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Best System For An Addition

George J
George J Member Posts: 7
I have just completed framing on a first floor addition. I was all set to use a local HVAC contractor but after talking to a few I am confused on what is best to do.
Current Situation:
I have a split level home. There is a main heating branch serving the bedrooms and another serving the existing single story (living area side) but all the supplies and returns have been removed due to wall reconfiguration. The single story portion of the house is now 1,400 sf with an open floor plan with pocket doors separating the living room and the dining room from the family room and consists of kitchen 8 ft ceiling, living room 8 ft ceiling, dining room 9' ceiling and family room 10 ' ceiling. The left side of the house (1 1/2 story is 1000 sqft includes 3 bedrooms on top story and 1 playroom and unheated garage underneath. The single story side has full basement underneath it and mechanicals are in basement centrally located along wall that divides the 2 sides of he house. I have an 8 year old Bryant forced air system 110000 BTU in / 85,000 BTU out no AC. All contractors agree that this is not adequate for the house given the added space.

We want to add air conditioning. My wife often complains that the forced air system is hot or cold but never even.

I have received as many recommendations as I have interviewed contractors. I have no idea which solution is best. I need some help narrowing these down ASAP. My project is on hold until I figure out the HVAC. Here is what I heard.

#1) Replace furnace with bigger furnace and single outside condenser and add automatic zoning between single story (living area) and 2 story side of house (basically sleeping area accept for playroom).

2) Keep existing furnace and use it to heat only bedroom and playroom side and add condenser to it. Add new furnace to heat single story (living Area) Add a 2nd condenser for it.

3) Replace existing furnace w/ boiler and 2 air handlers creating Hydro Air system. Add two condensers outside. Others have told me that the Hydro air is not much better than the forced air and still has all the same issues with uneven heat.

4) Keep existing furnace, add condenser to it for bedroom and playroom side. Add boiler with 3 in-the-wall cast iron radiators 1 in dining room and 2 in the family room. Pull duct of furnace to feed living room. A 2 Ton Sanyo split system AC on single story living side of house. Add toe kick register under kitchen cabinet. Another contractor said this approach was not good because the Sanyo split system (inside portion located in family room would not provide even cooling through out the living area. Also heard that ductless split systems have condensation problems. Another on tractor said the radiators will not provide even heat on the first floor.

5) Keep existing furnace, add condenser to it for bedroom and playroom side. Add boiler with radiant floor heat for the single story living area side. Put air handler in attic of single story living area side with ceiling vents for cooling only along with a separate condenser for it.

By themselves each one sounds like a reasonable approach. What surprised me most was that no one had the same approach. I would appreciate any help in choosing the right option or even eliminating any that is not good. Than you.


  • brucewo1b
    brucewo1b Member Posts: 638

    When one is married he can be right or he can be happy, if you want to be happy give her as much radiant style heating as you can afford and when she is warm and happy so are you.
  • Mike
    Mike Member Posts: 94

    i would nix, the ductless split. generally, there used when there are no options for ducts. sounds like like you have plenty. the radiant floor heat is the way to go, you'll love it. especially in the kitchen, then kick yourself for not doing the whole house. just my opinion.
  • Ted_9
    Ted_9 Member Posts: 1,718
    heating and cooling

    I'd propose something similar to #3 and 4.

    Add a properly sized boiler for the entire house. Hydro air for the existing system. All radiant or panel radiators in the addition. Either use a hydro air for the new addition if any supplemental is needed or most likely use a ductless spit system.

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  • George J
    George J Member Posts: 7

    Thanks to those who replied so far!
    I should add that I live in New York state about 25 miles North of New York City on the New York Connecticut border.
    This means we use a little AC in June and September and a lot of AC in July and August - none the rest of the year. For heating we start needing heat in late October, need gets greater as we move toward January and starts dropping off again in early March and is done in April. Heaviest heating load is late December thru late February with most days in the low 30's and nights in upper 20's but we can get a few weeks down in the teens - lower at night.

    Based on the responses I am wondering if Radient heat will be enough to heat the living area or if I will also need supplemental heat.

    Also, still wondering if Hydro air is really that much better than standard forced air for my bedroom area - i.e. is it worth it to toss my 8 year old furnace and replace it with Hydro Air for the bedroom area if I am getting a boiler anyway for the Hydornic heat in my living area.

    Finally, if I do not go radiant heat but use radiators - do radiators heat a room more evenly than a forced air or Hydro air system or is it the same with warmest area next to radiator and coolest areas away from the radiator?
  • Ted_9
    Ted_9 Member Posts: 1,718

    In my experience, forced hot water heats best. Radiant, panel rads, and cast iron heat best. Then copper fin tube and other finned convectors are next.

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  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    If you don't go radiant

    cast-iron baseboard is a good second choice. It will hold heat like an old iron radiator.

    Any hydronic option will work better than a furnace. Even hydro-air, since you run the risk of carbon-monoxide poisoning if a furnace heat exchanger cracks. But radiant, baseboard or panels have the advantage of not blowing the air around, which makes you feel cooler.

    Your existing ductwork could be retained for cooling only.

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  • jerry scharf_3
    jerry scharf_3 Member Posts: 419
    What's best, part 1??


    Many people have designed systems that they think are best, which like beauty is in the eye of the beholder. You posted this question to people who specialize in steam and hot water heat, so don't expect too many people to say "more furnaces." :)

    I'll split this into a couple parts. I hope this doesn't come of as lecturing in this post, I'm just trying to set the stage to be able to discuss what system you want.

    I know your project is hung up, but it's time to start doing the research to decide what you want. A week or two now will compare against years of living with the system is a good trade. The key word is SYSTEM, you want all the parts to work together to solve the problem.

    I have 6 goals for a heating/cooling system: Saftey, health, comfort, efficiency, reliability and low cost. This is an engineering problem, since you can't have them all and have to trade off between them. Also, you need to integrate this into the building that has already been framed. As you can see, different people have come up with different solutions to balancing these, and I can come up with 10 more.

    Safety comes first, does the installer do neat work, put in all the safety checks, test the system combustion as part of bringing the system on line? The people here see too many dangerous installs, don't ever take for ranted that the installer will do the job safely. These is also a myth that the combustion system comes ready to go from the factory. Every system must be tuned as part of the setup and be checked regularly afterwards.

    Health is not a thing that most people think of when they build a house. It's something that creaps up on people after they live there a few years, and its much harder and more expensive to fix it then. You will need adequate air exchange, and controlled humidity as a start. Go to www.healthyheating.com for more information.

    Comfort may be in the body of the beholder, but there has been a lot of research on this. Radiant heating of the body is more comfortable than heating the air. The body is more sensative to radiant heat than air temperature. Healthyheating has loads of information on this as well. The critical factors are the temperature, the radiant component of the heat, the rate of air flow and the amount of temperature swing. Room to room heating balance is also part of comfort.

    Efficiency is a system thing and it's easy to measure the result. It's harder to get there.

    The number 1 thing for efficiency is improving the building envelope. So not just what the listed R value on what goes in the wall, but what type it is, how carefully it is installed, how well the cracks are sealed. Top quality windows and door. This can often be cash neutral, the more money you spend on the envelope, the lesst you need to spend on the heating system. Then all the savings are gravy.

    Next is heating system. It is more efficient to pump water than air as a way to move heat. Lowering the air motion also allows a lower air temp to be comfortable. AFUE comparisons between different types of heat sources (furnace, cast iron boiler, modulating/condensing boiler) don't work. The most efficient units seem to perform better in real life than on the tests. They also only measure part of the system. But this is also very dependent on the type of output is used.

    The same boiler may be far more efficient on a radiant floor installation as compared to baseboard. Finally, contractors rarely talk about the system controls. Is it a single thermostat and 1 zone, or is it a top of the line system with multiple zones and room temperature sensors? What type of emiiters are in use?

    Reliability. Nobody wants a system that dies. In the middle of winter. At 2AM on a sunday morning. Complex systems have more things to fail. Lining up someone to do annual service and have parts for after hours repairs is a big plus.

    Cost of the system can cover a wide span. Systems with better controls, more efficienct boilers and more comfortable emitters will cost more. In new house construction, this cost is often rolled into a mortgage, so you can compare the increased monthly mortgage against the guesstimate of expected savings. With the clear trend in fuel costs, it's only a guess how high energy costs will go over the next 10-30 years. I'm fairly certain that they won't be going down.

  • jerry scharf_3
    jerry scharf_3 Member Posts: 419
    What's best?? part 2


    So you have existing ductwork in part of the house. It sounds like that ductwork is set up for heating, which will mean it is not optimal for cooling. Ideal heating setup is suuply and return registers near the floor on opposite sides of the room. All rooms except for bathrooms and kitchens (excluded because of exhaust fans) should have a return duct. For A/C, you want the supply and return registers in/near the ceiling.

    I believe that any system can be safe if installed and maintained correctly. It is your job to demand this and pay for it. Systems being set up with a combustion analyzer capable of measuring CO (cabron monoxide) is a must, IMO. Loys of "old timers" and others will tell you this is not necessary, they can tell by eye. The very best in the business know they can not tell by eye and use a high quality combustion analyzer every time. If you get a printout of the combustion analyzer readings every time the system is tuned and kept right on the furnace or boiler, that is the ideal.

    Air intake and combustion exhaust, ducting and/or piping must be to manufacturer specs and codes. If the install requires deviating from the printed manual, they must get manufacturer approval for the setup. That way you know the warranty is good. (Some installers think the instruction manuals are knee pads. :( ) "We've always done it this way" counts for zero when the way is wrong.

    For health, controlling humidity, supplying fresh air and fintration are the main things. Most people don't need a whole house true HEPA filter, but some kind of better than average air filtration is important for the system. Replacing stale air with fresh air is an important function, and needs to be addressed. HRVs and ERVs can both take care of the requirement and save energy at the same time.

    Humidity control comes in two parts: getting rid of it when there is too much, and preventing there from being too little. The air replacement and air conditioning can usually manage the too much humidity situation. The too little humidity situation is mostly caused by cold outside air being exchanged with warm inside air. Before you add a humidifier, make sure that the house is really well sealed.

    If you have ductwork, ideally this will be run within the "conditioned air space" of the house. Forced air running outside the insulation "envelope" is a problems. Any leaks cause significant in significant air loss and thsu will drop the inside humidity as well as lose energy. Also, you have much better insulation around your house than your ducts, even though the ducts have hotter air than the house. Can you see the energy running away?

    On to comfort. The higher the radiant component of heat, the more comfortable the humans are. The slower the air moves, the warmer people feel. The less the temperature swing, the better it feels. So the ideal is a large radiant surface (floors, walls ceilings) to heat the rooms. I have all three in parts of my house, and they all work. The next best thing is panel radiators, which have a significant radiant component and some convection as well. Next comes baseboard which has no radiant, and full convective output. Finally comes forced air, with the highest airflow rates. It also turns out that the rate at which they tunn on and off is the opposite, with forced air being the fastest and radiant surface being the slowest. This means that forced air will heat the room the fastest, but also makes it the least comfortable. Also, zoning can be a critical thing to comfort. Big zones that span the east and west side of a house can cause real problems on sunny winter days.

    Efficiency is next on the list. Water is easier to move, and because of it's size is much more economical to insulate well. The controls make a big difference, especially when combined with an condensing/modulating boiler.

    Reliability is as much or more a function of the installation and maintenance as the equipment. Many systems fail too soon because of incorrect installtion. Beyond correct is putting thisngs in so they can be maintained. Can you ge tot he filtes? Can they change a pump without draining the system? Boilers in general have a longer life than furnaces, but the lifetime in the field of the modern modulating/condensing boilers is less established than the older types. Furnaces usually have fewer parts, but can suffer more for bad maintenance.

    Cost: Forget the boiler or the furnace cost. You are trying to get a good system installed, and it's only the total cost and the total performance that count. You are paying for expertise as well as labor and parts.


    If you have the money, radiant surface is the most expensive system, the most comfortable and the highest efficiency. Since you are comparing to forced air, this may be out of the range. This should be paired with a modulating condensing boiler.

    My favorite solution for heat comfort, efficiency and install cost is a panel radiator setup with TRVs on the individual radiator. This allows each room to be controlled for excellent comfort, the controls are simple and the installation costs are reasonable. Paired with a modulating condensing boiler, this can attain excellent efficiency. These are reasonably easy to retrofit into exaisting areas as well. In this case, make sure you get someone who has installed this kind of system successfully before. Go and visit a job that has this, and you'll get why it's so nice.

    Forced air heat is my least favorite setup (no surprise.) If the ducts are not in conditioned space, the efficiency can be much lower, the comfort isn't there and long term reliability aren't there. They also have a failure mode when the heat exchanger fails that CO from the combustion gas is drawn directly into the house. Also, you can't set up the ducts ideally for both, so the A/C often suffers as well.

    As for your comment about mini-split systems, I have seen them installed in the tropics, so I doubt your humidity problems will be that hard to handle. In either case, setting the ducts up for A/C only will increase the comfort and efficeincy of that part as well.

    These turned out a lot longer than I expected. Sorry about that.

  • meryl joseph
    meryl joseph Member Posts: 2
    artist lofts

    Hi Jerry,

    Wondering if you could guide me along radiant lines. I am an artist who is developing a 3 story brick building in the berkshires of western mass, into 8 artist live/work lofts. The lofts will be built on the second and third floors of my building. The lofts will be a minimum of 2000 sq. feet each, with high ceilings (14-18 feet), as is typical in these kinds of buildings.

    I loathe forced hot air, yet that is the system that most people are putting into these loft conversions. I much prefer a radiant system, with some kind of continuous hot water loop for domestic hot water. And you seem to prefer that, too. Can you advise me what system would be best? The lofts are large open spaces (lofts!!!), so we are looking at long wall expanses which could house radiant baseboard.

    Thanks in advance.

  • jerry scharf_3
    jerry scharf_3 Member Posts: 419
    radiant and lofts


    My sister lives in West Hawley, so I have some idea of what the weather is like. She runs a cross country ski lodge.

    Radiant floors or ceilings are perfect for lofts. There is no such animal as a radiant baseboard. Baseboard works by convective not radiant heat. I read once of a church in England which had radiant floor heat. Someone did a test where they ran a thermometer from the floor to the top over 60' up. Less than a 5 degree variation in temp over the entire rise.

    First thing is to really insulate the units well. Lofts tend to have a lot of glass, so making sure the windows and doors are really good is really important. You will probably want some operable windows up high to allow the hot air out in the summer. With that I would doubt you would need A/C. Investments in the building envelope can often be close to cost neutral, the money spent there can result in a lower cost heating system.

    Once you have all the insulation, doors and windows figured out, it's time to get a pro to do a heat loss for wach lost and the common areas.

    How you do the radiant depends as much as anything on the construction of the building to start with. Depending on the access to the undersides of the floors, it may be easier to use one of the abover floor radiant systems like quick-track. (Ceiling height shouldn't be a problem.) I would definitely use a control system that has "indoor reset", since the solar heat gain can be quite significant. Hard to know how to zone the lofts without particular design information.

    You really want to pair this up with a modulating condensing boiler. You care less about the brand that the person who is installing it. They have to have the skills to make the job a success, too many will say they can do it when they can't. It will be sized from the heat loss calculation.

    Finally, I would put a good sized separate air ventilation system into each loft. Artist can use nasty things, and no reason to expose one person to another's fumes.

  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083

    if you'd like to talk, call me at 203-223-1262. My company in out of Stamford, and it sounds like we are close.
  • meryl joseph
    meryl joseph Member Posts: 2
    artist lofts again

    Hi Jerrry,
    Thanks so much for your reply. I guess I wasn't clear about the radiant. We have original maple floors in the building which are very thick and would preclude radiant floor heating. I was suggesting that we use baseboard (and there are two kinds, I think, convective and the kind that is just radiant, that sits closer to the wall.

    Do you think, for these 2000 sq. foot lofts in western Mass, that baseboard hot water could heat the spaces sufficiently and efficiently? Also, what do you think about on demand water systems?

    You're a big big help. Thanks again.
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