?? Diverting Home Water Heater For Radiant Heat To Greenhouse ??

[brown_thumb]

I need to add some heat to my makeshift greenhouse. I don't need much heat because I live in south Texas, USA. All I want to do is assure the plants never see temperatures fall below 50F (10C).

I've been considering LP gas heaters but those with thermostats are a bit pricey. An extra advantage to this type of heater is the CO2 emissions to help feed the plants. The downside is the cost of refueling the tanks and having to make many trips to do so. I do know to vent the greenhouse of CO before entering.

I've been wondering about diverting heated water from my electric home water heater to make radiant heat. The greenhouse has a rock floor approximately 3" (75mm) deep and the heating tubes could easily be buried in the base of those small stones. The advantage to this is not having to buy propane tanks and keep refilling them. The disadvantage is no extra CO2 emissions to help the plants grow and the increased electric bill. Also, I'm unsure how best to design and implement such a system. I know I'd need an electric pump to divert the hot water to the radiant system and return the cooled water to the water heater intake but I'm not sure how to make that function properly.

Your thoughts and advice are appreciated.

 

[justanotherbozo]

have you considered using a compost pile to heat your greenhouse? ...i can't remember the author or the title but i know there is a book out there written by a frenchman i think, ...anyway, what he did was make a large compost pile with hose wound within the pile and he hooked that hose to the conventional forced hot water heating system in his house so that water would circulate through the hot pile and then into his house.

...to make a long story short, he heated his house for free for the winter and then grew all the food needed for his family in the compost in the spring,...this shit is way more trouble to explain than it actually is.

...anyway, here's a link to some videos for you to check out, i'm betting you'll find something you can make work in your world.

https://www.youtube.com/watch?v=_mh9fgPGZHc

peace, bozo

 

[justanotherbozo]

...a few more links.

http://www.gardenguides.com/116339-heat-greenhouse-compost.html

https://www.permaculture.co.uk/articles/heating-greenhouse-compost-and-manure

http://www.compostpower.org

http://www.motherearthnews.com/renewable-energy/compost-water-heater-zmaz81jazraw

good luck, bozo

 

[brown_thumb]

Wow... what an excellent idea. If I had enough organic material to make a compost pile then I would definitely consider that. However, I live alone and don't have that much organic waste.

 

[justanotherbozo]

...i'm betting that if you enquired you would find MANY sources of free organic waste, i guess it boils down to whether you'd rather pay for your heat or work for it.

...there are other solar options but those would be more costly and more complex.

anyway, just putting it out there bro, only you can know what will work for you.

peace, bozo

 

[ChaosCatalunya]

You are needing this heat at night ?

You do not want extra CO2, the plants are giving off CO2 at night, it is only daytime that they use it, so a CO2 burner is not the best idea IMO

Personally, despite some possible practical issues, I like Wood burning stoves, you restrict the air entry so it burns slow, overnight, with no naked flames, you get heat, and also a really handy drying effect. Old houses with wide porous lime walls need wood fires to dry them out as much as heat, if you can sort out arrangement without melting your greenhouse

 

[brown_thumb]

...i'm betting that if you enquired you would find MANY sources of free organic waste, i guess it boils down to whether you'd rather pay for your heat or work for it.

...there are other solar options but those would be more costly and more complex.

anyway, just putting it out there bro, only you can know what will work for you.

peace, bozo

You may be right but the nearest town is very small. We have one Walmart and one large grocery store. I asked but neither give away their old produce. I might be able to work a deal with some small restaurants to save their waste but I can't be held down to specific pickup times.

You are needing this heat at night ?

You do not want extra CO2, the plants are giving off CO2 at night, it is only daytime that they use it, so a CO2 burner is not the best idea IMO

Personally, despite some possible practical issues, I like Wood burning stoves, you restrict the air entry so it burns slow, overnight, with no naked flames, you get heat, and also a really handy drying effect. Old houses with wide porous lime walls need wood fires to dry them out as much as heat, if you can sort out arrangement without melting your greenhouse

Yes, I need the heat at night (mostly) but there will be some days I need heat during daytime too.

I didn't know plants release CO2 during the night. Thanks for teaching me that.

I could install a wood burning stove and the energy would be free because I live on two acres with a stack of wood that's getting too old and plenty of other wood I need to have cut. If I could find a tiny stove that could be thermostatically controlled then I'd opt for that. But without it self regulating I'd worry about too much or too little heat. I'll do some research.

 

[brown_thumb]

So far I can't find any retrofit thermostatically controlled dampers for wood burning stoves. Stoves with them built in are extremely pricey and too large. So I started looking for retrofit automatic dampers for outdoor meat cookers (barbecue cookers). I've found a couple that may work but the probes are calibrated for measuring meat temperature so I'd have to modify either the probe or the electronics. Of course, I'd need a cooker that has a smoke stack so I can vent the fumes outside.

Any ideas, caveats, suggestions?

 

[brown_thumb]

What about something like THIS CHEAP WOOD BURNING STOVE with a digital thermostat and a control unit to open and close the air intake vent to regulate heat?

 

[justanotherbozo]

...here's the first video of at least 2 where a rocket mass heater is installed in a small greenhouse.

https://www.youtube.com/watch?v=U0V00ch5kIE

peace, bozo

...btw, here in the US it is common for folks to put out thier garden trash for pick up once a week, grass clippings, tree leaves, that sort of shit,...anyway, that was the sort of stuff i was thinking of to use as organic waste.

 

[brown_thumb]

...here's the first video of at least 2 where a rocket mass heater is installed in a small greenhouse.

https://www.youtube.com/watch?v=U0V00ch5kIE

peace, bozo

...btw, here in the US it is common for folks to put out thier garden trash for pick up once a week, grass clippings, tree leaves, that sort of shit,...anyway, that was the sort of stuff i was thinking of to use as organic waste.

Thanks for the rocket stove link. Maybe I can adapt a thermostatically controlled intake vent to one for moderation of heat production.

I live in a rural area so most folks don't catch their grass clippings and they toss their old vegetable/fruit produce into their yards or compost them... or they just burn them. Few people will bother to collect that material for me to pick up and if they're so inclined will surely be composting for their own use.

 

[stoned40yrs]

I could install a wood burning stove and the energy would be free because I live on two acres with a stack of wood that's getting too old and plenty of other wood I need to have cut. If I could find a tiny stove that could be thermostatically controlled then I'd opt for that. But without it self regulating I'd worry about too much or too little heat. I'll do some research.

Forget wood. The only thermostat that works is a human fire tender I burn between 10-15 cords a years in my house. You don't know what you don't know. Go with a oil drip stove or propane or something else you can have more control over.

 

[brown_thumb]

Forget wood. The only thermostat that works is a human fire tender I burn between 10-15 cords a years in my house. You don't know what you don't know. Go with a oil drip stove or propane or something else you can have more control over.

Yes but there are wood burning stoves that are thermostatically controlled so you don't have to do that manually. The overall temp is kept within 5 degrees F or so until the wood is nearly gone.

Some automation is more important for my application because I'd have to go outside to the greenhouse every hour all through the night to adjust the vents to keep the temperature within reasonable limits. I won't do that.

I don't know what oil drip stoves are but I'll research them. Propane will be costly for me because I'll have to use refillable portable tanks. I'm not ruling them out but apparently I'll have to find a stove or heater that vents exhaust outside. Again, I'm not ruling these out but wood fuel is free for me.

 

[brown_thumb]

^^^ Okay, I saw a waste oil drip stove and I like the concept but I live alone and produce almost zero used cooking oil. Maybe I could make a deal with local restaurants but most likely they'll take the easier, more reliable recycling option.

 

[coldcanna]

Why has no one mentioned ventless LP wall heaters...? It's only a couple hundred bucks and they have thermostats built in.....

And using your electric water heater for this application will make your electric bill sky rocket.... they have a 4500 watt heating element and if your constantly depleteing the tank that element is going to be drawing around the clock... there's a reason hydronic boilers use fossil fuels and not electricity

 

[stoned40yrs]

^^^ Okay, I saw a waste oil drip stove and I like the concept but I live alone and produce almost zero used cooking oil. Maybe I could make a deal with local restaurants but most likely they'll take the easier, more reliable recycling option.

I wasn't talking about burning French fry oil. Home heating oil, same as diesel oil only cheaper because you don't pay road tax. If you do go with wood please keep this thread alive with your journey with free wood and a stove that keeps the wood going and the temp within 5 degrees. I like a good laugh

 

[brown_thumb]

I'm considering a small wood burning stove LIKE THIS ONE

If I remove the legs and set the stove directly on top of a stack of fire bricks three layers deep, then surround the sides and back and cover the top with double or triple layers of fire brick... those bricks will absorb the heat and help moderate/extend the heating time from the stove. What do you folks think?

 

[stoned40yrs]

I like that stove. Might buy one for my collection. It's just a Yukon camp stove with a different name. They are used in tents, mostly during hunting season. They heat up a 8x10 wall tent pretty good. They don't hold much wood at all. You have to feed them at least once an hour. Your idea with the bricks would work but you still would be feeding that stove all the time. I have a big barrel stove in my shop surrounded by brick and they don't stay warm very long after the fire is out. Your idea will work in Texas, plants do ok in the 40s, you may be worrying too much about that. Goodluck!

 

[brown_thumb]

I like that stove. Might buy one for my collection. It's just a Yukon camp stove with a different name. They are used in tents, mostly during hunting season. They heat up a 8x10 wall tent pretty good. They don't hold much wood at all. You have to feed them at least once an hour. Your idea with the bricks would work but you still would be feeding that stove all the time. I have a big barrel stove in my shop surrounded by brick and they don't stay warm very long after the fire is out. Your idea will work in Texas, plants do ok in the 40s, you may be worrying too much about that. Goodluck!

I was hoping I could close the dampers and get a few hours of warmth from it. It really doesn't get very cold here... but the green house isn't insulated and it leaks like a sieve. One thing I don't want to do is wake up every hour to feed the stove. The temperature can drop into the low 20's F here but that's rare. It often reaches low thirties in January for a few nights though. Since I can't afford a pricey solution I may need to accept the fact I'll lose a lot of sleep for a couple months out of the year.

I guess when I add the CMH lights I won't have to worry about heat until those switch off. That'll help some, I suppose, but that doesn't help in the wee hours of the night.

Maybe adding an electric heater set very low will suffice for when the stove burns out. I'd really like to avoid pricey electric bills though, especially since my supply of wood is free.

 

[AppliedScience]

Is a regular 1500 watt space heater not powerful enough?

According to my calculations it would take about 7 minutes to heat up 3000 ft3 of air 10F, not accounting for heat loss through the walls.