I noticed my first freeze protection code after 2 years of operation.
I have a waterfurnace envision 050 on a closed ground loop.
My question is pertaining to current fp parameters setting currently set to open loop (OL)
3 settings are available. open loop, closed loop and process.
My logic is to change the parameter to closed loop which changes the set point from 32f down to 15f.
Is this a safe thing to do? Any suggestions would be helpful:)

Thank you
Rich

As long as you have freeze protection in your loop that is below the fault cutout, you will be fine...

In your ground loop did they mix in methanol or glycol or some form of antifreeze? On our loops we use a 20% methanol and 80% water mixture to get to the 15 degree freeze protection. Chances are they just forget to set the dip switch but I would call your installer to verify whats in the loop before changing anything.

Thanks for the quick reply's.
Of course my installer is out of business now
I was onsite when they used Methanol in my ground loop. I don recall the ratio.
Will your standard glycol meter work for methanol?
To my knowledge this is the only time the FP alarm code has happened, and the unit reset itself and started running again. (Is this something to concern myself with?)
In reading other posts on this site, some suggest the fp alarm originates on refrigerant side of the system. I don't see a sensor attached directly to the ground loop.
Are we certain the FP alarm is due to ground loop temperature?
Thanks for your input

Rich

Posted By kazam on 13 Jan 2013 08:20 PM

Will your standard glycol meter work for methanol?


Rich

No , you need a methanol tester, or put some in your freezer and try and catch it when the slush starts to form.   If it freezes solid,  take it out, let it start to thaw and then  measure the temp while it is till slushy.

WF's will throw a low loop temp code when in fact refrigerant charge has leaked enough to cause the temperature sensor (affixed to refrigerant line leaving loop heat exchanger) to see low temperatures.

It is a fairly cheap and simple matter to tape the probe of a $15 Walmart digital meat thermometer to various tubes within the system as long as one knows what one is looking at and steers well clear of potentially lethal voltages lurking therein.

Could also sample an ounce or two of loop fluid and set it in kitchen freezer, note temperature (using same $15 thermometer) at which slush forms to asses freeze protection since installing contractor has gone by the boards.

My geo unit had several fp alarms recently. Hvac guy came out and replaced the filter drier and i am back in action.
No obvious reason to why the drier plugged after 4 years of service. Any suggestions on how to prevent this from happening?

My output temperature to the ground loop is 38 degrees. I am only getting about 3 degrees differential on my ground loop. What is a best case/target temperature? How can I increase my differential temperature?
I have a 5 psi differential out of the geo unit, the manufactures manual equates that to 15gpm of flow.

Thanks for your input

Rich

Not enough info. What size unit? Are you reading temp difference with same thermometer? What is the entering and leaving air temperature (without stage 3)?

Thanks for response, I am using a digital fluke meter with two clamp on probes. This is a ground loop heat pump made by waterfurnace. Model nsw 050, 4.5 ton. No air handler involved. The unit installed in my garage were ambient temp hovers around 55 degrees. Outdoor temp aprox 40 degrees recently.

I am measuring ground loop temperatures at my flow center aprox 4 feet from geo pump.

I have two flow center circulator pumps on the ground loop. The are fixed flow rate models. grundfoss model UPS 99 FC.
I considered installing multispeed models to slow flow down somewhat, thinking I may pickup more heat transfer. Waterfurnace manual wants flow range between 12 an 17 gpm. Any suggestions

EAT/LAT? This is perhaps the most important thing you left out.
That is essentially a 4 ton so 12-13 GPM is indicated. What benefit do you expect from reducing GPM?

Entering air temp? I have a closed loop geothermal system. Water to water system with in floor heat.

Load temperatures to my buffer tank cuts in at 105 and cuts out at 115 degrees. At initial start up, the entering water temp is 105, leaving temp is 118, for a 13 degree differential.

Will reducing flow rate to my ground loop increase my temperature differential back to heat pump? Allow more time to extract heat from the ground?

My main concern is I am not extracting as much heat out of the ground as I should be. My output temperature to the ground loop is 38 degrees. I am only getting about 3 degrees differential on my ground loop. What is a best case/target temperature? How can I increase my differential temperature? This is 4 year old system, my loop diff used to be closer to 6 degrees. I am hoping nothing is going wrong with my ground loop itself. That is why I am leaning to a possible flow issue.

I assume there is no way to lower output temperature from geo unit to ground loop?

"my loop diff used to be closer to 6 degrees."

What did load side Delta T used to be?

BTU's extracted are a combination of GPM and temp difference (Delta T). You don't get more by reducing GPM to raise DT.

Assuming ground temperature is mostly constant. That leaves adjusting flow rates, lowering output water temp and/or increasing ground loop lengths.
What temp differential do you aim for in your ground loop systems?
Modifying my ground loop is not feasible. I am left with lowering my leaving water temp and/or adjusting my flow rate.
How would you resolve this?

Source deltaT change over that period of time suggests either flow has changed or HP performance has. Calculate HE Heat of Extraction and compare with published performance tables. You should be within 10%.
HE=DT x GPM x 485(or 500 plain water)

Using your numbers if accurate (should be verified).
3x15x485=21,285btu=HE
The performance charts say you should be around 30,000 btu

I am wondering why someone would change the filter/dryer in a factory charged unit unless other work was done on the refrigerant circuit.

If i am interpreting the water furnace tables correctly, My extraction should be closer to 44,200 btuh
I agree with your math, thats why I believe there is a problem.
I am using waterfurnace pressure drop tables to calc flow rate. with a 5 psi dif, i should be around 15gpm
I am considering installing a 1 inch inline flow meter to confirm.


In regards to the filter dryer. The hvac guy cant explain why the drier went bad. He filtered the refrigerent on the way out. pressure tested the system with nitro. replaced the filter/drier. refiltered the refrigerant back into the system. The unit has been running 5 days now.

Thanks for your feedback

To further confuse the issue on the load side if flowing minimum of 8gpm Heating Capacity HC=8x13x500=52,000btu Right on if not better than Spec. Numbers should be double checked.

"Assuming ground temperature is mostly constant. That leaves adjusting flow rates, lowering output water temp and/or increasing ground loop lengths.
What temp differential do you aim for in your ground loop systems?
Modifying my ground loop is not feasible. I am left with lowering my leaving water temp and/or adjusting my flow rate.
How would you resolve this?"

Again the source side DT may indicate trouble but is not the source of trouble, changing that will not make trouble go away. If the numbers you are offering are accurate, then your installer likely did not get the job done correctly (perhaps a little refrigerent was lost in the shuffle). But if the numbers you are offering are accurate then somehow your heat pump is overdelivering while underextracting which is not likely true.

I installed new pressure gauges on source loop fittings on the heat pump. Have a fluke meter with dual clamp on probes on Flow center EWT/LWT copper piping.

I use the same clamp on probes to monitor the load loop as well. I dont have pressure gauges on the load loop, nor do I know actual flow rate.

I am considering installing a inline flow meter on the source loop to confirm flow rate.

This is what I had in mind, any suggestions?
http://www.zorotools.com/g/Combo-GKW1/00065994/k-G2203336?CAPCID=24354086862&gclid=CPGI9b2SzL0CFQqEfgodFL4AMQ&CA_6C15C=1830885456

Thanks for your time

Nice piece of hardware, however the pressure drop introduced (4psi @ 10gpm & 9psi at 20gpm) will significantly reduce flow in your system.

Industry standard is pete's ports at the coil inlet and outlet. Measurements taken with the same gauge. Measurements taken anywhere else will include pressure drop from additional pipe and fittings.

have you put the fluke's clamp on probes side by side to verify calibration? Have you verified pressure gauges are calibrated. Most of the pro's use one gauge and 1 thermometer to avoid instrument fouling of the tests we take.