HVAC. Polar Vortex. Hows your system handling it?

buckeyefarmer · Jan 30, 2019

Shblack said:
Commissioned our waterfurnace 7 series last month, getting to know it. Really like the constant temperature and it’s quiet. Currently 17F outside, loop temperature is 36.2F, which is a bit cooler than I would have expected. Current electric load is 3.3 KW

My loops at 35°. Its 2° outside.

LD1 · Jan 31, 2019

s219 said:
Do you monitor your ground loop temperature? Be curious to know what it gets down to when the system is working hard for a long time in extreme cold ambient temperatures. Do you know what your lower limit cutoff temperature is? I think the real concern for me is if the geo runs so much that the ground loop doesn't have time to recover. At a minimum that can just mean the system makes less and less heat and/or won't be able to keep up, but if you hit the lower limit the system will cut off. I believe my lower limit is set to 10F for our particular methanol/water mix.

Last year we had some -5F ambient temps and my geo system was working very hard. It cut off a few times, which made me think the lower limit was triggered, but when I hooked up the diagnostic tool the next day, turns out it cut off due condensate drain overflow errors. That had me scratching my head, since the system should only be generating condensate in the summer with AC. Come to find out the drain line for our steam humidifier froze up and it back flowed up the common drain pipe and into the geo unit's condensate tray, triggering the overflow sensor.

The other problem we had was that we lost power a couple times overnight when the temperature was that low. I assume it was due to excessive demand on the utility. Every time that happened, the geo unit would go into a random purge delay before starting back up, and the humidifier would go through a drain/refill cycle. With a frozen drain line, that would then trigger the geo's overflow sensor all over again and it would not start up.

This winter, I put a valve on the drain line and now isolate the geo unit from the humidifier during the peak of heating season. If the drain line freezes the humidifier will cut off without flooding anything else, and we can certainly live without a humidifier.

I dont have an accurate way to measure loop temp. My probe thermometers I dont really trust.

But I do have a cheap plastic thermometer. The "resolution" isnt great.....but dropping it in the tank when its running and leaving it for ~5 minutes I am about 35-36 loopo temp.

That was last night....So that was after about 24 hrs of sub zero and almost continuous running.

I think properly sized.....loop "recovery" time is a non factor.

My unit is 4 ton.....That calls for 4 600' loops. I put in 4 800' loops. Plus the fact that most of the running is on single stage.....about half capacity....I dont think I am even coming close to needing to be worried.

With Probe thermometers....water going out is only ~2 degrees colder than coming in. So the ground doesnt need to do a whole lot.

Luvmyhindra · Jan 31, 2019

Mine has been holding well here in s.w wi. Runs quite a bit but the night before we had -28 and a high of -17 yesterday. Last night was suppose to hit -35 but I only have -28 as of now. Yesterday power went out in a few locations and again this morning I see some power outages. That is my worst fear in all this. My wife and I would be fine but there are a lot of elderly people who wouldn't. Well this is about over for now. I'll be breaking out the shorts this weekend as we are suppose to hit the 40's.

Malvern · Jan 31, 2019

I replaced my Bard 4 ton geo unit last fall with a duel fuel unit. On days like this the geo unit would run 24/7 with an out put temp of about 88 degrees. Loop temp be down in the 22 degree range, the loop was sized for just about 54,000 BTU's. Never ever felt warm in the 15 years we've lived in the house + the high electric bills.

The new unit is a 4 ton heat pump and 100,000 BTU propane furnace. HP is set at 30 degrees and the furnace will kick on an anything below set point. 2 things I've seen is a reduction of humidity and my wife and I are now warm. We just love this set up. My first tank of propane cost me $1.09 a gal and I got a $400 rebate from my co-op which pretty much paid for my 1st tank.

TheMan419 · Jan 31, 2019

We have a boiler installed probably in the 60s. We are at -20 actual air temp. Wind howling so windchill are -47. Pump is running pretty continuously but maintaining 71 degrees.

Found one window has a blown seal.

LD1 · Jan 31, 2019

Malvern said:
I replaced my Bard 4 ton geo unit last fall with a duel fuel unit. On days like this the geo unit would run 24/7 with an out put temp of about 88 degrees. Loop temp be down in the 22 degree range, the loop was sized for just about 54,000 BTU's. Never ever felt warm in the 15 years we've lived in the house + the high electric bills.

The new unit is a 4 ton heat pump and 100,000 BTU propane furnace. HP is set at 30 degrees and the furnace will kick on an anything below set point. 2 things I've seen is a reduction of humidity and my wife and I are now warm. We just love this set up. My first tank of propane cost me $1.09 a gal and I got a $400 rebate from my co-op which pretty much paid for my 1st tank.

Surprised you didnt feel warm with 88 degree output temp. Thats a fairly warm number for anything that relies on refrigerant. And according to the experts....humidity makes it "feel" warmer. As the moisture retains more heat and conducts it to your body better. Thus in the summer one goal of AC is to REMOVE the humidity. And those that heat with wood or electric it is advised to get a humidifier or boil some water.

Malvern · Jan 31, 2019

I agree with every thing you said. On day like these I'd wipe the moisture off the inside of the windows. Humidity be about 50 / 51% on the coldest days. Now I'm at 38 to 41% with this new combo. My furnace guy said I never built up enough heat to keep the humidity in check and what I'm seeing proves his theory.

teejk · Jan 31, 2019

Our modern LP fired boiler is struggling to keep up...5 zones all calling for heat at the same time but it was -40F so understandable.

Shblack · Jan 31, 2019

We hung in pretty well last night, dropped down the setpoint on a couple of zones which freed up capacity on the main zone. Our system provides on-line monitoring on the exit loop temperature, currently running 36.4F. Our loop is a pair of 300’ wells into solid limestone, each has a loop of 1” HDPE pipe in it, wells are backfilled with bentonite clay. Note that we started out with a horizontal loop, digging the loop (700’ of 6’ deep trench) got to be problematic (high ground water, gravel soil that caused the trench walls to collapse), installer was unable to install the loop.