Docjenser: you make a very good point. I shouldn't be telling the contractor to switch pipe to straight...especially if that means they wouldn't put in a larger field. I was just going off what I heard. Perhaps 3,600' of slinky is equivalent to 4,800' of straight (first vs second bids respectively).

ICFHybrid: thanks again for your input. I do need more quotes and am researching companies now. And yes, I have seen the ceiling mounted ductless fixtures, and that would work fine for the upstairs, but there is no getting around the main floor without one of those large bulky units on the wall. And I, like my wife, do not like the looks of them at all (again, I do understand what a great technology they are; so no offense :-).

Based on prior posts, I thought all necessary geothermal components could be had from the junk yard for $39.95 (and included getting your car painted.) $30K is progress. :-)

Posted By geome on 08 May 2011 07:03 PM
Based on prior posts, I thought all necessary geothermal components could be had from the junk yard for $39.95 (and included getting your car painted.) $30K is progress. :-)

You misunderstand GM- 30K comes with a free (and handy) backhoe.

You misunderstand GM- 30K comes with a free (and handy) backhoe.

I'd rather spend twenty grand more and go for the free excavator.

Based on prior posts, I thought all necessary geothermal components could be had from the junk yard for $39.95 (and included getting your car painted.)

Tongue in cheek aside, there is almost no getting around using a new (or at least lightly used) scroll compressor to make one's time worthwhile.

I could machine out all the parts and draw the wire from scrap copper and make the winding insulation from beetle wings dissolved in old mimeograph fluid, but there are some cost-effectiveness limits to DIY  

Hard to find a new 4T copeland scroll for $39.95, best I've seen is about $180 plus shipping. 


BTW, the way you paint your car cheap is to tape up the windows and park it downwind of a new housing development (which are rare nowadays)

Posted By Tyler23 on 08 May 2011 06:00 PM
Docjenser: you make a very good point. I shouldn't be telling the contractor to switch pipe to straight...especially if that means they wouldn't put in a larger field. I was just going off what I heard. Perhaps 3,600' of slinky is equivalent to 4,800' of straight (first vs second bids respectively).

ICFHybrid: thanks again for your input. I do need more quotes and am researching companies now. And yes, I have seen the ceiling mounted ductless fixtures, and that would work fine for the upstairs, but there is no getting around the main floor without one of those large bulky units on the wall. And I, like my wife, do not like the looks of them at all (again, I do understand what a great technology they are; so no offense :-).

Usually it is the opposite, slinkies tend to be longer than straight, because the pipe overlaps, and you have to compensate for this and put more pipe in. Although I do not have any experience with horizontal drilling ( I assume that the pipes are close together). Also, 72 KBTU in Portland, Oregon should call for a 5 ton unit, saving you about $150 in annual operating costs, plus lesser installment costs. But I can understand your contractor, backing himself up for bit unknown performance of the house pending the efficiency upgrades.

Agreed, slinky uses more pipe but less trench for equivalent performance (per Ground Loop Design software).

Ok, so then company #2 is looking even better since they're proposing 4,800' with straight pipe over 3,600' of slinky.

Posted By Tyler23 on 09 May 2011 04:48 PM
Ok, so then company #2 is looking even better since they're proposing 4,800' with straight pipe over 3,600' of slinky.

Not necessarily. Normally we did excavate with a 3-4' shovel, and put straight pipe 3-4' apart. In a drilling scenario, the pipes are closer together, stealing heat from each other, which might actually perform worse than a slinky. I don't know.

If you run geo design software, you'll find a 6 pipe trench will have more pipe than a 4'/ft slinky trench.
j

that would work fine for the upstairs, but there is no getting around the main floor without one of those large bulky units on the wall

Aren't they designed slim and flat so they go up between the floor joists regardless of whether it is the first or second floor?

Not according to the companies I've spoken to around here.

Not according to the companies I've spoken to around here.

Haven't they shown you any product brochures?

Here is just one example of a ceiling-mounted flush cassette.

http://www.fujitsugeneral.com/cassette.htm

Call me crazy, but a heat load of 73K for a 4300' house in that location seems outlandishly high.  The ASHRAE 97.5% design temp for Longview WA is +24F, a temp at which my 2200' (+ 1500' of semi conditioned 65F basement) 2x4 framed 1.5 story with circa 1923 double-hungs + exterior storms and ~R20 roof is running  a heating oad ~20-22K. 

If your heat load is TRULY 73K @ 24F (or 20F, or even 10F) you can probably cut that by half for less than the $25-30K you'd be spending on geo.  If you're planning to tighen up the place (and it sounds as if you are, if you're planning to replace the windows), the heating design should be for the AFTER picture, not the existing.  Every extra ton you have to add now is money wasted if in the end you'll be 2x oversized, which puts you sliding on the steep knee of the efficiency curve.   It's better to buy the building envelope efficiency upgrades now, and buy less heating system so that it runs efficiently both now and later.

If you have a lot of 1960s vintage single-pane picture windows/sliders that aren't retrofittable with exterior storms, replace them- it's the most cost-effective solution. But if you have windows that are reasonably tight but retrofittable, quality exterior storms are by far more affordable than a high-performance new window.

If you have a full basement with uninsulated walls, that could easily be 20% of seasonal heat loss (if a smaller fraction of your peak heat load.)  An inch of semi-permeable XPS against the foundation + an interior studwall with UNFACED (to allow the foundation to dry to the interior) batts would bring you up to ~R15 for a whole-wall R on the basement. Then 2" of closed cell foam on the band joist & foundation sill completes the package.

Get a calibrated blower door test & infrared imaging scan to find all of the insulation gaps and air leaks (having done construction in that area in the '70s I can tell you with certainty there are LOTS of leaks, compressions and gaps.)  A typical western WA stick built in 1968 was 2x4 16" on center, with R11 batts. Those batts were probably mis-installed a the "typical" level, with lots of compressions gaps & voids, and the whole-wall R probably isn't over R7.5. (If perfect the whole-wall R would still be only ~ R9.5-ish.)  A retrofit of non expanding injection foam (more expensive) would bring that up to about R11+, but a retrofit of  (less expensive) dense packed or even low-density cellulose would bring it up to ~R10 performance, and either solution would reduce the air infiltration through walls by more than 75%.  Similarly, if you have the typical ill-fitting R19 batts (or less) in the attic, air-sealing every ceiling penetration/flue/chase then doing a foot of cellulose over them is CHEAP compared to the cost of installing the extra capacity of geo required to handle the difference in heating load.

Seriously- air seal first, then insulate, replace or remediate the worst of the glazing issues, and THEN size the heating system, not the other way around.  Find an insulation contractor who offers air-sealing as a service.

Also, with a 24F design temp it's hard to make a rationale for geo vs. air-source too (or even air-to-water rather than a standard air-to-air or mini-split.)  At the high end of air source units, you can easily hit geo-type numbers.  From a comfort point of view low-temp hydronic panels are more comfortable than low-temp air.  Some variant of the Daikin Altherma air-to-hydronic may be worth it- probably cheaper than geo with similar performance. 

Whether air-source or geo, considert that summertime dew points in WA are low enough that sensible cooling can be done with panel radiators without running into condensation issues.  Low temp radiant panels (eg Runtal UF  or VLX series) are pretty non-intrusive, and it's a lot easier to thread PEX plumbing through joist bays, chases &  wall framing than it is to retrofit seal & insulate a bunch of duct work, and the pumping power required to move heat in water is a tiny fraction of that of air-handlers. The net system efficiency (not just the heat-pump efficiency) goes up along with the comfort level, and the noise factor goes down.

ICF: we have a company coming out for a bid Tuesday that does ductless, so I will ask him about that.

Dana: thanks for the info. I'm afraid I do not understand a ton about this, but I get your point. The second geo contractor just provided his quote last night. He took full measurements of rooms and windows (and their orientation) and came up with a heating load of 75,595 and a cooling load of 81,533 (!!) using temps of 15 and 95 degrees respectively. He was saying that the 6 ton won't keep up with the cooling needs (but can be rectified with proper zoning) and the heat strip will be needed on occasion to keep up with heating.

15F is an unnecessarily low design constraint- it's 5V below the design temps for Vancouver B.C. (which is definitely cooler than Vancouver WA.) A more realistic design temp would be 25F (only 3% of the hours in a winter would be cooler than hours that occur in the pre-dawn hours when most people are warm, in bed.) By dropping it those 10 degrees to 15F you're adding ~20% to the size of the system, for no good reason. While the first ton of geo is the most expensive the other 5 still add up. If you can peel off 2-3 tons it makes a difference (both on system efficiency and installed price.)

But even using 15F as a design temp, to have an actual heat load north of 75K means you either live in a glass house or have the draftiest least-insulated house in SW WA. Reality is likely to come in at about half that, maybe even 2/3 of that number if you have a lot of single-pane glass.

If 6 tons isn't going to keep up in summer it must mean that you have a lots SOUTH facing high-gain glass with no shading. (This load too can be drastically reduced for far less than the cost of a couple tons of geo.)

How are you currently heating the house (equipment type, and approximate AFUE efficiency), and what is your energy use like? It's possible to calculate a very close approximation of the whole-house load at any given temp by correlating heating energy use at the efficiency of the heating equipment against heating degree-day weather data.

It's common amongst heating contractors to make the worst-case assumptions on insulation & infiltration factors when doing heat load estimates, and even if all of the date is accurate the heat-load software packages pad it out by 15-25%. A common net result (even amongst well-intentioned practitioners) is to end up with numbers that are 2x oversized, sometimes even more. Unlike heat load calculations, correlating energy use against weather data is a MEASUREMENT, with far less inherent error. While that measurement doesn't give you the room-by-room balance information, the whole-house number is quite real. The only time you end up with errors as large as a heat-loss calc using those methods is if you're supplementing the primary heating system, such wood stoves, etc., or have a huge solar gain from south facing glass, but those too can be accounted for with sufficient wood-use and weather data, if need be.

Money is money- when buying into a high-ticket heating system, it pays to do the real math, get out a sharp pencil and calculate where it's more expensive to pluck the low-hanging fruit of upgrading the building than up-sizing the system. A ton of reduced load is more valuable than a ton of system capacity, since the ton of load reduction has no operating cost, and a much longer lifecycle. When in doubt, err toward the building upgrades. A less-drafty better-insulated house with higher efficiency windows is far more comfortable at any given indoor air temp & humidity than the less-tight less-insulated version of the house with a bigger HVAC equipment.

came up with a heating load of 75,595 and a cooling load of 81,533

WOW - what Dana said, totally unrealistic, even with single pane windows.

FWIW, own house built in 1974 is 5300 sq ft just up I-5 near Seattle. Last winter, it got down to 12 F one night, and the GSHP did not come on more than 50% of the time. Have turned on the AC only twice in the last 10 years.

The 76K heating is high, but the 81K cooling load is absurd for Longview or Vancouver, WA. -- unless maybe you have a 40 foot by 8 foot window wall for a Mt. Hood view.

That's what I was thinkin'... it has to be an all-glass house, with all windows facing south! ;-)

That would do it!

And a few sashes is a lot cheaper than the geo required to support the heating & cooling loads of missing windows, eh? A missing window is a rough approximation of "typical" pre-air sealing air infiltration in a 1960s vintage house though.

For most 1968 homes at a minimum it's appropriate to:

1: air seal the place to under 3 air changes per hour @ 50 pascals (ACH50)- under 2 if it looks like you can. Start with all of the big holes as a DIY, let the pros handle the rest. The biggest untreated less-obvious leak in most homes is the foundation sill & band joist. One or two inches of closed cell foam as an air-seal/insulation on the band joist often does wonders. Top sealing flue dampers for fireplaces, backflow preventers on kitchen & bath fans/vents, air-tight boxes over recessed light fixtures, foam/cellulose fill in any plumbing & electrical chases. Most places will have air leakage the size of a small to mid-sized window if they've never been treated. Some will have leakage equivalent to a large missing window.

2: Add insulation where ever it's easy, cheap or just plain missing (like the band joist & foundation walls.)

3: add storm windows or replacements (& exterior shades where appropriate for limiting summertime solar gain.)

Most 1960s homes in WA came with zero foundation insulation, air-leaky and little wall insulation, single pane (sometimes leaky aluminum frame) windows, and scant attic insulation. Spending even $10K on the most-obvious be might be enough to cut the peak heat heat load (and annual heating/cooling energy consumption) by more than half, to the point where most of the heating & cooling could be handled by a mini-split. Only when all of the low-hanging fruit has been plucked does sizing a heating system make sense, and with high-ticket heating systems it pays to pluck a bit higher up the tree.

But we can get a better handle on the true as-is heat load if we had some heating fuel use info, if Tyler want's to share.

For the $25-30KUSD we're talking about pouring into geo it's often possilbe to attack the building retrofit on multiple fronts at once rather than piecemeal, and you can do a LOT with a circa 1968 stick-built without gutting it (only sometimes is it easier to do from the inside-out):

http://www.buildingscienceconsulting.com/presentations/documents/2010-04-14_Deep_Energy_Retrofits_Details.pdf

http://newenglandgreenbuild.com/DeepEnergyRetrofit.aspx

https://www.powerofaction.com/media/pdf/DER_CaseStudy_Belchertown_MA.pdf

https://www.powerofaction.com/media/pdf/DER_CaseStudy_Millbury_MA.pdf

http://www.lowesforpros.com/deep-energy-retrofits-for-existing-homes