Tag: Geothermal

Energy Usage

We’ve now been using our WaterFurnace geothermal system for a few months. This winter has been an odd combination of fifteen degree highs and seventy degree highs (yes, we went to the beach and played in the sand in February), but we’re starting to see significant energy savings v/s the Trane XV20i air exchange heat pump. Not only are we seeing lower electrical usage, but we keep the house at 72 degrees this year — almost too warm on occasion. With the air exchange heat pump, we were layering up, keeping the house at 68, and still feeling cold.

Energy use by the heat strips was my biggest concern with the system — that we’d still see the heat strips engaged in the middle of winter. Glad to report auxiliary heating system was not engaged since the earth loop was installed (December 2016, before the earth loop was hooked up, we used emergency mode to provide some heat from the coils – supplementing wood burned in our fireplace).

Our HVAC-related energy costs for the first three months of usage:

Jan 2017     131$ total, 75$ stage 1, 55$ stage 2
Feb 2017      93$ total, 55$ stage 1, 38$ stage 2
Mar 2017      81$ total, 43$ stage 1, 38$ stage 2

Comparing our kWh used year-to-year, our total consumption is significantly reduced during colder weather.

Our septic aerator used slightly less electricity than our HVAC did in March! As the temperatures warm up, I’m sure we’ll reach a point where the aerator is our high draw item (i.e. the thing that gets replaced next). We’re going to use our AeonLabs HEMs and some smart outlets that report energy usage to isolate other high-draw items and see what can be eliminated or upgraded … but we’ve certainly made progress in purchasing the geothermal system.

Geothermal Running Rates

I’m getting code together to scrape the Symphony data into OpenHAB. In the interim, we’re watching the stats from the WaterFurnace Symphony web site. We’re running between 1,800 watts and 2,800 Watts to keep the house really warm (72 degrees at the thermostat) with outdoor temps in the 20’s. The loop temperature has stayed pretty consistent as well. It’s not cheap, per se, to heat 4k square feet; but this is a lot better than the power usage with the air exchange heat pump at similar temperatures.

Geothermal Is Online!

We’ve got a functioning geothermal HVAC system running! They finished up the piping from the exterior wall to the furnace.

I was rather excited to see the containers of methanol — filling the tubes is the last step before bringing the system online. I like a nice fire … but it’s a cold way to heat your house.

The loop filling contraption – hooks up to the domestic water supply, mixes the methanol, and pumps it into the loop field. Over a hundred gallons – since we know the diameter (3/4″ in the loopfield, 1.5″ to the house) and the length (8x 200′) … we’ll calculate the volume of the cylinder some day. But for now … we’re got HEAT!!!

Geothermal – Digging and Drilling

We have construction equipment! They just finished up with the previous job, and the equipment has been delivered to our property.

The geothermal system — WaterFurnace Series 7 — is installed in our house. There’s a pump mounted to the wall, but nothing is plumbed together because the loop field has not yet been installed. That’s what this equipment is for – they are going to dig a big hole in the yard (maybe 8 foot by 4 foot). A whole bunch of 3/4″ tubes will run into this hold & connect to a manifold. There’s another hole dug next to the house, and 1.5″ tube will go from the manifold to the exterior wall, through the exterior wall, through the pantry, and into the furnace room to attach to the pump.

The fluid that’s run through the loop field is run through the WaterFurnace unit, and heat is extracted into the refrigerant. And that’s what will heat our house. There are a lot of good non-technical write-ups of how geothermal heating works, but I found a decent somewhat technical write-up from a geothermal installer in Western PA.

This heat will be used to heat the house … and as long as the loop field temperature stays fairly reasonable (upper 30’s, I think), we should be able to sustain a comfortable temperature without engaging the heat strips. We’ve talked to quite a few people who use new-ish geothermal units that have only used the heat strips in extreme temperatures (it was -20 for a week a few years back) or when they increase the thermostat by more than two or three degrees. If you lower the house temperature to go away on holiday, don’t set the thermostat back to normal immediately upon returning home. Slowly increase the set-point by a degree or two every few hours a day before you plan to return – by slowly increasing the temperature, you’ll avoid using the heat strips.

Geothermal Phase 1

We have heat! Well, we’ve had heat – when we were house shopping, fireplaces were a big thing to some people. Kind of a ‘whatever’ to me – not like I’d refuse to consider a house because of a fireplace, but I didn’t care if there was no fireplace either. The house we purchased has this Lopi Freedom Bay wood burning insert. More of a curiosity to me when we were house shopping, but it’s allowed us to make non-hasty decisions about HVAC equipment twice now. We got a super high end (and super expensive) air exchange heat pump in November of last year. It didn’t work well for us — 20kW of heat strips kicking in for a few months gets expensive. The service from the company that installed it, however, was right abysmal. Things we reported in November of 2015 were still unresolved during the summer of 2016. And, yeah, we could have been ringing them every day to force some action … but few of the issues were worth that level of effort. The thermostat software locks & the system is in the state is was at lockup (i.e. you wake up shivering in mid-summer because the AC has been running full-blast for hours). It reboots and works for another month or two. The air handler leaked, but until they patched it and our lower level got ten degrees warmer … I didn’t realize how MUCH it leaked. And so on — so we’d bother them every month or two, sometimes get some action and sometimes not. The installer, though, had a one year 100% satisfaction guarantee. Without a bunch of fine print or conditions. Which, really, is why I was OK getting an air exchange heat pump from them.

On several levels, we were not satisfied. The company tried adding some conditions to their written guarantee after-the-fact, but they eventually relented and removed the system from our house and refunded the full contract price. They were not, however, able to restore us to the original condition … not that I wanted an old gas Trane with a cracked heat exchanger … but the circuit breakers and copper wire they pulled would have been nice. They were willing to leave the NEW circuit breakers and wiring in for the > 900$ line item from their bill. But, seriously, 200$ of stuff from Home Depot is not something for which I’m keen on paying near a grand.

Initially, I wasn’t sure how much more a geothermal system would cost … until we got some quotes and discovered that we could get a fully variable geothermal system for 500$ less than we payed for the air exchange heat pump. WOW! The configuration we chose ended up being 100$ more – we added an additional 200′ bore. Because it is going to take about three weeks before the drilling can commence, they installed the HVAC equipment without connecting it to the earth loops & set it up to run in emergency heat mode — which is essentially a really expensive 20kW electric heater. But it keeps us from freezing when the fire goes out overnight 🙂

Geothermal Pricing

I’ll start out with an acknowledgement that what makes this comparison so shocking is the 30% federal tax credit. A straight comparison of a super high-end HVAC system with a geothermal system will be a completely different scenario if the tax credit expires.

Last year, we got the top of the line air-exchange heat pump. And we’ve had a lot of problems. Installation problems, air leakage problems, thermostat problems … all compounded by terrible difficulties getting service people out to sort the issues. And at the end of the day, the house isn’t comfortable. The “this is the only thermostat you can use” thermostat … well, first off all freezes up every now and again and the system is either ON or OFF at the time and stays there. But from a firmware / logic standpoint – there is nothing that looks at the relative humidity in our house and says “hey, we should drop the temperature set-point a degree or two to avoid living in a swamp”. Which wouldn’t be a problem if we could tie the thing into OpenHAB. But we cannot.

The system came with a 365 day 100% satisfaction guarantee … which, really, was the reason I was OK with installing it last year. Worst case, we ask for it to be removed & the entire contract price gets refunded. Well, we are not satisfied … but that means we’re back to shopping for an HVAC system.

I researched geothermal system manufacturers. Evidently there are only a few actual manufacturers whose product is sold under a lot of different labels. I contacted local installers to get a quote for each of the major systems I found. My expectation was that a geothermal system would be a couple thousand more than we paid for the air exchange heat pump once you take off the 30% tax credit money.

We got our first quote today — for 600$ less than the air exchange heat pump. It’ll be more to do vertical bores instead of horizontal bores, but that’s a decision to spend money for efficiency. I expect vertical bores will take us into the “couple grand more than we paid” territory. But I don’t see the point of high-end air exchange heat pump systems up North here — a two-stage geothermal system is going to be quite a bit more efficient, not engage the backup heating as often, and cost less than the top of the line variable speed air exchange systems.

The HVAC company that installed our current unit had horror stories of people having to rip out entire yards because of leaking tubes … but, thinking about it without needing to make a decision now … I suspect those are older installations. So, yeah, we have the possibility of leaking lines twenty years from now (lines are warrantied for 50 years, but you are still paying labor). And that would totally suck, but do I really expect the air-exchange heat pump sitting outside is going to be in service twenty years from now?