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Question DetailsAsked on 12/31/2017

I have baseboard heating.Huge job to switch to forced air?

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Certainly not little - and bear in mind following num,bers are VERY rough because every house is differnet, and of course I have no idea of what climate you are in.

Can be not too bad in a one-story house with accessible crawlspace (though energy inefficient to run ducts there is unheated) or basement where you can tolerate exposed (or drywall-wrappin in soffit) ducting, a two story house can mean a lot more tearing into walls and ceilings, though there is the option of running the ducting in an insulated soffit on the outside of the house (rarely done for appearance reasons) or through the attic - both of those require a LOT of insulation around the ducting if it is not to be an energy hog.

Sometimes you can do the job for around $10,000-15,000 rough ballpark for a normal 1500-2000SF single story house with access underneath - can more commonly run in $15,000-20,000 range for normal two-story or single story with finished basement, and for single story built ona slab-on-grade and some multi-level splits and modernistic housing unless you want exposed ducting can run into much more than that at times. About $3,000 to up to $10,000 of that cost, depending on brand and heating unit efficiency chosen, can be for the furnace itself rest for ducting and labor.

And of course, if you add A/C to make a complete Central Air HVAC system, commonly $3,000-7,000 more for the A/C system and integrating it into the furnace - more with very high efficiency unit. If you have existing A/C - can be left alone if mini-split, or converted to central air (evaporator in the ducting) for typically a couple thousand range.

Bear in mind, generally speaking, forced air generally makes for a more variable heating/cooling over time - more extremes in in-house temp than the more averaging effect of baseboard (though unlikely you have cooling with that at all). Cold air at foot level and cold floors is also a more common complaint with forced air systems, and cold air drafts coming off windows (which forced air systems commonly mitigate by putting the radiator elements below the windows).

Does tend to be, unless the house is not at all air-tight, a bit more energy efficient with modern units IF the ducting is all inside the "conditioned space" AND not run in exterior walls, for the simple reason the air blows directly into the room and heats it directly with less loss to the walls, whereas most baseboard heating is in exterior walls so a significant amount of the heat goes into the wall and radiates to the outside of the house, so is wasted. Forced air is more popular in houses in less cold climates, many very cold climate areas tend to have baseboard heating because of the long residual heating effet as the piping and radiators cool off after each heating cycle. Also, the piping in the subfloors tends to keep floors warmer, and prevent the near-exterior-wall cold wall and floor issues common with forced air heating, which is pretty inefficient about heating floors. Numbers vary a lot, but a forced air system in a drafty house can be 10-25% LESS efficient that baseboard, and around 10% more efficient than baseboard in a relatively draft-free house. Generally, probably the majority of houses would be less efficient with forced air heating, given comparable efficiency heating units, jsut because most have a lot more air losses than you realize.

If your heating unit is outside the conditioned space, so the waste heat from it does NOT go to heating the house, then a furnace (which is "hot" only when heat is called for) can also be another 10-20% more efficient than a boiler, which tends to stay hot all the time (at least in heating season) so radiates its waste heat continually - which is wasted if located outside the conditioned space or heating what would otherwise be "outdoor cold" space.

For instance - my roughly 78-80% efficient gas boiler, with baseboard heat, actually calculates out to about a 98% efficient system if turned off in the non-heating season, because the waste heat keeps the otherwise unheated garage warm and the metal flue heat radiates into the center of the house on its way to the roof - thereby keeping a full house width interior wall and almost half the upstairs floors warm and providing some interior core heating, so most of that "waste" heat is utilized by the time the exhaust exits at about 70-80 F.

A detailed calculation of the heating load, layout of the distribution system (using ACCA Manuals J, S and D to calculate thermal load, HVAC system sizing, and duct layout/sizing respectively) and evaluation of the amount of wall/ceiling damage that would occur in putting in ducts could give you a better picture of the probable cost - and of the amount of remedial drywall/plaster/panelling repair which will be needed after the ducting is put in. A major factor in the ducting cost is whether you go with the more durable and higher airflow efficiency metal ducting or the quicker and easier but less efficient and shorter life flex ducting, whether much of it can be run exposed in crawlspace/basement, and especially what space you have and what direction the joists run where it needs to traverse the house if it has to be concealed - runnig between floor joists is usually pretty easy, running crosswise if it has to be concealed can be quite a problem.

Another factor is what electrical and plumbing is in the way - and whether there is room to run ducting over or below it or if it has to be relocated to make room for the ducting, That is where flex ducting 9much as I hate to admit it) has a real leg up on metal ducting in retrofits like you are talking about - not only because it can snake around many obstructions and through cross bracing and such, but a duct can somewhat more easily be split into two parallel smaller diameter runs if needed to get through tight spots.

If your heating loads are not high (i.e. you are in an area where furnace is not needed real often and does not have to handle real low temps- say below 10 or so) a Heat Pump system would also be a possibility - a Mini Split system (look that up) which is like an air conditioner which both heats and cools (extracting heat from the outside ari in heating mode, and using auxiliary gas or electric heat in temps below about 40-45) feeding to several distributed units similar to the wall (not window) air conditioner/heater units in many motels/hotels. Since the fluid runs in small tubing, the disturbance of walls/ceilings is much less.

One thing you did not say was WHJY you are looking at doing this - there might be things you can more economically do to your existing baseboard heating which would solve any problems you have with it, too.

Answered 10 months ago by LCD

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