Cost of replacing boiler with forced air?

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Old 01-14-13, 05:03 PM
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Cost of replacing boiler with forced air?

I have an inefficient, expensive, pain-in-the-rear oil-burning boiler that I'd like to replace with a natural gas forced-air furnace system. Or at least that's the dream. It would probably be more than I could ever afford but I have to ask all the same: does anyone have a rough guestimate of what that would cost?

I have city natural gas piped to my house already. Of course there is no ductwork or vents in place but it seems like I could do that myself. I have crawl space access and am pretty handy. I heat almost exclusively w/my wood-burning fireplace insert but when it gets really cold I need more. Space heaters did it for a while but not when the temps get below zero at night and stay below freezing for weeks. My pipes all freeze.

My house is 1340 sf. I keep the guestroom cold: 40 or less. I keep the master bedroom between 45 & 50. The rest of the house is hard to heat: about 200 sf of single-pane glass in the main living area. I love my house but it's hell to heat.

Thanks!
June
 
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Old 01-14-13, 05:58 PM
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I'd guess wildly you need two tons of cooling so at 4500 a ton your looking at about 9 grand.
 
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Old 01-14-13, 07:55 PM
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Augh!

Thanks much. That's exactly what I needed - some rough idea of how much. I figured it'd be bad. I'm going to look into some kind of electric room heaters. Frozen pipes tonight - what fun. Back to Ace tomorrow.
 
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Old 01-14-13, 08:37 PM
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Focus on reducing heat loss before you replace the heating system.

A furnace/boiler can only be as good as the house it's heating.

Why do you want forced air when there are already radiators? For less money you can have a gas fired boiler installed.

I'm for forced air (ability to add a/c, dehumidify/humidify, ventilate), but hot water heat is very comfortable since the water stays warm long after boiler shuts off.

The higher end furnaces can also provide very comfortable heat, but you're probably looking at $15k+ to rip out a hot water system and install a high end furnace/ac - not including drywall/plaster repair. That money could be better put towards air sealing, attic/basement insulation, or double pane windows.
 
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Old 01-14-13, 08:40 PM
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You mentioned that the ductwork would have to be installed in the crawlspace; if it's ventilated and unheated, you'll be in for some very high gas bills even if insulated ductwork is installed.
 
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Old 01-15-13, 08:24 AM
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Good advice -thanks. I've done all I can to prevent heat loss except for the windows which are the biggest. I plan to replace my bedroom and kitchen windows w/double pane this winter and get a quote on the picture windows in the living area. They're going to be expensive.

My crawl space is unheated and ventilated. I have a space heater down there right now to keep my pipes from freezing again. I can see that I'll have to stay w/the boiler. And that's exactly what I wanted to find out - thanks! But I'll research ideas to supplement my fireplace insert in these cold spells so I don't have to use the boiler much. It's really expensive.

Thanks again,
June
 
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Old 01-15-13, 07:27 PM
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Ductless split heat pump........................
 
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Old 01-15-13, 07:59 PM
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My crawl space is unheated and ventilated. I have a space heater down there right now to keep my pipes from freezing again. I can see that I'll have to stay w/the boiler. And that's exactly what I wanted to find out - thanks!
Is the floor above the crawlspace insulated and air sealed? If not, the unheated crawlspace is one of your greatest sources of heat loss.

Ventilation doesn't work very well in the summer because outdoor air holds a lot of moisture. In the winter, as you've found out, ventilation makes the crawlspace very cold.

The best option is to close the vents, air seal, and run a dehumidifier down there in the summer. Insulation can be safely put above grade, but not below unless the foundation has been waterproofed.

With respect to heating, going from a old 50-70% efficient oil boiler to a 80%+ efficient gas model can potentially reduce your heating costs by 50%+.

-------------------
Re: windows, how about shrink wrap?
 
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Old 01-17-13, 09:18 AM
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I have shrinkwrapped all my windows. It helps.

There is nothing between my crawl space and the living space but the joists, subfloor and flooring. I wondered why there was so much open ventilation down there. The crawlspace is always bone dry so it's not as if I have a humidity problem. Since I have a boiler the crawlspace walls are insulated (insulated walls next to open vents - what's wrong w/this picture?) and as I said always dry so probably the foundation has been waterproofed. The climate here is dry too: I'm in the foothills of the east side of the Sierra Nevadas, with desert to the east.

So the crawlspace is my next project. Closing the vents is easy. And it looks like a dehumidifier would only run me a couple of hundred. I watched some Youtube vids on airsealing but there's a huge range in what one can do. Since the ground is dry and the walls are insulated, I could just seal the vents w/maybe blocks of dense foam and do some spray foam around the walls above the foundation. I could do that myself. But I don't know what to do about insulating/sealing the subfloor. It sounds like something I might have to have someone come in and do. Money is an issue - it's always expensive to hire a job out. What do you think?

As always on this site - I get so much great info.
Thanks!!!
June
 
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Old 01-17-13, 07:20 PM
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June. Those vents could be thre for combustion air. I would not seal these intell you check on this. Also if you need a dehumidifier your crawl is not bone dry. Cover the floor and run up the walls with a 6mil VB
 
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Old 01-18-13, 01:52 AM
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It's actually much better to have insulated crawlspace walls than it is to have an insulated/air-sealed floor.

Crawlspaces are best treated like basements -> insulate, heat it in the winter; dehumidify it in the summer if needed.


For some reason I assumed that you were in a wetter climate.

If your basement doesn't get damp and musty in the summer, a dehumidifier isn't necessary. If the outdoor air is always dry in the summer, there's nothing wrong with ventilation.


airman has a great point -> The vents might be there for combustion air. How many vents are there? Sizes?

Be careful with combustion air and close off the vents in such a way that they can easily be re-opened in the summer.
 
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Old 01-18-13, 01:58 AM
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Old 01-19-13, 09:08 AM
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Re: combustible air: there's nothing in the crawlspace but pipes. The boiler is aboveground in a compartment attached to the house.
 
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Old 01-19-13, 09:24 AM
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Re "Treat your crawl space like a mini-basement"
Excellent article - thank you! I can do all of this myself. And it makes sense to not seal off the floor. I can cut the foam around the vents so it's easy to pull the foam plugs out in the summer. Will have to wait til things warm up here a bit before I do anything - it hasn't gotten above freezing for about a month. But I'm already anticipating no more cold feet in the winter.
June
 
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