New to Geo and Confused at high energy bills and lack of comfort

Mudley007

I promised to get back and I am.

I am glad to hear about the sys config issues that we think are fixed. I hope so.

Yes t-stats make a HUGE differance in how a geo or non-geo system works..In fact IMHO controls and stratigies for controls are at least 35% of new owner issues.

Let's think about what we want the system to do.

Keep you warm.

Work as promissed.

Be reasonably priced as to cost for fuel to keep you warm and work as promissed.

Did I miss anything?

To get all three things to happen we want to use the lowest cost sorce of heat. The geo heat pump comes to mind. WF in their rating tables for the wrost your new equipment will do at an EWT of 31*F at 11 GPM is 31,000 BTUH and it will do that all day long, 24/7 at a COP of 4.7. What does that mean? For every $1.00 you send the electric company your new heat pump gives yo $4.71 in heat. That is a great deal in the dead of the coldest winter. We want to take all of that we can get.

Now what? 31,000 BTUH is not enough. We need 54,000 BTUH according to the geolink PDF. So we are short 17,000 BTUH. Well look it up or trust me at 240 VAC 10 KW of strip heat is 17,000 BTUH. That in my thinking is a tad close to real design, but accurate just the same. There is no room for emergancy heat as your system is set up.

On the other hand the house was OK but expencive while running on the strip heat only.

Lloyd has his points that I will grant in theory. Joe and I have holes in our checkbooks from misstakes.

I might up-grade the strip heat to 15 or 20 KW and see how she cools.

 

Mudly

Glad to hear you are up and running the way intended.

Mark,

The Boy Scouts were over today ice fishing. A number of large mouth bass were caught using minnows. The Cub Scouts are coming next weekend for the Klondike Derby with some ice fishing mixed in.

For the doubters who thought the pond would be an ice cube by now I am happy to report the ice thickness was the normal 10 or so inches for this time of year. After very cold weather last weekend we continue to see EWT's in the 36*-38* range (never seen lower than 35* and I watch quite a bit). We are warm and happy! Especially after the National Grid bill arrived yesterday in the amount of $230.85 (alll heat, DHW, and household electrc use).

 

Uh, that's very close to half right: 10 kW = 34,121 BTUH

...just sayin'

Looby

 

TY Lobby

10KW at 120vac, sorry so lets see. Know we have 35k BTUH out of the strips, (I will go re-check my math) so nothing needs to be done. Just wait for summer.

 

My calculations are aprox 37000 for the geo unit at 3.7 COP based on 30F ewt.and add in the 34121 for the electirc strip heater for a total of 71,121 btu hr. That should be more than enough for the unit to shut off, even with -10F.

Now that you have it all working, and the thermostat set correctly, if the unit can not keep up and shut off part of every hour when the electric supplement is running in conjunction with the second stage of the geo, then the house is not performing as you expect. It should run alot in first stage and it should be able to maintain the temperature set without any problem. Depending on the differential set to delay the electric supplement, the temp may drop a little before the electric heat kicks in after the geo has run on second stage for a bit when the load exceeds the capacity of the geo alone.

I suggest you do at least a blower door test with a thermal imaging camera. You go through the house and find all the air leaks with the blower door on. It works best when its cold out. A scan of the outside before you start up the blower door, without the sun heating up the walls is also helpful. It is amazing where all the leaks are, and you can assure yourself you home is performing at its best. I hope you have a HRV or ERV for ventilation.

I know it is to late for you, but those who are hoping to build a high performance home should engage a building performance specialist to assist and make sure to participate in the Energy Star program. It is the only way to assure success.

They are finally, in 2011, lifting the Energy Star program standards up to actually provide comprehensive building science IT IS ABOUT TIME Of course the building codes are now, generally, making the old Energy Star home the minimum code so its time for a higher Energy Star standard.

Net Zero Energy Buildings (NZEB) will eventually be the Energy Star Standard, and then somewhere around 2030 NZEB will be code.

 

Ah,
a unit running 100% 0f time in the 20's or teens that has a balance point of 5 is not necessarily performing poorly.
A two stage heat pump in my neck of the woods will generally run 100% of the time 15 to 20 degrees above balance point.
Lloyd the more you editorialize the more I suspect your experience.
Being a hundred percent loader is a difference of design opinion. Saying a unit is poorly sized if it does not turn off for part of the hour at low temp is incorrect.
J

 

Joe,
First, personal attacks are inappropriate!

Second, if my calculations are correct, and they are close enough to yours that the difference is not of consequence here, then when this unit is running in second stage with the aux heat on, the unit should be shutting off. If it is not then the load of the house is higher than calculated and it is highly likely that the infiltration is higher than expected. This is just a read of the numbers, nothing more. My experience with functioning high performance homes is that manual J over calculates the loads, due to fixed and hidden safety factors in the calculatons. Using blower door verified leakage rates reduces this over calculation. In high performance homes with high energy bills, the blower door verified leakage rate usually accounts for most of the poor performance. The thermal imaging camera finds the air and thermal leaks.

Third, If a geo units run time is 100% when outside temps are 20F above the design temp, then the electric is going to be supplying more than 1% to 2% of the load. Or am I missing something?

 

I Don't recall a personal attack. Just observations.

So you know, when a unit runs 100% of the time it might be exclusively 1st stage. If load is low (depending on thermostat) it may never get to second stage. If third stage is required (again depending on thermostat) it can be just to recover a fractional degree at which point geo will shift back down to second or first stage (without ever shutting off)......and yes all this can be done while the aux carries only a small pct of the load.

Ergo you are definately missing something (to answer your final question) therefore your experience is definately suspect to answer your allegation of personal attack.

If you are what you say then instead of taking offense you might find out how everybody else here avoids aux. use even while unit is running 100% of the hour (or keeps aux. contribution to a few pct under the same conditions).

There are lots of certified installers and some designers who have never installed a heat pump.
j

 

I don't have much experience with aux strips - don't need 'em in Florida

That said, once a two stageunit is operating in a regime where some aux is needed, I wouldn't expect it to shut off for many hours. If aux is needed, load is greater than stage 2 can supply. That means it is well above what stage 1 can supply, so I'd expect the unit to stay running until load falls to below stage 1 capacity, and I'd expect that to be hours, maybe days away.

Does that make any sense?

 

Makes perfect sense, to me -- with the caveat that some thermostats are
overly eager to call for aux. Thus, it's quite possible for aux to engage
(briefly, we hope) when the load does not exceed stage-2 capacity.

 

True

 

I want to reiterate for the browsers/shoppers/consumers of geo. A unit that never shuts off at certain temps, could be running very efficiently.
A unit that cycles on and off in extreme weather is likely poorly designed for the job as installer has grossly oversized system robbing you of the benefit of 2 stage technology.
j

 

Joe, the method you are employing by having the thermostat ramp the three stages up and down to maintain internal set point is great with the two stage compressor and supplemental electric, using the Water Furnace suggested guidlines where the unit is sized to meet 85% of the design load.

I agree that with this thermostat configuration, you will get the best overall performance for your design principles, provided the loop is capable of keeping the ewt in the 30F range during cold spells and you are not using 30% propylene glycol in the loop.

As you know, I prefer to increase the time in first stage and decrease the time in second and especially third stage by increasing the loop capacity, which in turn increases the heating capacity of the heat pump and the minute by minute btu output of the geo system in first and second stage.

The same heat pump sized for 85% of the design load would meet more of the total load by adding loop capacity and less of the total load by reducing the loop capacity, due to changes in the ewt.

 

The incremental increase in heat pump capacity arising from such an increase in loop length / capacity may never pay for itself. Furthermore, greatly increasing loop capacity may also greatly increase pumping power, overwhelming any savings arising from increased compressor capacity and COP.

Published AHRI unit efficiency figures incorporate only pumping power through the unit's heat exchanger, not the much larger power needed to pump through a typical loop.

One has to consider the whole system's installed cost and operating cost to correctly infer lifetime cost of ownership, the only reasonable yardstick for comparison.

 

I mentioned before the homeowner with a 20 year old pump and dump CM that wanted to go closed loop. After reading the manual I noticed a minimum EWT in the mid to high 40's. The resulting requirement was about 5 miles of loop.
We can create any EWT one likes, but the loop field in this case cost more than a new heat pump.
j

 

Without a doubt!

Loop fields are going to last more than a lifetime. Buildings have been replaced around loop fields. (Commercial buildings are often torn down and new ones built and buildings of all types are destroyed by nature) Additions often get added to buildings.

One should definitely consider the long term cost of ownership as the yardstick to make decisions by when installing a geothermal HVAC system. Those who are building their dream home and consider it a legacy home for generations to come need to think of the VERY long term cost of ownership.

Most buildings have enormous energy losses, often more than a third of the yearly heating and cooling costs can be eliminated with the application of building science and some capital. More capital investment can reduce the costs by more than half.

Fix the air and thermal control failures in a building with a well designed geothermal system and the system will become more efficient and have higher ewts, making an already efficient system even more efficient. An inefficient geothermal system will become efficient, just by reducing the load.

 

Well, looks like my system still isn't working properly. I am definately thinking that my unit and loop is not large enough to support my home heat loss. I don’t know how to confirm that because waterfurnace won’t allow me to talk to an engineer or technical support person because I am a homeowner. They are telling me to call my HVAC contractor for support. Unfortunately that is the person whose opinion I can’t trust. Ultimately if the system is too small and designed poorly his “workmanship” warranty is on the line… So far he isn’t willing to take a hit to get this thing working right.

This AM, thermostat read 69. It was set to 70 running in Stage 2 (had been for the entire night) My CALIBRATED Fluke thermometer said 66.8 1/2 inch away from thermostat. I agree with 66.8 b ecause my nose is cold! I am getting tired of calling this guy! apparently he replaced the waterfurnace brand thermostat the last time he was out.

HOW DO I PROVE MY SYSTEM ISN’T DESIGNED PROPERLY? Anybody?

In an attempt to find out I am having another contractor in my area that has been in the business for 30 years and actually heats his own home with geothermal come and take a look at my brand new expensive system that costs $550/month to run... Based on our initial conversations and information I provded he too believes I am undersized and that there is a chance my woes are not over. That year after year they could actually get worse… He told me a story about an individual that started getting higher heating bills year after year because the loop was too small... Is this possible?

It would be nice to have some sort of indicator as to who is any good at installing and designing geo systems. Why is there not such a thing? There seem to be a lot of crackpots around and we lowly consumers can't always know who knows what they are talking about. These systems need such careful design to work efficiently that you cannot afford to have an amateur do the work. Experience Experience Experience… Wow if I would have known…

Perhaps GEOEXCHANGE can start sponsoring contractor reviews based on geographical locations to ensure the consumer is educated and can share experiences.

 

Our stories are quite similar. My electric bills the last 2 months have been in excess of $350 due to the aux heat running a great deal of the time.

I've installed a WEL Temperature and Energy logging by: Web Energy Logger and am able to see the details of how the unit is running. The last graph dramatically shows why my bill is so high. The aux heat has been on over 60 hours out of the last 96.

I fell out with my contractor and fired him several months ago after we could no longer communicate in a constructive fashion. I too started a relationship with a new contractor whose background is quite similar to the one you are describing. So far, he's been great to deal with and we get along very well.

I asked the first contractor, through my attorney, to mediate some sort of settlement. He refused. I now need to decide if I want to pursue stronger legal options.

What should have been an exciting undertaking has turned into a bad dream.

 

If your heat loss calc is accurate and you have 150' of 6 pipe trench/ton you are designed okay.

The other contractor that claimed the effects of short loops are cumulative (from 1 season to the next) is also full of bunk.

I don't know what's going on here, but it is not sizing.

Please PM me your E-mail address if you would like me to have a look.
J

 

I'm New Too

Mudly007 & Others,

I will be following your thread. I too have a new home of similar size (2200 Sq. Ft. Bungalow) I have 5 Tons of Water-Water & 3 Tons of Water-Air. Won't have it up and running till next winter.

I am curious because you seem to have half the capacity that I have for a similar house. My home is ICF in the basement, 3.5" WallTite in walls and 5" WallTite in Roofdeck. I have two loops in each 5' x 600' trench for each 2 tons of capacity. My trenches are 10' deep. My location is 52.8391, -106.0894 Google Map coordinates.

My system is Next Energy; 3 ton TMW Tranquility & 5 TonTranquility 20. My total heat loss calc is 55,024 with no HRV. When you run HRV wide open the HL goes up to 68,373

reason why i'm watching your thread is because I'm a bit nervous about how my system will perform and I seem to have almost twice the capacity.