Residential geothermal ???

[mackdx]

I have a 2,500 sq. ft. house with a 1,200 s.f. garage situated on 23 acres in southern Maine. The house is 5 years old and is heated by forced hot water (Viessmann oil fired burner). The garage has radiant heat in the slab. I have been curious about geothermal for awhile now and with heating oil prices over $3/gal and uncertaintainty in the petrolem markets, but just don't have enough information to make a judgement of costs vs. benefits.

Some background and random thoughts:

- The land is all field. Heavy clay soil with absolutely no rocks. Easy trenching.

- My brother is a self employed lic. plumber and willing to help.

- I know geothermal is better suited for forced hot air delivery, but I am not a fan of hot air. Since we are in Maine and have a nearly constant breeze, I am not as concerned about having A/C in the summer.

- Ideally, what I would like to do is keep the oil burner and base board for the upstairs (and backup heat) and convert the downstairs to radiant (tubing installed below the subfloor from the basement) and heat the downstairs and the garage with geothermal.

- No carpet downstairs - hardwood and tile.

- We are in this house for the long term.

- I am presuming with the easy digging and access to a professional plumber, I can do this cheaper than most folks.

- Tax credit still available?


Anyone with geothermal knowledge have any thoughts? suggestions? regrets? better ideas? I realize that I would not be utilizing the system to its full potential with respect to cooling, but am more intersted in mitigating long term heating oil costs.

 

[Zapko Motorsports]

I'm also interested in hearing responses to your question. In my research, I have found that vertical loops are MUCH more efficient than the horizontal loops that you are possibly referring to. I believe the tax credit of 30% and no cap on geothermal installations was extended into 2011 as well. I was quoted at $21K for the whole kit and caboodle, and I think we'll pull the trigger in the spring. I can put as little as 5K down and the state will finance the remainder, and the 7K should come back on my taxes at the end of 2011. This price also includes a/c and heating 30% of my domestic hot water supply in the summer.

 

[SPDMETL]

I need to know this stuff too-new house is burning ten gallons of oil a day. Big Owwwie ! I'm inclined to use the vertical loop as well. Seems like by the time you pay to dig up the woods you could just have another well and be done with it. $20K actually doesn't sound as bad as I feared. Still alot though...

 

[jvitez]

We have geothermal heat. Our house was custom built in 2006. Here's our system:

Well to well open loop.
Two water to water heat pumps.
Four zones.
Four fan coils.
Four 40 gal water tanks, each tank feeding one fan coil.

We have extreme variation in summer to winter temps here on the Canadian prairies, from -40C to +32 summers, so we need heat and AC. Our system is a water to water system, which is exactly what is needed for in floor radiant heat. If we didn't need AC I would definitely have spec'd in floor radiant. We could have done open loop or closed loop, no difference. We did open loop because closed loop can actually freeze the ground and shut off the heat pumps meaning we're running on straight electric heat, vs a steady aquifer water temp of 43F winter and 53F summer, so we always have above freezing water to extract heat from.

The heat pump heats water in a 40 gal tank. This water could be fed directly to an in floor radiant zone, or to a fan coil. For your property, I suspect trenched slinky loops would be the most cost effective method if you want closed loop.

We just finished a few -30C nights, and today is in that range with the windchill. Our house stays nice and even in all zones at the thermostat setting of 21C.

 

[rsanter]

geothermal is a really nice system. we have 2 at work
natural gass is generally more cost effective but if you do not have regualar access then geothermal can be a good alternatice

there is a water exchange system and a direct exchange, the water exchange seems to run more efficient

a couple of tips, the deeper you go the more stable the tempature. for sure get under the frost line and then a little more

the major cost is the excavation and pluming. if you can cover that then you are in great shape

I think they are better for cooling than heating, but our system does heat well

bob

 

[6768rogues]

Vertical systems use a casing driven or drilled into the ground. Inside the casing is a pipe that goes down, makes a u-bend at the bottom, then comes back up. After installing the inside pipe, the casing is filled with a cement mixture that is good at transferring heat. The finished product is a sealed closed loop. The water going down pushes the water going up, so all the pump has to do is keep things moving. With a horizontal system, you have to push the water through the piping without gravity to help.
The bottom line is that a horizontal system might be cheaper to install, but will need a larger pump and more electricity to keep the fluid moving.

 

[JCoggin]

I have a WaterFurnace Envision 5 ton geothermal system in my home and we love it. It has been installed for two years and has cut our annual fuel consumption by 1/3. Our system is water to air and we are also using the desuperheater to provide a good portion of our DHW. My loop field is horizontal, five - three hundred foot loops for a total of 3,000ft. + of HDPE pipe.

JC

 

[jkeyser14]

If you can afford it, by all means do it. We did our house last year and love it. Water to water geothermal is not as common as forced air, but it is still done all the time. If I were you, I would run the whole house on the geothermal and just keep the oil heater as a backup since you need some sort of backup anyway.

Having a licensed plumber probably won't help you save money. Having a bobcat and knowing how to use it would save you a lot more. The pipes are a large diameter pex tubing that require special tools to weld the joints, but if done correctly it will be almost one continuous run with almost no joints. Most geothermal outfits won't warranty the system if they don't do the install, but if you prep the ground for them to lay the loops in it will save you some of the cost (maybe $2k). Remember that the trenches should be 6+ feet deep though.

As already mentioned, vertical loops are more efficient and it make it less likely for the loops to get damaged by shifting ground, tree roots, digging, etc. However, they are a lot more expensive to install as you can imagine. I went with vertical loops for ease of mind more than for the efficiency.

Give a few companies a call and get estimates. Call their references. And by all means, do a lot of reading at http://forum.geoexchange.org/

 

[tommudd]

Good info I am looking at a house to buy next week that is advertised as having geothermal heat.

For the experts what all do I need to look at to make sure its good system, or questions to ask.
Thanks for any and all information. Sorry to but into this conversation but it will maybe help everyone in whats good and bad

 

[mackdx]

I would have to go with a closed (horizontal) loop system simply because the digging is so easy at my place. I suspect a day with a 8-10' ditch witch would be sufficient. Also, with respect to an open loop system, I have super corrosive salt water (all wells in the area are the same way) and I don't think I would want that circulating through any expensive equipment.

 

[jvitez]

Also, with respect to an open loop system, I have super corrosive salt water (all wells in the area are the same way) and I don't think I would want that circulating through any expensive equipment.

Well, our well water is 38 grains of hardness, no issues yet. The HVAC contractor said any modern heat pump is designed for hard water now, which wasn't the case in the past.

 

[jkeyser14]

Good info I am looking at a house to buy next week that is advertised as having geothermal heat.

For the experts what all do I need to look at to make sure its good system, or questions to ask.
Thanks for any and all information. Sorry to but into this conversation but it will maybe help everyone in whats good and bad

Find out if it is an open or closed loop system and how old it is (get a model number and you can do some research on the furnace). Ask the owners for a few of their electric bills so you can see how it performs, but remember this isn't a good estimate because some people are very energy thrifty, others are complete energy hogs. When the system is running listen to the loop piping and flow center pump (normally a groundfos pump) to see if you can hear any gurgling (air in the lines = very bad). That's really about all there is to it. The loops are normally estimated to last 50 years and the furnaces anywhere from 15-25 like a standard heating system.

 

[trythis]

We have a closed loop system, same square footage, 5 ton system, all vertical wells
Radiant heated floor, concrete, 14 foot ceiling in house.
Chiller coil as well that works for heat and AC.
Our backup is not electric, its gas.
If we have a extra fast temp drop and the floor cant keep up with the house air temp demand, the house air gets quick heated with the water from the Geo heat pump. The gas furnace blower is separated from the heat pump itself but has a water coil in it instead of a standard A coil. If the air temp sends demand for over 15 minutes, or if it is more than a couple of degrees behind, it fires up the gas. The gas heat even helps heat up the water as it goes through the water coil, speeding up the floor recovery.

The gas only runs if the system shuts down or cant keep up in case of several weeks of below 0 weather though and the floor rarely fails to keep up so its uncommon for the air to blow at all. If it does, I know its gonna be a cold morning.

Any heat pump will switch from heat to AC, so if you have duct work its an easy addition.
If the tax deal is there it will be worth it quick compared to heating oil, our total electric bill in worst month of winter was $190. What does oil cost? Much of the cost for us was drilling the wells, the pump isnt that expensive compared to a regular high efficiency system.
You need a 40 to 60 amp breaker to run the pump, and a couple for other things.
AC gives free hot water in summer, not that its a big need in summer.

 

[Zapko Motorsports]

My propane tank was just topped off yesterday.... and it pushes me closer and closer to sealing the 'geothermal deal'. 275 gallons used in the last 5 weeks = about $800.00! Ouch. The proposal I received mentioned that my break-even point on the 14K spent is about 7 years.
My only real concern is longevity and reliability. I still hear some negative comments from HVAC professionals. I don't know whether to chalk those comments up to misinformation or older, more unreliable systems, but I had an commercial properties engineer tell me that the 'technology just isn't there yet". I thought they've been around for quite some time and just recently have experienced a surge in popularity. Like I said, if anything reliability and longevity are my 2 main concerns and there aren't many people in the area who have lived with it for more than a couple years.

 

[Weedwaka]

I love the idea of geothermal. It didn't work for our place for a few reasons. We had a new geo company ready to sponsor some of the costs too. Here is what we found, hope it helps.

Heat loads. Being a new build, it was more cost effective to insulate very well than to add the geo. Your home is already constructed and your heat costs are high so going with this setup makes total financial sense for sure.

Mechanical complexity. Geo systems are wonderful and can also be very complex. When doing research we found many people facing expensive repair / maintenance costs that would really push back your "system pay back" date. Premature equipment failures etc. You may never have a problem or you may get a few issues, its just something to think about. I would think that if you keep it simple and buy equipment that is proven, you should be fine.

Wood. For us, where we are located, wood is cheap. A good, high end exterior wood burning furnace with water to water heat exchanger came out far ahead of geo in inital costs and potential future failure costs. Something to possibly look at. Loading and storing wood does ****.

Rocky Ground. Digging it is a ***** here and $$ . Sounds like you have perfect ground for this. I say go for it.

 

[Weedwaka]

http://www.centralboiler.com/e-classic.html

 

[Zapko Motorsports]

That may be feasible for some, but it doesn't provide a/c, nor will my wife care for running out on zero degree mornings before she showers to throw wood in furnace. I spend too much time out of town. Maybe when I retire!

 

[jkeyser14]

Mechanical complexity. Geo systems are wonderful and can also be very complex. When doing research we found many people facing expensive repair / maintenance costs that would really push back your "system pay back" date. Premature equipment failures etc. You may never have a problem or you may get a few issues, its just something to think about. I would think that if you keep it simple and buy equipment that is proven, you should be fine.

Wood. For us, where we are located, wood is cheap. A good, high end exterior wood burning furnace with water to water heat exchanger came out far ahead of geo in inital costs and potential future failure costs. Something to possibly look at. Loading and storing wood does ****.

Rocky Ground. Digging it is a ***** here and $$ . Sounds like you have perfect ground for this. I say go for it.

I think most of the issues people have are with bad, untrained, or uncertified installers. Anyone interested in geothermal should only use IGSHPA certified people (International Ground Source Heat Pump Association). Ask whoever is doing your quote if they AND their installers all have certifications too. It doesn't help if just one head guy at the company is certified since he won't be the one doing the labor.

As for wood, I have free wood already split and sitting out back and I've got a nice woodstove. I very rarely use it due to the hassle of heating with wood when compared with geothermal (just set a temp and walk away).

And rocky ground shouldn't be an issue. I live in an area that's very rocky. The drillers who did my loops didn't have any problems though. It's no different than drilling for a well and they have it down to a science.

 

[Dragster Racer]

How are the electric bills with the geo? A coworker of my wifes built a new house with geo, and were totally disappointed. Their electric bills are way out there. I think they figured out that the system was undersized for their home. Bad install I guess.

 

[V-10 Killer]

Vertical systems use a casing driven or drilled into the ground. Inside the casing is a pipe that goes down, makes a u-bend at the bottom, then comes back up. After installing the inside pipe, the casing is filled with a cement mixture that is good at transferring heat. The finished product is a sealed closed loop. The water going down pushes the water going up, so all the pump has to do is keep things moving. With a horizontal system, you have to push the water through the piping without gravity to help.
The bottom line is that a horizontal system might be cheaper to install, but will need a larger pump and more electricity to keep the fluid moving.

In the case of a vertical well, is there any easy way to tell how deep/big you have to go for a system? I have an old 4" water well pipe in the front yard I no longer use due to having city water piped up now. If memory serves, it goes down ~100-130'. I had actually thought about having it uncapped and filled in, but I wonder if it could be retrofitted for something like this...

This has me curious. My wife and I had discussed geothermal, but are currently leaning more towards upgrading to a high efficiency furnace.

 

[jvitez]

How are the electric bills with the geo? A coworker of my wifes built a new house with geo, and were totally disappointed. Their electric bills are way out there. I think they figured out that the system was undersized for their home. Bad install I guess.

Our geo house has 46% more heated volume than our previous house, and we pay the same total energy bill. Not quite apple:apples though, as the new house has more insulation and better windows, and uses almost 100% electricity. Previous house had a hugely oversize mid efficiency forced air NG furnace, NG dryer, and NG water heater, and even though electricity is quite reasonable here, it's still more than NG. But all in all, we're saving money every month, and the house has even temperatures throughout.

 

[jkeyser14]

In the case of a vertical well, is there any easy way to tell how deep/big you have to go for a system? I have an old 4" water well pipe in the front yard I no longer use due to having city water piped up now. If memory serves, it goes down ~100-130'. I had actually thought about having it uncapped and filled in, but I wonder if it could be retrofitted for something like this...

This has me curious. My wife and I had discussed geothermal, but are currently leaning more towards upgrading to a high efficiency furnace.

That really depends on the climate and soil/ground composition and moisture content. My 3 ton system has two 250' deep bores.

 

[kmsss]

Before installing geo I learned everything from www.greenbuildingtalk.com. Awesome forum on geothermal.
Geothermal was the best investment we could have made. Our first winter in a 10yr old house we went threw 500 gallons of propane in 4 weeks during the coldest stretch. My bill for heat (set 3 degrees warmer) and hot water would have been uder $175. We spent over $800 to fill that propane tank ONCE!
Oh yeh, AC is awesome in the summer.
You can look at my geothermal operation at www.welserver.com/WEL0226

 

[Zick]

In the case of a vertical well, is there any easy way to tell how deep/big you have to go for a system? I have an old 4" water well pipe in the front yard I no longer use due to having city water piped up now. If memory serves, it goes down ~100-130'. I had actually thought about having it uncapped and filled in, but I wonder if it could be retrofitted for something like this...

This has me curious. My wife and I had discussed geothermal, but are currently leaning more towards upgrading to a high efficiency furnace.

Depends on the size of system you need. We have a 5 ton unit with 5 wells that are each 150' deep.

 

[Zick]

Before installing geo I learned everything from www.greenbuildingtalk.com. Awesome forum on geothermal.
Geothermal was the best investment we could have made. Our first winter in a 10yr old house we went threw 500 gallons of propane in 4 weeks during the coldest stretch. My bill for heat (set 3 degrees warmer) and hot water would have been uder $175. We spent over $800 to fill that propane tank ONCE!
Oh yeh, AC is awesome in the summer.
You can look at my geothermal operation at www.welserver.com/WEL0226

Greenbuildingtalk is great and has tons of information!

I checked out your welsever, I love those things and have been thinking about getting one for ours.
One thing that caught my attention was your incoming ground loop temps seemed really low. I thought they would be closer to 40* or higher. I haven't had a chance to check ours yet. What kind of loops do you have? (Horizontal, wells, depth, etc)

 

[kmsss]

Yeh, wel logger is great for keeping an eye on the system!
You got me thinking about the temps... I looked at several other hoz. systems in my temp zone. They were all in the low 30's.
You should see temps around 40 being vertical.
I have 3200' 3/4" (4 800' out and back circuits to a 1 1/4" main into the house) buried 7', backfilled 2' then back for an average depth of 6'.
We have a 4ton system. 2400 sq ft.

Would do it again in a second! Just make sure the system is sized correctly and INSTALLED correctly!! Kurt

 

[Traditional hotrodder]

I have been installing geothermal heat pumps for the past 2 years now. I strongly believe there is just too much misinformation and untrained people handling these systems. You wouldn't believe how many companies will submit a bid/proposal to a home owner and when the home owner goes to "sign on the dotted line" they are told that they have to pull the permit!? I've been on numerous service calls with my boss for performance issues on units installed by others. We have yet to have a customer not satisfied with a geo system installed by us.

 

[danski0224]

Wouldn't it be more economical to build better, first?

I could tear off all the drywall in my home and spray foam everything (walls and attic)and replace the windows for less money than a geothermal install. I've seen 1" of foam followed by dense pack blown in cellulose- but that was on 2 x 6 walls. My walls are 2 x 4, so are the roof trusses, so all foam would be a big improvement.

Due to my location, I would need 60k btu's to heat this house as-is without going to resistance backup.

I attended a Green Building seminar in Chicago with geothermal heating/cooling as the topic of discussion. The technology has a lot of promise, but the premium dollars for equipment that won't last any longer than traditional equipment and is more expensive to repair (plus the need for someone really specialized to get it right) or loop piping with a projected 50 year lifespan (really, just what do you do when a loop well goes bad?)... hard to make sense of it when this stuff is being used to crutch poor building practices and/or poorly installed traditional HVAC equipment.

Hell, if the traditional HVAC equipment is installed with substandard piping or ducting, that makes no sense, either... but it happens all the time. Oversized variable speed furnaces just don't work if the ducting is bad.

I see so many forced air and regular boiler systems hacked in... I would hate to see the same thing with a 2x to 3x more expensive geothermal system.

 

[SPDMETL]

Anybody have a link to approved/certified geo contractors ? I'm ready to do this as soon as the heating season is over...

 

[kmsss]

The cost of geothermal is mainly installation. Once all the piping and loop field is in the unit itself is no larger than a fossil fuel furnace and not that much more expensive. A 50 yr life of a loop field is pretty good in my eyes. What could go wrong with it? Its not going to rot! Throw ontop of that a 30% uncapped tax credit!

 

[Zapko Motorsports]

Before installing geo I learned everything from www.greenbuildingtalk.com. Awesome forum on geothermal.
Geothermal was the best investment we could have made. Our first winter in a 10yr old house we went threw 500 gallons of propane in 4 weeks during the coldest stretch. My bill for heat (set 3 degrees warmer) and hot water would have been uder $175. We spent over $800 to fill that propane tank ONCE!
Oh yeh, AC is awesome in the summer.
You can look at my geothermal operation at www.welserver.com/WEL0226

INCREDIBLY informative post. Thank you, sir, it is very much appreciated!

 

[Traditional hotrodder]

The plastic lines that the loop field or vertical loops are made from is warrantied for 50 yrs. by the manufacturer. The actual lifespan of the plastic is indefinite.

 

[danski0224]

The plastic lines that the loop field or vertical loops are made from is warrantied for 50 yrs. by the manufacturer. The actual lifespan of the plastic is indefinite.

I have found warranties to be mostly meaningless.

The siding on my home has a lifetime warranty... not good because the company is out of business.

Ever tried to get a roof warranteed? It just doesn't happen... there is always wiggle room or something not done exactly to mfg. specs (no drip edge, starter strip, improper fasteners used [staples/nails/length], improper exposure, improper nail pattern, non-certified installer and more).

These examples are items that have a large labor and minimal (comparatively) parts cost. They are also items that are typically manufactured by one entity and installed by another.

In comparison, the lifetime warranty on a Harbor Freight tool is easy to honor because the item is easily inspected and most importantly, cheap. They can give you several new imported ratchets for the retail price of one.

Tire warranties also ****. Yep, it reads pretty simply as far as the manufacturer is concerned... but going through the place of purchase/installation adds a whole new layer of excuses.

Call me paranoid, but I would place very little faith in the claimed 50 year "warranty", especially if it has no 3rd party underwriting. Of course, all bets would be off if the installing contractor isn't "certified".

 

[kmsss]

I have found warranties to be mostly meaningless.

The siding on my home has a lifetime warranty... not good because the company is out of business.

Ever tried to get a roof warranteed? It just doesn't happen... there is always wiggle room or something not done exactly to mfg. specs (no drip edge, starter strip, improper fasteners used [staples/nails/length], improper exposure, improper nail pattern, non-certified installer and more).

These examples are items that have a large labor and minimal (comparatively) parts cost. They are also items that are typically manufactured by one entity and installed by another.

In comparison, the lifetime warranty on a Harbor Freight tool is easy to honor because the item is easily inspected and most importantly, cheap. They can give you several new imported ratchets for the retail price of one.

Tire warranties also ****. Yep, it reads pretty simply as far as the manufacturer is concerned... but going through the place of purchase/installation adds a whole new layer of excuses.

Call me paranoid, but I would place very little faith in the claimed 50 year "warranty", especially if it has no 3rd party underwriting. Of course, all bets would be off if the installing contractor isn't "certified".

Sounds like you better get tearing off drywall!

 

[danski0224]

Sounds like you better get tearing off drywall!

Not today

 

[bookman51]

Knock on wood, but this is the 6-7 year in a house with geothermal heating/cooling. It is an all electric house and I would guess out heating/cooling runs about a $100 a month average. Last month (December), our cost was $145. It gets down to the $70-$80 for the cheapest months. I live out in the country and it is an open system and the water is discharged.

The system came with the house, and I cannot tell you about cost or how well the house is insulated. However, so far I am quite pleased. No doubt mileage can vary.

Bookman

 

[Dkramer]

You mentioned that the garage is radiant, but you don't say whether the hydronic heat in the house is radiant floor heat or baseboard/radiators. If you are all radiant floor heat, then water to water geo is a great way to go. If you have baseboard/radiators geo more then likely won't be able to provide the water temp that is necessary to heat the house. Modern geo units can only heat the water to maybe 130 degrees without stressing the heat pump. You will also need a buffer tank with water to water. 2 gallons for every 1000 btu's of heat pump capacity. ( A 24000 btu heat pump would need at least a 50 gallon buffer tank.)

 

[jkeyser14]

For all those wondering about savings, this is from this months utility bill. My geothermal system was installed last January and for a few days of that time our old oil furnace was ripped out and our geothermal system wasn't up and running yet so we were using 100% electric heat which is why the kwh reading is so high.

My total utility bill this month was $203. We average ~$110-120 in electric usage during the months when we aren't heating or cooling. Before getting geothermal, this past month would have cost us $500-600 because we were oil heat (no natural gas on my street). If enough people are interested I'll go through all my utility bills for the past year and post the info here for people to look at.

 

[jkeyser14]

Wouldn't it be more economical to build better, first?

I could tear off all the drywall in my home and spray foam everything (walls and attic)and replace the windows for less money than a geothermal install. I've seen 1" of foam followed by dense pack blown in cellulose- but that was on 2 x 6 walls. My walls are 2 x 4, so are the roof trusses, so all foam would be a big improvement.

Due to my location, I would need 60k btu's to heat this house as-is without going to resistance backup.

I attended a Green Building seminar in Chicago with geothermal heating/cooling as the topic of discussion. The technology has a lot of promise, but the premium dollars for equipment that won't last any longer than traditional equipment and is more expensive to repair (plus the need for someone really specialized to get it right) or loop piping with a projected 50 year lifespan (really, just what do you do when a loop well goes bad?)... hard to make sense of it when this stuff is being used to crutch poor building practices and/or poorly installed traditional HVAC equipment.

Hell, if the traditional HVAC equipment is installed with substandard piping or ducting, that makes no sense, either... but it happens all the time. Oversized variable speed furnaces just don't work if the ducting is bad.

I see so many forced air and regular boiler systems hacked in... I would hate to see the same thing with a 2x to 3x more expensive geothermal system.

You should get a quote on new windows before you start tearing out the old ones. Good double panes start at about $400 each. Good triple panes start at about $650 each. My house has 26 windows. It was cheaper to install the geothermal.

 

[danski0224]

You should get a quote on new windows before you start tearing out the old ones. Good double panes start at about $400 each. Good triple panes start at about $650 each. My house has 26 windows. It was cheaper to install the geothermal.

Well, my windows are builders grade vintage 1967.

They are in bad shape right now, and will need to be replaced if this place is to sell at some point in the future. I can't get many of the old storm windows off (paint not dried fully before reinstallation before I moved here), so the windows can't be cleaned.

As far as number of panes is concerned, single pane windows with good fitting storms will outperform clear double pane windows without storms.

Triple pane windows are marketing hype, and offer very little in return for the significant price difference.

Run a HVAC load calculation and discover the truth.

The only way to do window replacement right is to get back to the rough opening. Leaving the old jambs in the wall is pointless- the original air leaks will remain, and you pay more for a smaller window opening.

I was quoted $600 a window for replacement type windows a while ago... and this is for cheap vinyl. I can get very good new construction windows for similar money, and install them myself with more effort but better results.