunities for inefficiency. For starters, air is a poor conductor of heat and ducts are notorious for leakage. Because heat needs to move through the room to do its work, it creates air movement across your skin, which has a natural cooling effect. The furnace's blower also pressurizes the room, forcing heated air out of any crack or seam in the walls, floors and ceilings.

A furnace may be able to produce heat with efficiencies that rival a boiler, but it just can't compete with the distribution efficiency of a well-designed and installed hydronic heating system.

Next week I'll talk about the reliability advantages of hydronic heating systems.

Heidronically yours,

Wayne

# 1 – Comfort: Why a hydronic heating system is more comfortable than forced air

To answer this question, if helps to first understand how your body reacts to a room environment and how you know when you're comfortable.

A common misconception is that the way to make your home comfortable is to provide enough heat to keep your body warm. In fact, your body loses heat to its surroundings and the rate of that heat loss is what makes us comfortable – or not. You may remember from science class that heat always travels to cold because the environment is always trying to achieve thermal balance. Your body reacts the same way to its environment – giving off heat to the surrounding air and surfaces. The rate at which your body gives off that heat determines your comfort level. The slower your body gives up its heat, the more comfortable you feel. The job of your heating system is to slow the body's rate of heat lost to the environment.

Your body loses heat four ways:

• Radiation (heat lost to cooler surfaces in the room)
• Convection (heat lost to the air around you)
• Conduction (direct contact with cooler surfaces)
• Evaporation (from your skin)

About half of this lost body heat is through radiation, with another third through convection, and smaller amounts to conduction and evaporation.

Of these four, a hydronic heating system uses radiation as a large component of its heat-delivery method – which means it heats the objects in the room rather than just the air. Your body senses these warmer surfaces and gives off less heat to them. A forced air furnace delivers warm air to the room and heats the room surfaces through conduction, resulting in cooler surfaces and a less comfortable environment.

A hydronic system also delivers heat through convection. This creates a gentle, natural air flow as cooler room air flows across the radiator and is warmed by conduction. This air flow is imperceptible to your body but acts like a blanket of warmth. By contrast, a forced air furnace creates air flow using a blower, causing a cooling effect when that air contacts your skin. It's the same feeling you get when standing outside on a sunny but breezy day. The thermometer may indicate that the air temperature is warm, but the sensation on your body is that it's cooler.

Because the surfaces in a hydronically heated room are warmer to the touch, you lose less body heat and feel more comfortable when you touch other things or surfaces in the room. A great example is a radiantly heated floor. Your feet lose no heat to the floor, so your body feels more comfortable – even at a lower room air temperature. A conventional, forced air heated room will often have a “comfortable” air temperature but you'll feel cold because your feet are in contact with a floor that is several degrees cooler than the air, and much cooler than your body.

The last way your body loses heat is through evaporation. Your skin cools as its moisture is lost to the surrounding air. A hydronic heating system doesn't dry out the air as a forced air system will. This reduces the evaporative effect on your skin and leaves you feeling more comfortable.

When it comes to comfort, hydronic heat offers clear advantages over forced air.

Next week I'll discuss how hydronic heating systems are more efficient than forced air.

Heidronically yours,

Wayne

Top 7 reasons why a hydronic heating system is a better choice than forced air

1. Comfort – Your body naturally loses heat to the cooler surfaces in a room (windows, walls, floors and furniture). When those surfaces are warmer, you feel more comfortable. No system is more comfortable than a hydronic system, because it heats the objects and surfaces in the room. But because a forced air furnace heats the air, you only feel comfortable when the furnace blower is on.
2. Efficiency – There's more to heating efficiency than just the AFUE (annual fuel utilization efficiency) rating of a boiler or furnace. For example, a furnace blower can pressurize the room and force heated air out through small cracks in a building's walls, roof and floors (also called the “building envelope”). Hydronic heating systems don't pressurize the room during heating cycles, so there's less heat loss.
3. Reliability – It's not unusual to find well-installed 30- or 40-year-old cast-iron boiler still providing reliable service. Forced air furnaces have a typical lifespan of 15 - 20 years.
4. Versatility – The design flexibility of a hydronic system makes it exceptionally versatile. Systems can be configured to provide independent heating zones, domestic hot water or snowmelt, as just a few examples. A hydronic system is also a perfect complement to a ground-source heat pump (geo-thermal). A forced air system can't begin to compete in this category.
5. Quiet – There is no quieter heating system than a well-installed hydronic system. (If you hear a lot of noise in the pipes, something needs fixing!) Compared to forced air's noisy blower and frequent on-off cycles, there's just no contest.
6. Cleanliness -- With no blowers or leaky ducts, there's no dust blowing through the house. That means there's less housecleaning plus a healthier indoor environment, especially for people with allergies.
7. No need for humidification – A hydronic system doesn't dry out the indoor air because its water temperatures are usually much lower than the air temperatures of a forced air furnace. Because forced air makes indoor air so dry, most people need additional equipment (such as a humidifier) to add moisture back into the air to feel more comfortable.

Stay tuned. Starting next week, I'll expand on each of these seven advantages in more detail.

Heidronically yours,

Wayne

What is a hydronic heating system?

Webster's defines hydronics as “of, relating to, or being a system of heating or cooling that involves transfer of heat by a circulating fluid (as water or vapor) in a closed system of pipes”.

If you live with a hydronic heating system, you might define it as comfortable or efficient, or quiet, or all three.

It can be as simple as a 1950's system consisting of a cast iron water boiler and simple finned tube baseboard radiators. It can be “old school” hydronics like a 1920's one-pipe steam system with cast iron standing radiators. Or it can be a modern, state-of-the art high-efficiency system consisting of a modulating, condensing boiler and radiant panels.

It's luxurious comfort. But if you've ever lived with a hydronic heating system, you already know that.

Using water or steam as the medium to transfer heat from the source (boiler) to the living space is an incredibly efficient and versatile system. Unlike forced air heating systems, very little heat is lost in the delivery process. And with a radiant hydronic system, that heat is delivered directly to the objects and occupants in the room.

Hydronic heat can be used with traditional cast iron radiators or copper finned tube baseboard, modern panel radiators, radiant floors, radiant ceilings (yes, ceilings!) and walls, towel warmers, and much more. Modern controls provide energy conservation through zoning and outdoor reset control and added comfort with indoor reset and floor sensors. It can also provide almost unlimited quantities of domestic hot water for showers, laundry, and other household uses.

While the official definition is all about water, I think it's really all about comfort.