I have a WaterFurnace Envision, first winter with new system.
The system seems to be working but the flow center/pumps, there are two pumps, both have frost on them.
Should this be a concern. I am getting the idea from other posts that ice on the out flow is not uncommon but ice on the incoming one seems to indicate the groung loop is below 32 degrees.
Aux heat comes on occasional but not often, so far.
Any thoughts appreciated.

More information please?

 

What is your EWT?

What is your total tonnage?

Are you a horizontal or vertical loop field?

What size loop field?

Geographic location?

Eric

I met a new hvac contractor today
Air Doctorx
His business card states:

Diagnosis without prognosis is malpractice

That is just priceless

Thanks for the response. I live in South Western Ontario. Just south of Detroit,Michigan.
The house was built in 75 and is a 2000 sq ft ranch with a full basement, which is fully insulated but not finished.
The furnace is an Envision two stage with third stage element for back up.
NDV049   4.5 tons I believe.
The horizontal ground loop is 1 1/4 pipe 1000 feet out and 1000 feet back in two trenches 8 feet apart. Supposed to be at least 4-6 feet deep
Soil here is clay and generally moist, somewhat poor drainage.
Regarding EWT, I am not sure what the term refers to exactly.
There are no temperature gauges to read fluid temp coming or going so the frost/ice was the first indication something may be amiss.
Also, there is a slight leak of fluid near the pump. Contractor coming tomorrow to inspect and fix. He figures it is quite common for a slight leak where the pipe conects to the pump and should simply require tightening.
The system is providing heat normally and not relying excessively on the back up. It has come on occasionally, usually when the heat is turned up too much at once. It does seem to come on more if I try to maintain temps higher than 69. That is where it sits normally. The compressor does run a fair bit though.
Local temperatures recently have been between 15 and 30 degrees F.
Don't know if the ice(on both pumps) is a problem but it didn't seem to match with most other users experiences.
Thanks again for the reply.
Jason

EWT (Entering Water Temperature) is the temperature of the water or water+ antifreeze coming into the unit. The unit will pull heat from that fluid, reducing its temp by 5-10 degrees and return it to the loop field where it will get heated back up by the same 5-10 degrees.

Be certain leak fix also includes being certain loop is still under positive pressure, that no air has been pulled into loop. Even small amounts of air wreak havoc. Contractor should check pressure and purge system of air if necessary.

Lengthy compressor operation and limited aux heat operation as described sounds OK for this time of year, though design temperature for Detroit is 6 degrees, implying a good deal more aux strip operation is in store for you on design or worse days. That's not necessarily bad - savings in loop costs may buy many hours of backup heat usage

NDV049, though nominally a 4+ ton unit, only provides approximately 3 tons with EWT in 30s

My brother's first car was a VW. It did not have a gas gauge! Ground source heat pumps maid in China come with temperature and pressure gauges.

EWT is entering water temperature to the heat pump.

Regards, Masoud

Temp and pressure gauges should be standard.

Contractor coming this morning to fix leak. Hopefully no air or loss of pressure.

Thanks for input.

Jason

Temprature and pressure gauges installed on a closed loop residential system in my opinion are another possible failure point.  I do support the installation of PT ports so you can gather data when warranted.
Eric

I would rather see a broken temperature or pressure gauge in my basement, than being faced with a failed ground loop. If these little monitors were standard, a lot of problems brought up on these threads were better answered and more quickly resolved. More info please? I cannot tell you what I don't know.

Regards, Masoud

Contractor came this morning to fix leak. It appears a 90 degree fitting was the issue and (hopefully) tightening will fix.

Pressure is good in the system. Was told that the loop temp will get below 32, hence the frost. The upper pump is not as cold as the lower one which is going out. I can only judge by the amount and hardness of the frost on the pumps.

There are two small valves which are capped near the furnace to test pressure with a probe. I assume one can put a thermometer there as well.

I am thinking that a higher EWT would be more efficient but sadly I don't think there is much I can do about that at this stage.

Jason

Little valves are likely "pete's ports" for temp and pressure measurements.

If inbound waterside isn't iced it is probably OK, not great - we need to know where you live to further assess.

Many contractors resist installing permanent P / T indications as it may cause too many callbacks. A similar situation affects design of temperature and oil pressure guages in most cars - indications are deliberately severely dumbed down to reduce service calls.

For example it is common for oil pressure guages to read "normal" (and not move) for any pressure between 10-60 psig. Temperature guages are designed to swing in the low range but then center in normal for any coolant temperature between 150-210 or so. Consumer ignorance is bliss for dealers and manufacturers.

If I look at the flow center, one pump is mounted on top and one on the bottom. Bottom goes out top comes in.

The little black caps which cover the pumps don't stay on so the brass plate on both pumps is exposed. Both are frosted  over.

Lower slightly worse than the upper.

If I look at the pete's ports. The one for outflow is frosty and the one going in is not.

I am located near Windsor Ontario  south of Detroit.

What is the minimum temperature one should see in the loop.

Where can you buy the probes to stick in the petes ports?

Great forum, this is not new technology but it does have it variables and is not that common.

Thanks again for all the input

Jason

Hi Jason,
I am at lattitude 45° in northeastern wisconsin. I have an Envision NDV49A111CTR which I think is similar to yours. And this is also my first winter with it. My EWT is about 36° and I am also somewhat concerned about what it will be in a month or two because we have not reached the coldest part of the winter yet. Although we have had a colder than usual December and we're supposed to see 0° as a high next week. Our Waterfurnace was a replacement of a propane furnace and it is doing a great job so far. I tried inserting a cooking digital thermometer in the petes port to measure the EWT. I think it was a little too large in diameter and didn't force it but I believe the reading was close to accurate. Anyway, I also inserted an inexpensive Springlfield digital wireless sensor under the insulation on the entering line from the field and got the same temperature as inserting the cooking thermometer. The readings were about the same and have been monitoring it since. Bottom line is my Envision is working great so far and my EWT is hovering around 36° and actually goes up when we have a warm spell. I understand from other posts that the Envision can work down to 20° EWT. My field is 3,000 feet of tubing buried about 6 feet deep.

A digital thermometer strapped onto and as close to parallel as possible to the water line AND INSULATED will yield a fairly accurate water line temperature.

Deep ground temp in northeastern WI is about 48 according to a doc I have from McQuay, so icy EWT may be hard to avoid as winter wears on. I hope your loop design factored this in.

Pjp01, I read your deep ground temp at 53, FYI

"Deep ground temp in northeastern WI is about 48 according to a doc I have from McQuay, so icy EWT may be hard to avoid as winter wears on. I hope your loop design factored this in."

My loop was buried in a 10' wide trench 300' long. It has 5 loops spaced 1' apart out and back, so each loop is 600'. Our subsoil is a sandy loam glacial till that is probably a few feet above the normal high ground water level. The installer told me it is a 5 ton loop. Our WaterFurnace is supposed to be a 4 ton unit. Does that sound like the appropriate design ? Performance so far has been great. We turned off the electric backup by means of the dip switch. We only go into 2nd stage when it gets down to 0° and then only intermittently.

If you are comfortable without aux heat and with only intermittent use of stage 2 so far then yes, you probably have a successful installation. How have been your electric bills so far? Probably much higher than when you were burning propane but a heckuva lot less then the cost of the propane - yes?

I would expect heavier use of stage 2 on cold (0 - -15 deg F) days in January, with intermittent use of aux heat, more toward end of January early February. Some ice may appear, first on outlet line, then intermittently on inlet line - I hope this will not occur until end of January and cease in mid to late February. March-May should be a cakewalk, and you should have a cool and cheap air conditioning season next summer.

our propane use for the last 2 years was 770 gallons. so far we've used about $35 additional electricity in November and we just got our bill for December and it was about $125 more than the average for the last 2 years. I know that we will save at least $150 cooling costs in July, August because our old AC system was not very efficient and those months always spiked in electric use. I really don't expect to use aux heat. We've had -15° already and 2nd stage only came on occasionally. We've learned to just leave the thermostat at 70° 24/7. oh, and propane here is around $2.40 so, the way I see it, geothermal will pay for itself quite soon here. Actually, we needed to replace our old furnace and AC anyway, so if we subtract the cost for a traditional system, geo will pay for the diff in about 5 years at this rate.

thats 770 gallons each year

Great info,

I also replaced a propane furnace with the water furnace. Been in the house almost two years. When I checked with the propane supplier I discovered the usage history in the house was about 4000 liters per year. At the end of last year propane around here was selling for 75 cents a litre. That and the energy audit/grant program made my decision easy.
Only one hydro bill so far which is up about a hundred dollars from last year but I am still way ahead of the game from a cash flow perspestive. The propane furnace is only 8 years old, is high efficiency and comes with a central air unit. Available on kijiji for 500 bucks. No takers so far.

More to the point though: I did manage to insert a meat thermometer into my petes port and got an incoming reading of 32. Going was below the thermometers lowest reading which I am guessing is 32. System running well so far though. Temps definately lower than I would like to see with a couple more months of cold left.

My total cost for all of the installation and equipment including the field was $17,000. I anticipate getting the $2,000 tax credit on my 2008 federal tax return. So my actual final cost will be $15,000. How does that compare to where you are in Ontario ?
They installed the field in one day and the inside equipment in a day and a half. Of course, thats in US currency. I have no idea what the exchange rate is.

Just on my way out of town for the weekend so I will respond in detail on Sunday or Monday

Regards  Jason