Heating and cooling a sunroom

mrbreeze(z6/7 OK)February 3, 2009

I'm in the very early stages of planning for some type of sunroom. I know there are countless ways to heat and cool them so I was wondering if anyone has some actual 'real world' experiences to share about advantages/disadvantages of various methods?

More specifically, the contractor that was here today mentioned an Amana wall unit heater/AC similar to what my mother has in hers. It would be fine for hanging out but for growing orchids...it would have issues. Both the heating and the cooling would screw up the humidity. Maybe that cannot be avoided?

So some other possibilities would be: under floor heating, baseboard, electric space heater, gas fired of various types, and? For cooling, some type of evap. cooler makes the most sense but I don't know how one of those could be incorporated in a sunroom and I guess they couldn't be used in the cold months. I could use stand alone humidifiers and let them fight it out with the heater/AC I suppose.

There are french doors that would open into the room from the rest of the house. So another possibility might be to have them open to allow the temps to modulate but have some kind of plastic curtain to keep the humidity in. I can also design the floor so that it could be sprayed down (perhaps with a drain?) to increase humidity. Any thoughts are appreciated!

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xmpraedicta(3b Saskatoon)

Woah sounds like an amazing project. Is this going to be mainly utilized for growing plants, or will it be a sitting area with some plants in it?

Not much help, but we had a sunroom built 2 years ago, and it is heated by an artificial fireplace against one wall. However, it is open to the rest of the house, so there is heat exchange. Ours is mainly for human use though, so the only thing that benefits the plants is the extra bit of sun

    Bookmark   February 3, 2009 at 11:31PM
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mrbreeze(z6/7 OK)

Yea it'll be mainly for plants. I'd do a greenhouse but I'd rather spend the money on something that will also add value to the house. It would be for sun, space, and humidity reasons and to free up the space in the house.

    Bookmark   February 4, 2009 at 12:10AM
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Last year we enclosed our sunroom with windows and added insulation with a new wall inside and out. There are windows on the north, west, and south side, with the majority on the west side. It is about 22 feet long by 10 feet wide. It has an aluminum roof, so no sky-lights (regretably).

I have all my plants (houseplants and +40 orchids) overwintering in our attached sunroom, on tables, hanging, and on shelves, and while I am esctatic, other (older) people in the house are less than thrilled since the drafts seem to come through the expensive windows and go right down to the below-grade living area. This is the source of constant family arguements, so beware!! The room is accessed throught a sliding glass patio door that is pretty much open year round (thought about removing it, but the dog is not allowed in, just yet). There is another door, (stained glass with strom door) with access to the yard/garden.

That being said, we added a electric fireplace which runs at night almost all winter and the temp along the common wall is about 65-70F and night while the window ledge is around 55-60F depending on winds and temps. The humidity ranges from 40-60% all winter which is good for most plants. We also sliced the heating vent and ran one through the floorboard into the sunroom so the furnace does reach. In the summer, we can close the vent and leave the air off in the room and open all windows, but its so hot that we usually lower the shades and keep it a little cooler with closed windows (depends on the summer humidity). Next year I am going to try to seal all windows with plastic bubble wrap or the like to minimize drafts. The worst is over, now that teh days are getting longer the sun is actually warming it up. I have tried turning the fan on to circulate the air (counter-clockwise direction, I think) and I swear the temp warms up a bit, but others disagree.

I will try to post pics since I got a new camera, we'll see how that goes.

    Bookmark   February 4, 2009 at 6:50PM
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We rebuilt our sunroom this summer and it still isn't finished. Needs to have the floor put in. I've had the sunroom for 20 years and carpenter ants decided to eat it, thus the rebuilding. The old room was all sliding doors with skylights. We added windows and left two sliders plus the sky-lights. The room is 18 x 12 ft. I've grown my plants in that room all these years but it was never heated and would freeze in winter so they came in the house in Oct. Now it is insulated and tight. I run two space heaters and this is the first winter the plants have spent there. I can tell you the problems I've had so far.

I keep the space heaters set to 60-65. They run constantly at night . When the temps are low, like now - 10 degrees the room hoovers around 50-55. I do not keep Phals or warm growers in the room unless the night temps, outdoors stay above 40 degrees. I have all my Catts, some intergens, Odont's, Masdies and nobiles out there. They get tons of sunlight, but the days are short and I am not supplementing. I probably lost my flowers on the Catts.

Big problem is humidity. Desert dry. I gave up on running humidifiers. The space heaters dry out the air faster than the humidifiers can put the moisture in. Can't get humidity above 30% (on a good day). Furthermore, when the temps drop at night, the air is cold and moist (50%) and I develop moisture on the ceilings and walls-not good! I now only run the humidifiers during the day when the room temp stays above 60. The space heaters have a hard time. My electric bill is off the wall.

I pack the plants close together to create a micro-climate and they seem to be doing okay. I haven't had fungal problems surprisingly. I expected to develop fungal problems because of the cool damp nights. I need to water many plants 2-3 times a week. They dry out quickly.

Most of the plants have stalled but seem fine. Odont's are all spiking as is one Mastie. Cool intergens are making growths. Again, my warm growers are kept in the house.

I'm not thrilled with the results. So far I have only seen a difference with the cool growers. They love it. Catts are sitting with sheaths, no sign of growth. I have one SLC blooming and seems to love the cold, dry conditions.

Old room, with sliders, in summer.

Rebuilt room, taken in October.


    Bookmark   February 5, 2009 at 12:11AM
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mrbreeze(z6/7 OK)

Wow great info and thanks for the pics as well. Is your room open to the rest of your house, Jane? I wonder if the fact that mine would be accessed through a set of french doors but is otherwise isolated, might help the humidity issue.

I definitely appreciate the info on the heating. It doesn't get nearly so cold here but we do get cold and we often get ice storms. I think natural gas is going to be a must in case of power loss, especially since there is already a gas line nearby. I can't help wondering if an underfloor system fed by a small gas water tank might be worth considering. I'm sure it would be hella expensive up front but might pay off in the long run. Maybe I could even DIY it! For the most part, i'm not going to want the humidity *or* the temp to go much below 60.

    Bookmark   February 5, 2009 at 1:21AM
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Our sunroom, which looks about the size of Jane's, is open to the rest of the house. The southeast wall is entirely windows (fixed, plus some awning windows on the bottom near the floor for summer ventilation) and the other 2 walls are mostly taken up by large windows with just a little space above and below. It has a large overhead fan. Before I started growing orchids, I seldom used it but now it's on most of the time. We heat with natural gas and have a humidifier on the furnace for the cold weather months. I sit my orchids on those clear trays with ridges so I can pour in a little water but it doesn't touch the bottom of the pots. I don't know the humidity level--I should check. I figure they just have to adapt. Also, we don't have a lot of trees close to that end of the house so on sunny days we get a lot of sun and ambient heating. The windows are shaded by white vertical blinds which allows me to partially or fully close them when necessary.

    Bookmark   February 5, 2009 at 8:38AM
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cjwatson(Z8 FL)

The plants themselves will produce a good deal of humidity of you have anough of them in the room. Of course that means buying lots and lots of orchids. Big pots of bromeliads under the benches with their crowns filled with water help add to the humidity and look pretty and tropical at the same time. Even hanging baskets of Philodendrons add to humidity; mine are almost always dripped water from their leaves during the night -- there are many plants which do that.

Mike, do you think you will have a problem filling up the room with orchids and tropical plants? Just asking. Hehehehehehe.

    Bookmark   February 5, 2009 at 9:04AM
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We built a sunroom about three years ago.I live in northern Illinois about one hour north of Chicago.My sunroom is about 18'x12' off of my kitchen,with French doors to close it off.I have triple pane glass casement windows that open by crank to the outside,and 6 skylight windows that have blinds to open and close and the windows themselves can be cranked open.In the summer,I can get amazing ventilation in the room by adjusting these so that even though I have air conditioning available I have not needed to use it.
My heat is from radiant heat flooring that has worked very well for my area of the country.I have a back up heating unit(forced air)that we thought we might need in the coldest of winter days,but again,I think it kicked on once,and that was because I did not have its thermostat set correctly.
My floor is thick ceramic tile that I put a floor drain in,so watering the plants is no problem.I can wet down the floor for added humidity also.I run ahumidifier in winter and keep one of the French doors closed to try to contain it but I get about 30% at best.So I'm still working on that.

    Bookmark   February 5, 2009 at 11:19AM
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bcfromfl(z8a NW FL)

My dad has a 14x20 gh that he connected to his home with an insulated and drywalled passageway. He lives in upstate New York, and the humidity inside the gh is usually substantial.

Just a head's up -- the drywall around the door to the gh is starting to crumble from condensation/moisture. I'd imagine with a sunroom suitable for orchids you'd have similar issues.


    Bookmark   February 5, 2009 at 7:23PM
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we had our sunroom built about 3 years ago. it has sliding windows all around and sliding doors to the garden. there are no walls except the wall to the house. it is assessed thru the sliding patio doors from the house. we had decided to keep those so that it can be closed and so that the sunroom can be a separate unit with its own temp. control. there are also 2 skylights. we a have unit which is a combination air conditioner/heater made by sanyo. it draws air from the outside and runs with a fan so that in the winter, i don't need another fan to circulate the air. it is 12'x14'. i don't think i have any problems with humidity because i have alot of plants in there - the mounted ones - i water every second day and the others I water once every 7-10 days. and no fungal problems because of the fan from the heater. the windows are supposed to be thermal type. our electricity bill is about $40/mth more than if I were not heating it. I keep the temp. in there 50-55F. all the cool growing ones are in there. in the summer i open the windows on the 3 sides and i get good air movement flowing thru: have not had to use the air conditioner unless i find it too hot for myself. i have a ceiling fan which i thought i may need which i really haven't needed it. we also use the sunroom as living space - we enjoy having our coffee in there - (we turn the heat up when we are in there in the winter ).

    Bookmark   February 5, 2009 at 8:27PM
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My sun room is really a closed, with windows, front porch. No sky lights. South facing with no trees to shade it so it gets much light. I just moved to this house in the last summer so have much to learn. Humidity here is no problem, 90 % am 65 % pm average. Since my room is attached it stays warm in winter, My central AC/Heat is connected if needed. I have about 30 Catts there now and just need to learn how to make them thrive. Still struggling with watering, etc. Information in this forum is very helpful
Joe T

    Bookmark   February 5, 2009 at 9:43PM
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I would be more than happy to answer any questions regarding sunrooms. My family business has been building all types of them since my grandparents started the company in 1947. You could even check out website for different style and get my phone number there and give me a call. We're in Sacramento CA. but I'd be glad to help where ever you are.


Here is a link that might be useful: My family business website

    Bookmark   January 13, 2011 at 7:43PM
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ifraser25(z11 Brazil)

Interesting question . I had a sunroom in my house in England and made a lot of mistakes growing unsuitable plants. IMHO it is not a wise idea to heat too much in winter esp.in Oklahoma, where I guess it is not always cold anyway -you will get a lot of problems with pests/ low humidity. Aim to keep it just above freezing in winter. On the other hand, cool as much as you like during the summer, tropical plants adapt very well in general to lower day time temps, but keep them very dry when temps are low at night. There are plenty of systems but nothing beats a powerful A/C. Don't rely on external ventilation. If it gets as hot in Oklahoma (I guess it does) as it did in Texas, it will be no use. Best orchid (I know you like orchids): Cymbidium. Good luck - Ian.

    Bookmark   January 16, 2011 at 8:35PM
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