Which Closed Loop Geothermal HVAC System?

carova_2008

15 years ago

Hi!

I have two (hopefully simple) questions:

1) Which manufacturers have R410A two stage systems with scroll compressors, variable speed air handlers, re-heat capability (for dehumidification), and internal water-to-water subsystems (for constant hot water, not just during AC season)?

2) Which brands would you suggest? Which brands would you avoid?

Thanks!

Vince

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Comments (13)

fsq4cw
15 years ago
Virtually all GSHP manufacturers have the type of equipment youÂre asking about.

Google ClimateMaster, WaterFurnace, Carrier, Maritime Geothermal, Florida Heat Pump for starters.

Use the link below to find a qualified installer in youÂre area.

SR

Here is a link that might be useful: IGSHPA, International Ground Source Heat Pump Association at Oklahoma State University
funnycide
15 years ago
I know Climatemaster and Water Furnace make units with all the bells and whistles. I'm sure there are other brands too.
I'm not sure what you mean by internal water to water subsystem. You can get a hot water generator to make hot water when the compressor runs. I'm not sure what you are looking for.
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Here you go: After all rebates (there were several) & tax credit, my geothermal system ended up costing about $13,500. It looks like I'm going to be saving about 6000 kWh per year. When using an air source heat pump, I averaged about 27.5k kWh per year, and using the geothermal heat pump I'm averaging about 21.5k. Keep in mind that I don't even have a complete year of geothermal data, but I'm basing my estimates on what I have. Based on the numbers above and an electric rate of $0.11 per kWh, I'm saving $660/yr compared to my previous system. The ROI on that is about 20.5 years. So, if you have a working system and you're considering switching over to geo, based on my #s I'd strongly recommend against it as a 20+ year ROI is horrible. The reason I went with geo was that my old system died and needed replacement. I received several estimates for an air source heat pump, and they were around $9000. For me, it was a choice between a geo system for $13500, and an air source for $9000. I can't do much of an estimate comparing these two since I have no idea what sort of performance I'd be getting with a new air source heat pump. A huge plus for the geo system for me was that my geo system came with a 10 year parts and labor warranty. No one came even close for the air source heat pumps. Its also really neat that I don't have a loud evaporator in my back yard, but the value of that is very subjective.
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Yes - variable speed is HVAC or Heat pump. On the dehumidification, a tight house helps with humidity but if you are truly sensitive, then you have to take that into account. On my shoulder seasons, there may be a factor that keeps our humidity low. We like to sleep in a very cold environment. So even when relatively cool, we run the a/c for a time in the bedroom and that maybe the reason for our low RH in moderate temps. Variable speed and staged units are HVAC terms. Most houses are built with oversized a/c units. This leads to short run times, particularly in shoulder seasons, and poor humidity control. Staged units help with this because they run with less tonnage for longer periods of time. I still am confused about variable speed. It is a necessary component of a staged system but I don't see how it helps (by itself) for humidity control. Most stats do not even measure humidity so wouldn't be able to slow fan speed down if that helped. There are thermostats that increase run times and run based on humidity. So there are other options for better humidity control beyond staging - which adds costs and complexity. We shot low on our sizing, using 4 tons for 3800 sqft so our run times are reasonably long. Stating it this way is in no way endorsing sizing based on square footage, it is just for comparison sakes. We also went with simple, unstaged equipment. We still have an ECM motor but again I don't see how that helps for humidity. I think it is a mistake to use a prior house for reference if you have the ability to do it right this time. Most HVAC systems and houses are not designed with much care towards these issues. So the frame of reference is so bad as to be not helpful. Anderson 400 series. They are fine. Not amazing by any stretch. Reportedly they don't hold air tightness as well as others but they seem fine to me. Certainly don't hear any flow even during hurricane - although we haven't had a good direct hit since we moved in. We have had some good gusting during T-storm and never heard anything. In contrary to double hungs in last house, where a 50+ mph gust would cause some whistling.
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I'm disappointed that what had at first seemed a very balanced comment was followed by what seems to be misinformation and misdirection. People buy ground source heat pump equipment because they want to and can afford it. Or decide they need to in their locations. They're hugely more expensive than alternatives, which is why they're still not very common. "When’s the payback on a Tesla? People still choose to buy them for reasons other than the ‘bottom line’." Not a comparable. A false analogy. "I would not choose natural gas or propane for reasons relating to the environment, safety, IAQ & paying for yet another utility hookup for an energy source that might not even be used for months on end during the year." What effect having a gas furnace has on indoor air quality. Another hookup? Most people prefer gas cooking appliances and besides, the OP is talking about an existing home, he either has gas service or he doesn't. "Rather than spending perhaps tens of thousands of dollars on a Solar Array, I would sooner invest that same money, hopefully less, in a ground loop for a Geothermal system." Sure you would, that's the business you're in. The ground source heat pump market is not growing as expected by those in the industry, which suggests that your opinion isn't widely held or easily sellable. In many parts of the country, solar panels can have a quick payback. Not so ground source heat pumps. "I often hear about Solar Panels when geothermal is mentioned, as an alternative way to save money by creating energy." In a place like Texas, where electricity is cheap (other than during cold weather crises as they just experienced) there's likely no payback from a solar panel installation. People do it as a personal statement, call it for environmental or other personal reasons. Like buying the Tesla, not a financial decision. An HVAC system blows warm air when it's cold, cool air when it's hot. It's one of those things people don't care about - either it works or it doesn't work. Spending extra money for an exotic system doesn't equate to extra payback when the home is sold. Neither owners, nor visitors, nor people passing by, nor anyone else, concern themselves with what's doing the work. It's equipment that doesn't produce an experience for someone in the house if it's working. In the US, there are vast areas where electricity is cheap. It will remain so for some time. People don't spend money today to potentially save money 10 years out when market conditions may or may be different. I suspect you could build a house with mahogany or teak framing. Or you could paint the framing bright colors. Why bother, you can spend less money and effort and get something else that will do the same job. "We almost never use setbacks at our home - even when going on vacation for weeks on end with no one home, our geothermal just runs." You're combining two different things to produce confusion. Thermostats that have a setback feature ALL are set up to provide lower overnight temperatures to have more comfortable sleeping conditions and then a recovery in the morning before wakeup time. As sleep specialists recommend. That in demand comfort features isn't possible with ground source heat pumps because the warm up period from a setback is too slow to be convenient to use, absent triggering a secondary heating source (like a furnace) to help. THAT'S why you don't "believe" in setbacks with a heat pump - they don't work. Turning down a thermostat during heating season when the home will be unoccupied is not a "setback" as that word is most commonly used. It's done to save money, why heat a vacant house? No setback thermostat is needed, even a dumb 50 year old analog thermostat can be turned down.
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carova_2008
Original Author
15 years ago
funnycide,

Nearly all GLHP manufacturers have "desuperheaters" which take waste heat from the compressor and use it to provide hot water. On the two-stage units however, they operate on the "Low", extremely efficient mode 90% of the year and provide minimal waste heat that can be used for domestic hot water. I am looking for a system that has a dedicated "water-to-water" cycle that can provide continuous hot water even during the periods when no space heating or cooling is required for the house. Nearly all manufactures have these as seperate units. I am looking for one that is integrated into the HVAC sysstem.

Vince
fsq4cw
15 years ago
"I am looking for a system that has a dedicated "water-to-water" cycle that can provide continuous hot water even during the periods when no space heating or cooling is required for the house."

What youÂre looking for is a ÂNordic Triple FunctionÂ GSHP.

Go to:

http://www.nordicghp.com/mg/

Click on: ÂProductsÂ

Click on: ÂTF-SeriesÂ

Click on: ÂR410a Models PDF Download the Installation ManualÂ

Everything you want to know Â and more - is right there!

You can also download the PDF for the R22 Models.

BTW: I cannot, as of yet, say that in all my travels that IÂve seen a better built HP than Nordic.

IMO

SR

Here is a link that might be useful: Nordic Triple Function Series GSHP
carova_2008
Original Author
15 years ago
fsq4cw,

Thanks! That's exactly what I was looking for.

Vince
funnycide
15 years ago
I'm not familar with the Nordic model but Water Furnace makes a similiar model. The disclaimer at least with the WF unit is that there is only 1 compressor and it runs for either space heat (air) or water heat (radiant) not both. The space heat takes priority. This setup works good for bathroom floor heat which is supplemental heat.
If the compressor runs a really long time to satisify the space demand than the radiant heat will be missing. Not a big deal but something that people should be aware.

I'm not sure what you are planning on using the water heat for.
carova_2008
Original Author
15 years ago
funntcide,

The Water Furnace Synergy3D is the system that you are suggesting. I am surprised that it is not more efficient (24 EER / 4.2 COP) compared to their top-of-the-line Envision unit (30 EER / 5 COP), but at least it is integrated. Thanks for the pointer!

Vince

Here is a link that might be useful: Synergy3D
fsq4cw
15 years ago
Re: carova 2008

"The Water Furnace Synergy3D is the system that you are suggesting. I am surprised that it is not more efficient (24 EER / 4.2 COP) compared to their top-of-the-line Envision unit (30 EER / 5 COP)"

A COP of 4.2 is very good! COP of 5 is even (marginally) better. How do you think they achieve those higher COPs? Larger ground heat exchangers, more HDPE pipe, more drilling, more grouting, more fluid/antifreeze etcÂ Guess what Â more expensive! Should you still do it? MaybeÂ

SR
carova_2008
Original Author
15 years ago
fsq4cw,

Good point! The tradeoff is important if the payback period is considered.

Vince
funnycide
15 years ago
That's not really true. The manufacturers test the units to the same ARI standards for each unit. I believe it is 77Â° entering water for cooling and 32Â° entering water for heating. So if comparing units you can tell which units are more efficient (at those conditions).
Now you can make any geothermal unit more efficient by lowering the EWT for cooling and raising the EWT in the winter. This is typically done by increasing the ground loop.
It is be possible to calculate the payback for increasing the groundloop but it is very involved and wouldn't be done for a residential job.
I suspect that the reason the Synergy3 isn't the most efficient is the demand for that line is most likely pretty low and it isn't worth the money for WF to redesign the unit to include the latest design.

Vince, you never said what you want to use the hot water for.
fsq4cw
15 years ago
Re: funnycide

"That's not really true."

I believe it is really true. HereÂs why, during the Canadian GeoExchange Coalition Residential Designers Course, attended by the top technical trainer from WaterFurnace, this exact subject was brought up by the instructor Â one of the best minds in geothermal design in North America, this was his contention, that the loops have to be longer for higher COP units, all else being equal. Of course we all turned to the WaterFurnace rep that was in attendance with all his software and he concurred, that this in fact was indeed the case.

SR
carova_2008
Original Author
15 years ago
funnycide,

"Vince, you never said what you want to use the hot water for."

Domestic hot water

Vince
shark08
15 years ago
Hi Vince I am looking at a Nordic system R65HACW-P1T and although I did not consider a triple function heat pump, I am now curious as to how you concluded that a triple function heat pump would be beneficial (cost wise) for hot water versus only using the desuperheater in the heating and cooling season and supplementing it (example) with electric hot water?
Thanks
Shark08

Which Closed Loop Geothermal HVAC System?

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