Tigo Gateway 'fried', Desuperheater for upstairs, heat pump dryer

My Tigo Control Panel

So the guys from Renu Energy (formerly GreenSpring Energy) came by to check out why my Tigo is broken again.  After after 3 hours of work and constantly going from the roof to the attic to my bonus room (where the Tigo control panel is located), they finally gave up.  Essentially they think the Gateway (located on the roof) is 'fried'.  Tigo is going to send a new gateway to me which they'll exchange for my current one so they can try to diagnose what went wrong.  I'll hopefully get the new unit in 1-2 weeks and Tigo will be up and running.  Now, when I say fried...it just means that Tigo isn't transferring the data.  I'm still getting solar power generation, so that's good.  And I think I'm still getting the benefit of of the Tigo, just not the data.  So stay tuned for more info.

OK...next up, desuperheaters.  One thing that's always annoyed me was that my geothermal install only had 1 desuperheater located on my downstairs unit.  And over the summer and swing seasons I always felt that the upstairs unit ran far longer than the downstairs unit for A/C.  Recall...the longer the runtime for A/C, the more hot water is generated from the desuperheater.  Well, i just confirmed this using the Ecobees.  Overall, the upstairs unit runs 2.2x more than the downstairs units when the A/C is running.  Thus, I'm missing out on ~70% of the potential hot water generation.  Bah!  So I'm looking into getting a desuperheater for my upstairs unit.  I've contacted my HVAC guys (Panther HVAC) to see what they recommend as I'm unused if I'd be looking at a WaterFurnace related unit or if I should go with an aftermarket unit (such as the Turbotec Enviro-Pak).  Stay tuned for more info once I get a reply back from Turbotec on their price along with a reply from my HVAC folks.

BTW...for folks that have a normal heat pump or A/C, you can use the Turbotec system to generate hot water too. You don't need a geotrhermal system to do it.  It's just useful to hopefully have your airhandler and your water heater near to each other.

One final thing...I just saw that LG has released the first heat pump dryer in the US.  Hooray!  It's 50-60% more efficient at drying than a conventional dryer.  As of now, my dryer is by far the largest energy consumer in my house.  The only thing bigger is my emergency heat for the geothermal system and that should never run...except well for emergencies, which hasn't happened.  Unfortunately, it's priced at $1,600 (MSRP) so hopefully prices will drop soon.  Not to mention, I don't need a new washer/dryer as I highly doubt there's any ROI unless I have to replace my unit anyway.

New GE Geospring Hot Water Heater!

My new GE Geospring hot water heater in series with a preheat tank (not shown)

So I finally put in a new hot water heater.  As I had discussed in previous posts, I wanted a GE Geospring air source heat pump (ASHP) hot water heater.  Well, that's what I got.

Why am I so hyped about this?  Well for starters...

1)  The Geospring is rated at an energy factor of 2.5 which saves roughly 63% of the energy as compared to normal electric hot water heater (which I had).  On an annual average basis, my former HW tank was running 0.8 hrs/day @ 4.6 kW for 3.7 kWh/day.  Thus, this is expected to be reduce to 1.37 kWh/d.  

2) I had mentioned in some of a previous posts, that the geothermal supplemental hot water generator (desuperheater) really is not optimized when using one tank.  I'd read some forums that even claimed it could be costing me energy with calls for geothermal system manufacturers to remove the 1 tank setup from its installation procedures.   Well, this new hot water tank was connected in series with my "old" hot water tank (now un-powered).  The "old" tank will act like a preheat tank allowing for maximum hot water generation via the desuperheater.  This preheated water will feed the GE Geospring.  So overall, the energy required for hot water generation is cut substantially.

3) The Geospring is so efficient because its an ASHP hot water heater.  Essentially that means its an air conditioner connected to hot water heater.  So it will "condition" (remove heat and humidity) the air and instead of discharging the heat outside, it takes the heat and pumps it into the hot water tank.  Why does this benefit me?  Well, recall I've been using a dehumidifier in my crawl space to reduce moisture...and its been a fairly large energy consumer.  Well, the Geospring will now take the place of the dehumidifier by simultaneously conditioning the air (removing moisutre) as it heats the hot water.  Thus, I'll hopefully be able to negate using the dehumidifier entirely! That should save me somewhere around 7 kWh/day alone.

Overall, I'm hoping this work will reduce my overall power consumption by about 9.33 kWh/day.  It could be higher including optimization of the desuperheater, but I have not way to quantify this yet.  Even at 9.33 kWh/day this is about 280 kWh/month!  If you consider that in the last year (Sept 2011 - Sept 2012), I've averaged 853 kWh/month, then the 280 kWh/month will result in a roughly 33% reduction in consumption!  That equates to roughly $31/month.    This project cost me about $1200 to install, so that's a 3.19 ROI (not assuming any rate increases).  I'll take that... Only time will tell what I actually achieve...   

 

Energy/Cost Savings...What to do next?

Ok...I Friday and yesterday I spent countless hours trying to get my HTPC to shutdown and wakeup automatically.  When I manually told it to turn on in 5 minutes and shut it down manually, it worked fine, turning on automatically.  When I let it automatically turn off, it did just fine, but then it wouldn't turn back on.  It appears that I just can't get the system to pass the correct date/time in there.  Not sure why...Long story short...I'm fed up with it.  I'm no linux computer expert and I spent most of my time on Google trying to figure out commands.  I know enough to get by, but that's it.

So, I thought the next most logical step was to finally start looking at an upgrade to reduce power usage since this is on 24/7.  Well...a question arose...are there better investments?  Let's take a look...

I measured all my HTPC components with a Killawatt meter and the total usage is 120W when idle.  The computer itself uses 92W.  Reading online, a nice Intel Core i3 system (with all the accessories) uses around 40W when idle.  So that would save me 52W.  On a daily basis thats 1.2kWh which would save me $0.106/day = $3.23/mo = $38.72/yr.  Generally I would invest about $300 into this which gives me a simple return on investment (ROI) of 7.75 years.  Not all that great, right?

Well...looking at my TED, it's pretty obvious the one thing that is using the most power in my home is the hot water heater (see large single spikes).  The graph above shows last weeks worth of hourly energy usage.  The block on the first day (Sunday) is from doing laundry so that's a mix of hot water and dryer usage.  Overall, It's that time of the year when I don't need heating or cooling, so my geothermal is turned off (House stays between 67 and 75...comfy!).  With the system off, my desuperheater isn't heating my hot water.  So...does it make sense to upgrade my hot water heater?

Well, one of those GE hybrid hot water systems costs about $1400 from Lowe's (I'm not including the tax credit because I can't buy it this year).  If my current hot water heater (4.8kW) is on, say for 2 hrs/day (only 1 hr shown above, but let's factor in winter), then that I'd use 9.6kWh/d which is $0.82/day = $24.8/mo = $298/yr.  A hybrid hot water heater (according to the website) would save me 62%.  So, without factoring in the desuperheater, my ROI is 7.6 years.  With the desuperheater reducing hot water by 40% (a conservative value) then the ROI rises to 12.64 years.  Overall, I'd say this fix isn't worth it unless my hot water heater decides to break.

Out of curiosity, how about solar hot water?  Well...first, I'm not sure if my desuperheater and solar hot water can work together...but let's assume they can.  A solar hot water system (which is not a do-it-yourself job for me given my roof is so steep) would probably cost about $5000 installed.  This is just a guess looking online for similar systems.  What's the ROI?  16.8 years...so yeah, that's out of the question.

Out of these 3, upgrading the computer has the best ROI, albeit the overall savings are small.

However, I think my best bet is going to be contacting my geothermal MFR to see if there's a way for my desuperheater system to heat my hot water.  All the parts are there...there just needs to be some way for the hot water tank to contact the geothermal system to turn on.  And in hot water only mode, then the geothermal system would not turn on the fan.