Solar radiant heat

Lou Miller

I posted a few other threads about a shop I'm building. My latest thoughts on the subject are about using solar water heating to heat the shop. The shop I'm building is 35 x 60 and I'll be installing radiant heat. Some of you suggested using warmboard in my last round of questions and it looks like I'm going that route. The shop is 2100 SF and it will be insulated very well (R-26.2 for the walls and R-54 for the ceiling). I'm only looking for ambient temperatures of about 62-65 degrees. So it shouldn't take a whole lot to heat the shop. Just from browsing around the web, I've noticed a lot of stuff out on the market for solar hot water heating. It certainly has me intrigued.

The shop I'm building is going to have around 1,200 SF of roof with a southern exposure. It's possible to cover that entire 1200 sf with solar collectors and be able to heat the shop with just the use of the sun? At the very least, just use a little support from our boiler when needed? The shop is also going to have a 2100 SF basement that is intended for storage only. So adding a few solar storage tanks down there wouldn't be difficult at all.

I saw a site where they instruct you on how to build solar collectors. Pretty simple techniques are used and most of the materials I can get for very low cost.

Is all of this worth even looking into? Or am I just looking for far too much from solar heating here?

Nron_9

Solar

Depending n where you are a so;ar colector 4x8 can collect from 10-25mbh per day , what will you heat with at night large mass storage tanks can help and solar can save you money but is limited in the winter time for solar heateing if you make it big enough for the winter what will do with the heat in the summer months , somethings to think about the solar can get to 300 F

Lou Miller

I'm right outside Philly... I'm just feeling things out right now, so I don't even know if solar is something I'm going to pursue. The thought of it sure sounds good though. I've got all the room in the world for collectors and storage, so that wouldn't be much of an issue other than initial cost. A swimming pool is planned to be added sometime in the near future, so that, along with DHW, would take care of a fair portion of the heat in the summertime. I guess I would need to find a way to shut part of the system down in the summer... Heating at night and so forth is no problem as I'd incorporate my existing boiler into the system as a backup. I don't have any delusions that mother nature is going to pick up the whole load, but if I could even get 30-40% of the load picked up by solar, it would be worth the time and money to me. I ordered a couple of books on the subject so I plan to do some studying up before I do a thing. The radiant is going in during construction (initially will be fired from the existing boiler 100%), I'm just going to try and set things up so that if I do decide to go with solar intergration, it won't require major changes to the existing system.

Thanks for the reply.

Constantin

I would follow Bobs lead...

... and consider angling the collectors quite steeply to reduce their exposure during the summer and maximize it during the winter, when you need the heat. Perhaps a very good solar contractor can figure out a way to balance the need for heat in the wintertime w/DHW needs in the summer so the poor things don't stagnate too much. Plus, you'll get more bang for your buck...

However, using solar to heat a space is always tricky because there is usually much less sun in the wintertime, water temps have to be high to be effective at heating, etc. My guess is that you'd have to go evacuated tube (Thermomax) and that gets pricey...

Bob Gagnon plumbing and heating

go for it Lou!

I installed an array of 120 thermomax tubes and they make a lot of heat. until you put the pool in, you could simply cover them with a cloth boat type cover in the summer. I find it interesting that the solar detractors biggest complaint is that they make too much heat. You could also increase your summer domestic load- I'm going to do laundry with hot water, wash my car, boat , and truck with hot water, and maybe I'll heat an enclosed outdoor deck, at night it gets pretty cool up here. The dept. of energy's web site says you can save between 10% to 90% of you heating bill with solar radiant heating. I'll be glad to help in any way. Bob Gagnon

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Constantin

Allow me to quibble...

The issue is one of longevity. Allowing evacuated tubes to stagnate could create steam, make your transfer liquid go south, etc. Remember the post that showed 120 blown Thermomax tubes in NH when someone disconnected an indoor swimming pool but did not disconnect the tubes?

This is why having anything to dump the heat into is a good idea. With your large tank and heat emitters on the outside, you could even dump the extra heat at night when no-one notices and enjoy hot water all day too... or cover the extra tubes up as you suggest also.

Lou Miller

Bob,

My primary goal with any solar system is to heat my shop. If that works out, then I'll move on to DHW and then the space heating for the house. I'm only looking for an ambient temperature of 62 degrees in the shop. Basically just warm enough for glue and finishes to dry, I don't like my work area too warm. With the way I'm going to be (over?)insulating the space, using warmboard and so forth, I don't think the load is going to be all that high. I'm pretty confident that I can get the shop done from the little I've read on the subject already. Space heating for the house though... I dunno. We'll see. It's really going to come down to money for me, at least at first anyway. The budget for everything is already small. However, by learning as much as I can now, I plan to design the system so that the solar can be added at a later date when the funds do become available. Hiring a contractor for our house is one thing I don't mind doing when it's beyond my ability. I just spent a good buck on hiring out our boiler and indirect WH replacement (money very well spent though). However, the wife and I have an agreement that I can do whatever I want with the shop, provided I do the work myself and not hire it out. She would never have agreed to the size I'm building the shop if it wasn't for our agreement. So for now, a contractor is out of the question.

Radiantec has solar collectors (4x8) for under $400 (they aren't the evac tubes though). Either I can buy some from them, or I'm in the middle of reading a book that explains how to make the collects and a storage tank. I might end up buying the collectors from Radiantec and make the storage tank myself. I like your idea of simply covering the collectors in the summer.

Larry Weingarten

Used collectors...

...might be a less troublesome way to go than making them. I found used copper, glazed 4 by 8 foot collectors for $10 each and they are now nicely heating my home. I'd just make sure to learn what fluid was in them before. If it was poorly maintained glycol, corrosion will likely be a problem. Best would be from a drain-back system that used plain water. Put out word with all the local roofers.

Yours, Larry

thfurnitureguy_4

62deg. in a wood shop????? Ok so not a heating question but how long do you want to let your stain sit before you can top coat? 80f is nice if you finish lots of big stuff like kitchen cabinets and a dry room up to 140f for short between coat and glue cure is very nice. You may want to bag the water system and use a hot air (greenhouse type colector) My father heated a house with the waste heat from his green house. Just a stand pipe like duct that went up to and along the peek of the fiberglass pannel roof. His was a lean-to frame addition along the south side of the house. He had a room stat and a small furnace blower that came on when the peak was above 70deg. It blew in to a basement window and returned through a loover on the other end of the green house. Your needs in a shop are mostly during the day. Spend your money on steam system for a suplement because the rads are easyer to keep clean in your dusty environment. Boilers are showing up all the time in the papers some quite new. People going modern Haw Haw Just a thought from a fellow Dust Monkey (AKA wood guy)

Mark Eatherton1

I personally would NOT buy ANYTHING (Thanks Constantin..)

from Radiantec. But thats just my personal opinion.

ME

Lou Miller

Furniture guy,

62 is fine for me. I plan on having a dedicated finishing room where I will use some type of supplemental heat to speed up the finishes that need help to dry faster. However, I don't do much with oil based stuff, except for poly. I thin the poly with naptha so drying time isn't really much of an issue. I've been working in an unheated space for years now, and getting the temps up to 62 degrees would have been a huge luxury. If I heated my shop to 80 degrees, I'd never get anything done. My prefered temps for working conditions are around 55, but that's too low for the glue. I'm a one man show, so the speed that finishes dry and so forth is not really all that important to me. At 62 degrees, I can take the clamps off of glueups after about 2 hours and they are fine. I don't need to speed it up any more than that. Thanks for the input, but I've already committed to going radiant. Haven't I seen your name over at Woodnet?

Larry,

The used panels is certainly not a bad way to go. I'll look into that. Thanks for the advice.

Mark,

Just a hunch here, but why do I get the feeling you meant to say you wouldN'T, buy anything from Radiantec? Either way, how about a little elaboration on that? I'm curious as to what people think of Radiantec.

Constantin

Umm, perhaps you meant something different?

I think you may have left out a "NOT" considering the positions you have taken on said company in the past?

thfurnitureguy_4

We use lacquers and ngr stains some oil stains with grain fill. "if it aint dry underneath" it causes your lacquers to turn milky (The dreaded solvent capture) also the down the road once it is installed into a 70 degree house causes the HO to pass out from the fumes and the crazing from the finish drying all at once is not popular. Are you using waterborn lacquer? Your heating setup is interesting keep posting. See you on woodnet

Lou Miller

I very seldom use stains of any kind. I'm not a fan of coloring wood. If a customer wants a different color, I usually try talking them into a different species all together. If you want maple to end up the color of walnut, why not just use walnut to begin with, right? The majority of what I do just gets a protective clear coat and that's it. For the occasional job that must have some color, I normally go with an alcohol dye, or I tint shellac and use that to establish my color. I hate oil based stains and never use them. I'm not much of a fan of water based finishes either. I use one of NCL, poly or danish oil (I make my danish oil with naptha instead of mineral spirits though so it speeds up the drying time), or shellac and wax almost 100% of the time as my final coat.

Bob Gagnon plumbing and heating

dust

you will have a lot less dust with radiant.

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Lou Miller

Bob...

The dust, or lack thereof, was a huge factor in deciding to go with radiant. It would be a whole lot cheaper to go with some other type of heating (I have some electric heaters that I could throw in and they wouldn't cost me a penny other than operating cost), but the radiant just makes the most sense. For me anyway... I'm going to have this shop for the rest of my life, so there's no point in trying to cut corners.