# I need a new furnace for a crawl space



## HDZ06 (Mar 23, 2010)

Hello everybody this is my first post here. I'm a big DIY type guy and will have plenty of help from a professional plummer/electrician friend who has installed many furnaces and ac units. I have an old 20 year old gas furnace right now in my closet with the plenum down in the craw space with flexible hoses. I hate the furnace being in my bedroom closet. I was told I can put a new one in my craw and hang it from my floor joices. I have a decent size craw. My craw is roughly 40 inch's from the floor to the bottom of the joices. The craw has pea gravel thru out and a sump pump installed. Would anyone here have suggestions on what type/brand to buy. My home is a one floor with about 1200 sq ft. I have been reading up a lot on the high efffiency multi position type ( condensing gas furnace) ? That would let me vent the gases out the side of the foundation block using pvc pipe. I'm pretty sure a 60,000 btu would do the job but I could be wrong. I have 8 total vents in the home with cold air returns in the center hallway wall top and bottom. I'm in Ohio.Thanks in advance.


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## yuri (Nov 29, 2008)

You need to do a heat loss calculation to get the right size:Load Calculator
Personally I hate crawlspace furnaces. Difficult to service and the extra moisture in crawlspaces tends to shorten the life of circuit boards and other furnace components. It is your choice but you may regret crawling around there in the middle of the night when it fails. Most brands are good as long as they are installed properly. Not everyone makes a "multiposition" furnace which is what you need when you want to use it horizontally in a crawlspace or upside down (counterflow) as you have now. Most furnaces are called "upflow" but you can get multiposition if you do the research. If it gets cold enough down there you can have problems with the condensate from it freezing so the space should be insulated.


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## HDZ06 (Mar 23, 2010)

I don't mind getting under the crawl to service the unit . The benefits of not having it in my bedroom closet beside my bed would out way the bad of having it in he crawl. My old cheapy 20 year old furnace has never needed anything other then the orifices changed and filter change. So I would hope I would have the same luck with newer technology non pilot light type furnace. Rudd makes UGPH series a standard 80% that is for a crawl space and it sounds like a very well built unit . I found a Hamilton also for the same application.


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## beenthere (Oct 11, 2008)

Might want to check the install instructions first. I think you still need a power vent to sidewall vent that UGPH furnace.

Good chance a 40,000 BTU 95% furnace would be all the large furnace you need for that small house.
A load calc will tell you for sure.

Sounds like a damp crawl. Tends to rust out furnaces.
How does your current return system come back to the furnace? How will you run it to the new furnace? Return duct in a unconditioned crawl MUST be sealed real well. or you'll have a big heating bill.


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## yuri (Nov 29, 2008)

Ruud is quite good and I have worked on lots of them. I would buy the one with spark ignition. Igniters can burn out and I like their spark ignition models. The rest are pretty good also.


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## HDZ06 (Mar 23, 2010)

beenthere said:


> Might want to check the install instructions first. I think you still need a power vent to sidewall vent that UGPH furnace.
> 
> Good chance a 40,000 BTU 95% furnace would be all the large furnace you need for that small house.
> A load calc will tell you for sure.
> ...


 It is open air right now at the furnace top opening and it is also hooked up to the hallway return ducts also. I was planning on hooking up the new one in the craw space directly at the return inlet vent that goes to my hallway way wall, top and bottom vents. I hope this makes sense ? I'am aware that i might need a blower to get the gasses to exit out the pvc pipe.


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## beenthere (Oct 11, 2008)

80% don't vent with PVC.
90%+ do. And you can't use a power vent on them.

What is the dimension of the return duct/chaise?


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## yuri (Nov 29, 2008)

Post some pics of everything as our crystal ball is AWOL.:whistling2:


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## HDZ06 (Mar 23, 2010)

beenthere said:


> 80% don't vent with PVC.
> 90%+ do. And you can't use a power vent on them.
> 
> What is the dimension of the return duct/chaise?


 30x16 10" hose vent


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## beenthere (Oct 11, 2008)

Your return being in your wall like that. Isn't enough for a new 20,000BTU furnace.
The 10" tap on that return panning is restricted by the joist its split across.
And 10" is too small for a new 40,000BTU furnace.


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## HDZ06 (Mar 23, 2010)

I have more cold air returns one in each bedroom. So that would be 3 more. They are closed over right now because of the way we the old set up is right now pulling open air from the top of the existing furnace. The new furnace would be using all the returns hallway and bedrooms. I forgot about the bedroom ones untill it was mentioned.


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## beenthere (Oct 11, 2008)

If those other 3 returns are all the same size as what you posted a pic of. You have enough return for 50,000BTU input 95%. Maybe.


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## HDZ06 (Mar 23, 2010)

beenthere said:


> If those other 3 returns are all the same size as what you posted a pic of. You have enough return for 50,000BTU input 95%. Maybe.


 Ok well I have my eye on a 60,000 95.5% Hamilton High eff. Any recomendations for a certain furnace ?


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## beenthere (Oct 11, 2008)

Certain brand no. But, you should do a load calc to know what size you really need.

Guessing just makes you use more gas then you need to.

Do your own load calc  HVAC Calc 

Its worth the 49 dollar fee.

New furnaces need to move more air then older furnaces.


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## Marty S. (Oct 31, 2009)

Get one that parts are available local. Really stinks when it's -25 out and the wind is howling on a thursday only to find out the part you need will be there in 2 business days. Makes for a mighty cold weekend!


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