Loop design comparison

Back-up or third stage resistance heat is probably much cheaper insurance against those unusually long cold winters. You need a geo-pro who can run the numbers to compare the cost savings. Whoever gave you the advice that it was cheap insurance failed to advise you that oversizing is a down-payment on humidity problems in cooling mode.

 

"I was advised to go with the bigger system because the 5 ton heat pump won't be putting out 5 tons when EWT's get down to say 35* which could happen at the end of a long cold winter. So what I was told is that having more pipe in the ground and a bigger heat pump is cheap insurance against this situation. But I am now seeing the light that this may not be the way to go."

Glad you saw the light because that is ignorant advice. First, 35*EWT is higher than what cost effective loop systems trough at. Second, even at temperatures below freezing (EWT) a 5 ton still makes more heat than your peak load. Third, how cheap is this insurance vs buying a 3 ton?

I just ran the numbers for a goe shopper in TN with a 50ish MBH load the 3 ton was cheaper to install and operate than the 5 ton. So far you have shopped with companies that don't understand that. YMMV

There seems to be a few contractors out there that resist evolution and you may have found 2 of them. Quit worrying about loop design and worry about finding a contractor that evolves......then the loops will take care of themselves. A good bench mark would be to find one that monitors his systems. A good fall back is to discard anyone who brags his/her systems never use auxiliary heat.

 

I am not sure what makes this so hard.

Mark

 

Their are thousounds of hvac stories of people over sizing for cheap insurance, and it's just wasteful and expencive. If you have to, store a resistance heater in the closet and use it for that freak super freese. Even the load Calc that was done was oversized to a degree. Theirs no need to order a whole pizza just in case you could possibly be starving in 20 minutes when it arrives.

I've been researching the difference for a while as well, and I like the idea of more smaller pipe, as apposed to bigger. Look at all other radiators in everything, it always seem to work better with a series of small tubes and tons of surface area.

Slinkys seem to have their issues tho, if your system gets hot it tends to kink where the pipes cross, which is why they bed them in sand (witch only some times works). But sand is a horrible heat conductor, especially dry it has a decent r value.

The idea of returning them 2' higher sounds like a bad idea to me, not only are the now only 4' deep but theirs only 2' from the other pipes and you can expect alot of competition. Expecially cooling, the heat you dissipating will be collected as it rises up to the return.

Ideally you should run 3/4" sdr 11 in a few trenches either up and back one trench. Or a few pipes in a u shape with enough pipe to handle your tonnage.

You can go a head and try and reinvent the wheel and sub contract without an engeneer to save a buck or two, but perhaps you may save some time and possibly money hiring a professional. Please keep us posted on what you decide, best of luck.

 

You're digging up a 2 year old thread?

 

It's still the 3rd hit on google, are they alot of treads left open ended here?

 

Yes. Most threads are left open. People mine info then go.
Fortunately this one will miss your loop advice.
The best loop advice is get a good installer and let him worry about loops. With hundreds of miles of slinkies in the ground I've not seen the scenario you described. 6 pipe racetracks work well too. With an average depth of 5' they are often longer than slinkies with a 6' average depth.
Fact is it doesn't matter as long as there's enough of it. There are reasons the industry has moved away from two pipe trenches you describe as "ideal".
There are cases of persons who educate themselves on the Internet and offer good advice. So far you are not among them.

 

We also use exclusively slinkies for all our horizontal loops, which work great. We regularly publish long term monitoring data showing their performance.

Don't comment on things you have never done, and really don't understand, just because you read about it and then call it "research". You might mislead others....