Is there anyone out there with a greenhouse who's using in-slab radiant heat to help heat it?    I'm attaching a small greenhouse directly to my house in a new home construction (identical to the one below) and giving the greenhouse its own zone.   I'm curious how closely you had the PEX spaced, how much juice you're able to get from it, and what you may be using as an auxiliary heat source when it's really cold outside. Thanks.  


John

Bobby 'Boom Boom' Villa did a project(for his wife) with a greenhouse addition to his own house. He had a dedicated boiler and used baseboards as I recall. You might be able find a copy(tape/dvd) of the project.

I'm not a radiant pro, but if it really gets cold in your location, I doubt that radiant floor will produce enough heat for your needs. The heat loss in a glass building is extremely high. You might think about baseboard radiators or another type of radiator.

Also, 'Boom Boom' created a solar storage 'sink' below the floor. It was filled with rock, and the floor above it was pavers. I definitely think it would be worth your while to see the technologies that he used.

Thanks for the note.

I'll see if I can track down info online regarding that project.   Sounds like there might be some stuff worth knowing about.

I'm aware that radiant heat in a greenhouse floor (especially in Maine) would not be sufficient to heat the place.   I'm guessing that the radiant heat may supply 1/3 (at most) of the heat necessary in the dead of winter.  The question is whether to go baseboard, stick a Rinnai heater in there, or find another alternative altogether.   You indeed are correct:  Heating a greenhouse---even a small one like mine---requires a ton of BTUs.   This particular structure is only 306 sq ft , yet will require more BTUs when the outside temp drops to -20F than it would take to heat my whole house.   The question is how much juice could I potentially GET from radiant heat in that  floor.   I'm hiring a local outfit here to do heatload calcs and to make recommendations regarding the radiant heat, but I wanted to see if there were any out-of-the-box thinkers on here (like Vila) who may have ideas to consider that may make an in-slab radiant system even more efficient.   I'm also curious about the kinds of insulation that may be best beneath the slab to keep the heat from being wasted into the ground below.   I'd also like to learn more about this 'solar storage 'sink' you mention.

Thanks again,


John

It was just a Google away.   Here's the link to the greenhouse project he did.   Thanks for mentioning it.


John

As I recall(watch the project) he used 2" of styrofoam on the bottom and sides of the 'heat sink'. They then covered(filled) it with rock, and topped off the rock with pavers for the floor. I'm guessing that the 'heat sink' was about 2' deep.

I am also designing a greenhouse--with ICFs. How did yours come out? How did you design the greenhouse? Which process did you take?