Geothermal - Newbie needs help

15 years ago

We need to get a new HVAC system (33 year old oil furnace and 19 year old AC)and have decided to look into GeoThermal....however we do have our fair share of reservations due to the cost involved and uncertainty. It seems like a big risk to me.

Our house:

1976 2-story, brick colonial with vinyl siding back

2348 sq ft

Oil heating (no gas available to area)

Philadelphia suburbs

My main concerns or reservations with going Geothermal are as follows:

1) In general I am worried that the installer will not lay enough tubing (something not easily fixed) or that they will size the unit incorrectly.

2) We need to get a new HVAC system now (cracked heat exchanger) but we are planning on updating windows at some point down the line (they are the original storm windows). I am worried that once we get the new windows the unit will be oversized.

3) Our electric company (PECO) rate cap is expiring and starting in 2010 they are saying that rates could increase by 40% over the next 3 years. That concerns me...especially if the sizing is off.

I know there are manufacturer guarantees for the units but do installers offer guarantees? Something costing this much ...it would be nice to see them put some performance guarantees into place that if their calculations are WAY off that you get some sort of compensation or that they fix the problem.

Any advice or suggestions for a newbie?

I have done some research but we have our first appointment with an installer this weekend and I wanted to know what questions I should be asking.

Thanks!

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Comments (4)

cvandoren
15 years ago
Any qualified Geo contractor will know how much horizontal tubing to lay or how deep to drill the wells. You can check their integrity by seeing if they do a in depth heat loss calculation to size the system for you. They should because an oversized system costs mor in geo because you have to put more in ground piping in. They may charge for it though as the last step in the process.
I wouldn't worry too much about problems in the future with being oversized - about 90% of HVAC systems are oversized.
I assume you know about the 30% fed tax credit?
These systems are a pretty easy decision for people on oil or propane. They payback should be under 10 years, and if you sold before then, you would get more for your house anyway. In some cases your annual savings will pay all the payments on a 10 year home equity loan so the system saves you money from day one!
funnycide
15 years ago
A load calculation should be done to determine the heat loss and gain for the house. The problem is for a 19 year old house want insulation was installed and what is the integrity of the insulation. Since you already heating and cooling in the house you have something to go off of. What size is the AC and are you happy with its performance?
The oil furnace is probably oversized but maybe not. Do you have long run cycles on the coldest days or does it only run for maybe 10 minutes?
No contractor will offer a performance guarantee. The problem is he has no control over how you operate your house. That's not to say he shouldn't be held responsible for a system that doesn't operate the way it should. Just don't expect in writing that you will save x in x years.
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piscesgirl
Original Author
15 years ago
Funnycide - It is interesting you mention about the AC size. I have a great story about that.

We had our current oil company give us a quote on replacing the furnace and AC. He looked at the AC and asked us some questions about the house (sq ft, how many bedrooms,etc). Then he said, "well for a house your size you would want a 4 ton unit...which is what you have. The problem is your duct work is only sized to handle a 3 ton so I am going to price out a 3 ton because it is a waste of your money to buy a 4 ton". I asked if our duct work could be modified to handle 4 ton and he said no (I assume that meant that it wouldn't be cost effective).

The other option he gave me was to do split zone and put a 2 ton in the basement and then add duct work for a 2 ton unit in the attic. Unfortunatly that option was very costly. He quoted us around $10k for the oil furnace & AC with the current set up. He said to do the dual zone it would be about an additional $10k.

Question - is the current duct work issue going to be an issue with the GeoThermal?

Overall our house is probably like most 2 story homes built in the 70's. With the AC running the downstairs is always cool and the upstairs is warm (heat rises). We live on a partially shaded lot so that helps a little, but what can I say...it would be nice to have a house with a constant temperature in every room, but we are only in the bedrooms at night so it hasn't been that bad.

Regarding the guarantee - I would never expect that they would put in writing that you would save X in X years. To many variables (electric rates, weather, etc.) however I do want them to be responsible for our system if it is a complete nightmare and our electric usage goes through the roof. Sorry but I grew up in a house that had a heat pump and my parents had horrible electric bills. I just don't want to regret our decision and then have to spend double that to fix our mistake. I am sure you understand.
fsq4cw
15 years ago
Irrespective of what result a ÂManual JÂ load calculation my produce, you may (will) have problems if your current distribution system cannot handle the airflow (cfm) delivered by a heat pump Â any heat pump. Heat pumps are lower temperature devices than the furnace you now have and therefore are required to deliver larger volumes of air to compensate for that temperature differential. One way this problem could show up is as a noisier system (at the registers).

To answer some of your other questionsÂ Regarding proper size of ground loop etc., hire an accredited installer with references. Regarding the system being over sized after later renovations, it may be better to do those things first. However, with a 2-stage compressor and variable speed air-handler this is unlikely.

Regarding the escalation of energy costs, a geothermal HP will likely be 40 ~45% more efficient than a high efficiency air-source HP or air-conditioner so there will always be a relative savings. The life cycle of the geothermal unit will likely be twice that of conventional air-source equipment so there is that savings as well, if you plan on living in your home for a long time.

SR

Here is a link that might be useful: IGSHPA

Geothermal - Newbie needs help

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cvandoren

funnycide

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Geothermal - Newbie needs help

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cvandoren

funnycide

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