Bill:  I see your current daily average is 42 KWH.  This would be about 1260 KWH per month (don't the electric companies love these hot spells).  Looking at your monthly chart for HVAC consumption the average looks to be about 600-800 KWH per month.  The  chart mentions weekly but the data says monthly, I'm a little confused.  Is 700 KWH or so the average annual monthly HVAC KWH useage?

Yes, Joe, I'm curious too.

We're continuing to run a 4° setback scheme on all 4 zones.  77° during day in family areas (first chart below) with set back to 81°.  74° at night in bedroom zones with set back to 78° during the day (second chart below).

Unfortantely I'm not in a good position time-wise to do the experiement.  I've thought about it, but, it may just have to wait until next summer. 

The other problem I've got is that I'm 'full up' on my WEL using logic to compute various important measurements and indicators.  So I don't have any more room to put in the logic to show real time charts of a KWH/DD index.  I of course can still do it off line, using the WEL's minute by minute data sampling feature, but, this is more time consuming.

Just looking at the real-time charts ( http://welserver.com/WEL0043/ ), one thing I notice is that the 4° set back on the big 5 ton 50 KBTU/hr (1st stage) unit is allowing the earth some amount time at night to recover from the 750 - 800 KBTU per day amount of heat being dumped into the earth.  Whether or not this set back is cost effective, though, would need an experiment to confirm.

Best regards,

Bill

mack, I'm having trouble figuring out the question here - may need some more help.

The first online chart (system diagram - http://welserver.com/WEL0043/system.png ) shows 42 KWH Avg Daily Usage MTD for HVAC, and 656 KWH total MTD for HVAC usage.  The 656 KWH is month to date, not average for the month.

A few charts down, the Daily KWH Consumption chart - http://welserver.com/cgi-bin/plot/WEL0043/DailyKWHConsumption.gif - shows about 42 KWH avg daily usage for HVAC (cyan line).  The blue line shows actual HVAC KWH consumption by day, raning from 40 - 50 KWH each day for the hot days.

The next chart, a bar chart of monthly KWH Consumption, in WEL format - http://welserver.com/cgi-bin/plot/WEL0043/MonthlyEnergyConsumption.gif - shows about 650 KWH consumed so far for HVAC (blue line mostly hidden by the red line).  If indeed the 42 KWH/day continues for HVAC for the rest of the month, then yes, my month HVAC KWH total for July will be in the 1200 - 1300 range.  You can further see on the chart that 12 months earlier, i.e. July 2008, it was about 1300 KWH for HVAC KWH usage.

The chart below, summarizing data from the WEL's log files, shows that I'm averaging, on a 12 month rolling basis, about 19 KWH / day just for HVAC.  On a monthly rolling average basis, it's 572 KWH/mo (and on an annual basis it's 6868 KWH/yr.).  Parenthetically, HVAC is only 24% of my total KWH consumption, again on average across an entire 12 months.

Summary? 

My average annual monthly HVAC KWH usage is 572 at the moment (3400 sf., 8 tons total, 2 water-to-air GSHPs with vertical bore field, Dallas climate, 77° daytime / 74 - 76° nighttime tstat settings, with 4° setback scheme, with 4 zone system).

I'm unable to find the reference to "weekly" on my chart - I'll need some help to see it.

Hope this helps.  Done properly, geothermal HVAC, at least in a hot Dallas climate, is the 'real deal' (I've got some zoning that helps too.)

Best regards,

Bill

Thanks Bill.  You answered my question.  572 KWH/mo average for the year.  The weekly reference was at the bottom of the chart where is says "(history in weeks, 480 min Samples) ".   I was unclear if the time numbers on the graph were weekly or for a month. 

Some of the monthly EWT temperature increase is probably due to the top 15-25 feet of ground becoming warmer as summer progresses. Your wells are spaced plenty far apart so you may not see any longterm heat gain. You'll probably see the max EWT somewhere in September.

Question about your pool.  Are you heating it?  Is it an indoor pool?  Does it have a spa?  I ask because I am surprised at how much energy it uses.

Also is your DSH disconnected?  If so why if not, what do  you think of the DSH?  (if you answered this in other post point me there).

And Bill, thank you for the data and putting your WEL up where we can watch it too.  I find it very interesting.

Alex, thanks for the note.

Max EWT for the year, on a daily avg basis, has already occurred, a few weeks ago (late July, and just like last year.  See the EWT chart at http://welserver.com/cgi-bin/plot/WEL0043/EnteringWaterTemperatureDailyAvg.gif . showing 55 weeks of EWT.  Max EWT for this year and last both peaked at about 83°.

No, I'm not heating the pool.  And no, it's not an indoor pool.  It does have a spa.

I have a 2.5 hp pump for filtration purposes that at the moment runs 10 hrs per day (9 - 1 PM, 2 - 6 PM, 7 - 9 PM).  I have a 1/2 hp pump that runs a cleaner that runs 3 hrs per day (10 - 1 PM).  I have a 3 hp motor for a water fountain that runs about 15 min. (6:15  - 6:30 PM) per day.

On a 12 month rolling avg basis, energy consumption for the pool is 24% of my total electrical consumption.  (HVAC is 23%. and base load (lighting, appliances, computers, etc.) is 52%.)

On this same 12 month rolling avg basis, energy consumption for the pool averages 19 KWH per day, or 582 KWH per month, or 6989 KWH per year.  At our current electric rate, it costs us about $2/day, or $58/mo., or $700/yr. to run the pool pumps.

Sadly, we spend more running the pool pumps than running the HVAC.  (Although it wasn't this way until we install GSHPs.)

I've looked at a variable speed filtration pump as a more efficient option.  Unfortunately, they're expensive, on the order of $1 - 1.5K.

My DSHs for both units are indeed disconnected.  At the time of installation my installer told me I was responsible for plumbing work, and, didn't tell me that a buffer tank was needed.  Thus, I direct connected my gas-fired HWH to my DSH.  I did later considerable analysis to show that a direct connect gas-fired HWH to a DSH not only doesn't work, it actually makes the HVAC run less efficiently in cooling mode.  Look back in history for my considerable comments on this subject.

Hope this helps.

Best regards,

Bill

Bill: Thanks again for an enlightening post. Regarding max temp - I forgot your system is vertical so yes late July early August makes sense.

On the Desuperheater, did you try pulling water off the bottom of the tank and returning to the bottom of the tank using a tube in tube valve (sorry forgot the name of it). This lets you pull water off the bottom and return it to the bottom without going down the cold water inlet line that typically goes in the top of the tank, throught the hot water and down to the cooler water on the bottom.

I run my pool pump about 4-5 hours a day then an extra 2-3 hours on the weekend when I clean the pool. I am surprised your's takes so much filtration (but I don't know its size, outdoor condition, etc).

Again, thanks for the great information

Alex, for the DSH, no, I didn't use a concentric fitting.  I can barely spell the word 'plumbing,' and am not skilled at it.  But, I can follow instructions well, and thus simply connected the DSH to the HWH exactly per the WaterFurnace instructions.  And yes, as your guessed, I'm thus connected to the cold water inlet line at the top of the tank.

Some day I'll fix this.

My pool filtration knowledge is limited.

In Texas, it doesn't require much filtration to maintain necessary pool chemistry.  What is a challenge is avoiding algae during time periods like now when it's not uncommon to have 90° pool water.

The best preventative is to religiously maintain good water chemistry (I have this automated quite well) and to keep the water well filtered (now filtering at 10 hrs/day).

Looking at the below chart, you'll see (green line) that the filter plus cleaner pumps require about 3300 watts, and the filter pump alone is about 2000 watts.

Once the water temp drops to about 80°, I'll reduce the filter pump to 8 hrs. per day.  And when the water temp gets down to 65° I'll reduce the filter pump to 4 hrs. per day.

I wish I knew what the relationship is between the 3 key variables: filtration time, avoidance of algae, and water temp.  I'd use this knowledge to adjust filtration pump usage to minimum time.

Parenthetically, I've got a 30K gallon pool, with a 53 s.f. DE filter, with a 2.5 hp filter pump.

I'm impressed that you can get away with just 4-5 hours of pool filtration during the heat of the summer in Florida.

Best regards,

Bill

Bill:

Filtration doesn’t prevent algae. Chlorine does. I am guessing that running the pump adds more chlorine. Summer is tough because as the water warms chlorine volatilizes faster. And you are right, algae will grow faster in warm water.

Buy a bottle of phosphate remover ($25 or so) and treat your pool. I do this each spring without fail now. Before I began doing this I had terrible algae problems - even with 1 ppm of chlorine in the water. If I ran out of chlorine for a day, well, it looked like a swamp the next morning. Pinch-a-Penny pool supply company was stumped because my green water always had about 1 ppm of chlorine.

I began researching and finally learned that if phosphate levels are high enough algae will grow in chlorinated water. Tested the water for phosphate and yep, that was the problem. Gave the pool a double treatment of phosphate remover and it has been crystal clear since. Even if I run out of chlorine for a day or two the algae has not reappeared.

You might want to try it.

Alex

Alex, thanks.

I reduced the filtration pump run time from 10 to 8 hours per day, and, increased the ORP to maintain an additional 0.5 ppm of free chlorine (will raise chlorine ppm from about 1.5 to about 2.0).  We'll see how this works.

For me a 2 hour reduction per day translates to a 4 KWH/day savings, or about 120 KWH/mo.  At my current electric rate ($0.10/KWH) this results in a $12/mo savings.

The $12/mo savings is offset by my increased chlorine consumption.  If all goes well at 8 hrs/day of filtration, I'll return the chlorine to the lower level.

As you know, the trick here is not to incur other expenses fighting algae problems.  Otherwise the $12/mo savings gets washed out due to algae fighting chemical costs.

I do as you do with respect to paying attention to phosphate levels.  Once per week I add a phosphate removing product called PhosFree ( http://naturalchemistry.com/pool-and-spa-products/products/show/8 ).

Thanks once again.

Best regards,

Bill

 

Alex & Bill,

We do not use, or recommend, concentric fittings for the desuperheater. The concentric fittings tend to pull sediments into the impeller and clog the small openings of the fitting. Pulling up through the dip tube ensures no sediments will fowl the impeller. Make sure you remove any type of backflow preventer from the dip tube or cold inlet nipple.

Bergy

Bill:

You should not need to add Phosphate remover weekly....unless you are fertilizing your pool *wink*. Phosphate gets in pools from rain (if fires are nearby) and leaves/grass, and similar. I'd have the water tested prior to adding the phosphate remover weekly.... Unless your water replacement water is high in phosphate too since you probably have a good bit of evaporation with pool waters near 90 F.

Alex, this is very helpful.  I'll stop adding PhosFree weekly.  Instead, I'll invest in phosphate test strips and add PhosFree as indicated by testing.

Many thanks!

Best regards,

Bill

Bergy, much appreciate the comments, and the connection diagram.  I printed it and taped it to my GSHP unit as a reminder as to what to do, when I do tackle this project.  Also, your connection diagram exactly matches WaterFurnace's instructions.

Many thanks!

Best regards,

Bill

Sorry for the off topic question. I am about to have a GSHP installed with DSH. I was not aware of the need for a buffer tank. My plan was to use a single 85 or 104 gallon Marathon and turn the power to the elements off per the drawings from HydroTemp. Why is a buffer tank needed and where can I get more information?

Thanks,
Gary

The 'imperativeness' of a buffer tank depends on whether or not the HWH is gas-fired or electric (more of a problem if gas), whether or not the GSHP is R22 or R410a (more of a problem if R410a), and how hot you want your DHW.

The combination of direct connecting a gas-fired HWH to an R410a GSHP, with a HW temp setting set at moderate or hotter, will result in the most GSHP inefficiency.

How much the inefficiency is dependens on climate - running in cooling mode with cooler EWT (i.e., in Spring and Fall seasons) will be the worse case situation.

Here's a chart for my system, showing that my direct-connected gas-fired HWH to an R410a GSHP results in less efficient GSHP performance when I'm in cooling mode and the EWT is about 72° or cooler (i.e., this Spring season up until about late May.

Below is a chart showing the facts.

Considerable material has been written on this - do a search of the archives for more detail.

Best regards,

Bill

Gary,

You can not use a single un-powered tank for a desuperheater.
The desuperheater only operates when the unit is running.  If the HydroTemp has priority hot water generation, be aware, there have been problems associated with on demand hot water production. We just replaced a three year old HydroDelta that had two compressors put in it and would squeel like a pig when running. The owner finally got fed up with it and hired us to install a water to air unit for the home and a water to water unit for the basement radiant.

A desuperheater needs a buffer tank because the electric eliments fight the desuperheater when trying to heat the water. A buffer tank allows the desuperheater to condition the water whenever it runs, untill the buffer gets to temp and the circulator shuts down.

Bergy

To further the point about the Hydro unit. On demand HW does not require buffer tank but does have specific installation requirements including 1" insulated process pipe and removal of any 3/4" galvanized fittings. Check your installation instructions for specifics and make sure it is done correctly. New owners of the Hydro label tell me (not suprisingly) that installation is seldom done correctly and may be the root of many of their problems. Let us know how it works for you in your own thread.
Good luck,
Joe

I agree with Bill. You need a buffer tank if you have a gas fired unit. You may need a buffer tank for any unit if using R410a vice R22. You don't have to have the buffer tank for the electrical unit. On many units they recommend that you set the lower element at 95 F so that you can add some heat to the unit. In the heat of the summer you probably can turn the bottom element off.

A few years back bought a device Global Energy Group called the Energy Gain System (EGS). It was basically a small, simple heat exchanger that sat beside the hot water tank. You ran the freon line from the compressor to the EGS and back to the unit. This provided me with 100% of my hot water for 3 months of the year (maybe longer but I sold the house so I did not get to test it later in the year). The advantage to the EGS is that it had no moving parts. The company is out of business now I think but you can still see the device on their website at http://www.gegsolutions.com/egs.html.

Also, you can use the concentric fitting if you will keep your tank clean. By this I mean drain some of the water off the bottom every other month to get rid of the sludge. This draining is actually a good practice anyway. If you don't do this then you can get some particulate matter flowing in your water lines.