fair enough doc I am thinking in context of tamar employing another company.

before it goes that far, the do have 6 or so tons available (not likely to get a full 5 tons out of spacepak which IMHO is another efficiency faux pas). That sais as long as tamar is relatively indifferent to where the heat comes from I think the problem is meat ware not hardware.

Posted By joe.ami on 10 Apr 2013 11:34 PM
I told my children when they were young......2 words to live by: dad is right!

There are three kinds of people in the world:
those who can count, and those who can't.

"You see, in this world there's two kinds of people, my friend: those with loaded guns ... and those who dig. ... You dig."

Posted By Looby on 11 Apr 2013 10:57 AM

Posted By joe.ami on 10 Apr 2013 11:34 PM
I told my children when they were young......2 words to live by: dad is right!

There are three kinds of people in the world:
those who can count, and those who can't.

Naw, there are really only 10 types of people in the world, those who understand binary arithmetic, and those who don't.

Yesterday after I screwed something up in the lab a co-worker asked me how many languages I could count to three in- came up with only 8 (if Punjabi, Hindi, and Urdu are a single greater-northwestern Hindustani language, which seems mostly the case, not that I have much fluency or vocabulary to work with- they could be different enough to matter.  I counted Afrikaans, Flemish & Dutch as one. Despite sometimes strong dialect differences- I can at least confidently order a beer competently enough anyway, after which fluency goes way up. I'm far less sure about Hindustani.)  But how I came up with four while counting in US-'merican is still a mystery...    Next time it's gonna be "ek, do, tin..." or "ichi, ni, san..."

But how you get from a boiler replacement to an oversized dysfunctional geo system seems as complicated a path as the Odyssey.  Unless the client has a real grasp of how this stuff all works it's hard to place fault on them even if they WERE directing the contractor to do stupid stuff.  It's the contractor's job to know that it's stupid and explain it to the client, not to just duck their heads and start walking down a road to hell at the clients' bidding. I'm sure this has been VERY educational for all parties- hopefully none of them will go broke on it.

Posted By Dana1 on 11 Apr 2013 04:23 PM
Naw, there are really only 10 types of people in the world, those who understand binary arithmetic, and those who don't.

USof'Murican contractors should take to binary arithmetic quite naturally. For
example: 0.1", 0.01", 0.001" are half, quarter, and eighth inches, respectively.

...and wall studs are on 10000.00" centers,

Looby

Posted By jonr on 11 Apr 2013 07:51 AM

It does not matter if you heatpump can make 140F, it does not have enough capacity to heat the amount of water up to that temperature.

I would be careful about confusing slow response with lack of capacity.

I am not confused. Need 65-75 KBTU/h to heat this house at a design day, Plus the need to heat up the system when temps drop quick outside, Have 30 KBTU/H for W-W system. Meaning lack of capacity!

So we agree that "the amount of water" isn't a "enough capacity to heat" issue. It's a response time issue (and it's better than a concrete slab radiator). Total systems btu/hr output vs demand is the capacity issue (and there is plenty if you count the other heat sources).

I am now starting to worry that there is a problem with the loopfield or pipe.

This morning, I again requested the information from the installer so that I could get an opinion from y'all on the pumps. The installer sidestepped the request by saying that I'd have the results if his evaluation later today. So, I have asked him to provide not only the results, but how he got there. I have a bad feeling about this; I hope I am wrong.

Hoping this is a good way to post the design of our system.... http://www.flickr.com/photos/tamar_tamar/8642059499/in/photostream

Unfortuanately that doesn't really tell us anything. Is there no buffer tank for your high temp geo? Should be one between the geo and the gas boiler.

Might be useful to have a local designer (not installer) review this combined WtW, WtA and DHW system design:

http://www.ourcoolhouse.com/monitor/monitor.htm

Posted By joe.ami on 12 Apr 2013 10:30 AM
Unfortuanately that doesn't really tell us anything. Is there no buffer tank for your high temp geo? Should be one between the geo and the gas boiler.

There is a small dark gray tank between the geo and the boiler; is that the buffer tank?   http://www.flickr.com/photos/tamar_tamar/8643242268/

From left to right, the components are the aux summer hot water buffer tank, the hot water heater, the Phoenix boiler, and then the two geo units sitting one on top of the other. Right now the breaker for the W2W is pulled (as you might be able to see).

We did have a "second opinion" in, it was someone our installer arranged for. He was certified and not associated with the installer's company. Wiring changes and staging adjustments were made after his visit in August 2011.

Small gray tank is an expansion tank. I'm losing faith in your installers odds of making this right.
Get a geo hydronic company to tell you how to fix the design and threaten legal action.

I got the analysis from the installer. He says that the system needs 3 pumps. The Reynolds number with 2 pumps is flagged as too low at 1788. I have attached the calc he did with 3 pumps. Sorry for the eye chart, it's really difficult to upload stuff to this site.

From this it looks like you have 6 bores in parallel at 205' each with 3/4" u-bends in each = 1230 total bore. Thats a pretty decent size loop set up and should be good for 6 or so tons of load depending on local soil/rock. It looks like they gave you some decent loops, so that very important and is some good news. Looks like they designed the flow for just the 5 ton running.

You only need to really worry about the renolds number when you get closer to the design load. If you run just the 3 ton W-W, you likely could get by with just one pump on. The limit for the heat extraction will not be the renolds number in that scenario. You need to assure that you have the minimum flow rate for just the 3 ton by checking delta p and t at the unit. Not hard to do. You may need some valves to assure you divert the loop to just wich geo is on. I can't tell from your diagram what your plumbing is betwwen the loop and the geo units.

If you are running with just the larger unit, you may be able to get by with just two pumps. This can be confirmed be testing delta p and t at that unit. Actual field testing is better than going over the calcs at this point. IMO. Your local code may allow methanol mix (not sure) and that will lower viscosity and up the renolds number and flow rate. Also, your loop is pretty big, so if you mid to end of winter loop temps stay above 30 deg F, you may be able to water down the glycol mix some instead since you don't need such deep freeze protection and that may gain you some.

You can do this pump control with some cheap relays and valving. Leave your extra pump in there as a spare.

As Joe noted, that is an expansion tank which leads us to think there is no hydronic buffer tank at all. Is this true? If so, you need some serious design help.

Good news- looks like you got a decent loop based on your peak heat load. That is worth a lot. If you get this to work, you may have some good efficiency if set up right. A buffer (if you get one) served by the 3 ton W-W with outdoor reset to keep it only as hot as needed with the gas boiler as back up for cold snaps.

Do you run both geo's at the same time? Do you know the control scenario?

Breathing a sigh of relief that the loop is okay.

Here's the CURRENT control scenario. I am taking this from an email that the installer printed out and left at our house (perhaps by mistake) last week:

Stage 1: Hi-velocity geo

Aux Heat/Stage 2: Hi-velocity geo, W2W geo, gas boiler     Stage 2 demand is triggered by 45 min of runtime @ Stage 1, 3 degree droop, or below 15 degree outdoor temp

W2W operation: Aquastat limits the return temp from exceeding 135 degrees. At this point, the call would drop. customer will operate disconnect to allow or discontinue operation of this unit

Boiler/Hot water tank: set to maximum temp     (Hmmmm...does this mean the boiler IS our buffer tank? Could that be and is that a feasible design?)

Humidifier action: only during call for heat

This is correct, right?

WtA geo $5.86/MBtu
Nat gas $7.61/MBtu
WtW geo $8.20/MBtu

It seems pretty clear to me that you want the WtW geo removed (a nice simplification) and the WtA geo as primary.

Your loopfield is not OK. While he calculates the larger of the 2 heatpumps needing 15 gpm (5 tons x 3 gpm/ton) he neglected that the header pipe and the loopfield should be designed for 24 gpm when both heatpumps are running. The Reynolds numbers are not the issue here, but him needing to push 24 GPM to and back from the loopfield through 200 ft of 1.25 is the issue. His calculations show that he calculated the header pipe and the loopfild only with 15 gpm, not the 24 nominally needed for 2 heatpumps.


The absolute killer is also the 10 ft of 1" pipe which sees the entire system flow of 24 gpm.

Even if you take the flow down to 19 gpm, which is considered the minimum (not the optimal), (2) 26-99 can only do 17 gpm under this design. He should have done those calcs before he put the pipes in, not after the fact. Although I am not sure here if he tries to run calcs now which fit his current design, of if he just does not know better.



Another issue is the control setup. Don't you want the radiant heat going first, and only when it is not enough the 2nd stage (forced air) comes on?


Both the control strategy, equipment selection and the loopfield design renders the geosystem inefficient. Especially when he keep adding pumps to overcome the inefficient flow design. The loops in the ground are OK, but you should add re-piping the header pipe to the boreholes to the list here. You need a 2" pipe here, also 2" pipe inside which see the whole system flow.
You are at the point where you need to rip everything out inside, exchange the header pipe outside, and redesign the system.

You (he) could put a 5 ton w-w in, and use the high temp as a second stage. Keep the Split for AC or as a 3rd stage.
Every one is up in arms here about popping in a 7 ton high temp WF, but this might be the cheapest options here. One single heatpump conditioning a buffer tank with an outdoor reset would do it all. Very simple.

Is it possible for a head to be spinning at the same time light bulbs are going on?