geothermal questions and possible DIY

[LD1]

I was finally able to speak with a 4th contractor yesterday. He is the one who installed my parents air-air setup, and is a good friend of my uncle. He knows me fairly well and what I am capable of.

He actually encouraged me to install myself. Looking at the 4-ton 2-stage units from ingrams, complete with DIY install packages and everything are a little under 10k for a climatemaster, which he actually spoke highly of and said its a good unit. Also looking at the units from terrasource, all though I dont know the brand? But they are also 10k.

I explained to him my biggest concerns is the plumbing, and making sure I do it correctly. He said he would be willing to lend me a hand and offer some advise when I get to that point as well as hanging duct work if I decide I do not want to do that. I know a lot of experience and knowledge goes into duct work sizing to make things run properly.

He is also just gonna give me a quote to do it all as well. But after speaking with him on the phone, he agreed that it seems others were charging too much since I am doing the excavation. He is gonna come out next week sometime and we will talk more about it.

Hoping if money allows to do this sometime in spring/summer. But next year...my new shop build is gonna take priority.

 

[shaley]

Friend of mine is a HVAC contractor. He gave me a price of $5000 for a 3 Ton split system (2 stage, open loop, Air handler and Outside unit). This is the equipment only. He said he doubles this price for the consumer and then adds labor. Ebay has some great deals and they some sellers offer a DIY kit.

 

[techman]

He actually encouraged me to install myself. Looking at the 4-ton 2-stage units from ingrams, complete with DIY install packages and everything are a little under 10k for a climatemaster, which he actually spoke highly of and said its a good unit.

I installed my system, although I do have a side HVAC business. You can see it here: http://www.tractorbynet.com/forums/rural-living/74680-geothermal-heat-pump-project.html?highlight=

It is all relatively easy, with a few exceptions. Putting in the pipe is easy, but for best results you need good coupling to the ground. Do not use sand as it is a good insulator if not wet. On recommendations from a wholesaler with a lot of install experience, I used screenings. About 1 foot around the pipes. Packs and is almost like solid rock in the end. Just backfill above/around it. Next is the issue of connecting the pipes. The only accepted method is thermal fusing. Do not use any type of mechanical fittings, they will likely corrode and fail in time. There are some places that will rent the tools to do thermal fusion joints. I rented them from a supplier, who also provided me with about 1 hour of training. The last issue for a DIY is flushing the system. You need a flushing cart or something similar to flush and get the air out of the system. I could have rented a cart, but instead made up my own rig using a 3/4 HP pool pump. The rig has valves associated with it. You need to be able to reverse flow, block and build pressure and monitor the flow for air. A large (20-30 gallon) tank should be used. This is also used to mix the antifreeze and get it well circulated, and mixed.

A couple of other recommendations: it was recommended to me to install a small bladder expansion tank in the loop. I have put this in all of the syatems I have done. You must use the type for potable water since the fluid sees the inside of the bladder and not the steel tank. This keeps rust from forming. The tank is small but takes up seasonal temp variations and keeps the loop pressure relatively constant. Without you will see 20-40 PSI seasonal pressure changes. Also put in a 50 gallon water heater as a preheat tank to your conventional water heater. Connect the desuperheater (DHW) on the heat pump to the preheat tank. You will get more heat into your domestic hot water this way, since the temps in the regular tank are hotter and will limit the amount of transfer. Next for antifreeze, avoid glycols. Lower capacity and it gets thick when cold, which usually requires a second or bigger circ pump as a result. Many jurisdictions do not allow methanol due to potential toxicity if you have a leak, so the best alternative is an ethanol based antifreeze. It costs more, but properties are better and pumping characteristics are the same as water. Last I would stick with Climatemaster, Water Furnace or Bosch for a unit. I went with Climatemaster which I consider a top unit (along with the other two) but I got a better price from them. I have had no problems and highly recommend them.

paul

 

[LD1]

Friend of mine is a HVAC contractor. He gave me a price of $5000 for a 3 Ton split system (2 stage, open loop, Air handler and Outside unit). This is the equipment only. He said he doubles this price for the consumer and then adds labor. Ebay has some great deals and they some sellers offer a DIY kit.

IS that a Geo unit or air to air? Not familiar with a split system geo unit, what part goes outside?

 

[LD1]

I installed my system, although I do have a side HVAC business. You can see it here: http://www.tractorbynet.com/forums/rural-living/74680-geothermal-heat-pump-project.html?highlight=

It is all relatively easy, with a few exceptions. Putting in the pipe is easy, but for best results you need good coupling to the ground. Do not use sand as it is a good insulator if not wet. On recommendations from a wholesaler with a lot of install experience, I used screenings. About 1 foot around the pipes. Packs and is almost like solid rock in the end. Just backfill above/around it. Next is the issue of connecting the pipes. The only accepted method is thermal fusing. Do not use any type of mechanical fittings, they will likely corrode and fail in time. There are some places that will rent the tools to do thermal fusion joints. I rented them from a supplier, who also provided me with about 1 hour of training. The last issue for a DIY is flushing the system. You need a flushing cart or something similar to flush and get the air out of the system. I could have rented a cart, but instead made up my own rig using a 3/4 HP pool pump. The rig has valves associated with it. You need to be able to reverse flow, block and build pressure and monitor the flow for air. A large (20-30 gallon) tank should be used. This is also used to mix the antifreeze and get it well circulated, and mixed.

A couple of other recommendations: it was recommended to me to install a small bladder expansion tank in the loop. I have put this in all of the syatems I have done. You must use the type for potable water since the fluid sees the inside of the bladder and not the steel tank. This keeps rust from forming. The tank is small but takes up seasonal temp variations and keeps the loop pressure relatively constant. Without you will see 20-40 PSI seasonal pressure changes. Also put in a 50 gallon water heater as a preheat tank to your conventional water heater. Connect the desuperheater (DHW) on the heat pump to the preheat tank. You will get more heat into your domestic hot water this way, since the temps in the regular tank are hotter and will limit the amount of transfer. Next for antifreeze, avoid glycols. Lower capacity and it gets thick when cold, which usually requires a second or bigger circ pump as a result. Many jurisdictions do not allow methanol due to potential toxicity if you have a leak, so the best alternative is an ethanol based antifreeze. It costs more, but properties are better and pumping characteristics are the same as water. Last I would stick with Climatemaster, Water Furnace or Bosch for a unit. I went with Climatemaster which I consider a top unit (along with the other two) but I got a better price from them. I have had no problems and highly recommend them.

paul

Thanks for taking the time to post. Lots of good info to digest and some questions I have for you:

1. About couplings and thermal fusing the pipes. I am not sure what the DIY kits from ingrams or terrasource come with, but my though was to not have ANY joints, fused or otherwise, outside in the ground. I want the header inside. Each parallel loop will punch through the wall and tie in IN THE BASEMENT. I havent got into sizing yet and dont know exactally how much pipe I need to bury, but the though was to get pipe in 500' rolls, and lay slinky style in a trench. Continuous pipe outside, no joints. All of that will be inside where I have access to it if needed.

2. About the screenings to backfill. Was that reccomendation for gravel screenings of limestone screenings. I have access to both.

3. Flushing. I have many pool pumps. I can make something pretty easy. We use a ton of pool pumps at work for the water in cylinder pressure test chambers. When something goes bad, we replace the unit as a whole. Sometimes its an impeller, sometimes a cracked housing, sometimes a bad motor. I save them and take 2 or 3 bad ones and make a good one. For spares for the swimming pool.

4. Pretty sure methanol bases is okay in my area. The one contractor actually mentioned flushing and filling with it.

I am sure I will come up with more questions when the time gets closer.

 

[dodge man]

OK, I have a question. When my geo was installed they put in a new water heater and a second tank. My system is a closed loop system if that makes a difference. So how exactly does the second tank work? Does the system actually have to be running, as in making heat or AC and you have to be running hot water for this tank to be making hot water? The guy that installed mine said the system would make more hot water when the AC was running. Does this sound right?

 

[MacLawn]

LD, sounds to me like you have a good deal with ye uncle's friend. I'd go with him. Letting you do what you can, and him advising and encouraging you sounds great to me. I like ye idea of putting NO couplings anywhere but at the manifold in basement. I've been researching geo since 2002-2003 when I had my current air to air (Is that a-a, etc.? whew, all the acronyms used here has me haid spinning!) installed.

Split unit - I thought even geothermal has to have a split - one unit outside, and the thingamajig inside just like air to air heat pump. At least I read that somewhere. Those inside thingamajigs are what has caused me more troubles over the years than anything else! Just last month, mine was leaking condensate and leaked all under part of my 3/4 oak hardwood floor before I noticed a leak! Condensate only in a/c mode of course, which we use a lot here in Georgia. If I knew that geo could do away with that inside condensate issue, I'd order one next week! Then, figure out how to pay!

 

[dodge man]

As far as I know I have nothing outside my house with the geo other than the underground piping.

 

[techman]

1. About couplings and thermal fusing the pipes. I am not sure what the DIY kits from ingrams or terrasource come with, but my though was to not have ANY joints, fused or otherwise, outside in the ground. I want the header inside. Each parallel loop will punch through the wall and tie in IN THE BASEMENT. I havent got into sizing yet and dont know exactally how much pipe I need to bury, but the though was to get pipe in 500' rolls, and lay slinky style in a trench. Continuous pipe outside, no joints. All of that will be inside where I have access to it if needed.

If you do the fittings inside, you do not have that risk. In my system I put headers in the trench and brought in a single, larger pipe. Just be aware that the longest pipe you can get is 500' (as far as I know). This means the trench and run to the house must fit this length.

2. About the screenings to backfill. Was that reccomendation for gravel screenings of limestone screenings. I have access to both.

It was recommended to me, and I used (what we call) screenings, which are stone (granite I believe) in fine sand particle size and consistency. It will pack solid and thermally couple well.

3. Flushing. I have many pool pumps. I can make something pretty easy. We use a ton of pool pumps at work for the water in cylinder pressure test chambers. When something goes bad, we replace the unit as a whole. Sometimes its an impeller, sometimes a cracked housing, sometimes a bad motor. I save them and take 2 or 3 bad ones and make a good one. For spares for the swimming pool.

Pool pump works. You need some ball valves, fittings, etc. and a large tank as mentioned.

4. Pretty sure methanol bases is okay in my area. The one contractor actually mentioned flushing and filling with it.

Methanol, or other antifreeze that you use will need to be added to meet the desired freeze temp for your system.

 

[techman]

OK, I have a question. When my geo was installed they put in a new water heater and a second tank. My system is a closed loop system if that makes a difference. So how exactly does the second tank work? Does the system actually have to be running, as in making heat or AC and you have to be running hot water for this tank to be making hot water? The guy that installed mine said the system would make more hot water when the AC was running. Does this sound right?

The desuperheater (as it is known) in a geo unit removes the heat of compression and uses it for heating domestic HW. The cheap method is to connect it to your water heater. Problem is that the max temp of the desuperheater is around 110-120 deg. If the water you are heating is near that temp, you do not get much transfer due to the small delta T. The better method is to add a second tank in series with the cold water feed to the DHW tank. You then use the geo to heat this second tank as a pre-heat tank. The increase in temp feeding your DHW heater is pure savings since you are heating water from 70 or 80 deg, instead of the normal 50 deg coming into the house. You get much more out of it in the winter than summer. During the longer cold snaps we get I can get 100+ deg in the preheat tank.

As for cooling and heating season, there are a lot of stories about AC being better for HW heating, but it is not true. It is a bit of a long explanation of thermodynamics, but in a nutshell:

When cooling, the loop water is 50-60 deg. You want the air handler to be around 50 deg, so the refrigeration does not do a lot of work. This means compressing the freon to a low pressure. For R410 this is 150-170 PSI. The heat of this compression is removed by the desuperheater loop for DHW.

When heating, the loop is colder and the condenser is now for heating the house. You want that to be 90-110 deg so the compressor must get to 257-375 PSI. There is much more heat of compression (higher temp) that can be removed to heat DHW.

Just for reference, on a 4 ton ClimateMaster TT, cooling with 50 deg loop water, the DHW heating can supply 800-900 BTUH. In heating (same unit) with 40 deg loop water, the DHW heating can supply 3300 BTUH.

Paul