New York Tranquility 27 fine tuning

Hi All,

I've been spending recent days installing my WEL (http://www.welserver.com/WEL0899/) and analyzing some data. During that, I wanted to also compute the heat of extraction. I was hoping you could confirm my math:

Delta T = 7 deg F
Pressure drop = 2 psi
Flow (according to attached manufacturer's table) = approx. 8 gpm
I'm running glycol at an assumed 25%.

8 gpm X 7 deg delta T X 485 = 27160 BTU/hr

Given that I've got a 4 ton Tranquility 27, the HOE number is low, correct? So I thought about the possible causes. One thing that caught my attention is that my QT flow center has a single Grundfos UPS 26-99F/3 pump. The manufacturer's (B&D) instructions say this unit is good for up to 3.5 tons. Over that the two-pump version is needed. How important is this? Also, the Grundfos pump has 3 selectable speeds. Will changing the speed have any impact on either my GPM (seems obvious it will) or my delta T?

From reading on this forum, it seems that my GPM should be 12. 3 gpm per ton is what's prescribed in the Tranquility manual. However, 12 gpm is at the extreme high end of the table I attached.

It also seems my delta T should be lower (lots of folks are at around 2 deg F).

Your thoughts are appreciated.

PS - WEL setup is still rough. Looking for some free time to improve on it.

 

If you raise the gpm, the delta T will drop and the Heat of Extraction will stay the same.

 

Thanks for confirming that. Is there anything of significance I should note regarding my delta T being higher than most? And what do you make of my 27,160 BTU/hr HOE given that I have a 4 ton unit?

 

The HOE seem a bit low, but I did not do the testing or the math.

You should be at around 3 gpm per ton R-22 or R-410A. If you measure by delta "P" at 12.3 for the system you are in acceptable range. If you are at measured 12.3 gpm per ton you are way more than is needed.

How are you measuring the pressure drop through the machine?

Mark

 

Mark -

I'm measuring entering and leaving water pressures with a 0-60 pressure gauge through p/t ports right at the heat pump.

Sorry, I made a typo above. The "12" shouldn't have been there. I meant to say the manual specifies 3 gpm per ton, and this is quite common from my reading here. My observation is that my 4 ton unit should have 12 gpm, and I'm calculating only 8 gpm. My 8 gpm seems to be right in the middle of the chart, and 12 at the high end. Not sure if that's anything of importance.

 

You have a single 26-99 on an open flow center?

I would fight with folks here about tubulant flow and other things, but if you think you are at 8 gpm then you need to look at that line on the chart. When on that line with your EWT and LWT numbers re crunch your heat of extraction.

I think you might need a bigger or second pump.

440.223.0840

 

We think that Delta T should be in the range of 5 - 10 °

 

Yes, single 26-99, but with 3 speeds, on an unpressurized closed loop of 4x200' deep boreholes. I was looking at 8 gpm on the chart, and that's how I ultimately arrived at my heat of extraction figure. If I was to increase pump size/capacity, I assume the objective would be for a higher flow rate, say 12 gpm? That seems to yield the same outcome based on what Dewayne wrote up near the top of this thread.

Dewayne - thanks for pointing out your desired delta T range. It's somewhat comforting that I'm "normal" at something!

 

I am impressed that your EWT is in the 50's. This is better than normal for most loops

 

We have been fortunate weather-wise this winter in my locale. Essentially no snow and just a few short spells in the teens. Always questioning myself, I thought my EWT sensor was reading incorrectly. But it does match 2 other WEL sites near me.

 

Before condemning HOE I'd want to have a go at the other side of the equation...verify air flow and air delta T. Do a heat balance - add compressor and blower power to HOE and see if that total heat transfer lines up. Low air flow can drive down system efficiency and HOE.

 

Thanks Curt. I hope to have my EAT & LAT sensors in place this weekend. Wattnode is on the wish list, but I may just work with a clamp on amp meter for now. Can you explain how to factor in the compressor and blower power into my analysis?

 

I'm looking in my tranquility 27 book as we speak...for the tt049 which im assuming is your 4 ton unit the manufacturer info for an entering liquid temp of 50 degrees shows the following:
Without HWG active
Full load heating
2.25 gpm
Suction pressure 98-108 psig
Discharge pressure 320-340 psig
Temperature drop 8.7-10.7 degrees F
Air temp rise 24-30 degrees F

Hope this helps at all

 

Steve

I have a 4 ton Hydron Module water- air unit with a QT two 26-99 pump. My loop is a horizontal 4 x 500' 3/4" slinky with 20% methanol.

It is very easy with the QT flow center to measure flow by making an adapter with 1" PVC fittings and an inline flowmeter. I found a Blue-White Model F410 17 GPM flowmeter on eBay. This flow meter adapter just slips on to loop return pipe inside the QT reservoir.

I also have a WEL #0058. Have found that the loop flow to be consist though the season so is a fixed value in the WEL config. All the other values are dynamic.

Attached a snapshot of my WEL from the day while the unit was running...

EWT 39.9
LWT 35.2
DTW 4.6
GPM 13 @ 17 psi
HE 29,248 btu
HC 41,268 btu
KW 3,523 watts
COP 3.43 including pumps

It is interesting looking at other WEL system this time of year.

Bob G.

 

Bob G,

The text on the welserver site suggests that you shut one of your 26-99 pumps off (but left it in place). Is your 13gpm figure from after this modification? Your system and loop field have been performing well since then? If so, that's awesome. Your experience of how you reached that conclusion may help this thread.

 

Stick,

Heat added to system airflow is the total of HoE + compressor power + blower power. Suppose your system's compressor and blower together draw 15 amps (measured) at 235 Vac (also measured). 15 x 235 = 3525 Volt-Amperes. For purposes of this calculation I'll assume unity power factor and thus equate VA to Watts. (My system's PF is typically in the upper 90s, so it's a fair shortcut.)

3525 VA ~ 3525 Watts. Watt to Btuh conversion factor is x 3.413, so compressor and blower are adding 12,030 Btuh. That plus 27,160 Btuh HoE = 39190 total heating.

Compare that to manufacturer specification for your system at your specific operating conditions (EWT, water flow, EAT, airflow) and it should be within 10%. If not, review your instruments and assumptions.

Airflow heat rise calculation: CFM x Delta-T x 1.08. Example: If you have 1400 CFM entering at 68*F, leaving at 93 *F that works out to: 1400 x 1.08 x (93-68) = 37,800 Btuh = close enough.

Some notes on air flow - Total airflow is a bit difficult to measure but should be within 10% of configured airflow if system is operating below design static pressure and does not have an evil return bypass duct.

Caution - to measure volts and amps on a running system you will have to use instruments in close proximity to potentially lethal voltages. If you lack training / skill / confidence to do this, then don't.

I need to take small exception to the earlier remarks that HoE won't change with GPM - reduced GPM at same EWT will slightly reduce HoE. Increased GPM at same EWT will slightly increase HoE. However, in both cases EWT will likely slightly change as the system and loop rebalance. At any rate, the system should perform satisfactorily at GPMs between 2 and 3 per ton.

For extra credit you can experiment with various pump speeds and HoE results to figure out optimum setting for highest overall Coefficient of Performance. Pumps are more efficient at slower speeds.

If you can work out the above for your system DIY, you'd be one up on 90% of the geo contractor wannabes down here...need a job?

 

Birkie,

Good catch! Sorry should have fixed that. Both pumps are running now.

Last year ago, had tried running with one pump by using a switch to disable the upper pump for two months. One day between seasons had a lock out due to low- flow switch trip during unit startup. The working pump was not working. Pulled and found it was gummed up with black sticky coating. Not sure what it was. Ordered a new pump and two pump cartridges. Now have one spare pump on hand. Added a cup of bleach to GL fluid since there was some green staining inside QT reservoir. This is the only problem since the system came online in Feb 2008.

To reflect back as being a GsHp owner for seven years now, I firmly believe in K.I.S.S. With this technology is so true. There seems to be a diminishing rate of return trying to achieve the highest COP. My Hydron-Module may not be highest COP but the simplicity and quality has proven the reliability of the system.

Just update WEL site to show both pumps running when HP is on.

Thanks,

Bob G.

 

Guess need reading glasses since had respond to Chris! Reply for engineer...

What your describing in IGSHPA world would be 'Heating Capacity'. Taught that 'HE' is heat extraction from the ground loop in BTU/hour.


Thank you for all your posts,

Bob G.

 

Thank you all for the contributions! Had to take a sick day yesterday, but hope to have some numbers later today.

 

Just wondering what your pump power is since you figure it into COP. Trying to optimize an open loop system and looking to see where I am at in comparison to others.