# Ideas for backup heat in new construction (small house)



## Alan Gage (Jan 22, 2011)

Howdy all,

Getting ready to built a roughly 750 sq. ft. house this spring with full basement. Both basement and main level will be insulated to at least r-20 and probably r-60 in the attic. The basement will just be a work shop now but could be finished off in the future. It should be a very easy house to heat and I plan on heating 100% with wood, which I've been doing already the past few years.

What I need to decide on though is a backup heat source for when I leave for a couple days or more in the winter to keep the pipes from freezing. Either electric or propane are options. I'm hoping I can get by without any duct work and just let the heat from the basement radiate up through the floor to keep the main level above freezing. Sound plausible?

Propane would be more efficient but would require plumbing fresh air and exhaust. For the little use the heater will see I wonder if the better efficiency of propane is worth it?

I'm pretty unfamiliar with what's available out there besides your run of the mill forced air furnaces and electric baseboard heaters. What are some of you using and what would you recommend I look into? I'm in northern Iowa and our winters get pretty cold so a heat pump is out. I'll probably get some sort of air exchanger for the house so something that could take care of that as well without having to run the furnace would be a bonus.

Thanks,

Alan


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## semipro (Jan 22, 2011)

How about some hydronics and an electric or propane water heater.  The hyrdronics could either be under the first floor or baseboard type.  I think you can even use the same standard water heater for your hot tap water.  

Here's an article in Fine Homebuilding and the house sounds somewhat similar to what you're building. 

http://tinyurl.com/4aq7oer


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## Alan Gage (Jan 22, 2011)

I'd never considered hydronics before, I don't know anything about them. I started doing some looking around and it would seem I've got some learning to do. Guess I'll just add it to the endless list of things to research. I was hoping to start building in April but with so many things to learn about before starting it might be a couple more years! 

I'll try and read the article later. I'm on a slow connection with an old computer now and I can't open it.

Thanks,

Alan


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## jimbom (Jan 22, 2011)

We can leave our house for a week in the coldest winter and it does not get below 40 F.  Our basement floor stays about 60 F all year.  As the temperature in the basement drops past 60 F, the floor starts radiating heat into the house.  Temperature differences of 20 F will radiate approximately 23 BTU/hr-ft^2 into the house from the basement floor.  Keep the plumbing out of the exterior walls and you might be good to go without backup.  I learned this the hard way in a week long ice storm power outage.  That experience caused me to buy our  wood stove.  ASHRAE design temperature here is 0 F.

Our biggest problem coming home to a cold house in the winter is the long time it takes to get the joint warmed up.  Just is not fun at all for a couple of days.


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## Jeff S (Jan 22, 2011)

What an excellent article.I really liked how they tied solar into the system to offset fuel cost.I've checked into these Polaris water heaters before and they are offered in both NG and propane.


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## btuser (Jan 22, 2011)

I second the notion about keepin the plumbing out of the exterior walls.  Basboard usually wraps the walls, and is often the first to freeze when the power goes out.


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## semipro (Jan 22, 2011)

I agree also that plumbing shouldn't go in the exterior walls.  I don't really like it in any house.  Exterior walls are for fenestrations and insulation.  


It sounds like a great vacation cabin feature would be if you were able to call the place up and turn on the heat a day before you planned to be there.   If you have a phone line I think that's a relatively simple thing to do.  

I'd be concerned about how to keep the pipes from freezing if you run out of gas or the electricity goes out.


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## benjamin (Jan 22, 2011)

I'm twenty miles on the other side of the Lansing bridge so I know your area.

In this case, keep it simple. Electricity at $.10/KWH is cheaper than propane at $3 or less depending on the efficiency.  Electric baseboards are cheapest.  Electric radiant heat would be nice, especially in the bathroom where you want to feel the heat instantly.  Geothermal heat pumps are a good option, especially if you want AC or someday want the option of not burning wood. 

Unless you want propane for cooking or hot water it's not worth the hassle just for a few weekends a year.  

The article was interesting, but how do they justify all of that garbage for a small house?  If I was going to live in a "styrofoam cooler" I wouldn't want to spend $10,000+ on HVAC without the AC.

Structural Insulated Panels are nice, but disposable.  Insulated Concrete Forms are a waste of insulation and thermal mass.  

What kind of house are you building?  and what do you want to accomplish?  If you design the basement right you will be able to store a lot of heat in the concrete, whether that is wood heat or passive solar, then you can make the upper floor more conventional.  The heat will travel up through the floor, better if you have some air circulation and a low heat loss.

Keep the questions coming, feel free to get ahold of me if you want to hear more crazy ideas or see some examples.


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## begreen (Jan 22, 2011)

I would look into the newer super-efficient mini-split heat pumps. That will give you heating and cooling with great efficiency. This will only heat down to about 10-15F, so you will need backup for deep freeze times like you are experiencing today. That can be wood or resistance electric. But it will still cover a good 90% of the heating. On the opposite spectrum, it will really be appreciated when the temps are too mild for wood burning, but still need heat. Daikin, Sanyo, Fujitsu all make good units.


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## colebrookman (Jan 22, 2011)

Check the latest issue of Fine Homebuilding for ideas on back up heating in well insulated homes.  We cook with propane and use a direct vent propane heater when the wood stove is out.  Make sure to get a pilot light so the stove will work during power outages if you aren't home.  Be safe.
Ed


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## Alan Gage (Jan 23, 2011)

A little more info about the house:

Their won't be any concrete in the basement other than the floor as I'll be doing a wood foundation. It's possible I could be doing SIPs instead of standard stick construction as there is a manufacturer only about 15 miles from here. I still need to talk to them though. If I go with stick construction I'll probably be doing wet blown cellulose insulation in the basement (work shop) and main level and loose blown in the attic so it should be sealed up pretty tight. I'll have an Englander 13 wood stove on the main level which will be the main heat source. It should be more than enough to heat me out of the house. 

I already have a 500lb. propane tank on the property and will have it piped into the house anyway for hot water and cooking. 

The backup heat source in the basement would also be used to warm the basement a little, if needed, when I want to go down there and work. Other than that it will hopefully never be on other than when I leave the place empty for a few days. I'd like to keep it contained in the basement and let the heat radiate up through the floor to keep the main level above freezing.

I've thought about heat pumps but the majority of the usage would come with temperatures below they range they can operate efficiently. Price is higher than I'd like to pay as well. The benefit would be AC in the summer but for now I think I can get by without.

Hot water heat looks interesting and I need to do some more research but I'm wondering if it's not a bit more complication and expense than I want for a backup heat source. 

Electric heat would certainly be the easiest and cheapest to install but the most expensive to run. But with the small amount I'll be using them maybe it won't really matter.

A wall mounted direct vent propane unit looks promising as well. Relatively cheap ($1000 or under), would provide plenty of heat if I wanted to keep the basement warmer than normal, and would be cheaper than propane to run. No need to exhaust out the roof, just a single hole through the side of the house. 

Thanks again for all the ideas.

Alan


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## DBoon (Jan 23, 2011)

Hi Alan, 

I've had a small 10,000 btu Monitor natural gas-fired heater in my finished basement in my condo.  It heats the basement level (~300 square feet) and the entire upstairs (~1000 square feet) down to about 10 degrees F outside.  There is not a lot of ability to "pick up" from a colder than desired 68 or 70 degree inside temperature, but it does well to supply heat to keep it warm.  These run on propane or kerosene as well. 

If by "wood" foundation you mean a pressure treated wood foundation, I would strongly urge you not to go this route.  These have a forty year life and are a problem waiting to happen.  Spend a few more bucks and get a good masonry foundation below grade.


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## benjamin (Jan 23, 2011)

Alan Gage said:
			
		

> Hot water heat looks interesting and I need to do some more research but I'm wondering if it's not a bit more complication and expense than I want for a backup heat source.
> 
> 
> Alan



Bingo!  I think hot water radiant floors make sense for a main heat source even for efficient and/or small buildings, but there's no way it makes sense for a backup like you're describing, unless you wanted to use the water heater for the backup... 

A water based heat pump won't lose efficiency, the outside temperature doesn't have any effect on the performance, which is based on the inside temperature and the temperature of the water. You can install one yourself for not much more than the options you're talking about, it's no more complicated than any other water system.  

I wouldn't worry about the wood foundation, it's not like you're building a nuclear waste vault here.  There are enough wood foundations around, anybody here of failures?


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## Alan Gage (Jan 23, 2011)

As I've been researching wood foundations I've come across lots of complaints and failures. It sounds like the majority were poorly planned and executed construction though (improper drainage, poor site choice, or incorrect treatment on the lumber). I was leaning heavily to a wood foundation but wanted to check with our local building center, where I'll be buying all the lumber for the house, first. I half expected them to recommend against but they said they've been very impressed with the ones they've seen done in the area, as longs as they've been done correctly. The only ones they were aware of that had problems were done otherwise. 

I'll be building on what amounts to a gravel pit with a very low water table so it should be nearly ideal conditions for a wood foundation. We're also drier than the east coast.

I talked to some people in town that have a 35 year old wood foundation and have had no problems. I know there are some others in the area that are 50 years old now and still going strong. 
Alan


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## begreen (Jan 23, 2011)

Alan Gage said:
			
		

> I've thought about heat pumps but the majority of the usage would come with temperatures below they range they can operate efficiently. Price is higher than I'd like to pay as well. The benefit would be AC in the summer but for now I think I can get by without.
> 
> Hot water heat looks interesting and I need to do some more research but I'm wondering if it's not a bit more complication and expense than I want for a backup heat source.
> 
> ...



Based on the weather history for the area I would say it is the opposite. There would be some days, like the current cold snap, where supplemental resistance heat would be needed, but for the majority of time the heat pump would handle Iowa weather fine. Des Moines shows an average January temp of 15-30F which can be handled by the units mentioned. During the nasty cold snaps, turn up the baseboard heaters or the wood stove.

The black lines are the average low/highs for Des Moines.


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## Alan Gage (Jan 23, 2011)

They're a bunch of wienies down in Des Moines, that's the deep south.  Our weather would be about the same as Minneapolis. While we've been below average temps this month we still haven't had any really cold weather. Usually we have a week or two in January where the lows dip to around -20 and the highs stay below zero. 

I still haven't dismissed heat pumps though. My grandfather had one on a new (large) house he built and was very happy with it. He had a bunch of deals worked out with the electric company so it cost him a ridiculously low amount to run. I talked with our provider a bit and it doesn't sound like they offer as good of a deal here, more like they give a discount on the heat pump instead of lower rates. 

I've also talked to a couple of the HVAC guys in town and they don't think much of them for our climate, I don't know of very many around. 

What I really meant about the heat pump mostly running in too cold of temps was that when I leave for a trip in the winter I try to coincide it with the coldest weather, so a good part of that time it will probably need a backup as well. Since the unit will be installed in the basement having the ability to use it for AC in the summer isn't a big benefit either. 

They really look like a slick outfit though and if I didn't have my heart set on providing as much heat as I can with wood it would be a no brainer to install one on the main level.

Alan


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## Alan Gage (Jan 23, 2011)

I just checked our average temps this is what I found:

Dec Avg. (High/Low): 27/9

Jan. Avg. (High/Low): 23/4

Feb. Avg (High/Low):  29/10

Alan


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## begreen (Jan 23, 2011)

You're right, that's quite a bit colder than Des Moines. The heat pump would carry the place during the day. You would need a good unit, but the place is small. Once you have the heat load calcs done you can make a more informed decision. If it can be heated with 12K btus, the Fujitsu is the one I would look at. It's only a single unit setup, but will work ok at 10 degrees. Sorry to say the US units don't come close to that.


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## benjamin (Jan 23, 2011)

Air source and ground/water source heat pumps are very different in operation, even if they're similar technology.  It was -20 this morning and -26 a couple of mornings ago, air source heat pumps just don't make much sense here.  Begreen lives in a climate that has almost as many heating degree days even though it barely freezes there.  A cool mild climate makes an air source heat pump work a lot better (so does cheap hydo power).

If you were willing to DIY, you could put a ground source heat pump in that place for $1,500-2,000 that would heat for a  fraction of the price of propane, cool for much less than the highest efficiency central AC and provide some cheap/free hot water.


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## pyper (Jan 24, 2011)

Given your described usage, it sounds like electric baseboard would be a pretty good option, especially if all your plumbing is pretty much in one spot. An electric baseboard heater is really cheap to buy, cheap to install, and needs no maintenance (aside from occasional vacuum). You can get them with a dial thermostat that seems to turn them on at about 50F. True they cost more to run, but if you compare how much it would cost to buy a heat pump and put it in you can buy a lot of electric.

The only thing it won't do is come on if the power is out.


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## Alan Gage (Jan 24, 2011)

I'm house sitting for some people this winter who have had a ground source heat pump for quite a few years now and they've gotten along great with it. It's more than I want to tackle DIY though and more than I want to pay someone else for an install. 

I did do some more research on the mini splits and they are looking pretty impressive. Still leaning towards a direct vent wall mounted propane or electric baseboard. Nice thing about the small units like the mini splits or wall mounted propane heaters is they'll still be easy to add after construction if I decide to upgrade in the future.

Alan


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## woodsmaster (Jan 24, 2011)

Just for backup for a house that size I think I'd probably go with a ventless propane wall hung unit probably under $500.00 You could even be toasty when the power is out.


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## Highbeam (Jan 24, 2011)

10 cents a KWH? Very occasional backup heat? Buy a silly 50$ electric wall heater from Lowes and be done with it. It's just not worth it to futz around with anything else.


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## jebatty (Jan 24, 2011)

> What I need to decide on though is a backup heat source for when I leave for a couple days or more in the winter to keep the pipes from freezing. Either electric or propane are options. Iâ€™m hoping I can get by without any duct work and just let the heat from the basement radiate up through the floor to keep the main level above freezing.



For backup for what you want to heat, as infrequently as your suggest, I 2nd an electric wall heater, 240V, 3000 watt (10,200 btu). Right now, although the house is heated with the wood stove, I have one of these in the basement to maintain 50F temp. Alternative would a portable unit. I have a 3500/5000 watt unit; have used it in the basement of the house, in the shop, and in an old barn when I need temporary heat. 5000 watts is about 17,000 btu, which should be plenty to heat a house your size.


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## Highbeam (Jan 24, 2011)

BG, I was checking out the fujitsu site and their mini heat pumps are only rated to heat down to 45 degrees F. The specs didn't talk about what happens when you have 10-15 degree temps as you suggest.


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## begreen (Jan 24, 2011)

The unit I saw was the AOU 12RLS. 12KBTU is it's cooling capacity. 16K BTU is its nominal heating capacity. I am pretty sure the unit I looked at was rated 25 SEER 12 HSPF. They rate it for heating down to 5Â°F. The fact that they can do this at all is remarkable. That it is so quiet and efficient doing so is simply amazing.

http://www.fujitsugeneral.com/PDF_06/halcyon06_brochure.pdf

I just ran a basic heat calculation for this unit compared to electric resistance heat for a 50 yr old house in Olympia at $0.10/kwh. The calculator showed $1706 total annual heating cost for the resistance heat and $816 for this heat pump. Using a 90% efficient propane unit, with fuel costs at $3.50/gal the difference was $2461 vs $816. You can see how this can save a lot of money quickly. And you get a nice, quiet AC unit with the deal.


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## Seasoned Oak (Jan 25, 2011)

If you decide to go electric they have a nice built in the wall type heater at lowes about $120.00 FIts nice between 2 wall studs,and has a grill type cover that is flush with the wall. also a temp dial. .  Much nicer than bulky wall baseboard units.   I use em in bathrooms for extra heat with hot tubs.If the main furnace fails at least the bathroom would have heat
They have different size models but i usually only need the small ones. A larger one would do a whole floor to keep it above freezing.


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## Alan Gage (Jan 26, 2011)

Lots of thinking and mind changing the last couple days but this evening I settled on electric and feel pretty good about it. If I use it as little as I hope the extra expense of running it will be more than offset by the money saved on buying the heater. 

It will be no problem installing the electric after the house is built so I can wait until next winter and see how the basement and house hold heat first before deciding how big of a unit to get. If in the future I decide I don't want to use the wood stove as my main heat source I'll probably add a ductless heat pump upstairs. The electric in the basement will always be there as a backup.

Then again there's still a couple months before I start building so I'll probably change my mind about a dozen more times by then.

Thanks again for all the good ideas.

Alan


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## GaryGary (Jan 26, 2011)

Hi,
For the keeping the pipes from freezing when you go away, I'd consider making the plumbing system so that its easy to drain, and letting the cabin go cold.   

I used to put in some time at a volunteer labor ski lodge.  The lodge was only open on the weekends -- for the rest of the week there was no heat to the building at all.  The system for protecting the plumbing (as near as I can remember) 1) open the plumbing drain valve, 2) go around and open all the faucets, 3) drain the hot water tank (which could be a tankless these days -- so would drain very easily), 4) flush the toilets and pump the toilet bowls out.  
This sounds like a bit of work, but it was actually very fast.  
This lodge has been in continuous operation since the 1920's, so its a pretty well proven system 
There was no power of any kind into the lodge when it was not occupied as a fire safety measure.

The plumbing in this lodge was all built with a bit of slope for drainage -- if you did not have this, you might have to have a little compressed air to blow the water out of the pipes.

The nice thing about this is that you aren't spending money (or carbon) for heat when you are not there, and you don't have to worry about power failures or running out of fuel.

You do have to be careful to let things warm up when you get back so that the pipes are above freezing when you turn the water on.

Gary


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## jebatty (Jan 26, 2011)

Draining a system can be a bit more critical, with refrigerators with ice/water systems, dishwashers, washing machines, and other appliances connected to water. Most if not all of these retain some water after draining, and unless blown out very well, might be subject to freezing and damage; or introduction of non-toxic antifreeze may be required.


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## henkmeuzelaar (Jan 30, 2011)

If it is just to prevent "the pipes from freezing" while you are away and the areas that need some heating are limited in size I would just go with electric as it is safe, easy, clean and cheap to install.

I just phoned the Sensaphone monitor in our house in the Idaho Rocky Mountains that we often need to leave alone for awhile and heard that everything is fine (temperature, power, noise level).  A landline-based Sensaphone does not cost more than $ 350 or so and they will call YOU if anything is wrong. (For the record; I do not have any connection, whatsoever, with the manufacturer or dealrs of this device)

Although it is a relatively big log home and the temperatures do get plenty low, just a few electric heaters set very low will do the job. For one area over the garage where some water pipes run in the floor, we sometimes even spread a simple heating blanket on the floor and set it at the lowest level.  

Also HomeDepot and other home improvement stores sell simple, inexpensive plug-molds that only switch on at 35F, or so. Just in case a particular heater might break, a second heater set at "high" and connected to that plug-mold might save the day (together with the alarm system).

Unless you enjoy installing some of the more advanced back-up systems as a hobby of sorts, I do not see why simple electric resistive heating solutions would not fit the bill (unless your electric power rates are exorbitantly high).

Success!

Henk


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