Pennsylvania Higher than expected electric use

Andrew:

You can do anything you want with statistical numbers. What you want is comfort at a reasonable cost.

You have a ton of money in a system that does not make you happy. I think we can make it work better or at least lower the electric bill.

I can and will come to you.

Mark
Lake-Erie-indoor-air services.net

 

There are spreedsheets out there like www.eia.gov/tools/faqs/heatcalc.xls

You also have GeoDesigner software out there where you can build different types of systems including gas/oil. I have the ClimateMaster software installed since that is the unit I went with.
http://www.climatemaster.com/geothermal-dealer/geothermal-sales-tools/geodesigner/
(just make sure you don't put in $.011/kwh vs $.110/kwh )

It's very tough to beat the running cost of Geo unless you have access to cheap natural gas (and your electric rates are high). You must have a ton of $$ invested in the system already so it's really trying to get to an acceptable operating cost level.

I would really shut down one of your units. Maybe you could rotate which one you shut down. Having the fourth one running is costing you extra wear and tear on the equipment plus another 3 pumps worth of power which you really don't need according to your load numbers.

Yeah, the parts needed would be maybe $20-30 and a day or so to program it up.... plus you have all the flexibility you would every want.

 

Mark

I do have a ton of money in this system. I'm just not clear on how well it is performing and if I should be happy or disappointed with the operating costs. It seems that the loops themselves are performing okay and the HPs are the HPs, so the opportunities to save money are on the load side configuration, loop combining and the circulators.

The two biggest issues that I'm aware of are the poor staging control and one-temp water being supplied to all of the zones. The staging can be handled with some sort of PLC or perhaps a Takmar Boiler Control, and the two temperature zone water by adding another tank and separating the HPs by tank. I suppose then maybe I could just add another 406 to control that tank / HP. But is segregating the HPs going to make the system more costly to run b/c I will always need at least two running when heating? No simple answers here.

But regardless, if I'm going to make any changes, it likely makes sense to combine the loops, add air separators and install constant pressure pumps on that side, too.

Tonight though, it seems one of my air zones is acting up. I have 82F in a room with a set point of 67F! A zone is turned on even thought it seems that it's not calling for heat. I set the thermostat to OFF and that seems to have fixed it. Restarting the entire system did not.

I still need to determine if any additional investment is worth it... and this comes back to knowing how well my system is really performing now.

Andrew

 

Pretty good.
Lets see if I am not too rusty in this. The measurements indicate that Andrew gets a 5F delta at about 37F EWT, and if the units operate correctly, they should have about 33,000 BTU/h heat extraction. So assuming 25% glycol, 5 F delta T, you should have about 13.5 gpm flow on the source side, which means 47 .5 ft hd with (2) 26-99 in series.
Now you could go down to 12 gpm per heatpump on the source side, which gets your head pressure down to about 37 ft hd. If you combine the loop field his EWTs should stay above 35F, so he should be able to do this easily (go down to 12 gpm per heatpump). Now if he takes a single pump GV-15 flow center, the Wilo Stratus 1.5 x 3-40 could make 11 gpm per heat pump in the rare occasion that all 4 heat pumps are running, using 450 watts max. Most of the time with 2 Heat Pumps running average it would use less than 150 watts. All it would do is increase his delta T by 2 degrees, again in the rare case that all HPs are running.

 

Andrew,

sorry but you are quite a bit away from me. Too far. You should not touch the mechanical part until the heating season is over.

Outdoor reset should get you longer runtimes in the floors. That is actually an indicator that the supply temps are too high, when your floors shut of on the coldest days. You should be able to use your existing 406, or may be replace one with a 274 and a couple 152.

Used circulators usually don't sell well. Craigslist is the best I can think about. A couple of them you might be able to use on the load side between buffer tank and heat pump, depending on your final design. The whole flow centers are obsolete, you could sell them as flow centers with circulation pumps.

 

Would the 274 or 284 work for cooling? Would the 152 add that capability?

How do you kn0w that the floors are shutting off? (I'm not aware of how I can tell this besides adding current monitoring to the circulator for that zone.)

So the scope would be:

Geo loops:

1. Install new flow center and manifold all geo loops together.​

Load Side

Option 1: Install 2nd buffer tank and split HPs and zones so that one is for air handlers and carpeted floors and one is for hardwood radiant. Use Wilo calculators and zone valves.

Option 2: Use a combination of closely spaced Ts and circulators / zone valves to create a two temperature system attached to existing buffer tank.​

Controls

Install 284/274, etc to control the staging of HPs in heating and cooling.
​

Right now, thermostats consider radiant as "heating" and the air handler as backup heat. Does this mean that the Tekmar controls are unaware that the first stage is actually radiant?

 

You should be using communicating stats, I think 259.

The 406 can be trained by the stats to know W1, W2 and W3. My go to guy no longer reps Tekmar, but I think I can sort it out with Paul Williams' help.

Again the piping needs to match one of their drawings.

What manual do you have?

I am in PJs so I am not going out to pull manuals out of my truck @13*F.

 

All of the thermostats that I have are Tekmar U527, U557, U530 or D161.

I'm not sure that I have a "manual." I've have all of the documents available here: http://tekmarcontrols.com/products/alternative-energy/406.html

 

We use either a seasonal switchover with a single tank, and two tanks, one for cooling and one for heating. 274 would be a 4 stage boiler control, and the 152 for cooling to control the buffer tank in the summer. I am not saying that the 406 could not do it with 2 stages, but I enjoy multiple heat pumps coming on in stages. I don't consider primary / secondary and option, it will decrease efficiency when the returning water is mixed with the supply water.
I have asked others to explain their notion to me, nobody did so far. I'll start another thread.

 

I would agree with Doc. Primary secondary would work to give the zones the temperatures they need but the buffer tank would always have to be the higher temperature. The higher temperature output from the heat pumps the more the compressor has to work. The more the compressor has to work the lower the COP.

It all makes sense to me the higher the lift from the source temp the harder the compressor has to pump, the more electricity needed, the less efficacy.


If you can run 2 buffer tanks, say 3 units for low temp floors and 1 unit for high temp air handlers. I would think that would be more efficient. (Load Calcs would need to be done to see if 3 on the floor and 1 on the air would keep the building happy)


Edit. This also depends on required water temps. If you can heat the floor with 90-100 degree water and the air handlers need 130+ this would make my argument more reasonable. If the air handlers need 110 and the floor 100 primary secondary might be a better option.

 

If you need 130F supply temperature a conventional heat pump cannot do this unless you bypass the buffer tank. Still no need for primary/secondary in 110F applications. In that case you send 110F directly to each zone.

 

Ok It was just a (bad) example. I will move continue this on your other thread.

 

I was able to measure pressure on:

HP1(vertical) 52 & 44 psi
HP3 (horizontal) 65 & 60 psi

 

At 14F outside, I measured the following:

1. 54/49 psi
2. 58/54 psi
3. 66/62 psi


1. 35.6/31.1F
2. 34.7/29.0F
3. 29.8/24.7F

I measured the pressure using this: http://geohydrosupply.com/tools/tlpg.html

I found a curve for this pump, but these psi readings, when converted to ft-head, are off the charts. What does this mean?



http://www.climatemaster.com/downloads/RP391.pdf

 

AndrewL,

Take the delta P's - 5,4,4,... and pull up your equipment specifications. There will be a table converting that psi to a flow through equipment. That is what you're looking for.

 

those equate to 11.5 and 9.2 ft head which puts flow around 29 to 30 GPM.

 

You have a 4 to 5 psi drop. Or 4-5 delta p.

The gshp charts show how many gpm for 4 to 5 psi drop?

Your numbers sound high. But I did not look it up. You looking for 3 gpm per ton.

 

Page 23 of this http://www.waterfurnace.com/literature/envision/SC1006WN.pdf. indicates about 13 GPM and units (60s) are 5 ton, so that seems reasonable.

 

OK 13 gpm. Now what pump do you have.

If you have a single 26-99 then you have about 23 ft of head on that loop at 13 gpm.

If you have double 26-99 pumps you have about 45 ft of head at 13 gpm.

According to the pump curve you posted above.

 

Double, this agrees with what Doc calculated above.