Heat Pump vs. Geothermal Heat Pump

[gigawatt1010]

I’m in the process of looking at Geothermal for our home in Orange County, NY. These guys seemed to have found a way to make the drilling process easier.

I’m working with them to install geothermal for our home.

 

[willow_hiller]

I’m working with them to install geothermal for our home.

Sounds really promising. I filled out their information form, but unfortunately they're just installing in NY State for the moment.

 

[Feathermerchan]

One thing packaged systems like GSHP and water heater heat pumps have as an advantage is that they are charged at the factory. No need for a tech to do anything but verify it works unless it leaks which is rare.

 

[gigawatt1010]

Their process is literally taking a play out of the solar playbook. NY state also has quite a bit of incentives for geothermal and solar. As of 3 days ago, NYSERDA is giving out $25k, 0% interest, 15 year loans to homeowners putting geothermal in their homes.

 

[nwdiver]

One thing packaged systems like GSHP and water heater heat pumps have as an advantage is that they are charged at the factory. No need for a tech to do anything but verify it works unless it leaks which is rare.

The mini-splits I've installed come charged but you do need to evacuate the lines and connect the line sets. I have heard of people that have had Issued but I've DIY'd ~4 each with ~12 connections I had to make and I've never had a problem. Flare fittings seem to be fairly fool proof; Also possible I've just been lucky.

 

[Feathermerchan]

My dad built his own house and bought the A/C from Sears. Even the lines came charged. They were sealed of course and when you bolted them together, they came open without leaking any charge. I don't think he ever had a problem.

 

[iPlug]

Green-pressuring seems to have paid off with my folks who will soon be upgrading their central ducted HVAC system. Their NG furnace is coming out and the AC system is being replaced with a 4-ton Carrier heat pump (25V4NA series). Single zone will be upgraded to dual zone, ducting will be upgraded to R8, and a 3rd air return will be added.

Specs include:
-24 SEER
-13 HSPF
-infinitely variable speeds between 25-100% capacity
-"Most Efficient of ENERGY STAR® 2020"
-sound level as low as 51 dBA at lowest speed


https://www.carrier.com/residential/en/us/products/heat-pumps/25vna4/

 

[SageBrush]

Green-pressuring seems to have paid off with my folks who will soon be upgrading their central ducted HVAC system.

How much did it cost you ?

Just kidding -- congrats, and way to go !

 

[mspohr]

One thing packaged systems like GSHP and water heater heat pumps have as an advantage is that they are charged at the factory. No need for a tech to do anything but verify it works unless it leaks which is rare.

I installed a Chiltrix unit at my house for hydronic heating and hot water. It's a high efficiency unit. It heats (or chills) water/glycol so the refrigeration unit is sealed and no need to ever open the refrigerant lines.
CX34
3 Tons Heating / 2.0 Tons Cooling
Stackable to create systems of 2 ,4, 6 Tons, etc
IPLV 26,150 BTU Cooling / 33,813 BTU Heating
IPLV EER 23
Flexible Design Options:
Mini-split / Ductless, Central Ducted, or
Integration w/ Floor Heat, Boiler or Solar Thermal

$4300
Small Heat Pump Chillers | Chiller Air Conditioner For Home or Office | Residential Ductless Mini Split Chillers

 

[willow_hiller]

Still collecting quotes, but so far it's not looking great for geothermal.

So far:

1. $36k before incentives for a Climatemaster Tranquility 30 ground source installation with 3 ton loop
2. $30k before incentives for a Waterfurnace Series 5 ground source installation with 3 ton loop
   
3. $27k before incentives for a Waterfurnace Series 3 ground source installation with 2.5 ton loop

So even after applying incentives, (26% federal, $3,000 state, $1,500 utility), the cheapest ground source heat pump comes to ~$15k.

And maybe someone here will be able to correct me, but at least according to Energystar the Waterfurnaces don't actually save much compared to a variable-speed air source? Our current HVAC guy installs Bryant primarily so I'm comparing the Waterfurnace 3 series with the Bryant 280A Evolution.

Sources ENERGY STAR Most Efficient 2020 — Geothermal Heat Pumps and ENERGY STAR Most Efficient 2020 — Central Air Conditioners and Air Source Heat Pumps respectively.

Comparing the 35,100 BTU Waterfurnace to the 33,200 BTU Bryant, it looks like the difference in annual consumption is only 163 kWh less?

I'm still waiting on a quote for the Bryant installation, but it should come in for less than $10k. I'm not sure how geothermal could be the winner in this situation.

 

[nwdiver]

And maybe someone here will be able to correct me, but at least according to Energystar the Waterfurnaces don't actually save much compared to a variable-speed air source?

It's very application specific. If you see 20 day stretches of temperatures <0F then ground source is likely to be a lot more efficient than air source. If that rarely occurs then you're not going to save much compared to a modern efficient variable-speed ASHP.

 

[willow_hiller]

It's very application specific. If you see 20 day stretches of temperatures <0F then ground source is likely to be a lot more efficient than air source. If that rarely occurs then you're not going to save much compared to a modern efficient variable-speed ASHP.

Excellent point. I wonder what climate Energystar uses for the national average.

Even still, I'm amazed at how well some of these modern air source heat pumps perform in cold weather now. I was reading this page: Heat Pump Reviews and Prices 2020 and they include the Bryant 280A in a "cold climate air source heat pumps" (ccASHP) category where it can maintain a COP of 1.75 or greater at 5F.

 

[ChadS]

My last house had a 2010 Daikin Altherma air-to-water heat pump that had a nominal COP of 4.0 and claimed "still efficient" (by which I assumed it meant COP of 1 or greater) at 4F.

The heat pump and its 80-gallon hot water storage tank each had 3kW resistance heaters as a backup in case the heat pump couldn't produce enough heat (for the house via radiant floors AND for domestic hot water). Using those backup heaters clearly would drop the effective COP quickly. At least one of them would come on fairly often when it was below freezing (it never got below 20F while we lived there). My unit was supposedly the "most efficient" unit on the market at the time, but I really don't think I would have gotten 1.75 at 5F, so apparently the industry has indeed improved over the last decade.

 

[willow_hiller]

Reviving this thread for 2021. After much research about mini-splits, geothermal, and variable speed air-to-air heat pumps, we finally settled on an interesting option I hadn't heard anyone else mention.

Today we just had a Bosch BOVA 2.0 inverter ducted split system installed. Product information here: Inverter Ducted Split System (IDS 2.0) | Air-to-Air Heat Pump Systems | Heat Pump Systems | Products | Residential

It's a really fascinating device. My HVAC tech said it's basically mini-split technology applied to a ducted system. Really quiet at 56 dB. SEER 20.5. Inverter-driven variable speed fans on both the condenser and the air handler. And most interesting, it's variable speed without the need for a special thermostat or running new lines for signalling. From my understanding, the heat pump control board just monitors the pressure of the coolant coming back from the air handler, and from there it can tell how much heating/cooling is needed. And likewise the air handler monitors the pressure coming from the condenser and adjusts the fan speed accordingly. So my Ecobee controls it as if it's a single stage device. It's also meant to operate down to -5 F! I'll be surprised if my resistive heat ever turns on again.

3 ton system installed for just over $10k.

 

[nwdiver]

Reviving this thread for 2021. After much research about mini-splits, geothermal, and variable speed air-to-air heat pumps, we finally settled on an interesting option I hadn't heard anyone else mention.

Today we just had a Bosch BOVA 2.0 inverter ducted split system installed. Product information here: Inverter Ducted Split System (IDS 2.0) | Air-to-Air Heat Pump Systems | Heat Pump Systems | Products | Residential

It's a really fascinating device. My HVAC tech said it's basically mini-split technology applied to a ducted system. Really quiet at 56 dB. SEER 20.5. Inverter-driven variable speed fans on both the condenser and the air handler. And most interesting, it's variable speed without the need for a special thermostat or running new lines for signalling. From my understanding, the heat pump control board just monitors the pressure of the coolant coming back from the air handler, and from there it can tell how much heating/cooling is needed. And likewise the air handler monitors the pressure coming from the condenser and adjusts the fan speed accordingly. So my Ecobee controls it as if it's a single stage device. It's also meant to operate down to -5 F! I'll be surprised if my resistive heat ever turns on again.

3 ton system installed for just over $10k.

Glad to see that VFDs are finally becoming more common. IMHO it's crazy to have any motor directly driven by grid frequency in 2021.

'I want 500RPM for peak performance' ; '3600 RPM it is!'

 

[Feathermerchan]

The main advantage of VFD on a compressor is efficiency and comfort. Running on at full capacity and off wasted energy and can cause humidity problems. Up till pretty recently VFD at the residential level was just too expensive and unreliable. With the advent of scroll compressors, efficiency went up about 10% and cost very little. Scroll compressors have other advantages too. Liquid refrigerant flowing back to them won't usually damage them.
I see that system actually uses 10 discrete speeds on the compressor and a two speed indoor fan. Not entirely VFD. And at $10,000 it's quite expensive for a 3 ton unit. But good efficiency. At an SEER of 10, a 3 ton unit draws about 3.6 kW. In my climate (DFW) it would run about 1,700 hours. That's 3.6 X 1,700 = 6120 kWh (about $612 at 10¢/kWh). A 3 ton unit operating at 20 SEER would save you about $306 per year. That's about $1,000 every 3 years of AC use. You'll also save on heating.
The SEER doesn't tell the whole story though. It must make assumptions on where you set your thermostat. You save if you set your thermostat higher of course but compared to a single speed unit with the thermostat set higher, you'll save more because the unit will run more efficiently with reduced load.

 

[willow_hiller]

And at $10,000 it's quite expensive for a 3 ton unit.

I believe most of that cost is installation just due to the cost of living in my metro area. I was comparing it with a Bryant single speed, 16 SEER unit from the same installer, and the Bosch was only $1,600 more.

Looks like the Bosch equipment itself is $4-5k: Bosch Heat Pump Reviews & Cost 2020

 

[Feathermerchan]

Installed cost double equip cost not surprising. Labor on site is always expensive. Hope it serves you well. I've got about 35 years on my Lennox 2 speed unit. Builder told me it would not be big enough. He didn't do the calculations though.

 

[Dave EV]

The main advantage of VFD on a compressor is efficiency and comfort.

One aspect of comfort that is often overlooked with VFD is noise. I bought a Trane XL20i 3-ton heat pump hybrid system (gas backup) about 11 years ago, thinking I bought the quietest system on the market, with it being the top of the line model with two stage heat pump.

I find the outdoor compressor to be embarrassingly loud, and it's supposedly rated at 72 dB. VFD compressors were pretty uncommon at the time, except with mini-splits. Also, despite being a 3-ton system by my request (the old furnace had a crazy 80-90,0000 BTU rating and most HVAC contractors were fairly insistent that I needed a 4-ton system for my 2000 sq/ft house), duct sizes in the house are barely adequate based on air noise levels as well at high speeds.

A variable speed system would almost certainly almost never push maximum air speeds, leading to much quieter operation both indoors and out. Also being able to interface with a standard thermostat is a benefit - there is no way to use a standard thermostat with this Trane communicating system.

In my situation, I am torn between replacing the outdoor compressor with Trane's XV19 outdoor VFD heat pump, and tossing the whole system for something like this Bosch system which looks very nice. Too bad there's no market for used, good condition HVAC equipment. I'm sure that my system would be an upgrade for someone out there.

 

[Feathermerchan]

Dave - I agree. My variable speed indoor fan is night and day better. My A/C unit sits beside the house near the Master Bedroom but there are no windows. I can barely hear it.