No, you are misunderstanding all of us.
1) My comments would suggest that their design is 1-2 tons different than I would design it in my area. I would consider 20 to 33% more than not far off.
That is based on the load calcs provided you not some revised ones with future insulation.
2) Most geo pros do not try to cover 100% of the heat load with the heat pumps, relying on auxiliary for 2-8% of the requirement. Persons who look at a 75MBH load and select a 6 ton in a relatively mild climate cost your more on the initial install and quite possibly more during operation (heavier compressor 7/24/365 vs a little auxiliary now and then).
If any have offered op cost calculations on software, ask them to plug in 4 or 5 tons vs 6 and see how the projections compare.
3) I don't know what you mean by" less extreme temps". One should use a standard weather average value for a given area.

Again I reiterate my feeling that geo may save you little over air source on the smaller zone.
j

Bids for what?

HVAC work. You weren't on the list.

What time frame constitutes "recently"?

Last 3-5 months. Hope that helps you.

ICFHybrid, did you also neglect to tell the contractor that the cost and/or the cost/value ratio was important to you?

I know you're getting at something, but it just isn't at all clear what it is or even what you think it is.

You told Tyler23:

Posted By ICFHybrid on 22 May 2011 09:32 AM
Maybe you neglected to tell them that cost and/or the cost/value ratio was important to you, the consumer.

And in the sentence immediately before that, you said:

Posted By ICFHybrid on 22 May 2011 09:32 AM
I've seen five out of five bids that way, recently.

Then I said:

Posted By geome on 22 May 2011 12:24 PM
ICFHybrid, did you also neglect to tell the contractor that the cost and/or the cost/value ratio was important to you?

Honestly ICFHybrid, an elementary school student could have followed this.

Any progress on your little to no geothermal experience, and your continued non-disclosure of this fact?

Honestly ICFHybrid, an elementary school student could have followed this.

Followed what? Sometimes, gomer, we have to use our words in order to communicate something. You need to try that now.

Any progress on your little to no geothermal experience, and your continued non-disclosure of this fact?

Progress? I still don't get it.
Is it customary to outline the pinnacle of one's achievement in that little box at the bottom?

Posted By ICFHybrid on 23 May 2011 08:15 AM

Honestly ICFHybrid, an elementary school student could have followed this.

Followed what? Sometimes, gomer, we have to use our words in order to communicate something. You need to try that now.

Any progress on your little to no geothermal experience, and your continued non-disclosure of this fact?

Progress? I still don't get it.
Is it customary to outline the pinnacle of one's achievement in that little box at the bottom?

You're not getting much today.  I'll find a 5th grader to explain this to you. 

If it is "customary to outline the pinnacle of one's achievement in that little box at the bottom", I can certainly understand why your box is blank.

When giving advise it is nice to know the experience level of the person providing it.  Even though this is not a forum rule, most professionals and many homeowners here who provide advise have managed to grasp this concept.  Please list your experience with equipment that is relevant to this forum for all to see.

Please list your experience with equipment that is relevant to this forum for all to see.

Your compulsion over this is hovering somewhere around "mildly amusing" for me.

There is no standard here (whatsoever) for doing that.

Posted By ICFHybrid on 23 May 2011 08:59 AM

Please list your experience with equipment that is relevant to this forum for all to see.

Your compulsion over this is hovering somewhere around "mildly amusing" for me.

There is no standard here (whatsoever) for doing that.

We aim to amuse.    No there isn't a standard, as I have just stated (duh.)  But, your refusal to do so when directly asked (in wording that you seem to understand) speaks volumes. 

Posted By Tyler23 on 20 May 2011 06:30 PM
Dana, thanks. My zip is 98642 and meter reading is done on the 4th - 6th of each month (so April's usage was based on a 5/5 reading). Days per cycle are as follows:

4/11: 2940 Reading 5/5 (29 days)
3/11: 3300 Reading 4/6 (33 days)
2/11: 3420 Reading 3/4 (28 days)
1/11: 3300 Reading 2/4 (29 days)
12/10: 3960 Reading 1/6 (31 days)
11/10: 4140 Reading 12/6 (32 days)
10/10: 1890 Reading 11/4 (29 days)

Please note that the home is 4,307 sq ft and 1,208 sq ft of it was pretty much unheated. Plus we were pretty stingy with the temps in the heated areas. I am not trying to argue with your numbers, but a 2- 3 ton system seems ridiculously small for this size of house.

Using BizEE 65F degree-day data from the Vancouver WA airport  (the closest weather station that had sufficiently continuous data), between 1/11 and 3/11 there were 1334 heating degree days

 in which you used (3420+3300=) 6720kwh. 

That's 6720/1334= 5.04kwh/hdd

or

(5.04 x 3412=) 17,196 BTU/HDD

or

(17196/24=) 716 BTU per heating degree hour. 

At 20F you have (65-20)= 45 heating degrees,

and load STRICTLY LESS THAN (716 x 45)= 32,220 BTU/hr

At the ridiculously low design temp of 15F your load is less than 716 x 50=35800 BTU/hr

This is better than any Manual-J or other heat-loss calc for the whole-house load, it's a measurement. 

And since it includes your hot water & lighting use, a significant fraction of which is either sent down the drain or expended outdoors, it's an over-estimate of the whole house loads.  The design temp heat load for the house at the temperatures you run it cannot possibly be higher than the total energy input to the house. It would be insane to install anything more than 3 tons of compressor here.  A "typical" US home with 3-4 people averages about 1KW or 3.2KBTU/hr of non-heating/cooling power use, so it's safe to assume that your 15F heat load could be handled with ~33KBTU/hr of heat pump output before the auxilliary heating strips would have to kick in.  With 3 tons of heat pump output you would do just fine without auxilliary heat.

If you're looking to maximize comfort, consider serioiusly a Daikin Altherma air-source heat pump & radiant-baseboard/panel-radiator solution rather than a tepid-air ducted solution.  The coldest day in that perior was 26 February, and even then the average temp for that day was +26F, , and the min temp was 17F, a temp at which the Altherma delivers more than enough heat at a COP better than 3.0.  Even some of the Mitsubishi "Hyper Heat" mini splits  ) deliver a COP of 2.77 at 17F, and better than 4.0 @ 47F (they have bigger units than that one, but a pair of 1.5-tons, one for each zone could handle it.)  Your average COP with any decent mini/multi- split would be over 3.0, and with the Altherma hydronic version it would be about 4.

Dana is right, your usage numbers do not match your manual J calculation. Even if you assume that all your electricity is converted into heat, you are simply not getting there. Unless you never kept your house comfortable heated, your usage data suggests 3 tons, even 4 tons would be on the high side.
Given your mild climate, air source pumps might be more efficient and cheaper to install.

FWIW: I know of a few antique houses in central MA (99% design temp ~ 0F) in the 3500-4000' size range that are running 3 ton geo after modest upgrades to the building envelope. Also, I have about 3500' of space that's kept at 65F or above (2000' of it over 68F), and the measured heat load at my place at 0F is about 3 tons (measured) the way my heating system is configured, at the temps I'm running it the radiation literally CAN'T deliver more than ~42K (less than 4 tons) and it kept up just fine the night it hit -9F this season.

To say "...2- 3 ton system seems ridiculously small for this size of house" may be right compared to what "most people" are installing in your neighborhood, but it just isn't supported by the arithmetic. (And the arithmetic doesn't have an opinion, is just is what it is.) Heat loss calculations are VERY squishy numbers, subject to the fears/whims/prejudices of whomever entered the data. 100% oversizing (or more) by contractors is VERY common- there's no downside to THEM for oversizing, and it means they never get the 5AM call from the irate freezing custom. This is why it's important to run the numbers on actual usage against heating degree day data when you can. It puts an irrefutable stake in the ground from which you can then estimate based on the other factors, such as "we turned the temp way down at night, let the upstairs rooms coast", etc. But even with all that, unless you only kept a few small rooms at temp and closed the doors everywhere, etc. it's extremely unlikely you'd have cut the heat usage in half.

Roughly 1/4-1/3 of the house was "unheated" but that really means "less heated"- call it half-heat for the unheated portion. If you upsize 15-25% from the actual usage calc you'd be there with huge margin, and still be less than 4 tons. It's also likely that you can peel a peak-ton off with cost effective building envelope upgrades. But more than just the cost effectiveness relative to a net-present-value calc on the operating costs & upfront costs of the smaller heating system, upgrading the envelope results in higher comfort levels, even at the same interior air temps. When all else is equal, putting the money into the building envelope is the better deal for those who actually spend time in the place.

But lets say the numbers are off, and you ended up UNDER-sizing the compressor by fully 20% from the peak load, that only means A: You run the aux heat a bit more than is perfectly optimal or B: It takes longer to recover from those coldest of nights. But the daily average temp on even the coldest night of the year would usually be well within the 80%-of-peak-load. The day it' gets down to 0F in Ridgeview are remarkably few (but it happens), but even that wouldn't take a 6 ton system. (but it might take a 4). See: http://weatherspark.com/#!graphs;a=USA/Washington (It looks like the cold snap of Dec 2009 made 15F seem like a reasonable design temp, but that's still a 99.9% kind of number, not the number you should size the compressor to.)

Size the compressor for the 97.5th percentile heat load at most, let the aux heat take care of the rest. In your neighborhood that's 23F (Portland) to 24F (Longview), according to ASHRAE data, not 15F. Using your usage data multiplier of 716, your 23F heat load is 30KBTU/hr- 2.5 tons, not more. Take off 3K for "other uses, call it 27K, then upsize 25% because some of the house was "unheated", and you're still at 33.8K, not quite 3 tons. If you figure there's 1/2-1 ton of peak-peeling in the envelope upgrades to come, you're still only looking at 2-2.5tons for right-sizing of the compressor. A 2-ton prior to-upgrades would be a bit small, but it wouldn't leave you cold with sufficient auxiliary heat-strip. A pair of the Mitsubishi Hyper-Heat mini-splits would run about $9-10K installed (I've seen a 3-fer quoted at $13K for installed price for a 3-family building near me recently), and could deliver 3.5 tons of output from the compressors at 15F. There are other good mini & multi splits out there too (Fujitsu, Sanyo, etc.) some with concealed ceiling-output options rather than the wall-bump, etc. You can do a lot of upgrading (thermal & other) with the price difference between that approach a vs. an oversized geo setup of approximately equivalent efficiency, that also requires a lot more system-design smarts to get the performance out of.

"Ridiculous" would be putting a 5-6 ton geo on this place. With a 5-6 ton system it means you'd be good down to something like -25F or -45F before the aux heat kicked on. I'm sure that has happened there, but the last time Ridgeview saw that temp was toward the end of the last ice age.

Doc, my wife would probably argue that we did not keep our house comfortably heated (ever). :-) And so far the air source heat pumps aren't coming in much cheaper (if at all).

Dana, I appreciate all of the input; I really do. I have another company coming in about 15 min to give a bid. What I am really struggling with, however, is the fact that all of these companies use a manual J. If that spits out a 75k load and they design around that, how am I to convince them that they should install half of what they say/think (whether it's geo, air source, etc.)? I would think most would have a real issue warrantying their work.

And again, as much as I appreciate the merits of mini-splits, panel radiators, etc....they will never be installed in this house.

Tyler......why don't you print out what Dana just posted. Have the contractor come up with their numbers and compare what Dana wrote. If their numbers are still coming out allot dif. from what Dana said, ask them WHY......Dana knows what she's talking about.

Posted By Tyler23 on 23 May 2011 05:51 PM
Doc, my wife would probably argue that we did not keep our house comfortably heated (ever). :-) And so far the air source heat pumps aren't coming in much cheaper (if at all).

Dana, I appreciate all of the input; I really do. I have another company coming in about 15 min to give a bid. What I am really struggling with, however, is the fact that all of these companies use a manual J. If that spits out a 75k load and they design around that, how am I to convince them that they should install half of what they say/think (whether it's geo, air source, etc.)? I would think most would have a real issue warrantying their work.

And again, as much as I appreciate the merits of mini-splits, panel radiators, etc....they will never be installed in this house.

I understand that it is hard for you to judge. We are not onsite, and that is our limitations. On the other side, we are unbias. Your usage numbers for your house in your climate suggest a much smaller system, even with some safety margins. Will a 6ton system heat your house? Yes. Will it cool your house? Yes. Will it do so with best efficiency? No. Will it cost you unnecessary more money to install. Yes. Will it give you the best possible comfort level? No Will you know the difference if you decide to put a 6ton system in? No, because you would not know the difference, since you have no comparison. My calcs show me that you are paying $765 for both a 3 and a 4 ton system for heating and AC, $810 for a 5 ton system, and $900 for a 6 ton system in annual running costs. I would suggest to confront the companies which have given you the estimates with your usage data and ask them explain why your house will now use so much more energy than before. Sorry, you came here for unbias advise, now that you got it, it is up to you to decide what to make of it. Dana could not have been more spot on with his assessment.

ClimateMaster and others have a method to disable the desuperheater operation if the ground loop temperature gets too cold.  So unless the owner wants to put in extra ground loops, the ground loop would get too cold, and the desuperheater would not run all the time when the compressor is operating. 

Posted By robinnc on 23 May 2011 07:04 PM
Tyler......why don't you print out what Dana just posted. Have the contractor come up with their numbers and compare what Dana wrote. If their numbers are still coming out allot dif. from what Dana said, ask them WHY......Dana knows what she's talking about.

Last time "she" looked she was still a he, but ya never know...

I may be a lowly engineer, but I know how to measure things with moderate precision, and I DO know what I'm talking about (at least most of the time. )  There are some error bars around which to frame the 2.5ton estimate using power use against degree day data, but it's at most +/- 25%, not +/-125%.  If you didn't use electricity for heating hot water, refrigeration, entertainment, &  lighting the error would be even narrower than that. The upper-bound error for space-heating alone would be barely over 3 tons (and it's probably nowhere near that.)

Manual-J is an estimate, based on many assumptions, any number of which can be outright wrong, or skewed by the data-entry person's biases.  They may even be well intentioned on how they skew the assumptions- they don't want to leave the client cold,  but even  done perfectly-by-the-book Manual-J has  built-in fudge factors to prevent that even with 0% oversizing from the estimate. Manual-J overestimates by 15-25% when done perfectly.  Done with a cascading nudges in assumptions it's easily blown way out.

Tyler:  Ductless mini & multi-splits would likely come in much-much cheaper than ducted air-source or geo systems.  It's a lot cheaper & easier to find ways to thread refrigeration lines through the available spaces than ducts.  Mini-splits have an advantage over custom air-source or geo, in that the system engineering is already done- it's very low risk, and unlike bungled custom systems, they DO perform to spec.  Geo requires some real design, they're complicated to install, and need to be done right in both design & implementation to get the touted performance out of them.  Typical geo systems in my neighborhood rarely exceed 3.0 for an average COP (some nudge up to 4 or so), and many operate in the mid-2s.  By contrast, mini-splits are pre-engineered cookie cutter designs, simple to install, and (even in southern new England) reliably hit the high-2s, sometimes low 3s for average performance.  With your climate your average will be in the 3s.  If you oversize a geo system by 2-3x,  fuggedaboudit- you'll be sub-3.  It's always better to be 10% undersized than even 50% oversized, from a net efficiency & total power use point of view.  Geo done right can be a wonderful thing, particularly in cold to very cold climates, but the average winter temps in the PNW are just SO moderate (Ridgefield's mean January temp is  about +40F, compared to +25F in my MA neighborhood, or +5F for Fargo ND), that the smarter bet is to go with pre-engineered air-source system rather than full-custom geo that may well underperform the cookie-cutter design costing less than half.

But all mechanical systems break- it's a better longer term investment to spend some real money to lower the load, by  air-sealing, insulation, & window upgrades, in approximately that order (but some windows might be a real energy-emergency.)   If you're ever planning to re-side the place, plan for at least an inch or two of exterior rigid or spray foam (close cell), which could more than double the whole-wall R value (thermal bridging of the framing included.) 

The bigger heat loss/gain is still likely to be windows than walls, particularly if they leak air, have alumimum frames, and no exterior storms, but they're just more cash outlay up front, and less cost effective per kwh saved than air sealing and insulation. When replacing a window, think carefully about whether it needs to be operable (or even as big.)  Consider going with only push-out awning or casement types- they leak less air than sliders or double-hungs,  and offer more egress area for the same amount of glazed area.  Every square foot of single pane glass is an R1 hole in your ~ R10 wall, so a 10 square foot window loses as much heat as 100 square feet of wall.  Add a storm window and you cut it in half, put in a modestly better than average double-pane, you're then looking at an R3 hole in your wall.  Add an inch of foam sheathing, now you're talking about R15 walls, 2" makes is ~R20, outperforming a 2x6" studwall w/R21 batts (which is only ~R15 when thermal bridging of the studs is factored in.)  It's usually cheaper to gain performance by shrinking windows 25% (displacing that 25% with insulated wall) than going super-high performance on overly large windows.

If you ever feel like going nuts on the place, in your location you could get your design day heat load down to a ton or so for a lot less money than this guy did.

Posted By docjenser on 24 May 2011 01:39 AM
Will you know the difference if you decide to put a 6ton system in? No, because you would not know the difference, since you have no comparison. My calcs show me that you are paying $765 for both a 3 and a 4 ton system for heating and AC, $810 for a 5 ton system, and $900 for a 6 ton system in annual running costs. I would suggest to confront the companies which have given you the estimates with your usage data and ask them explain why your house will now use so much more energy than before. Sorry, you came here for unbias advise, now that you got it, it is up to you to decide what to make of it. Dana could not have been more spot on with his assessment.

Hi Doc. I understand your points and I will try to provide this info to the companies to see what they come up with. One thing I am not clear on is what you stated in bold above. How are you determining that we would be using more energy than before? You state operating costs of $900/yr for the 6 ton. Were certainly spending more than that now on heat. Sorry if I am missing the obvious.

Dana: regarding the ductless/mini-splits. I asked the estimator who came out yesterday about these. He was saying one way we could go about ductless is using the floor models for the downstairs, and then using an attic mounted "ducted" mini for the upstairs with ducts running to each bedroom. He said this would look like a traditional system in that there would be an air handler in the attic but it would use the inverter technology with the variable-speed compressor of the minis; all would tie back to one outdoor unit.

However, he stated that the upstairs units are a newer technology and the cost would pretty much even out with a geo (after the tax creds and rebates) and a air-source system so it would be close to a wash. Certainly not half or less of the cost. (I've stated before that we do not want the large wall mounted units common with ductless so it would have to be something more traditional for the upstairs. The floor models for downstairs would still be a stretch but I am at least looking at them.)

I hope to see some numbers from them later this week or early next. And I did discuss what has transpired here and explained my concerns with oversizing; I felt he got the message....but we shall see.

Posted By Tyler23 on 24 May 2011 06:42 PM

Posted By docjenser on 24 May 2011 01:39 AM
Will you know the difference if you decide to put a 6ton system in? No, because you would not know the difference, since you have no comparison. My calcs show me that you are paying $765 for both a 3 and a 4 ton system for heating and AC, $810 for a 5 ton system, and $900 for a 6 ton system in annual running costs. I would suggest to confront the companies which have given you the estimates with your usage data and ask them explain why your house will now use so much more energy than before. Sorry, you came here for unbias advise, now that you got it, it is up to you to decide what to make of it. Dana could not have been more spot on with his assessment.

Hi Doc. I understand your points and I will try to provide this info to the companies to see what they come up with. One thing I am not clear on is what you stated in bold above. How are you determining that we would be using more energy than before? You state operating costs of $900/yr for the 6 ton. Were certainly spending more than that now on heat. Sorry if I am missing the obvious.

Given your electrical consumption, you are putting a certain amount of BTU's(KWs) in you house to heat it. That matched with the weather data for your location in WA gives you the heatloss of 33 KBTU/H, which is conservatively calculated by Dana, which is the amount of heat your house looses at design temperature, in your case 23F outside. Because the geosystems take 60-80% of the energy out of the ground, your operating costs will be significantly less,despite putting the same amount of heat energy into the house. The calcs show that the 3 and 4ton are on par, and 5 and 6ton cost you more to run, since they would run less efficient. The question you should ask: Since you are using 33 kBTU/H right now to heat your house when it is 24 F outside, why do they recommend a system which provides 60 KBTU/H of heating?

"Since you are using 33 kBTU/H right now to heat your house when it is 24 F outside, why do they recommend a system which provides 60 KBTU/H of heating?"

...especially when there are known envelope improvements in the project pipeline that will likely knock that back to 22-26K in short years. In some ways doing the heating system first is a cart-before-horse strategy, since oversizing the system costs more up front, and every year thereafter. Starting off with a contractor who would place higher cred on the heat loss calc over power use/HDD, and use a design temp more appropriate for sizing a 2 stage gas furnace than sizing a heat pump compressor isn't a good indication that the even more subtle aspects of the design would be right. Right-sizing is a first & fundamental part to nail down, and missing the mark by 50-150% seems like gross error (or worse.) Their room by room heat loss calc can be used to achieve good balance, but since there's a whole house load MEASUREMENT, possible, IT is a far more appropriate method of sizing the compressor output.

If you're starting out with 60-70K of compressor for a 33K design load @ the 97.5th percentile temp, it's already bad enough- you're 2x oversized and on the knee of the efficiency regression curve. But by the time you've spent $3-5k air sealing, spot insulating and taking on the most-critical of the windows you'll be getting on to 3x oversized, operating on the steep & slippery part of the curve. To have any hope of getting the performance of the equipment you need to stay well under 1.5x oversizing, or install some insane volume of thermal mass (usually in the form of a large buffer tank, which adds to the expense.) These are the kinds of reasons that the average geo system in New England is only pulling down an average COP of ~ 2.5 rather than 3.5 or 4. Every step of the way the sizing gets padded, to be "conservative".

If anything it's more conservative to start out UNDERSIZING it by 10-20% from the measured heat load, when there are clear paths to tightening up the envelope. If time were infinite it's possible to model fairly accurately where things are now, and where different improvements would take it, and you could run an NPV calc on each step, but the thermal efficiency of almost any house fitting the description of yours can be boosted 20% without breaking the bank.

Dana & Doc, thanks.

Here is an email I would like to send to the first company (who bid both air source and geo). Please let me know if this looks correct:

Based on info I found here (link to degreedays.net), there were 3,506 heating degree days (HDD) from 12/1/10 – 4/30/11 for Ridgefield. During that time, we used 16,920 KWH. That equates to 4.83 KWH/HDD, or 16,468 BTU/HDD (4.83 x 3412.3) or 686.16 BTU per heating degree hour (16,468/24). At a base temperature of 65 degrees and an outside temp of 15 deg, we would need to 34,308 BTU/hr to cover that. So that’s 34,308/12,000 = 2.859 tons of capacity.

The electricity we used during that time also included all lighting, appliances and hot water, so not everything was going to heat. But to be on the safe side, if we assume a 25% increase in heating load and all electric used was for heat, we could add 8,577 BTU/hr of capacity to 42,885/12,000 = 3.57 tons.

So I guess my question is: if we needed only 35k BTUs to heat our home this past winter, why would we need 72k (6 tons) to do so moving forward?