Geothermal heat pump: first winter results

[techman]

Here to compare:

 

[MacLawn]

Thanks for that chart, techman. Looks like my savings would be like this:

Heat Pump $.10 $16.25

Geothermal $.10 $8.39

Hmmmm, looks pretty good to me, as long as I stay comfortable winter/summer, for me because of fibromyalgia pain, that means about 74° winter, 73° summer. And, maintenance is cheaper than my current heat pump (I just figured out that when y'all boys use "HP", ye mean heat pump, not Hewitt Packard!).

 

[truckdiagnostics]

Fordmantpw, the 7 series by water furnace is the Mac Daddy of Furnaces. If one is concerned about back up heat, install the water coil in the plenum of a gas furnace(use the 500R011), use it as an air handler, then you have the gas for back up. You will loose the electric coil in the plenum and maybe some of the ramp up features. The kid and I have talked about it, if you got the right gas furnace you might be able to get the ramp up in fan speed. A heat pump when it runs and the geothermal for that matter puts out a cooler heat. So, if memory serves me correct when the WF (unit that comes with the air handler) starts up the electric grid will turn on for a while giving the initial warm up of air. That is why I unplugged mine. I have a zone with a water coil running off the shop unit as a zone. Cold start up? yes, but you can hold the fan until water temp gets higher and minimize that.
As for things to watch for having a big enough loop and deep enough. Saskatchewan, Moose jaw Regina area 10 ft depth, central Wisconsin I'm at 6ft should have gone 8' or maybe bigger loop for the shop. I buried those two loops side by-side, everything was sized for the shop, then I added an 800 sq ft office using an air handler and it has to work hard, its maxed out.
In the summer, depending on the unit, you have free hot water for your pool. A water to water ex-changer and you have free heat.

 

[techman]

Thanks for that chart, techman. Looks like my savings would be like this:

Heat Pump $.10 $16.25

Geothermal $.10 $8.39

Hmmmm, looks pretty good to me, as long as I stay comfortable winter/summer, for me because of fibromyalgia pain, that means about 74° winter, 73° summer. And, maintenance is cheaper than my current heat pump (I just figured out that when y'all boys use "HP", ye mean heat pump, not Hewitt Packard!).

You will get more heat from a geo heat pump than an air unit. Do to the higher temps of water compared to air (in the winter).

paul

 

[fordmantpw]

Fordmantpw, the 7 series by water furnace is the Mac Daddy of Furnaces.

Yeah, I really like the 7 series. It's the only way we could get separate zones for my office and our sun room, each about 170 square feet. I work from home, so I want to keep that room at a constant temp. Our sun room has 10 3'x5' windows, so I felt we needed something there to make it a four seasons room.

The unit is a 5 ton unit, but we had 6 ton worth of loops put in. That is the only way the co-op would give us the rebate. He wasn't comfortable with the sun room, and felt we would come back on him for too high of an electric bill. The HVAC company was 100% comfortable with the 5 ton, so I didn't really care what the co-op guy thought. We spent the extra few hundred bucks to keep him happy and avoid issues, but I think that was the right thing to do anyway. Nobody ever says you have too much capacity!

 

[truckdiagnostics]

Yeah, I really like the 7 series. It's the only way we could get separate zones for my office and our sun room, each about 170 square feet. I work from home, so I want to keep that room at a constant temp. Our sun room has 10 3'x5' windows, so I felt we needed something there to make it a four seasons room.

The unit is a 5 ton unit, but we had 6 ton worth of loops put in. That is the only way the co-op would give us the rebate. He wasn't comfortable with the sun room, and felt we would come back on him for too high of an electric bill. The HVAC company was 100% comfortable with the 5 ton, so I didn't really care what the co-op guy thought. We spent the extra few hundred bucks to keep him happy and avoid issues, but I think that was the right thing to do anyway. Nobody ever says you have too much capacity!

Adding to the loop was smart and I believe the co-op guy was right. When the unit gets to max. It can actually freeze or cool the ground around it such that it can not get as mush heat out of it. Therefore having to work harder. That is the advantage of using water from well. Issue there the discharge, and if you have a place for the discharge that is the way to go. back to your loop.... when they figure the loop size they figure the unit will shut off, therefore giving the ground time to warm back up so to speak. I will have issues with the unit in the shop, some springs when the frost pushes deep or I run it really hard for extended periods. So, whoever sized your loop new what they where doing! And having the loop size checked and the installation making sure it is actually at the depth they said it is going to be is a big deal. Go out there with a tape measure and check it. They use a sub contract to dig and back fill the whole.

 

[fordmantpw]

Adding to the loop was smart and I believe the co-op guy was right. When the unit gets to max. It can actually freeze or cool the ground around it such that it can not get as mush heat out of it. Therefore having to work harder. That is the advantage of using water from well. Issue there the discharge, and if you have a place for the discharge that is the way to go. back to your loop.... when they figure the loop size they figure the unit will shut off, therefore giving the ground time to warm back up so to speak. I will have issues with the unit in the shop, some springs when the frost pushes deep or I run it really hard for extended periods. So, whoever sized your loop new what they where doing! And having the loop size checked and the installation making sure it is actually at the depth they said it is going to be is a big deal. Go out there with a tape measure and check it. They use a sub contract to dig and back fill the whole.

How am I supposed to measure holes 150' deep?

I trust the folks that did the installation. I personally know the folks that drilled the wells (distant family) and hooked up the loops. I'm confident that they did it right.

I considered an open loop system, but we have really hard water hear and didn't want the hassle and issues associated with that. We plan to build a lake in a few years, and the discharge would have been perfect to keep fresh water running into the lake (albeit slowly ). Practically nobody in our area does open loop.

Our unit has never run at max. Even when we were sub-zero here, we had lots of reserve left on the unit (running at ~50% power for short periods, then backing down to 30-40%). I credit our tight, well-insulated house for a lot of that.

Another thing that needs to be mentioned (if it hasn't already) is that geothermal units are not meant to be used with a programmable thermostat. My office is in the basement, and I had it programmed to drop to 66 at night, then back to 70 by 8:00 am. The unit would run all morning to warm it up to 70 by noon because it would run at such a low power. This would negate any savings by setting it back at night, so we shut it off. We do typically drop the temp in our bedroom 1 degree at night in the summer because we like it cooler, but the unit can recover a lot quicker when it is cooling than when it is heating.

 

[buckeyefarmer]

What lengths of loops and how many do people have?

i have 5 loops, each 700' long total pipe in slinkies. slinkies are 3' wide by 70' each.

 

[fordmantpw]

I have 5 holes 180' deep (I think).

 

[buckeyefarmer]

I should have added i have 5 tons in 2 units.

 

[truckdiagnostics]

fordmantpw, I have horizontal loop hence the 8 instead of 6. More cost effective and if you have the space. I just paid the farmer to come out for the day with his excavator. The big reason for the 6 instead of the 8 is we would have had to bank it, for safety in the trench. Up until say winter before last has not been issue. I have also heard bad things about the slinkies. We laid out our own loop and make up own manifolds. Also, based on my understanding on how the 7 series it is a nice unit..... Both our units do not have staged compressor, not available back then. Also believe the 7 is a whole bunch quieter. The unit in the house is under the bed room and when it is running has a nasty hum. Putting it there not one of my smarter ideas. I have heard other complaints on the noise/hum. So consider that when locating.

 

[jk96]

Nobody ever says you have too much capacity!

A word of caution. We had geo installed and actually did have problems with too much capacity. Basically due to how tight the house is along with spray foam insulation our run times were averaging anywhere from 8-15 minutes even when the temp was in the teens. Multiple zones also compounded the problem. This led to inefficient run times in the winter and high humidity in the summer due to short cycling.

Jeremy

 

[fordmantpw]

fordmantpw, I have horizontal loop hence the 8 instead of 6. More cost effective and if you have the space. I just paid the farmer to come out for the day with his excavator. The big reason for the 6 instead of the 8 is we would have had to bank it, for safety in the trench. Up until say winter before last has not been issue. I have also heard bad things about the slinkies. We laid out our own loop and make up own manifolds. Also, based on my understanding on how the 7 series it is a nice unit..... Both our units do not have staged compressor, not available back then. Also believe the 7 is a whole bunch quieter. The unit in the house is under the bed room and when it is running has a nasty hum. Putting it there not one of my smarter ideas. I have heard other complaints on the noise/hum. So consider that when locating.

I figured you had horizontal, just joking on the tape measure comment.

For us, they said the cost to go horizontal was only about $1k less than vertical. Then you have to deal with settling, etc., and it just wasn't worth it. I'm sure I could have done some of that myself to save more $$, but frankly, I just didn't have the time with everything else going on.

Our 7 Series is extremely quiet. Actually, we hear the water pump pumping the water through the loops over the furnace itself. And with the variable speed compressor and fan, that just aids in the quietness.

 

[fordmantpw]

A word of caution. We had geo installed and actually did have problems with too much capacity. Basically due to how tight the house is along with spray foam insulation our run times were averaging anywhere from 8-15 minutes even when the temp was in the teens. Multiple zones also compounded the problem. This led to inefficient run times in the winter and high humidity in the summer due to short cycling.

Jeremy

That's a very good point, but based more on the unit size than loop size. My parents have a geo unit in their house and they actually have to 'dump' a bunch of air in the basement to help with the issue. The joke is that you can hang meat in their basement in the summer! They were right on the fringe on unit size and decided to go up a size.

A note on the efficiency side. On the very coldest days, our unit would average around 1500 watts +/- for the day. Think about that for a minute. Many hair dryers use 1500 watts. A ceramic space heater uses 1500 watts on high. We were heating our entire house for the cost of running a hair dryer or space heater.

 

[dodge man]

Yes, mine also uses less than 2000 watts when it running.

One problem with ours is I like it cold at night when I sleep. I usually only turn it down 1 or 2 degrees at night but it would be better if I didn't change the temp at all.

 

[MacLawn]

On the unit sizing, going too big can cause clamy, damp feeling in summer. Any ac unit needs to run at a bit warmer and run a bit longer to properly remove humidity. Bigger is not better here.

My man said if we drill instead of dig trenches, we would need 3 200' holes, but cost would be $5,000 more to drill! I have space to trench, but dagnabbit, I just hate to have all that Georgia red clay dug up like again at me place! That stuff will stick to ye hide!

 

[fordmantpw]

Do you know how close the water is to the surface at your place? When they put ours in, they said they hit water early, which helps drastically with performance of the system and make it more efficient. Now, that won't make up the $5k difference, but it will make up some over the long haul. I'm with you on digging up the yard to trench it. Man, it just never seems right after that. We've got a lot of clay here too, but we've also got tons of rocks. The rocks come to the surface and you are picking them up for years, they destroy lawnmower blades, bust windows, etc. $5k seems like a lot, but when you factor everything else in, I would say it gets cut in half. You have to work it up, seed it, straw it, water it, overseed it the next year, yada yada yada.

 

[Redneck in training]

Find somebody doing directional drilling. The guy who installed ours geo had directional drilling machine. They could install loops from one relatively small hole. I can't recall the brand of the machine. It used a pipe made of mild steel that was passed through several pulleys to bend is in such arc that it would emerge from ground in certain distance. On the front of the pipe was hydraulic motor driving the drilling head. The motor was powered by a drilling polymer that lubricated the bore and provided a thermal contact when the loop pipe was pulled in the bore by retracting drill. They could install loops under the buildings or trees.

 

[fordmantpw]

Find somebody doing directional drilling. The guy who installed ours geo had directional drilling machine. They could install loops from one relatively small hole. I can't recall the brand of the machine. It used a pipe made of mild steel that was passed through several pulleys to bend is in such arc that it would emerge from ground in certain distance. On the front of the pipe was hydraulic motor driving the drilling head. The motor was powered by a drilling polymer that lubricated the bore and provided a thermal contact when the loop pipe was pulled in the bore by retracting drill. They could install loops under the buildings or trees.

That's awesome! Would love to see one of them machines work.

 

[truckdiagnostics]

i believe when he said more is better is he may have been referring to loop size, if that is the case I would agree to a certain extent. I put the trench in when the foundation was going in so everything already dug up. Feel for you on the clay, we have it here but they put rocks in ours and sometimes really big boulders, our loop makes a curve because of one.
Maclawn, is he using your old heat pump air handler our is he installing a new one?