Extreme Price Difference on 'same' HVAC System

dboyer76October 5, 2011

We are building a new 7000sq ft house. We want in floor heat in the basement and forced air on the 1st and 2nd floors. We have worked with an installer who was recommended by the builder thus far but I wanted to get another quote just to make sure. The second quote came in at 30,000 less! Not what I expected. The person with the lower quote won't tell me tonnage, number of runs, or break down the material and labor until I sign with him. I am having a really hard time comparing the two for these reasons. Please give me some suggestions!

Here are the systems:

1. Split system- 2 Geo Comfort GTC Heat pumps (040, 060) using Carrier Infinity Air Handlers, 6 zones w/ controls and sensors, hydronic coils, DeSuperheat tank, Lochinvar Boiler, 80 gal Boiler mate, 10 Ton capacity, etc.

2. Single Units- 2 Trane Forced Air Geothermal Pumps (T2GY), domestic hot water option, 2-40 gal buffer tanks, 6 zones w/ controls, etc.

I realize these are different systems but I can't figure in that much price difference. How do I compare or figure out which one is going to give us the most comfort? All suggestions and/or comments welcome!!

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does the 2nd cheaper quote include the geo-thermal loops in the ground?

    Bookmark   October 5, 2011 at 12:58PM
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We are actually doing an open loop system where we "dump" into the lake so they both include that. I'm thinking one of the main differences is the boiler option in the first quote for the infloor heat. I have since learned that the Trane system shares duties between forced air and infloor and it has to choose which one takes priority vs. the Carrier bid which can take care of both simultaneously. I am also thinking that the carrier thermostat and hygrometer are more advanced than the Water Furnace unit?

    Bookmark   October 5, 2011 at 2:42PM
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What climate are you in? I"m pretty sure pump and dump systems can give very high COP (efficiency), but I hear the life of the system is usually drastically shortened because water quality usually destroys the equipment. Do you have access to natural gas?

    Bookmark   October 5, 2011 at 3:43PM
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We live in Northern Lower Michigan. We do not have access to Natural gas. Concerning water quality we are drilling a new well and hope to find good water. If not, it is my understanding that we may have to do a yearly or bi-annual flush/cleaning of the system to prevent build-up. Any thoughts on the system differences?

    Bookmark   October 5, 2011 at 3:55PM
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That was a good explanation. The 2nd quote doesn't mention the type of controllers. The first quote uses the carrier infinity controls which are top of the line. Those type of controls with the air handler allow you to control humidity.

Does the 2nd quote have variable speed air handlers? If it does they will be comparable and have the ability to dehumify on demand with the correct t-stat.

I would probably go with the 2nd quote. 30K is alot of money to be saved, and the system would likely provide you plenty of comfort.

Is your new home going to be very well insulated? I hope so with northern michigan winters. Your geo heatpump won't have to go into defrost like a regular air-source heatpump. It also won't lose efficiency like a regular air-source heatpump. This is a good solution.

    Bookmark   October 6, 2011 at 7:41AM
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Does the installer of the 30K less system have ANY experience with geothermal? The Trane system is a rebranded WaterFurnace and in my area Trane is pushing dealers with little experience to install geothermal systems. However some of us Trane dealers already have experience and have products like the Synergy 3D(or the trane unit you mention) that can heat water and air and cool air and have a desuperheater.

I personally would be very nervous about somebody not showing sizes. It is common practice to not show Manual J before paying but they are being way to vague and I would tell them they are the top runner but only if they provide a detailed contract with equipment and controllers and piping schematics and then a Manual J after payment.

    Bookmark   October 6, 2011 at 5:31PM
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We're talking about an HVAC system which has an influence over ones health, finances and protection of an asset well over a million bones - $30,000 differnce? Hire a P.E. to act on your behalf. It's a no brainer.

    Bookmark   October 10, 2011 at 12:26AM
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Thanks Healthyheating. I agree with what you say I just am trying to figure out the difference. Sorry though, P.E.? What is that? We are just trying to be frugal without being cheap!!

    Bookmark   October 10, 2011 at 7:00AM
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Thanks again. I feel we fall somewhere in the middle of your two descriptions. Our design was created with Southern exposure, solar gain, ample overhang, high efficiency, quality construction, etc. in mind. Architecture and aesthetics undoubtedly played a major role. I don't think we will be LEED certified but it is not your average house. That being said, we did not begin with our expected monthly utility bill as the basis for design. I think we have been reasonably responsible with our design choices thus far. Hence the Geo system. I, not knowing the trade inside and out, am just trying to get the most comfort (and pleasure) out of our system. I think that the higher end system will, without a doubt, provide the level I expect. What I am trying to glean is the sacrifices we would make if we spend less. I realize that the desuper heater and boiler will provide more consistent heat in the basement and that it will also be a more efficient back up/supplemental heat on the very cold days. The question becomes how much less comfortable will the basement be? How many days a year will we need the supplemental heat and is it worth the extra expense. How much better is an Infinity Carrier air handler than the Trane air handler? Will it be noticeably better? I need someone who knows to help me answer these questions. We are not against spending the money if the differences are going to be compromises we regret but we don't know how to figure that out before hand...

    Bookmark   October 10, 2011 at 1:12PM
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Re: "I need someone who knows to help me answer these questions"

The short response: yes - so hire an independent professional engineer. The magnitude and scope of this project warrants it.

The long response: Because you don't have the necessary skills to evaluate this - you have become susceptible to accepting answers from equipment sellers and contractors that make sense to you which may not be strictly correct from a technical perspective...thus the reason for hiring an independent professional engineer who has no vested interest other than helping you with your expectations.

    Bookmark   October 10, 2011 at 4:40PM
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I read this thread but can't offer anything as geothermal is so beyond me. I can say that some contractors will see what you are building and know the wallet must be pretty fat. They might say anything to get your business, or they might be excellent at what they do, but not going to give you the best price.

Seems like the advice to hire someone will be $$ well spent. They can tell you what you need and then you can solicit bids based on the specs YOU provide (if I understand the concept correctly.) At least you will know what you need and can make sure you get it. They will be less likely to bid a job they aren't up to if they know there will be oversight and not "just a homeowner."

Good luck.

    Bookmark   November 3, 2012 at 11:18PM
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For radiant in-floor heating in the basement I would suggest that the basement slab be well insulated so you don't loose heat to the ground.

I would also suggest at least one triple function geothermal unit if you plan to do radiant in-floor heating. If you are doing split systems I recommend the Carrier Infinity fan coil units with the new Carrier Infinity WiFi zoned T-stat.

I would not recommend opened loop for reasons of water wastage and potentially high cost of maintenance due to contamination of heat exchanger and the potential for high cost of pumping from a deep well, among other reasons. Closed loop of any well-designed configuration is a much safer approach.

I would do my own research, hire my own contractors for HVAC, and probably leave the builder and his contractors out of it. Consider, if necessary, hiring a separate contractor for the radiant in-floor only.

Hire accredited professionals with proven credentials and experience! Be sure you know what you're doing before signing. Go for MAXIMUM efficiency at every stage! That means parallel piping of both the ground loops AND the radiant in-floor system. Research and understand the benefits of variable speed pumps, headers (reverse return) and various plumbing configurations, integrated controls and gauges.


Here is a link that might be useful: Nordic Triple Function Geothermal Heat Pump

    Bookmark   November 4, 2012 at 5:15PM
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