Greenhouse heat

[bullsie]

I am putting on a few rooms at my end of the world (going to move Mom in with us) and am planning a greenhouse to be attached in back. It will not be a lean-to style but an even span with a breezeway attachment directly to the house. My question is my heating system. In the house is hot water floor heating. I want to run the hot water system out to the greenhouse but know the floor heating, as such, will not work in the greenhouse. So what I am thinking of are pipes and/or cast iron radiators.

Either go with a piping system as in the old style greenhouses and possibly the fins on for better heat radiation. Or try the low broad cast iron radiators. Or are there other options?

I guess my question is, for those with hot water greenhouse heating, how are you set up? Pros and cons and what would you change.

Appreciate any feedback possible. Greenhouse going in this spring, addition going up now.

 

[Lycaste53]

Normally, floor heating works with lower temperatures as radiators. If you use the same water for both, you have to use more radiators- or bigger ones- to get the same temperatures. Maybe you can do floor heating in the greenhouse to provide a certain temperature level in addition with a second heating system for very cold days.
In my greenhouse, I have both, and it works very well.

 

[cnycharles]

radiant floor heating can be very helpful, and can provide quite a bit of heat if it's set up right. in some of our newer ranges at work, there is floor heat, then hot water pipes (not steam) and then natural gas blower/heaters mounted along the walls. also, many radiant heating systems put flexible piping directly underneath the tops of the benches so that the heat is used directly upwards through the plants, which they usually like pretty well. where we are we have boilers but then there is a large heat exchanger between the warm/hot water heating system and the boiler system. you also need a fairly large water expansion tank for your hot water supply. also you need to be adjusting the water supply in your heating system so that the pH and all isn't going to corrode your pipes; I think with the flexible bench and floor heating, it may be plastic lined so I don't know if you need to do the chemical adjustments of the water. you can check out small greenhouse supply companies and they should be able to tell you just what you would need for a certain size greenhouse, as they often supply those systems

a steam boiler would be 'simple' sort of, but you have to adjust the pH so your pipes don't wear out/rust. I don't know how a direct hot water heating system works without a 'boiler' system hooked to it, don't know if you need a heat exchanger in between or not. the flexible piping under benches you can use with moveable benches

 

[Bob in Albany N.Y.]

I heat my greenhouse with the same furnace that I heat my home with. Luckily, when I upgraded the heating system I got a larger boiler than I needed as I too was thinking of adding on a room for Mom. My boiler is oil heated and have two sets of pipes running on all the walls of the greenhouse. These are hot water pipes. One wouldn't have given me enough heat. The biggest problem I had was trying to get a programmable thermostat that would keep working in there. I finally bought one that was mounted in my living room but had a lead out into the greenhouse. That is a must and I had a hard time finding such a thing but can give you more information later if you need it. I also installed a large hot water heater before the furnace. This allows the water to preheat before entering the furnace, thus a faster turn around time. I only turn that on, when we are in single digits.

 

[bullsie]

I will be putting a coal boiler in and it does both domestic hot water and heating the home. I grew up with that and have not been satisfied with - nor can I afford - the oil furnace.

I remember the old commercial greenhouses that had several rows of iron pipes running through. I was unsure if floor heating was possible in a greenhouse, but the idea of using it about benches is a thought. Running several pipes along the wall - as you have done Bob - is what I had originally thought.

Wow, the thermostat! I never even gave it a thought. Better add that to the list of things I will need to look into. Yes, thanks muchly Bob.

I have to run a seperate water line in to the greenhouse due to the water softener. So, I figure a little this way and a little that way. Eventually, it all gets figured out. But I will definitely be looking for any helpful suggestions and ideas.

 

[cnycharles]

in some of our smaller houses that had steam heat, each section also had steam pipes running along the floor (as well as pipes along the outside wall). also in some houses there were a few large pipes heating up in the air

 

[bullsie]

cnycharles, I remember the upper pipes in the oldies. It really was great looking. And because of the weight, nothing was hung on them so they were rather obvious to see - as all space was used for plants.

I am still trying to formulate best heating method and am looking into keeping most if not all the foundation blocks below ground. Keeping it low in the ground may help with the heating. I see how the layout of the land is as this building project pans out.

 

[Rick]

Ross Hella (Paphreek) put radiant floor heating into his GH.

You may check out his GH construction series.

His pec tubing is on top of Styrofoam sheet buried in sand with a layer of gravel on top. Following up with him, he indicated that he thought the tubing was buried too deep, but essentially the system works.

I've pulled a couple of other radiant floor systems for GH's off the web, and it didn't seem to make a difference if the system was buried in sand or covered in concrete.

 

[Ross]

Ross Hella (Paphreek) put radiant floor heating into his GH.

You may check out his GH construction series.

His pec tubing is on top of Styrofoam sheet buried in sand with a layer of gravel on top. Following up with him, he indicated that he thought the tubing was buried too deep, but essentially the system works.

I've pulled a couple of other radiant floor systems for GH's off the web, and it didn't seem to make a difference if the system was buried in sand or covered in concrete.

An update: My in "floor" heat keeps the greenhouse at a minimum of 60F even in the coldest weather. Daylight sun will generally warm the greenhouse to 68-78F depending on the angle of the sun. I use the overhead Hot Dawg as backup in case of electrical outage, to raise the temp a bit if I want to on a cloudy day, and to help dry out the plants after watering on these short, low light days.

Here's a link to the photos of in floor heat installation. Unfortunately there is not a lot of detail as I was at work while it was being put in. http://www.slippertalk.com/forum/showthread.php?t=16251&highlight=construction&page=2 and another link: http://www.slippertalk.com/forum/showthread.php?t=16251&highlight=construction&page=4

 

[Rick]

Ok had the first power outage of the season. Power was out for at least 3 hours.

It was probably good that it was only down to about 40 or so (with heavy cloud cover).

The Blueflame propane heater supported a constant 60-62F at the thermometers. I checked the data logger which is at head height in the GH. My wife periodically checked the thermometer on the other side of the GH (also at head height, and it also showed a pretty constant 60 or so).

So without any electricity to run the circulatory fans I was pretty impressed that the temp didn't seem to radically stratify and cook the top while freezing the bottom. It could be that since this GH is a few feet taller (and much better insulated) that the rising heat off the heater is causing its own rolling circulation pattern.

I still went and bought a small backup generator to get enough juice for the fans (actually its big enough to run the well pump, so we can still get some water in the house while waiting for the power to come back on!!!)

 

[Ray]

No that Rob has rejoined us, I'll pass on some great advice he gave me:

My area is plagued by frequent power outages, so I bought a generator. However, when it's rainy/snowing/cold at 3 am, it's a pain to get out of bed and go start the thing. So, at Rob's suggestion, I bought a deep cycle marine battery and a charger/inverter, to which the heater and fans are connected.

During normal power, it keeps the battery topped-up. Upon loss of power, it automatically - and instantly - switches over to battery power, and the greenhouse stays comfortable. With my current battery, it appears to be good for about 6 hours, which is plenty of time for power resumption most of the time, and certainly enough to get the generator going. I may add batteries to give me even more time - or kill the fan addition, as they eat up the amps.

 

[cnycharles]

how about a solar panel to keep the batteries topped up, then you don't need to buy the electric, and maybe use the panel for emergency fans when there isn't any power, or to open vents etc? I think I see that maybe a bunch of fans might not work on a solar panel by itself but if the fans draw down the batteries a lot, and it's sunny, then the panel could help keep the battery up as well. granted the power going out is a good 'switch' to use for turning on the backup when main goes out

 

[Rick]

how about a solar panel to keep the batteries topped up, then you don't need to buy the electric, and maybe use the panel for emergency fans when there isn't any power, or to open vents etc? I think I see that maybe a bunch of fans might not work on a solar panel by itself but if the fans draw down the batteries a lot, and it's sunny, then the panel could help keep the battery up as well. granted the power going out is a good 'switch' to use for turning on the backup when main goes out

So far I've been really depressed about the cost of solar charging of the back up and the cost of the auto transfer.

I had a deep cycle battery and DC/AC inverter, but the auto transfer was out of my price range at the time. And since then the inverter rotted out from the humidity of the GH. Next time I guess it all needs to be in a low humidity shed or box outside of the GH.

They also make DC fan motors so you don't even need the inverter, but the last time I checked these were pretty pricey too.

When I was adding a ventilator fan for our attic I did find (standard home depot availability) a solar powered attic fan (I think It may be DC??) that I think was about $300.

 

[cnycharles]

there are also some solar powered vents in some of the greenhouse supply magazines (not just the vent that lifts up but a fan)

 

[Rick]

there are also some solar powered vents in some of the greenhouse supply magazines (not just the vent that lifts up but a fan)

Can they be hooked up to a deep cycle battery back up system?

 

[keithrs]

The only problem with battery back up is that...

1) Batteries (6v) are expensive.
2) limited life
3) Need to keep charged
4) Output, AH, Battery Life are dependent on temp.
5) Need to be vented outside(unless you want a explosion)

These are only some of the draw backs!

I think I would go with a standby Gen. A small LP/NG standby gen are fairly cheap(depending on who eyes your looking through) and can run off the same source as your heaters. And if your on a well you'll have a toilet you can use!:roll happy:

Or you can use a "X" wattage electric start Gen and a add a Tri fuel kit and hook it up to a auto start control panel.(RV store carry them)

 

[cnycharles]

Can they be hooked up to a deep cycle battery back up system?

I think they are self-contained, but if there was some sun, then they would vent; otherwise if no light then likely might not need to vent.

below is the link where you can see two models

http://www.growerssupply.com/farm/s...DefaultPerPage=10&searchQuery=solar+power+fan

if that doesn't work, just go to www.growerssupply.com and type in 'solar fan' into search box; top two or three results are the same as above.

each fan plus solar panel and wiring is $265. one is roof-mounted like for attics, and the other is gable-mounted. both will work completely independently of a power supply. this company does sell solar grids and I've seen them around, seemingly more affordable in recent times. I would love to be off the grid....

 

[Rick]

I would also love to be off the grid (one way or another). Or generally drastically cut my carbon footprint. So far the economics just aren't getting me there.

I just paid $500 for the generator I just picked up, and it will supply enough power to keep the fans in the GH going as well as my well pump and a few small appliances in the house.

It will cost me probably another $500 to add a transfer station so that I can keep the generator hooked up to the house and just flip switches to link it to the appropriate circuits (also after a manual starting) rather than to drag out a bunch of extension chords to hook to various appliances.

For $500 in DC solar fans and a maybe the battery backup. I do get automated airflow in the GH, but my wife will be wondering how come the GH gets electricity, while she has to hike to the creek to fetch water for the house:sob:

 

[Ray]

My generator powers the greenhouse 100%, and in my home the furnace, well pump, and enough other circuits to give us light.

I am considering converting it to propane, as gas is SO bad these days (with the ethanol), the the carb gets gummed up in no time.

 

[cnycharles]

For $500 in DC solar fans and a maybe the battery backup. I do get automated airflow in the GH, but my wife will be wondering how come the GH gets electricity, while she has to hike to the creek to fetch water for the house:sob:

well, you could tell her that the orchids are 'defense-less' and can't run to the creek to water themselves, but I wouldn't advise it