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  1. #1
    Join Date
    Jul 2007
    Location
    Seattle
    Posts
    2

    Benefits of Hydronic vs. Forced Air?

    Hello. I've been lurking here for a couple weeks and am continually impressed by the knowledgable advice. I have browsed through the archives and did not see this question. If I missed an equivalent discussion please let me know where to look.

    I just bought a 90 year old two story house of approximatley 2000sf. It currently has ~50 year old electic radiant heaters in almost every room and no central heating. Since I am opening several walls for other renovations I am planning on installing a central heating system and am looking at forced air (natural gas) or a hydronic system with a high effeciancy boiler.

    From my initial discussions HVAC contractors it looks as if a hydronic system will cost about twice what a forced are system will. My questions for experts and homeowners who have expereince with both systems are:

    My questions to those of you who have lived with both systems are:

    1) Will the hydronic system be more efficient? (assume high efficiency boiler vs. furnace). In other words, if I'm using the same fuel (Nat Gas) and have the same heat loss won't both systems require roughly the same amount of fuel at roughly the same cost?

    2) I've heard hydronic described as a more "comfortable" heat? Any comments on that? Is that just hype or will I notice a big difference?

    3) Do hydronic systems really cost twice forced air systems on average (current est is 20K hydronic vs. 10K forced air) or can I expect further bids to come in closer together?

    Thanks in advance for your comments and insights.

  2. #2
    Join Date
    Jul 2007
    Location
    In an attic!
    Posts
    25
    Are you sure that the 90 year old house has natural gas service? My cousin just moved to a brand new house in Seattle, and his house is at the end of the cul de sac and to his dismay the gas company only pipe the main up half his street. He can pay them to finish but he works for the electric company anyways and now get rebates for all his appliances. Just thought I should ask.

  3. #3
    Join Date
    Nov 2005
    Posts
    1,350
    Sea town

    Ist he hydronic you are talking about using your potable hot water to heat fan coil units that go in the wall and in toe kicks?
    I have put in forced air and hydronic for years and the complaint I get about hydro is, stale air, and too hot in the summer. It does cost less money to run then forced air. For a retro fit it will cost a lot more then new construction, and twice the price is about right. The pay off is in the winter, and with the comfort level of the home. Remember no A/C with the hydronic, unless you install a chiller, and that is even more $.
    I STARTED WITH NOTHING, AND I STILL HAVE MOST OF IT!

  4. #4
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    Whew. I could write a book on this topic. Where would you like to start? FYI, we do heating systems with oil or gas, water, air, geothermal, hydro-air, dual fuel, radiant heated floors, ceilings or walls or any combination thereof. So when you say 'hydronics', as you can see, we could have a very long discussion.

    Basically, the forced water hydronics got a good reputation over warm air systems for some very simple reasons. A. They hot air systems of old were 1-stage, on/off, all or nothing systems that would heat up quickly but cool down just as quickly. Forced water on the other hand tends to heat up more slowly and likewise, cool down more slowly. A second issue is that in days of old, plumbers were the leaders in installing the hydronic systems. Warm air heat was left to 'others'. Often those 'others' lacked the knowledge to install anything that would approach a professional job. The end result was a lot of systems that were too hot at one end of the home, okay in the middle and freezing in the far end (usually the bedroom end). The main reason behind this discomfort was a fireplace/chimney in the living room that doubled with a second flue for the oil or gas furnace. That was furthest from the bedrooms and with a dsitinct lack of duct design, the results were, shall we say, less than 'stellar'.

    But now we're in an age where things have changed. The gas industry has done wonders for the comfort of gas warm air furnaces and some oil units are also doing the same. By this I'm talking about 2-stage furnaces w/variable speed blower motors. The most comfortable heat, be it water or air, is when the heat comes on and stays on for a very long time. Thus radiant floors, particularly masonry floors, heat up very slowly and cool down even more slowly. So they're kind of the gold standard of heating. The true, 2-stage furnaces that are out there today can come very close to that type of operation, particularly as the weather gets colder outdoors. The colder it is, the longer the 1st stage heat is on until at some point, it doesn't shut off and the 2nd stage starts cycling on and off. That's continuous heat and is very comfortable. That of course, assumes that the installing company did proper load analysis, duct design and installation.

    In summation, before I go on too long, I think unless you're going to do radiant heating, I'd recommend a dual fuel 2-stage heat pump, 2-stage gas furnace, zone controlsl by the equipment manufacturer if you want it, electronic air cleaner, steam humifier, and ultra-violet lights. All ducts to be sealed and the system properly balanced using a flow hood when the job is commissioned. We will be starting a system exactly like that within the next 4-weeks, using Bryant equipment, with zone controls, and I know our client will love the system when we're done. No question.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  5. #5
    Join Date
    Jun 2000
    Location
    WYO
    Posts
    2,019
    #1. No
    #2. No
    #3. Yes
    If you want A/C and hydronic, figure in a lot more $$$.
    never say never

  6. #6
    Join Date
    Nov 2001
    Location
    Moose Jaw, Saskatchewan, Canada Occupation:Interprovincial Plumber, Commercial Gasfitter Interests:
    Posts
    2,412
    Quote Originally Posted by contactor View Post
    #1. No
    #2. No
    #3. Yes
    If you want A/C and hydronic, figure in a lot more $$$.
    #1 maybe
    #2 maybe


    #3 Yes
    If you want A/C and hydronic, figure in a lot more $$$.
    I love my job, but paydays Thursday

  7. #7
    Join Date
    Jun 2000
    Location
    WYO
    Posts
    2,019
    I,ll give you credit Rich, just for stepping up to the plate.
    # 1. Dependable boiler with an AFUE of over 92% ?
    #2. Boilers are very quiet and even temp, so are furnaces if properly installed, now, I work on both systems. I believe Boilers are more dependable maintanence wise. I also believe a boiler will have less service problems.
    JMO. Boilers are great and efficient and Quiet.

    In your instance Seattledude, running ducts instead of hydronic registers may overcome the installation budget. Thats another factor.

    Dependable boilers have an AFUE of 84% OR slightly lower which isn't that much.
    I may even consider a boiler in a cold climate myself, in my own home, even if it's more money up front.
    The furnace is the heart of the home.
    I sell forced air, but, I know how well hydronic heat works. It is excellent.
    never say never

  8. #8
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    Obviously one of the decisions you need to make is whether you're interested in AC or not? Indoor air quality is also a potential issue for you. While it is possible to do IAQ in conjunction with hydronics, each system would be an independent system and therefore increase installations costs disproportionately. With a ducted system, those products are far more easily introduced to the distribution system and IMO, do a much better job. So if allergies of other health problems are a consideration, you might want to factor those things into your decision.

    If your home is being built to have a minimal air leak rate (a tight home) then I would also recommend the installation of one or more heat exchangers, perhaps heat recovery units (HRV). These will serve to exchange stale indoor air for fresh outdoor air while recovering some of the temperature of the treated air in the home and exchanging that with the outdoor air being brought in.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  9. #9
    Join Date
    Jul 2007
    Location
    Seattle
    Posts
    2
    Thanks everyone for the advice. I am not interested in AC as it only gets used a few times a year in Seattle. However I am interested in my kid's indoor air quality so having ducts for a forced air system would be more cost effective than adding a whole new system if I were to choose hydronic heating.

    skippedover: sorry for the ignorant question but regarding your recommendation "I'd recommend a dual fuel 2-stage heat pump, 2-stage gas furnace, zone controlsl by the equipment manufacturer if you want it, electronic air cleaner, steam humifier, and ultra-violet lights"

    Why the hp AND the furnace? hp for AC? or are you recommending one OR the other?
    Are most forced air systems zoned? I thought they were typically one zone.
    Why a steam humidifier? I've never noticed I'm sensitivity. Would that be the main reason?
    What are uv lights for? cleaning the air of viruses?

    I think I've come to the conclusion that forced air will be my best choice. I haven't heard anything that makes be believe hydronic is worth twice the retrofit cost.
    Last edited by SeattleDude; 07-12-2007 at 09:47 AM.

  10. #10
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    Quote Originally Posted by SeattleDude View Post
    Thanks everyone for the advice. I am not interested in AC as it only gets used a few times a year in Seattle. However I am interested in my kid's indoor air quality so having ducts for a forced air system would be more cost effective than adding a whole new system if I were to choose hydronic heating.

    skippedover: sorry for the ignorant question but regarding your recommendation "I'd recommend a dual fuel 2-stage heat pump, 2-stage gas furnace, zone controlsl by the equipment manufacturer if you want it, electronic air cleaner, steam humifier, and ultra-violet lights"

    Why the hp AND the furnace? hp for AC? or are you recommending one OR the other?
    Are most forced air systems zoned? I thought they were typically one zone.
    Why a steam humidifier? I've never noticed I'm sensitivity. Would that be the main reason?
    What are uv lights for? cleaning the air of viruses?

    I think I've come to the conclusion that forced air will be my best choice. I haven't heard anything that makes be believe hydronic is worth twice the retrofit cost.
    Please know that our company philosophy is to always deliver all available information to the client and then let them choose. Better to have a client who refuses a producct than to have one who says 3 months after the job is done, "If you'd only told me...". So that's where a lot of that comes from.

    A dual fuel system would be recommended if your climate is such that a heat pump is not the most efficient way to heat your home in the winter. If a hp will do the job, then forget the dual fuel. A hp also works as an AC unit in the summer for those 'few days'.

    Zone controls are used to balance the system, minute to minute. For example, if your home has a significant glass exposure on one side, of the home, it could require different heating/cooling needs during the day vs. the night. With a zoned system, you would maintain a balanced system. The majority of older systems using warm air were a single zone because the installers lacked the skills needed to properly zone the systems. Today companies like Carrier/Bryant have controls that make zoning a snap to give great results without a lot of installation headaches and the result for the client are stellar, provided proper load and distribution practices are followed.

    Regarding humidification: Many people develope dry conditions in their homes in the winter when the heat is on. This varies depending on how much heat is needed, how often the heater runs and the temperatures used to warm the treated space. Some people suffer from stuffy noses, irritated eyes, coughs and other symptoms of low humidity levels in the home. A standard 'cold' humidifier can do a nice job, particularly when the gas furnace or heat pump is in operation. But when the system shuts down, the heat source is lost and even if the ran is selected to run continuously, the amount of humidity being introduced is diminished. With a steam humidifier, there's actually an electric heater within the unit that boils the water in the humidifier, creating steam that is blown into the living space, thus provided much better humidity control. Being from the Northeast, we've go a lot of clients who benefit from the use of steam humidification.

    The best way to understand UV lights is to think of them as bringing 'sunshine' into the home. Nature benefits from sunshine that kills many spores, mildews and other things that like warm, dark spaces to grow. UV lights kill those things. People with allergies often benefit from such appliances. Likewise the electronic air cleaner. There are some that are very easy to maintain and do a really good job. All for the sake of better indoor air quality = good health.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

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