The Best Off Grid Heating System

March 14, 2015 · 16 comments

Would you do us a huge favor by sharing?

Our secret waepon for radinat heat and domestic hot water.The greatest advance in home heating in the past few decades has to be the Open Direct System invented by Radiantec.

The Open Direct System uses a highly efficient condensing tank-style water heater that provides both radiant space heating and domestic hot water all in one unit cutting electricity requirements for those of us living off the power grid.

There are no heat exchangers (unless you want to subsidize with solar hot water), no poisonous antifreeze and no complicated controls. The same water that flows through your floor, goes through your water heater/boiler and comes out of your hot water tap.

Although this may sound strange, the pipe in your radiant heat system is no different from the pipe everywhere else in your home from the well to the taps.

The secret weapon of this system is the Polaris PG10 34-100-2 hot water. It truly is amazing with a real efficiency of 96%. It can heat water as fast as you can use it (5-6 gallons per minute), has a stainless steel storage tank holding 34 gallons and has standby losses of only 1%.

We love it and it has changed the way we heat our home and domestic hot water forever! We are saving about $400 CAD every year compared to burning wood.

Good places to buy the Polaris water heater/boiler and their parts:(as of August 23, 2015)

USA as low as $2941.44 USD for the 100,000 BTU 34 gallon model LP or NG (free shipping in the USA)

Radiantec $3299.00 for the 100,000 BTU 34 gallon model LP or NG (free shipping in the USA)


None – Will likely have to have one shipped to a community (from just across the US border and bring it across yourself.

Central / South America

Far East / Asia Pacific

Vikrant Malhotra   +91-9901011002


Contact U.S. Exports and Caribbean Sales at:


The best heating system

The Polaris truly is our secret weapon for designing a super high-efficiency heating system. There is nothing like it! It produces 100,000 BTU, uses very little electricity and is as easy as connecting the gas supply, cold water in and cold water out.

This high-efficiency heating system is designed to work in a radiant heat application as the water traveling through your floor needs to be approximately the same temperature as the water going to your hot water tap. Radiant heat applications use warm water (100-140oF) to heat your floor as opposed to baseboard heaters and radiators that use much hotter water (160-190oF).

Here is how it works. When your zones (or a zone) need heat, the circulating pump will make hot water will flow from the water heater, through the check valve, through the pump, to the heating zone and back. This will heat your floor effectively and is pretty normal.making heatIf you look at the above drawing, you can follow the hot water from the top of the water heater through the check valve, through the circulating pump(s), through the heating zone (floor) and back to the water heater.

The real difference begins now…

When you open a hot water faucet, cold water enters the system from the cold water supply (well or municipal water system), goes through the heating zones, and enters the hot water tank. This forces hot water out of the top of the water heater, into your hot water piping and out the hot water tap.

providing hot water

In the above drawing, you can follow the hot water out the top of the water heater to the piping that leads to your hot water fixtures. The water is replaced by going from the cold water piping, through the circulating pump(s), through the zone and back to the hot water heater.

By the time this cold water reaches the hot water heater, it has already been preheated by the floor. In the heating season, the cold water will be warm by the time it reaches the hot water heater. This doesn’t really save money as you have already heated that water with your Polaris water heater/boiler.

Although this system works awesome in the winter, the real energy savings are in the summer as all the water entering your water heater has to go through the floor first.

The cold water leaves your well (or municipal system) goes through all the zones of your heating system and is warmed/pre-heated.

In the summer you can expect an increase of 10-20 degrees (for free) as the water flows through your floor.

This cold water cools your floor in the summer and provides some free air conditioning. By the way we have never had any condensation build-up on any concrete, wood, ceramic tile or click flooring that is being used to pre-heat the water.

The cold water will always flow through your floor first because of the check valve in the system.


If you close a zone (heating loop) the water in that loop will get stagnant and could become a health risk the next time it is opened and that water is allowed back into the system if you drink your hot water from the tap (which most folks don’t).

 If you are planning on installing a solar water heating system, the open direct is the perfect companion. Look at the photo below. Every BTU collected with solar, will cut your fuel consumption. It is just a matter of plumbing in a new loop for the solar collectors if you live in a no freeze zone. If you live in the north, simply add a heat exchanger and antifreeze.

solar water heating

The Polaris/open direct system will work for hot water baseboard heating. Hot water baseboard requires higher temperatures and the Polaris will handle it but the Polaris is not as efficient at higher temperatures.

using a mixing valve to keep tap water at a safe temperatureAnother consideration is the resulting water temperature would be too high for bathing, showering or washing dishes.

Make sure you add a mixing valve to the water heading out to your taps if you use the open direct system for hot water baseboard or radiator heating systems.

A mixing valve is simply a device (that you connect your domestic hot water supply to fixtures and your cold water supply) that mixes cold water into your domestic hot water to lower the temperature to prevent burns at your taps or shower. They are adjustable to your preferred temperature and very reliable.

Good places to buy mixing valves:(as of August 23, 2015)

USA as low as $77.41 USD for a Taco 5004-C3 1″ Union-Sweat Mixing Valve ASSE 1017 (plus $9.38 shipping in the USA)

Radiantec $129.00 USD for the Honeywell AM102-US-1 Series  1″ Mixing Valves (plus $20.00 shipping in the USA)

Canada as low as $89.99 CAD for the Honeywell RC-AM101C-US-1 Mixing Valve (free shipping in Canada)

We will do our best to find worldwide suppliers of these mixing valves ASAP.

Advantages of Using the Polaris in an Open-Direct-System:

This system eliminates one of the biggest problems with radiant heating systems….air.

In most radiant heating systems, air gets trapped in the piping and pumps making the system work poorly. In the open-direct-system, air is forced out of the lines every time you open a hot water fixture as the full pressure of your pumping system is plenty to flush out any air. No need for air traps as in traditional radiant or base board systems.

Radiant heating systems work best at temperatures of 100-140 degrees F. The Polaris is designed to work the best at 100-140 degrees F. It is a match made in heaven.

If you try to use a standard boiler with radiant heat, you will always be operating your boiler at a lower temperature than it was designed to operate or use a mixing valve. Mixing valves are not efficient in this situation as you are paying money to heat your water only to cool it down with a mixing valve.

You only need to buy one hot water heater instead of a domestic water heater and boiler. This saves a lot of money and also saves standby losses. Every hot water heater you have will add another standby loss (through the sides and top) as well as an electrical load to your off-the-grid renewable energy system.

The open-direct-system is incredibly simple and code approved by the International Code Council (ICC). Email us at if you would like the documentation supporting the open-direct-system.

You WILL save on your heating and hot water energy costs. Think about the summer. Your floor is warm and the sun is shining. Every time you open a hot water faucet, cold water is directed through the floor, preheated and sent to the water heater. We see a 20 degree temperature rise in the middle of the summer in our home. That is a 100% free rise in water temperature.

With a little extra plumbing, you can also direct all the cold water through your floor in the summer months. This can make a decent decrease in cooling costs and provide a much cooler home. We do this with our gardening watering system and it makes a huge difference in our bedrooms.

We also feed our toilets with the preheated water to stop sweating on those humid days. The possibilities are almost endless.

To make the open-direct-system work the best, the Polaris is the most reliable, inexpensive and well built heater available today. We installed our first one about 8 years ago. If we find a better unit, we will update this page immediately.

Happy heating!

Leave a Comment

{ 16 comments… read them below or add one }

Peter October 24, 2016 at 11:15 am

I am researching a hot water heating system to heat my off the grid house.
I will be using a glycol mix to prevent freezing.
I will be using a mix of radiant floor heat and cast iron radiators.
Propane and possibly sun as fuel.
efficiency of course is important.
Any ideas would be appreciated
Thanks Peter Gobet


Jody Graham October 28, 2016 at 10:26 am

Hi Peter,

Thanks for commenting. Usually radiant heat is done with water temperatures around 120-140 degrees F and radiators are closer to 190 degrees F.

I would stick to a lower temp boiler like the Polaris or other condensing hot water heater/boiler. The radiators won’t be as hot but plenty to dry mittens and snow suits on and provide heat, especially if the water goes thru the radiators first and then the floor.

To add solar simply add a stainless single wall heat exchanger. Have a vent at the top of your hot water collectors in case the heat exchanger leaks. This will force hot potable water (under pressure) out the vent making it impossible for glycol to get into your domestic hot water. Don’t use a double walled heat exchanger as these are less efficient.

Expect trouble from your heating installer and building code officials as they tend to not think outside the box as we do.

If I can answer any other questions or didn’t answer this one, please do not hesitate. Jody


Brett October 9, 2016 at 1:57 pm

Interesting method. I like the concept, but I’m curious:

In winter, when using hot water (which introduces cold water into the radiant floor zone), doesn’t that end up cooling the floors (and associated space) you are trying to heat? I see that exchange adds efficiency in producing additional hot water for future use (and the advantages of this in summer are obvious), but I’m stuck on the cooling effect to the space you’re trying to heat with the radiant zone during the winter season.

Thanks in advance!


Jody Graham October 11, 2016 at 9:36 am

Awesome question Brett,

Thanks. The radiant concrete floor takes 24-48 hours to come up to full temperature depending on the size of floor and size of heating system. Running the hot water (cold going thru the floor) through for a few minutes or hours is negligible compared to the 24-48 hours of heat stored in the floor. Plus how often is the water water running in the average home per day? Not much! We have been using the system for 8 years? and the only time I notice the cold water causing the floor to be cold is in the summer when I want to cool the house and preheat the water going in to the hot water heater. Hope I have answered your question. If not, please let me know…


Frank Larson June 13, 2016 at 11:05 pm

Sure glad I found you as we are starting to build our home on a concrete slab with in-floor heating. Love your ideas. Am seriously looking into doing as your plans show. Any suggestions on insulating the slab? Do you have to us blue board or not? Thanks so much

Your friend,

Frank Larson


Jody Graham June 14, 2016 at 2:55 pm

Hi Frank,
Thank you for your comments. I am in Zimbabwe, Africa training solar installers but will return in a few days. Usually we put blue board insulation around the inside perimeter (4 feet wide) and leave the middle open to the earth as a means of thermal mass. I will answer more questions when I return. Have a great day…Jody


Sue October 27, 2015 at 2:51 pm

Hi there,
We are moving to an 1100 sq ft bungalow which we want to take off-grid by adding solar. We live in Canada, just north of Toronto. Currently it is using an oil forced air furnace. We will be completely gutting the home and re-insulating with spray foam and updating all window with new efficient ones. We will also be installing a wood stove or fireplace with a wood insert.

We will be removing the oil furnace and are considering our options that work best with solar. Similar to you most of our needs will be met with propane (cooking, clothes dryer etc). We are considering an efficient propane boiler with radiators (prefer radiant heat to forced air because it reduces dust and allergens) but this system you talk about is also intriguing. Here are my questions.

1. What kind of flooring can be placed over the radiant in floor heat? I’m told stone is best but I don’t want stone throughout (fine for kitchen, baths and entry). Does it work with hardwood or carpet?
2. Does the radiant flooring have to be embedded in concrete? If so do you need to consider weight and the load that your home can carry?
3. Does this system continuously draw from your well water or does it recirculate the water? Our well does not have the best refill rate at the moment.
4. Would a regular (efficient) propane boiler with radiator heaters and an on-demand hot water heating system be efficient, despite the added cost of purchasing two units?



Daniel February 3, 2015 at 11:03 pm

I’m curious – do you use propane gas with this? Do you have one of those big liquid propane tank? How much propane (or natural gas, if that’s what you use) do you estimate this system uses per month?

(I know I just asked this about the Peerless gas range also heheh, can you guess where my focus is this week?)

Thanks!! 🙂


Jody Graham February 4, 2015 at 3:10 pm

Hi Daniel,

We use propane with the Polaris water heater/boiler. This provides all of our heat for our 2 story 24′ x 32′ home as well as all domestic hot water. We operate the following on propane:


We consume 3000 liters per year for propane. This year that will cost us $1560 per year or $130 per month at $0.52 per liter. We use two of the following tanks for our home:
123 Gal Tank / 420 lb / 375 Liters Cylinder
Height 53″ Diameter 30″ Weight 272 lbs Footring Diam. 22″

I would estimate we consume about 400-500 liters per month (up to $260) for the boiler in the coldest months. Our home is poorly insulated with many windows. We used to use wood and would use 4-5 cords of wood per heating season at a cost of $325 per cord. Since we have 5 heating months per year, it cost us at least $325 a month for wood compared to $260 for propane.

It is our plan and goal to connect to the power grid at some point so we can participate in net metering. Right now we dump tens of kilowatts per day in the summer that I could bank with the power company. Then I could use that banked electricity to operate a heat pump and heat my home at almost no cost. We also have a 2 kilowatt wind turbine that has been sitting for 3 years due to illness that would help us in our quest to get away from propane.

I cannot say enough about the Polaris condensing water heater. It really has changed my life. Its crazy fast recovery and 95-96% efficiency is almost too good to be true. The exhaust coming out of the Polaris is barely lukewarm. You can put your face directly in front of the exhaust and it is not even close to being hot.

One liter of propane ($0.52) contains 24,200 BTUs of which we capture 23,232 BTUs with the Polaris (24,200 BTUs x 96%). 10,000 BTUs cost $0.22

One cord of hardwood ($325.00) contains 24,000,000 of BTUs of which we will be lucky to capture 12,000,000 BTUs with a woodstove (24,000,000 of BTUs x 50%). 10,000 BTUs cost $0.27

Obviously wood is better from an environmental perspective but since I have been ill, the propane powered Polaris has been a God send.

Daniel please keep the questions coming. It lets me know people actually read the website and get some value from it. I will likely make a video about the Polaris, how we use it and why we like it. Take care…Jody


Gary Stack November 14, 2015 at 3:39 pm

Hey, Has anyone thought of the day that one cannot obtain propane or any fossil fuel. Are you prepared for that? If you folks think that propane will always be available, think again!
Good Luck,



Jody Graham November 14, 2015 at 6:05 pm

Hi Gary,

While I totally agree with you the day is coming when fossil fuels will either be unavailable or not affordable we have not focused on WROL or SHTF issues. But you have inspired me to add a section about how to survive a total economic crash which is inevitable with our (Canada’s) debt based fiat currency and more importantly the USA’s fiat debt based currency. The day is coming soon. I have been struggling a lot with my health lately and have not been able to tackle all the issues I have wanted. We have recently purchased a large steam engine from a world war two navy ship. It was fitted with a 120 volt DC generator capable of producing 2500 watts. Our goal is to mount it to a lumber mill as well as a Ford alternator to charge our 48 volt battery bank. We have 20 acres of forest and alder bushes that would be capable of running our steam engine for many years.

If you would be willing to write an article with photos showing what you have done to prepare for SHTF I would love to make a new section where readers can show off their ideas and projects. I know you are very intelligent and could help a multitude of folks. If you are at all interested please email me at . If not I completely understand and would love to hear anything about your adventures…Jody


JonFranton May 22, 2013 at 12:38 pm

Do you really think a Polaris is big enough to heat a home and provide hot water? Are there any other brands you recommend? I can’t seem to find a Polaris. Thanks for your help…


Jody Graham February 1, 2014 at 12:23 pm

Hi John,
The Polaris is absolutely big enough to heat the average home. It has an output of 100,000 BTUs which is as much as most wood boilers. The little bit of energy required to heat the hot water of domestic use is insignificant. It can heat about 4 gallons per minute as well as you always have a storage of 34 gallons. It should not be though of as a hot water heater but more like a boiler. We have used one in our home in eastern Canada for years. The temperature here can go down to -30F. Good luck in your heating adventures….Jody


Jody Graham February 1, 2014 at 12:24 pm

I do not know of any other brands that perform like the Polaris with a small electric power consumption. Try as they are a stocking distributor in Vermont.


Luis July 25, 2014 at 3:14 pm

Hi Jody… you said, “This cold water cools your floor in the summer and provides some free air conditioning. The cold water will always flow through your floor first because of the check valve in the system.”

In the summer time, is there any risk of the cold well water running through the heating loop and cooling the tiles above it so much that water starts to collect on top of the tiles (similar to water collecting on the outside of a glass of ice water)?


Jody Graham August 12, 2014 at 10:02 pm

You know I have never had that experience or had anyone else complain of condensation on the floor. It could happen but I think it doesn’t as the temperature change is so gradual and gentle. The only cool water going through the floor is any water that is filling the hot water heater and that usually isn’t enough to cause any type of water condensation buildup. If anyone has experienced this issue please let us know…Jody