Just starting to research. Help please.

[heaterman]

Slant Fin just released an updated version of their heat loss calc. It's a very good place to start. Here's a link to the article.

(broken link removed to http://www.prweb.com/releases/slantfin/heatlosscalculator/prweb9915043.htm)

 

[jrod770]

I came up with these numbers, Total UA 543 btu/hr and design loss 22819 btu/hr. Do these sound right? Are these the needed numbers?

 

[McKraut]

I just finished an install of a EKO Biomass 60. I can give you my specific numbers for costs if you are interested in them. Let me know what you need. I had a TARM in our basement for almost 20 years, and when it started having problems, I was told by my wife, that our new boiler was not going in the house.
Let me know if I can help you.

Bob

 

[arbutus]

Sounds reasonable for a new tight house in mid Ohio.
What size is the existing furnace? Does it short cycle?
With a heat loss that low, have you looked into geothermal or heat pumps?

 

[jrod770]

Sounds reasonable for a new tight house in mid Ohio.
What size is the existing furnace? Does it short cycle?
With a heat loss that low, have you looked into geothermal or heat pumps?

Existing furnace is 80,000 btu. No it doesn't short cycle, try not to use it. I do have a heat pump already, but I really do not like the heat from it. Hard to explain, but it's a cool heat and just never feels warm. I would consider geo if I didn't like to cut and burn wood and have a so much of it readily available.

 

[maple1]

Geothermal requires a huge capital outlay. And you still have monthly operating costs in electricity.

I considered it, but factoring in that I could install my new wood system for about 30% less than a geo, then have 'free' monthly operating costs for as long as I was able to process wood, led me to where I am.

BUT, everyones situation (and preferences, and priorities), are different....

 

[Floydian]

I came up with these numbers, Total UA 543 btu/hr and design loss 22819 btu/hr. Do these sound right? Are these the needed numbers?

Sounds too low to me, maybe way too low. Getting down to 10 btu/sq ft at design temp is no small feat in Ohio. Framing factors really brings down the whole wall R values when thermal bridging isn't addressed. A 2x6 wall with open cell spray foam and a 25% framing factor has a whole wall of about R16. Closed cell does a little better but the thermal bridging is a killer.

For a reference I am finishing up a new house for my folks. 2200 sq ft, 2x6 walls with damp spray cellulose(R20)+2.5" of Poly Iso (R15) outside of the sheathing. This gives a whole wall R value of just over R30. The house is build very tight and has R5 triple pane windows, R60 attic, R15 basement floor, R20 basement walls below grade. At a design temp of 0(rare here though we live at 2400' in the mountains of VA) this house has a heat load of just under 21,000 btu/hr or just under 10 btu/sq ft/hr. This is equates to an annual heat load of about 22 million btu or about a cord of quality hardwood.
The house has a high efficiency Fujitsu Mini split HP that rivals the COP of many Ground source HPs for a fraction of the cost. Plus a tiny wood stove in the basement. Simple, comfortable and cost effective.

Existing furnace is 80,000 btu.

You posted this as I was typing. I bet this furnace is oversized. The numbers can really be all over the place without an accurate heat loss calculation but with the construction you mention I would guess that your heat load at design is somewhere around 40 to 50K btus but of course that means nothing.

If you can share some more details maybe we can get a more accurate number. Square footage of exterior walls, ceilings, windows and doors, below grade R values, etc. and what type of insulation?

Noah

 

[jrod770]

I remembered I had some paperwork hidden from when we built the house.It was a REScheck worksheet from the architect. It gives me a UA of 456. Is that the number we were looking for?

 

[jrod770]

OK, finally had some time to run the slant fin calcs for the house. By their calculations, I'm at 28,885 btu/hr. Does that number sound better? What would your recomendations be based upon that? I'm narrowing my search to a gasser to be placed in new boiler room that I will attach to existing detached garage. It will end up being about 30' from the house.

 

[heaterman]

Sounds like you are on the right track jrod. What design temperature sis you use for your location?

 

[jrod770]

From the Engineering Toolbox website, average low 28, average high 69.

 

[heaterman]

From the Engineering Toolbox website, average low 28, average high 69.

ASHREA design temps for the Columbus region is 5*F. Plug that number into the Slant Fin calc and you'll have what is needed to heat your place during 97th percentile weather conditions. I think using 28 as your low is going to leave you a little short. Not a bad thing really if you have auxiliary heat you bring on in a pinch. Those days usually happen about 2-3 times per season.

 

[jrod770]

Thinking about the Eko40. I wasn't planning on heating the garage, but since Itwill be attached to it, I might as well plan for it. Sizing sound correct for 2300 sq ft house and 24 x 48 building?