This is my 1st post. Thanks for posting all kinds of good information. I'm concerned there isn't enough moisture to do horizontal effectively at my site. - What is the definition of damp sand? Is there a rule of thumb for needed moisture percentage in sand? - Would it help to route the rain water from the rain gutters into a horizontal loop field? - Does moisture content typical go up as you go deeper (5ft vs 8ft)? - Is the ground which has snow on top hold more moisture in the winter, during the heating season? More Info (which most of which is probably irrelevant). Location - 10 miles Northwest of Big Rapids, Michigan, 45 miles east of Lake Michigan by crow. Rainfall - 33 inches Snowfall - 97 inches Water table depth (according to USGS map) is 45-60 feet. I have a backhoe which I can dig down to 17 feet. I have 40 acres of mostly yellow sand with small amounts of gravel, house location is on a 90 foot high gradually sloping ridge (up to 10%). The sand will cave in if there are no roots holding the top layer. Vegetation grows (my fruit tress which I planted 6 years ago are doing well). The natural grass is pretty thin (not a high number of blades per square inch). There is also about a 7 acre hardwoods on about a steeper ridge (up to 30% down slope) 100 feet from the building site. We will build a new house in 2015, and do most excavation in 2014. We will condition 1400 square feet, of which about 700 square feet is radiant flooring to keep my wife's feet warm. We will also carry about 60% of the heat load with a wood stove. In winter, the bedroom can be 50-55 degrees F. In summer, house can be 85 degrees F, as long as humidity is low. Therefore, I'm thinking a 2 ton combination unit, which I will let a local installer help deciding. I have briefly talked to a local installer, who I liked on the phone. He asked if I had house plans I could send (which I thought was good sign). I wasn't ready yet. He also didn't know if vertical loops over horizontal loops is a better choice based on our short phone conversation. Thanks, Todd
Todd: Your land is in the sand that was a Lake Michigan beach when hairy elephants lived in your yard. Sand lets water get away from the loop field pipes. So, if you can reach 17' with your hoe, and the ground does not cave in, I take loops at least a foot below what the LAHJ wants for a building footer. Mark
Combo units should be sized larger, since they must satisfy either radiant or forced air, before they switch over to the other, non prioritized zone. Why don't you do the whole house radiant, and then use a fan coil for A/C? Just to keep things simple. Also you should rethink the idea of cover 60% with a wood stove. To bold in a 4 ton unit is the same amount than a 2 ton unit, the incremental costs are only slightly higher. Loopfield: Rain water help, some people put even a soaker hose in. Moisture usually goes up the deeper you go. Yes, more moisture in the winter, less evaporation. Why don't you put more loop in to compensate for the dryer ground? You own the backhoe and plastic pipe is relatively inexpensive.
-- I definitely seems like beach sand. -- What do I do if dig up a hairy elephant? -- OK, 2 ton is probably too small then. -- The incremental costs if I can do horizontal are only slightly higher, but if I had to vertical wells, it would be significantly more. -- I'll let the installer make the decisions on how big and type of a unit I need after he does the manual J calculations. But I definitely want it sized for cooling/dehumidification. -- Does a fan coil do a good job of lowering humidity? -- How much efficiency would I lose? I don't think it matters much though. -- Can a fan coil do both heat and air conditioning? There will be an upstairs (600 square ft) in the house too, which will only be used when we have guests, which I'd like able to heat somewhat quickly. I want to keep the master bedroom colder. There will probably be enough heat from the bathroom and living room to heat the master bedroom. The total time heating with hot air around should be minimal. -- I've been using a wood stove about 35 of my 47 years on earth. I love gathering firewood, and watching the flame burn. It is a great excuse to get outside on a sunny winter day. -- 60% would be max. The stove I will get has the following ratings "11,194 BTU's/h for up to 30 hours" and"33,582 BTU's/h for 10 hours", so I will be somewhere in between. --If I can do trenches, then I don't have the cost of vertical wells, and putting in a bigger unit will be incrementally more expensive. If doing vertical wells, then the costs is no longer incremental. -- How much bigger is the question? The Enertech loop calculator which I just saw today shows 50%-100% bigger. The calculator actually defines the soil types, so I can see what kind of soil I have (heavy or light, damp or dry) by weighing it. When spring gets here, I will see what kind of trench I can dig, hoping to dig down 10' and 3' wide (hoe bucket is 3') without caving in, especially if I put the trenches in an area between red pine stumps whose roots will hold the sand. Is there a easier way to lay tubing without going in the trench? - My thought is to borrow a 16' aluminum scaffolding plank as a bridge across the trench. Lay some tubing, push tubing to sides with pole, move the plank 20', lay some tubing, push tubing to sides with pole, move the plank 20', lay ... Most likely 2 loops per trench. Nobody in the trench, nobody on the sides of the trench. Is there a max time the tubing can be in the ground before being hooked up? - This would allow me to do my trenching and tubing in 2014. - I think I read somewhere, that it doesn't like exposure to the sun, so I'd have to cover the ends where it connects up with the header. - Would it hurt to freeze over the winter - Does the tubing need to stay pressurized
It depends on the coil and the temperature of the chilled water. Yes, both heat and cooling, but you loose some efficiency, since the fan coils need higher supply temperatures for heating. That is all great, but you would be the first person in the world who does not get hurt, does not get ill, does not get older or simply does not pass on the house to another person who does not want to or cannot get outside on a winter day. I usually shy away from undersizing the system, since our name is on it, and than our geosystem "does not work" for the new owner. So what is the deal, dig a trench and make it 50-100% bigger. Do a slinky and you really save yourself some money/effort without sacrificing the performance. It can stay there forever, no need to keep it pressurized. I would seal it to keep the dirt out.
I cant speak for how well your sand would work I'm definitely not a expert. But having lived 100 yards from a Lake Michigan beach its basically silica sand which is far far different then what your describing. We have a racetrack loop field in a fine sandy gravely mix at about 6 ft, 600ft per ton. Our neighbors basement will have water coming in it after a short period if their sump quits. So our water table is much much higher.
So does mine. But before I put it in the ground, I cut the pipe open. If I do not hear it depressurizing, I become very suspicious.
We wouldn't let our son leave for Big Rapids yesterday and he is snowed in today. Go ahead and plan on a wood burner if you like, but plan on a right sized geo in case you don't want to haul lumber on days like today. A wood boiler would make a lot of sense and like anything else you use less fuel if you design for low temp delivery. Start with heat loss/gain when you get prints, set up 4 stages of heat- wood boiler hot water, WTW geo, hydronic air handler with hot water and electric auxiliary. That way if the wood burner goes out the geo kicks on automatically. 1 stage summer cooling with same air handler. If you need a site visit sometime it'll give me a good excuse for visiting boy.3
I'll only address this part of your post as I'm not qualified to answer any of the real questions...but What you've said was me a few years ago. You never know what life's going to throw at you, though. 3 years ago, it was a pretty bad back injury when I was working on my firewood supply. That took me out of cutting firewood and was the year we decided to put in our geo system. Last year, I nearly killed myself in a bicycling accident. Mostly healed up now, but I'm real happy we put in the geo system (that does all our heating) when we did. Oh, almost forgot to mention, I fell off a ladder this summer and dislocated my elbow. FWIW, I haven't cut wood in over 3 years and haven't missed it a bit. 2 cents of someone who thought he was indestructible (and who should stay away from work, off of fast things, and down from high places, but probably won't).
