Thoughts on heating a finished basement - Any furnace folks here?

[daveswoodhauler]

Ok, so we need more room in the house, and we are contemplating finishing off appx 2/3 rds of the basement for the kids to use as a playroom.
Some details of the house:

Poured Concrete Foundation - Built in 1999
Area: Central Massachusetts
Ceilings of the basement are currently insulated - and I'll probably be installing 2" board insulation for the walls. Celing will be on of those drop down/panel types
Enire foundation is below grade - not a walkout basement
Area we are looking to finish is appx 550 sq feet
We have good drainage, and never have had water in the basement. (Run dehumidifier in summer to get the musty smell out)
Current Electricity rate is appx .15/kw
Going to monitor temps in the basement over time this winter. Current temp outside is 35 and its 55 in the basement.

Question: Not sure if our furnace is large enough to handle the additional heating, so we were thinking of putting in electric baseboards instead. Based on our temps, I am thinking that we would be heating the space from mid October to end of March/Early April.

Anyone do something similar and what made you choose electric vs hot water/vice versa?

 

[stee6043]

My first thought is that you're going to want to insulate with a lot more than 2" insulation board. I'd run at least R19 fiberglass, if not more. Concrete can really soak up the heat, especially if you're 100% below grade.

For a home that is only 10 years old I'd be moderately surprised if your furnace wasn't already sized to heat the basement. You could easily call an HVAC guy to come out and confirm. I bet that would cost $50 or less....

 

[daveswoodhauler]

Thanks Stee...good suggestions.

Pulled some info off the current furnace:

Burnham - mfg in 1998
Oil Fired - Forced Hot Water
DOE Heat Capacity: 121 MBH ?
Water: 105 MBH?
Oil 1.05 GPH - guessing this is gallons per hour?

Right now, we have 2 zones, and we would be adding a third zone.....boiler is never really pushing hard, as the insert keeps the temps around 68-70 downstairs, and 64-65 upstairs. Current living area heated is 1800 sq/feet

 

[mayhem]

Long term you'll probably be better off adding a zone and running the boiler. Heavily insulated you'll heat the area and it'll stay warm for awhile.

If I read it correctly, your furnace can push upwards of 121,000 btu. Since you're only running 2 other zones and those are used infrequently I'd venture to guess you're fine as far as capacity.

 

[semipro]

I'd suggest you consider boiler-sourced hydronic heat, whether in baseboards or above the slab. There are systems availabe that allow you to install hydronic heat above slabs, essentially in a sleeper system. You should consider insulating the slab no matter how you heat. Building Science Corp. has some nice information here on finishing basements for comfort and water control.

(broken link removed to http://www.buildingscience.com/documents/information-sheets/5-thermal-control/basement-insulation/?searchterm=basement)

 

[daveswoodhauler]

Thanks for the replys, some good links for reading and getting an idea of what I need to do.
Question, on the insulation....I know that we are not in the middle of winter yet, but right now it is 16F outside, and the basement is still a constant 55F...still think I need a real high R value for insulation? (Probably doesnt hurt to over insulate, right?)
Also, does one recommend a special sheetrock to use downstairs? (I have heard that the paper backing can accumulate mold)
Thanks.

 

[dave11]

Thanks for the replys, some good links for reading and getting an idea of what I need to do.
Question, on the insulation....I know that we are not in the middle of winter yet, but right now it is 16F outside, and the basement is still a constant 55F...still think I need a real high R value for insulation? (Probably doesnt hurt to over insulate, right?)

Also, does one recommend a special sheetrock to use downstairs? (I have heard that the paper backing can accumulate mold)
Thanks.

It might sound like overkill, but I'd suggest starting with a heat-loss tally of at least your basement, and ideally the whole house, if you're going to be adding the basement to your home's heating system load. You can do them yourself, there are resources online that tell you how. Very informative to do, you start to really understand just where all the heat is going. Then you'll know for sure that your boiler can handle the extra load.

Basements fully below grade, like yours, generally don't require as much insulation as walls above-grade, because the surrounding dirt is a fair (not good) insulator, but much better than free air. I'm not in favor of fiberglass batts in walls if it can be avoided--they tend to sag and not stay tight to the wall, in which case you lose much of the R-value. The extruded poly boards are best for below-grade, make sure you use one that's somewhat vapor-permeable.

Also, remember to cover your rim joists, and seal the sill plates with silicone caulk.

They do sell "mold-resistant" drywall now, marketed for basements, but the studies on them I've seen suggest they are not really different from the cheaper basic drywall.

 

[billb3]

To increase the earth insulation capacity, I've found every effort to keep that earth as dry as possible at the foundation walls is worth the effort.

 

[jharkin]

It might sound like overkill, but I'd suggest starting with a heat-loss tally of at least your basement, and ideally the whole house, if you're going to be adding the basement to your home's heating system load. You can do them yourself, there are resources online that tell you how. Very informative to do, you start to really understand just where all the heat is going. Then you'll know for sure that your boiler can handle the extra load.

Second that recommendation. A heat loss will tell you if your current setup has enough extra capacity for an additional zone. There is a good chance it does, heating contractors often oversize.

Burnham - mfg in 1998
Oil Fired - Forced Hot Water
DOE Heat Capacity: 121 MBH ?
Water: 105 MBH?
Oil 1.05 GPH

What this means:
You are burning a 1.05 gallon/hour nozzle. Oil has 140k BTU/gallon, so your input rate is 147k BTU/hr.

The heat capacity is the gross output of the boiler - this is 121k BTU/hr. (the difference between 121k and 147k is whats lost up the stack, this is the AFUE and roughly analogous to the EPA efficiency rating of woodstoves)

The water rating is the net output. This is how much they figure actually gets to the baseboard/radiator after losses through the boiler jacket and piping. Those losses dont count for AFUE as its assumed the heat still ends up inside the envelop of the house. In your case your net output is 105k BTU/hr. So its assumed 121-105k BTU are already ending up in your basement as waste heat.

The reason it says "water" rating is that most boiler manufacturers make units that can do both FHW and steam. The gross ratings are the same but they have different net ratings for water and steam - steam is lower due to the larger piping mass and higher temp differential.



There is a great site called http://heatinghelp.com which will teach you more than you ever wanted to know on this stuff. Lots of pro heating guys there who will happily give advice.

-Jeremy

 

[daveswoodhauler]

Great, thanks for all the help.
Right now, the joists in the ceiling of the basement are all insulated, and the insulation goes to the exterior walls and covers the rim joists.
Some great posts here to help me out, so thanks for all the info. (Got me some reading to do, and I found a few of the heat loss calculators online)
Actually, have a furnace guy coming out today as I think the valve busted on the water temperature control valve, and I have some water and steam leaking out....Murphy's law I guess