Low power LP furnace ?

[noenegdod]

The fan on a forced air furnace uses 1200 watts or more .

This is not correct. 1200 watts would be about a 1.5 hp motor. The usual motor on a furnace is a 1/3 or as small as a 1/4 hp which would put you around 200-250 watts. The starting current would be in the 1200 watt or more range

 

[noenegdod]

I would have already got one but the ticking worries me. I've given up all my hopes & dreams except for a good nights sleep. My rooms I need to keep warm are 2x 20' shipping containers that are not connected side by side. If I have a forced air unit in one container ducked to the other, it will keep the unit its in from freezing also. Thats why I was not concerned about the efficiency. I'm pretty much just concerned electric consumption

Have you considered something hydronic? In the container that you dont sleep in, you can stick a propane natural draft water heater (no power) and fill it with glycol. Then simply plumb in a baseboard style fin tube: https://www.slantfin.com/products/fin-tube-bare-elements/ and a 12v circulation pump: https://www.amazon.ca/XS-Power-Water-Coolant-Intercooler-SuperCharger/dp/B07BVZ2297 (there are lots of different types, you will have to do your homework on flow and power consumption) simply controlled by a thermostat like this: https://www.amazon.ca/Inkbird-Heati...9Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

It would be very quiet and low power. Not really efficient from a fuel POV but no worse than one of those williams heaters (which is a good option too IMO, and a lot simpler)

 

[Wellbuilt]

This is not correct. 1200 watts would be about a 1.5 hp motor. The usual motor on a furnace is a 1/3 or as small as a 1/4 hp which would put you around 200-250 watts. The starting current would be in the 1200 watt or more range

Hmmm the blower on the hot air system I was checking on was for a 3000sf house with AC 4 ton unit .
I did not read the spec on the motor but by the size of it it could be 11/2 hp
It is a old 90s unit and has standing pilot .
It dose have a power vent but I’m sure that power is not drawn thru the furnace power system.
the motor is 6” round and 10” long ?
I checked the unit 25 years ago so I could be mistaken I heat with wood .
The funny thing is I just notice the pilot light was on last year , it been burning for 25years ?
i used it when my son came home from the hospital when he was born . He is 26 now and I have not used the gas heat since .

 

[Wellbuilt]

Have you considered something hydronic? In the container that you dont sleep in, you can stick a propane natural draft water heater (no power) and fill it with glycol. Then simply plumb in a baseboard style fin tube: https://www.slantfin.com/products/fin-tube-bare-elements/ and a 12v circulation pump: https://www.amazon.ca/XS-Power-Water-Coolant-Intercooler-SuperCharger/dp/B07BVZ2297 (there are lots of different types, you will have to do your homework on flow and power consumption) simply controlled by a thermostat like this: https://www.amazon.ca/Inkbird-Heati...9Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

It would be very quiet and low power. Not really efficient from a fuel POV but no worse than one of those williams heaters (which is a good option too IMO, and a lot simpler)

I think this would work good allso .
I don’t know how long the hot water heater would last ? And how much fuel it would burn ?
I’m planing on using a 80gallon ream water heater to heat my radiant heat floor @ 1300 sf 4 /5” thick slab
I don’t really know how it will work out .
I heat with wood so I just need the floor warmed up in the down stairs , The place is 2800 feet

 

[noenegdod]

Hmmm the blower on the hot air system I was checking on was for a 3000sf house with AC 4 ton unit .
I did not read the spec on the motor but by the size of it it could be 11/2 hp
It is a old 90s unit and has standing pilot .
It dose have a power vent but I’m sure that power is not drawn thru the furnace power system.
the motor is 6” round and 10” long ?
I checked the unit 25 years ago so I could be mistaken I heat with wood .
The funny thing is I just notice the pilot light was on last year , it been burning for 25years ?
i used it when my son came home from the hospital when he was born . He is 26 now and I have not used the gas heat since .

Who knows for sure, someone may have decided to stick a huge motor on your furnace. It isnt drawing 1200 watts though. 1200 watts would be a gale in a 3000 sf house.

I have been involved in indoor cultivation since the mid 90s and use a ton of used furnace blowers for air movement. They all have 1/4-1/3 and occasionally 1/2 hp motors.

 

[noenegdod]

I think this would work good allso .
I don’t know how long the hot water heater would last ? And how much fuel it would burn ?
I’m planing on using a 80gallon ream water heater to heat my radiant heat floor @ 1300 sf 4 /5” thick slab
I don’t really know how it will work out .
I heat with wood so I just need the floor warmed up in the down stairs , The place is 2800 feet

It will work and it addresses the ticking issue but adds level of complexity. I think the williams heater is a better/simpler option only considering function.

Another possibility and I think a better option (than hydronics) since it appears he is willing to cut holes for ducting between the two containers would be to install the williams in the back corner of the container that wont be used for sleeping, next to the container that will be slept in. Install a duct over top of the williams with an inline fan that will draw heat from directly over the heater to be blown into the sleeping container and install a return with a fan at the other end of the container near the floor. Wire these fans to a thermostat. The williams will keep the one container to temperature and when there is a call for heat in the sleeping container it will steal the heat until the sleeping container is warm and then turn off allowing the williams to heat the container it is in to temp. This is by far the simplest solution.

If they are full of glycol they last a lot longer than they do in a domestic water application. Especially if you use demineralized water for the mix.

Wellbuilt, just a little food for thought:

• For your application look at the btu not the gallons. I have no idea if they actually stick a bigger burner in an 80 but I know for a fact that for all the manufactures I have looked at (In the process of replacing 2 water heaters and 2 30 yr old furnaces in the house) 30, 40 and 60 gallon tanks all have the same burner in them with the same output. The amount of water storage in a heating application vs water usage is basically irrelevant. It is the heat input that matters.
• A natural draft water heater isnt much less efficent than a power vented unit when it is actually burning fuel. There is a huge difference in stand by losses however. Because it relies on natural draft, there is a constant flow of air through the combustion chamber which is constantly taking heat from the tank and sending it up the chimney. In an application where it was being constantly fired I would save the cost and just use a natural draft tank. However, it sounds like it is basically just going to be used to keep the chill off a concrete floor. The tank is going to be in stand by most of the time. A power vented unit has far less natural draft through them by virtue of the fact that the chimney is much shorter and the blower acts as a restriction when it is stationary. I would consider a small volume power vented unit for your application.

 

[Guda]

Correct, 8x8x20 x2. They are the core. The concrete truck didn't show last October & now I can't find help. If I ever get the 2 pours done it will be a lot bigger. Plan to heat all that with wood stoves, hot water & electric. Just need the core to have a thermostat LP furnace. That will keep the lifepo4 happy, water tanks & sewage treatment plant from freezing.

The ticking is nowheres near as loud as a fan blowing .

Fans are white noise.

If I knew we were going to have another freeze I might have bought one. I'll see if I can find a video of one. But I am a pretty light sleeper.

 

[Wellbuilt]

It will work and it addresses the ticking issue but adds level of complexity. I think the williams heater is a better/simpler option only considering function.

Another possibility and I think a better option (than hydronics) since it appears he is willing to cut holes for ducting between the two containers would be to install the williams in the back corner of the container that wont be used for sleeping, next to the container that will be slept in. Install a duct over top of the williams with an inline fan that will draw heat from directly over the heater to be blown into the sleeping container and install a return with a fan at the other end of the container near the floor. Wire these fans to a thermostat. The williams will keep the one container to temperature and when there is a call for heat in the sleeping container it will steal the heat until the sleeping container is warm and then turn off allowing the williams to heat the container it is in to temp. This is by far the simplest solution.

If they are full of glycol they last a lot longer than they do in a domestic water application. Especially if you use demineralized water for the mix.

Wellbuilt, just a little food for thought:

• For your application look at the btu not the gallons. I have no idea if they actually stick a bigger burner in an 80 but I know for a fact that for all the manufactures I have looked at (In the process of replacing 2 water heaters and 2 30 yr old furnaces in the house) 30, 40 and 60 gallon tanks all have the same burner in them with the same output. The amount of water storage in a heating application vs water usage is basically irrelevant. It is the heat input that matters.
• A natural draft water heater isnt much less efficent than a power vented unit when it is actually burning fuel. There is a huge difference in stand by losses however. Because it relies on natural draft, there is a constant flow of air through the combustion chamber which is constantly taking heat from the tank and sending it up the chimney. In an application where it was being constantly fired I would save the cost and just use a natural draft tank. However, it sounds like it is basically just going to be used to keep the chill off a concrete floor. The tank is going to be in stand by most of the time. A power vented unit has far less natural draft through them by virtue of the fact that the chimney is much shorter and the blower acts as a restriction when it is stationary. I would consider a small volume power vented unit for your application.

O my bad I ment to say 80k btu water heater
I reall don’t have a out side wall to mount the Direct hot water heater .
after the fact my Electrical inspector wanted me to change the location of my inverter .
I dident want a DV water heater next to the inverter so I am going to try a big water heater .
It seam like it will work , I’m not sure if the building inspector is going to like it

 

[Guda]

Another possibility and I think a better option (than hydronics) since it appears he is willing to cut holes for ducting between the two containers would be to install the williams in the back corner of the container that wont be used for sleeping, next to the container that will be slept in. Install a duct over top of the williams with an inline fan that will draw heat from directly over the heater to be blown into the sleeping container and install a return with a fan at the other end of the container near the floor. Wire these fans to a thermostat. The williams will keep the one container to temperature and when there is a call for heat in the sleeping container it will steal the heat until the sleeping container is warm and then turn off allowing the williams to heat the container it is in to temp. This is by far the simplest solution.

This is a good idea. But the utility container is old & gross. I don't want the air from the utility going into the bedroom.

For your application look at the btu not the gallons. I have no idea if they actually stick a bigger burner in an 80 but I know for a fact that for all the manufactures I have looked at (In the process of replacing 2 water heaters and 2 30 yr old furnaces in the house) 30, 40 and 60 gallon tanks all have the same burner in them with the same output. The amount of water storage in a heating application vs water usage is basically irrelevant. It is the heat input that matters.

Plan it to build a several hundred gallon tank. Filled with water (or glycol) with copper coil connected to the hot water heater. If I can get heating out of that, who knows.

Someone asked why I didn't read the Buddy directions. I bought it used with no directions. It worked untill 4am. Reading directions at 4am is not a thing in my world. I watched a couple quick fix videos that did not work.

Side note. In England they have a home smart IOT hot water tank that is grid level storage. Even without using their IOT function I think their tanks are far superior & solve all the issues you refer to.

I am going to start a thread with all this diesel heater info as its a lot of good info that can never be searched.

 

[Lancealott]

There a company it Vermont that specializes in heating with propane hot water heaters. I know a man that's heat about 2400 sq foot building with 2 water heaters.
I am going to use a combo one demand unit in my new to me house. I went from forced hot air to baseboards about 10 years ago I sure wish I had done it 35 years ago. It is much steadier heat uses a lot less electricity, no proof just the bill went down, and is so much quitter. A 1/8th horse power pump has to use less power than a blower. As you have out buildings, it seams, you could use a small propane boiler, used in my area $500 average. Put it in your battery room and never have to wory about cold batterys.

 

[50ShadesOfDirt]

All through this thread, I wasn't able to pick out how your propane is supplied ...

For our 900 sq ft home, and many of our outbuildings, we just use an inexpensive "mr heater" 30k btu indoor "blue-flame" propane ventless floor-standing (or can be wall-mounted) unit ... while not a furnace, this might also be a strength for it, as there's no ductwork to do. Just put one in each major space. No venting, o2 sensor ...

These have thermostats, no electricity needed, battery-operated pilot ignition. We light it once, and it runs throughout the season (or per bottle change, if using lp 20lb or larger outside tanks, poked through the wall). With one in each "room", we have fallback heat that always runs, and keeps temps where we want it.

We clean ours once per year, right before the heating season, and then it just works ... set the thermostat where you want it, and forget it. Some of the units are over 5 years old ... don't get the smaller ones (10k or 20k btu), get the 30k btu model.

You also get to see the pretty blue-flame effect ...

 

[Guda]

There a company it Vermont that specializes in heating with propane hot water heaters. I know a man that's heat about 2400 sq foot building with 2 water heaters.

Thats pretty cool

A 1/8th horse power pump has to use less power than a blower. As you have out buildings, it seams, you could use a small propane boiler, used in my area $500 average. Put it in your battery room and never have to wory about cold battery

Ideally propane is just a backup. Thats the concept tho. Batteries are in the core with the heating systems waste heat keeping them warm.

All through this thread, I wasn't able to pick out how your propane is supplied ...

Currently I have 5x 5gal tanks. I used to have 3x6, 3x 20 & 5x 5. 20 gal exploded during the fire. Sold the rest. Plan to buy a 500 gal & get delivery. Hopefully just once. Hopefully all my other heating does the job.

For our 900 sq ft home, and many of our outbuildings, we just use an inexpensive "mr heater" 30k btu indoor "blue-flame" propane ventless floor-standing (or can be wall-mounted) unit ... while not a furnace, this might also be a strength for it, as there's no ductwork to do. Just put one in each major space. No venting, o2 sensor ...

I used one for a couple days before it died & I didn't like it at all. I am trying to get away from things that need replacing &/or crazy maintenance. There is something bad about those, just not sure exactly what it is about them.

I'm just going to buy a furnace off eBay & keep fingers crossed its good. Hopefully I'll never have to use it.

 

[thegoogler]

What's your required heating load? Rule of thumb is 30-60 BTU per square foot, so 30k BTU implies you're trying to heat a 500-1000 square foot space. That rule of thumb is misleading though as the location (North Dakota vs Louisiana), construction materials (canvas yurt vs R19-insulated walls vs glass windows), etc will make a huge difference in the actual need.

What's your power consumption budget (# Amp-hours per day?)

If you want extremely low (or no) power consumption, then you should look at boilers and radiant options. Radiant flooring is more expensive to install, but baseboard radiators are as that expensive and work well. If you design the boiler/radiator system to be gravity fed then the only power required is for a few seconds to light the burner, and if your boiler uses a pilot and thermocouple then you don't even need power for that (though the pilot will consume a very small amount of propane all the time). If you use a circulating pump (which is more efficient for moving water and heating rooms quicker) then you will need to account for the pump draw, which is about 0.5A @ 120V.

If you want to stick with forced air, then I suggest looking for a variable speed residential furnace, as aside from a few seconds to power the igniter the majority of the power required to run the furnace is the blower.

 

[Guda]

What's your required heating load? Rule of thumb is 30-60 BTU per square foot, so 30k BTU implies you're trying to heat a 500-1000 square foot space. That rule of thumb is misleading though as the location (North Dakota vs Louisiana), construction materials (canvas yurt vs R19-insulated walls vs glass windows), etc will make a huge difference in the actual need.

You know! Yup, I have 8 months of freezing. I'm going wild with insulation. I am also only trying to heat the core of my place of my place with a furnace. So I can leave on vacation & not chill my lifepo4. Its crazy dark for 2 months & no fun.

I am just trying to heat 360sqft. 180 with on a thermostat 180 with the waste heat. Last resort heating.

Just pored 11 yards of 6.5 sack today. 7k gal of water tanks going in. So tired not even gaming tonight.

 

[thegoogler]

We live in Chicago, so winter temps can get down to about -10F for a week or two at times, and often hover around 0-10F with overnight lows. We heat about 3000 sq ft with about 200k BTU boiler through baseboard and free-standing radiators. Our walls have no insulation at all, windows and doors are from 1894 and very drafty, etc.

We also have a camping trailer which is about 200 sq ft. It has <2" of styrofoam insulation in the walls and ceiling. We've only camped down ~25F though I know people that have gone down below 10F for overnight low temps. That has a forced-air propane furnace which I believe is 15k BTU. We keep the thermostat set between 60-65F when we use it at night. The furnace blower is 12V and about 7A when it is running. I would say we used maybe 30 or 40 Ah overnight when it was 25F.

My point is that I think 30k BTU is a LOT for your space, even if it was poorly insulated. With good insulation you will need a lot less BTU. If you use a residential forced air furnace (most natural gas furnaces can be converted to propane) I doubt you'll need 30k BTU. Look for a variable model, or at least one that is a two stage model, which will almost always run on the low speed/low gas flow stage.

I still think if you're really concerned about power consumption you should look for a water-based radiant option. Baseboard radiators will do a really good job, and a 120V circulating pump draws less than 0.5A most of the time it runs. The nice thing is that the radiator will fire up, the pump will run, the water will heat, and then the radiator will reach temp and shut off along with the pump, but you'll still get radiant heat from the baseboards all around your place even while the unit is off. Once it cools it will fire up and run again for 5-10 minutes, and then it'll shut off and you'll get heat for another 20-30 minutes while it cools again, etc.

 

[Guda]

My point is that I think 30k BTU is a LOT for your space, even if it was poorly insulated. With good insulation you will need a lot less BTU. If you use a residential forced air furnace (most natural gas furnaces can be converted to propane) I doubt you'll need 30k BTU. Look for a variable model, or at least one that is a two stage model, which will almost always run on the low speed/low gas flow stage.

I might use the extra to heat a larger area. I just poured 400 more sqft. & have about that to go. I'll have about 1600sqft total. Plan to heat those other areas with alternative heating methods. I hope to almost never use the furnace.

I'll look to see if there is a smaller unit. 30k BTU is only $2000ish.

 

[thegoogler]

I might use the extra to heat a larger area. I just poured 400 more sqft. & have about that to go. I'll have about 1600sqft total. Plan to heat those other areas with alternative heating methods. I hope to almost never use the furnace.

I'll look to see if there is a smaller unit. 30k BTU is only $2000ish.

A 2 stage furnace will heat at 60% and run the fan at a lower speed unless it can’t keep up when it’s really cold. I’m not sure if you can find a 2 stage but if so it’ll list run at 18k btu normally and only at 30k if you’re trying to heat the room quickly