Are there any ball park estimates of how many BTUs you get per square foot of geo loops buried in a field or wide trenches?

I am wondering if I dug out the whole backyard and lined it with loops and buried it say 6' down what kind of area I'd need for 30 000 BTUs.

Thanks

John

Ballpark estimates are a great way of both wasting $$ as well as ending up with a geo-exchange systems that doesn't work. The proper thing to do is a soil conductivity check, with a depth of bury economic review, and the load side balance for either heating or cooling. The source side energy exchange needs to be balanced with the heat pump heating and cooling load.

It also depends on whether you are using slinky coils, straight pipe, what diameter, and what type of geo-exchange fluid you intend to use. A local geo-echange specialist who has done work in your area will at least be more knowledgable about the soil conditions and local climate with respect to a heat pump "system", and it IS a system - all parts have to be designed together - the geo field, the heat pump, the building heating and cooling terminals, and the controls.

ok so in Vancouver with typical soils, slinky coils, optimum diameter and fluid etc what range of areas might we be looking at?

Thanks

John

OK, really roughly - Vancouver climate, average starting soil temperatures of around 57F, 6 feet down slinkies with damp sand bedding, and at peak summer conditions if the cooling load is the dominant load, you'd need approximately 3 runs of 75 foot long slinky (equals about 250 feet lineal stretched out) separated by 6 feet, so that'd be roughly a minimum of 80 feet by 20 feet worth of area for 2.5 tons of cooling load source side.

You can mix and match that - use more, shorter runs of slinky to create more of a square layout.

That being said, the best practice around here is to install slinkies at least 8 feet down in a sand bedding. If one assumes the worst case of dry sand, then you'd have to multiply what I said above by at least 1.7 to get the same ground heat exchange capacity.

That's really useful info.

I assume heating would be similar. The coils would never be dry here with the winter rains - does that improve the situation and thus reduce the area that would be required for heating? Just a thought.

Thanks

John