Fitting Furnace into Small Space
I am considering building a much smaller house with only a partial basement.
I was wondering what the smallest possible space you could fit a gas or oil furnace into is?
Could you fit 1 into a 4 foot by 4 foot space or would you need more space? I was hoping to squeeze the washer dryer laundry tub water heater and furnace all into 1/2 of the (to be left unfinished) non living space basement so the other half could he used as a rec room.
The space would be approximately 10 foot 8 inches wide and the entire partial basement would be approximately 25 foot 4 inches long so let’s say 10 foot wide by 24 feet long to be safe (so I’d be wanting to squeeze all that and the electrical circuit board into half the basement which would be a 10 x 12 foot space (which means the area for the furnace would likely be about 4 foot by 4 foot.
Could a furnace (HVAC) fit into that small an area or would I have to give up the rec room in order to fit it and a laundry room space?
The other half of the house will be crawl space foundation to allow for the piping of the plumbing and ducting to the other half of the house.
so can a furnace or combination furnace air conditioning unit fit into a very small space (so as not to eat up all the basement)?
The main plan is a approximately 800 (technically 700 and some square feet) square feet and I’m going to pay to have the crawl space the plan originally comes with modified to have a partial basement. Minimal heating for the basement portion since it’s only going to be used as a utility room mainly on laundry day or the rec room part only when guests stay over or for parties for the rec room.
So at most probably maximum 1300 ish square feet heated but with dual thermostat heat controls so that the basement doesn’t get as much heat and only gets heated or cooled more when actually used (going to use a digital programed thermostat) since it’s mostly going to be used as a utility area and spare guest space when needed.
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Remember that it's not only the size of the equipment, but also the code-mandated clearances that determine the minimum size space you need for mechanicals like this. As an example, code requires a "dead front" clear space in front of your electric panel that is clear for 3 feet, from floor to ceiling. I don't work with heating equipment in residential setups, so I don't know exactly what code requires for those. You can have other issues such as ductwork feeding a side or bottom air entry also. There is more to it than just "how much space for an oil or gas furnace". You can share clear spaces in most cases, so that 3 foot dead front clear space in front of the electric panel can double as a maintenance access space for the furnace, for example, so that's a way to minimize the total space required if you need to keep things compact.
Note that mini splits don't even need a dedicated mechanical room since they are wall mounted in the living spaces. That could be another option for you.
As a very, very rough estimate though, I think you'll be able to fit your furnace, water heater, and electrical panel into a 10x12 foot space, and you could probably fit laundry equipment in there too if you can put things on opposite walls with a single isle in the middle.
BTW, the indoor part of central air conditioning is just an A coil that installs inside the supply duct (the "air output") from the furnace, so it sits on top of a typical gas furnace and doesn't use any additional floor space.
Bill
Bill, that’s very helpful advice. I will look into that. I hadn’t thought about positioning the laundry on the opposite wall to the furnace equipment with an island as a divider. . Thank you :)
For such a small space, considering skipping the furnace entirely. Maybe a ductless/ducted heat pump upstairs and an electric baseboard in the basement. Furnaces struggle with oversizing for homes that size.
Paul I’m not so sure about your suggestion (the heat pump part). I live where it can get as cold as -29 Celsius/-20 Fahrenheit in winter and I’ve heard heat pumps don’t heat well in cold clinmates. It gets up to 33 Celsius/90 Fahrenheit for a couple months in summer.
Easy, add in some resistance strips for the temperatures between -14 and -20. You won't need much output for this space.
I think I’m going to have to do more research on this option. Not saying I’ll chose it not saying I won’t. It’s definitely food for thought.
I would look at furnaces made for apartments, they are wall mounted and quite small. The Dettson Chinook comes to mind.
Kyle, do you have more information on them? I’ve always lived in a house so never heard about wall mounted apartment type furnaces before?
https://www.dettson.com/products/chinook-compact/
What exactly is your 99% design temperature? You can use this tool to find it on a map:
http://ashrae-meteo.info/v2.0/
Provided your hydro is reliable, for a small space like that you want a cold climate hyper heat ducted heat pump. There are many out there rated to deliver heat down to -20F, most if not all can also have a resistance heat strip installed to boost capacity for those polar vortex days.
The slim ducted units take up very little space, you can install them in the ceiling of a utility room or vertically in a wall. Here is 1.5 ton unit in a ceiling, the indoor unit (3'x3'x8") is the box in the farthest corner.
You may want to have a look at the HVAC equipment designed for mobile homes. The designs are optimized for the smallest number of square feet with zero clearance on the sides and back and the front visible in a hallway so that clearance space is not wasted.
https://hvacdirect.com/revolv-rg7-95-72-000-btu-style-crest-manufactured-home-gas-furnace-with-coil-cabinet-mg2r-072fb.html?
utm_source=%7Bgoogle%7D&utm_medium=%7Bcpc%7D&utm_campaign=16810625974&gclid=CjwKCAjwx7GYBhB7EiwA0d8oe_Rlw82r4TyXkFhmfIR5u_QppFpim3YgsgjaOCgk5NJUI4UUY9-XPBoCeBwQAvD_BwE
Walta
I live in the GTA area of Ontario Canada (the greater Toronto area), the build will be in the same general area but towards the north end (New Market) of it. In the last 35+ years it only got to the cold end of our climate map zone temp once (-29 C/-20F) it normally doesn’t drop below -25 C/-13 F but I’m currently about 10 miles (16 1/2 km) south of the intended build site where it’s usually only 2 degrees cooler then where I currently am when they forecast. So to -26 or -27 Celsius (14-16 F) if the online temperature converter I’m using is correct.
My Altitude 230m (740 feet) above sea. The build area isn’t much higher (I think about 30 feet) AKOS
I’m not sure about the rest of the things on that webpage (like the F, % part).
As to our hydro. It is reliable 99.9 % of the time (we’ve only had 2 extended time black outs ones lasting over 8 hrs caused by storms in the last 20 years and none to speak of prior to that. Normal interruptions are usually corrected within an hr and are rare as well.
You are just a bit north of me, looking at the airport near Barrie, the 99% design temperature is -18.5C. The way design temperature works is that although it might be colder than that, the number of hours in a year are very small. By the time sun comes up the temperature would get above this 99% value, so you only need to size the heating system for this value.
This puts you well into the range of one of the many hyper heat units. Once you have a more detailed design, I would run it through the on-line calculator here to figure out what you actually need:
https://betterbuiltnw.com/hvac-sizing-tool
Does require a free registration but it is pretty simple and does more accurate sizing that is needed to get a heat pump right.
A rough guess is between a 1.5 ton to 2 ton unit. Something like these bellow would probably work.
1.25 Ton Mitsubishi:
https://ashp.neep.org/#!/product/34564/7/25000///0
1.5 Ton Fujitsu mid static ducted unit:
https://ashp.neep.org/#!/product/25348/7/25000///0
1.5 Ton Carrier/Midea mid static:
https://ashp.neep.org/#!/product/36669/7/25000///0
All of these can come with a strip heater although I doubt you'll need it.
The basement is part of your conditioned space which means it should be insulated and fully conditioned. Properly air sealed an insulated, the heat loss there is pretty small a couple of registers tapping off the main trunk to the house above is all that is needed. You don't save much energy by running the basement colder, it turns into an uncomfortable space plus colder floors above.
If you must have gas, the other option is a hydronic coil unit hooked up to a high output water heater tank like this (see P39 for diagram):
http://www.airmaxtechnologies.com/a-img/downloads/maxair-lv-manual.pdf
These are commonly used in condos in the city, the air handler is mounted above the tank, easily fits into a 4'x4' closet.
If you look at the cost of natural gas vs electric heat with a heat pump, it is about a wash. Material cost is about the same and not having gas saves you the hookup, meter fee and needing CO sensors. Unlike natural gas, you can always generate your electricity with a PV array.
Thank you all (Bill, Paul, Kyle, AKOS, walta100).
You’ve provided me with plenty of useful information.
I’m going to carefully consider all these options, and once the home plans are finalized I’ll be discussing which is best with my contractor for the build. I haven’t selected a contractor yet, which makes your suggestions all the more helpful to me (as it gives me a general direction to go to and has made me aware of possible pitfalls of traditional furnace systems in small houses).
Anyone else with information or suggestions, please feel free to reply and add them and I’ll consider those ideas too (though, unless I have questions about the suggestions I may not reply back or and if I do it might be a while before I do because life gets busy at times especially at this time of year).
I have a lot to think about.
Again, thank you all for your help and information :)