Does anyone know approximately how many heating btu a 5 ton earthlink dx system puts out?

According to one contractor, I need approx 67,000 btu. He proposed a 6 or 7 ton climatemaster unit w/ a 2 stage 5/10 kw back up unit. The contractor that I like has proposed a 5 ton eathlinked dx unit w/ a 20 kw back up. The contractor w/ the dx unit didn't do a load calculation (but he has a very good reputation in my local area - New Lothrop, MI). The Climatemaster system is sized to heat the house w/o back up to -2 degrees at a temperature of 75 degrees.  The dx system is sized to heat to 70 degrees down to somewhere between 0-10 degrees. (or so he guesses).

Here is my dilemma. I need to get something done (Getting more estimates is problematic b/c it seems to take contractors in my area 2-3 weeks or more to get back w/ an estimate) I like am leaning to the dx system b/c it seems to be more efficient. The Climatemaster system is a few thousand dollars more, but the money isn't the largerst concern. Does anyone know if a 5 ton dx system is appropriate for a 67,000 btu heat load? Also, does anyone have any thoughts on the pro's and con's of the two systems for heating and coooling in Michigan?

The answer comes from ACCA Manual S.

Putting it simply, a given unit / tonnage must be evaluated against design conditions for YOUR site.

It is rarely economical in a cold climate to design a geo unit to meet demand on the coldest days - first cost is much higher and size of required ductwork may be larger than practical. Then you have a massive oversize to deal with for summer cooling, exacerbated in the case of DX by its inability to support 2 speed operation.

5 tons with backup strips may well be better overall than a 6-7 ton system, without going into brands.

The biggest up shot to DX systems in MI is that there is less reduction in btu's for heating. I've mentioned before that the closed loop horizontal systems in MI have a 20+% heating btu reduction (so a Climatemaster TTV064 may only yield as little as 48KBTU with 32 degree entering water). However, the Earthlinked manual suggests not to add more than 2 tons to the cooling load so we would use that to size your DX system. Because water source units can be 2 stage, we can stretch heating size a little more. The real consideration here is wether or not you have 5+ tons of duct work. It is quite common in our area to make up 20 or more thousand btu's with an electric coil. After all you may only need 67K 2% of the time.
I'd have to load the house. You're only about 30 miles from me and more than welcome to contact me through a private message on this site (our estimation turn around is about 2-3 days from the first meeting).

Oops, forgot to mention, book says heating btu's as high as 79.5K in certain conditions for 5 ton Earthlinked.
Joe

The duct work isn't really an issue b/c I am replacing all the old w/ new.

The incremental cost of the larger ductwork should be relatively minor. Finding the places to properly run it in walls and floor systems may pose additional constraints.

You'd do well to take JA up on his offer to load your house

I think I had a contractor do a JA - that is where the 67,000 btu came from (I think he said it was 47,000 for cooling), but he was behind w/ getting his quotes done (over 2 weeks) and was going on vacation for 3 week starting today so I have only spoke w/ him on the phone. I need to make decision before he returns. This is the 6-7 ton climatemaster guy.

2 weeks behind and leaving on a 3 week vacation?!
Are these numbers to heat/cool the house only? What are we doing with the pool?

I guess he has been working hard or maybe he has been busy so he has a lot of money.

Those numbers are for the house only. I am hoping to put a seperate 5 ton unit and a dehumidifier in the pool room but I haven't got any firm numbers for that. I was told the pool would cost between 35-40k for both systems. The only concrete numbers I have for the pool is for a Dry-Air Dehumdifier that is geo-based and can do 100 percent of the pool heat (both systems in one) for about 44k or 14,250 for just a dehumidifier, but then I would need another geo unit which from what I amd seeing should cost around 20k.

Wow, 67K Btuh. And the EarthLinked dealer didn't do a load? He ought to be fired. Unless he's trusting in the other contractor's load. Still, he should do his own load to be sure.

Get another estimate from Joe.ami. He knows your area, and from what I've read here on the forums, he knows his stuff.

It really does come down to the accurate load. Some contractors tend to over-emphasize the extremes to "buffer" their load. Of course, they think they do this to the advantage of the customer. They don't want to be short and have a customer be cold. But the more accurate the load can be figured, the more efficient, comfortable, and reliable your system will be (as long as it's then properly sized to that accurate load).

Good job on doing your homework to find these things out.

Clark,
I've been through my book and can not find different performance tables for Earthlinked based on ground temp (ie what is the btuh output for 5 ton with 35 degree surrounding soil). I extrapolated off DMH table which is obviously not ideal.
Joe
Incidentally to all, met with Ben today and have some thoughts I'll share later (with his permission of course).

Joe,
the lowest the book shows is for 40 deg. earth. EarthLinked says 2' below frost line should average the ground temp. For Michigan, the map shows about 40-45 deg. earth. The output is also based on the different types of loop. For horizontal, earth temp. of 40 deg. F., the output of a 5 ton unit is 42,105 BTUh. For vertical, it's 39,446 BTUh. These outputs are of course at design temps. In other words, these outputs are at full run time of the heat pump (90% duty cycle) and will be at least this output.

The outputs with different ground temps are linear, so I would extrapolate that a 5 ton would have 38,495 BTUh output with 35 deg. earth temp. and a horizontal field.

RE: engineer “It is rarely economical in a cold climate to design a geo unit to meet demand on the coldest days - first cost is much higher and size of required ductwork may be larger than practical. Then you have a massive oversize to deal with for summer cooling, exacerbated in the case of DX by its inability to support 2 speed operation.” Maritime Geothermal manufactures 2-speed compressor, variable speed blower DX GSHPs under the Nordic brand name, as well as 2-stage DX split units and 2-stage ECM blower triple function DX GSHPs. SR

fs, who reps Nordic in the states? I've repeatedly contacted their web site and get a pre-programmed response (in French no less).
Joe