Like most build industries, it is easy to low-ball a quote. Separate the end user from the product (ie- through a developer or builder) and that is the tendency - to bid low.
Here’s how it is done:
use junk for heat pumps: single speed, no warranty, single-walled exchanger, piston compressor, and the list goes on.
shortcuts on materials: no insulation, low quality circulation pumps, no valves, wrong materials.
shortcuts on labour: unlicensed trades, inexperienced installers, cash sales.
no design – yes, somehow this can still be done.
short looping – goes with the fact you did not have a design to begin with.
no accountability: hiding behind the fact you don’t have an educated client sometimes or the time period is such the installer is long gone before issues are noted.
I don’t know all this from experience. I know all this from troubleshooting.
It is pretty simple – you need a building energy analysis (building loads) done.
But it is often not done when a general contractor pulls apart construction tasks for tender. Frankly, I’m tired of “yelling” in the wind about public or private tenders that have inaccurate loop sizing requirements.
Somebody at sometime MUST determine the building loads. Don’t allow your tender document to have a S.W.A.G. (Scientific Wild Ass Guess) in it, unless your tender document requires building loads to be done.
Who do you blame when your building is too cold? Too hot? If I bid on your job, I will guarantee I put in the 60-ton ground loop you specified. But will I guarantee that your building can be heated and cooled by a 60-ton system? No. Whomever put the bid document together apparently is making that guarantee.
And those of us that have done this for awhile know that to specify a “60-ton” ground loop is a bit of nonsense. What are the expected equipment run times? What are the load imbalances? A 60-ton ground loop that is only fully required for 1-week of the year is a lot different in size than a 60-ton ground loop that is required for cooling only.
So who best makes this decision (besides phoning us)? Normally I would say your mechanical engineer, but too often I have seen this lead to a S.W.A.G. During new construction, expected building loads should be part of the architectural work. For retrofits, have a building load expert determine your requirements and then use the results to put together a bid document. Otherwise, the process is being set up to fail.
We can use manufacturer’s tables to determine a heat pump operating COP or we can measure it ourselves. My caveat is that you are measuring high voltage equipment. So don’t unless you know what you’re getting in to.
COP = Energy Output/ Power Input
We’ll focus on the load side as that is the easiest side to measure.
For heating:
Energy output= heat of compression + heat from ground loop.
Heat of compression = Power input (mechanical supplied)
To get power input you need to measure:
total amperage draw
total voltage draw
Volts x Amps = Watts
Watts x 3.412 converts it to Btu’s/hr
Note how this work is beneficial to the system when heating and not in cooling.
Your ground loop energy is now determined by measuring your loop fluid flows and temperatures based on:
BTU’s from ground = Q (us gal) x (Tin-Tout) x K
K = 500 for pure water
Q can be determined by the pressure drop
Constants K for antifreeze come from the forumla:
Kaf=(100%-AF%)x500 + AF%(500xSGRxSHR)
AF% = percent of antifreeze
SGR=specific gravity ratio of the antifreeze to water
SHR=specific heat ratio of the antifreeze to water
There are a lot of different ways to store and share information but we’ve found a few useful enough that it warrants sharing.
We use Blackberries. Nothing groundbreaking about that. You get phone calls. You get e-mails. You can text back and forth. You can even send site photos to one another. But what we’ve found especially useful is syncing our contact list with Google Contacts (off of gmail). This means our contact list is always accessible to us. Drop a phone down a borehole and we can still track down the phone number. When we get a new phone, we just re-sync and we have all our contacts ready to go again. Yes, Blackberry does have its own software that you can connect to your computer with – we don’t even load it.
The other syncing we can do with our Blackberries is to Google Calendars. I don’t think I need to go in to how important scheduling is to a contractor. The added bonus is we can use the same web-based program to track employee hours as well.
One of the funnest is Google Earth. By using placemarks we track our geothermal system locations. In the description we add a few details relevant to us, but basically it is a nice way of tracking what we have done and where. See an example printout below.
