Washington Bosch SM60 freeze error -- closed loop

This unit was installed in our new home January 2015. What are the first things to check on the freeze error and what sort of regular maintenance should be going on?
I believe the horizontal loop "hoses" are down about ten feet which should be around 53 deg F here in far NW Washington State. Everything has worked fine until recently when we noticed the aux heat was coming on more. So far this winter air temps have not gone below + 35 deg F I don't know exactly was liquid was put in the loop originally, but it hasn't been touched since 2015.

We have a technician coming out Friday.
(Bosch model number translation here)
https://www.bosch-climate.us/files/...14-008_76HMB5031_Code_String_July_7-18_US.pdf

Ours is:
Bosch Water Source Heat Pump Model
SM060-1CFC-SLBATA-EHGXXXXXD7XXXX8XXXXSBA
SM is series
60 is nominal ton capacity
1 means 220 volts 60 cycles
CF means downflow configuration
C means copper coax material
S means side water connections
L means left return air
B means bottom discharge air
A means const air flow ECM motor speed
T means Tin coated air coil material
A means level revision of the product
E means 20 kilowatt electric heat
H means painted steel 1/2 inch closed cell foam cabinet
G means geo thermal application
X's mean General Electrical Options is none
D means Heat Recovery Package for Refrigerant Circuit Options
7 means Transformer is 75 VA volt/amps
X means Controls = None
X means water flow control is none
X means economizer is none
X means "Open" ?? is none
8 Filtration (unideintifed ) character 33 in the model number string

 

Hi and welcome!
Be sure the technician confirms that the dip switches or jumper wires are configuered for closed loop operation. After that just follow the units diagnostic tree to isolate trouble.
Eric

 

Thanks. This video mentions that the default lock out is set at 30 degrees, but can be set to 15 if there is antifreeze protection . Looks like we or the technician need to determine if our system has antifreeze in it, and if so, it's condition. Since we're on a well with high-end filtration system, I suppose the purity of supply water and possible presence of air in the loop would need to be checked if it isn't an antifreeze problem.

 

Assuming your unit worked well in other years in colder temps, my money would be on refrigerant. Nothing beats a a proper diagnosis though. Let us know how you get on.
Eric

 

Thanks Eric. The tech is coming today. With a closed loop, if he needs to add water to the loop ( along with antifreeze ? ) I should probably tell him about the well water filtration we put in two years ago. I regularly get water out of the tap that initially has lots of tiny air bubbles in it --- shows up looking almost like diluted milk in our dog bowl, but of course the bubbles dissipate quickly. I'm assuming this would be bad going into a closed loop system.

 

My well water is low pH and corrosive to copper. So, when I had my system installed I had my installer bring the 200 gallons of water needed for my loop. It's not uncommon, because loops are installed in new homes before water is available, etc.

If you are just topping-off the loop you probably don't need very much water.

 

Or antifreeze.
Eric

 

Diagnosis is a dry loop, suggesting a leak. Next step is to use a conditioner solution to try and patch the leak. For a new unit and loop installed in new house exactly 5 years ago, this suggests an installation error ( if the loops are supposed to last up to 50 years ). When I walked the area during construction, the loop hoses seemed to be going ( horizontally ) into ditches that were 8-10 feet deep.

 

I've read that the manifold is a typical spot for leaks... It looks like it's under our front lawn several feet out from the front of the house... Photo taken July 2014 during construction

 

assuming everything branches out from the manifold and you have just an in and out pipe coming into your house, finding the manifold would seemingly be critical. You could isolate and pressurize individual loops to track down the leak from it. Maybe make a vault for it for future access while you have it excavated. Its weird that you got a leak 5 years in - anything in the yard change recently (excavation, earth movement, earth quake, etc.). HDPE is pretty tough stuff and assuming fusion connections, the connections tend to be stronger than the pipe.

 

I wonder if you could have had one of the 4 loops air locked, then the blockage opened up and fluid filled the empty loop.

The manifold is small and not sure if reverse return was implemented (first in last out)

Chris

 

No earthquakes or anything like that. I'm not sure if the loop hose type can be determined from the photo. Yes if the leak sealant doesn't fix it and we have to dig down to the manifold, preparing an access vault might not be a bad idea. I know the "heat fusion" technique for joining hoses to manifold requires a skill, I wasn't on hand to watch that being done. If the coiled loop hoses going out in the ditches is very unlikely to have been damaged and doesn't have joints to fail, the the manifold would seem the likely culprit. Now if they didn't put sand or something in the ditches to "cushion" the hose, then vehicle traffic over our driveway now could press the hose against a rock I suppose.

 

Chris, you'd have to explain that in laymen's terms.

 

When the loops are filled with water/antifreeze it’s possible that one of the 4 loops didn’t fill with fluid.

If after 5 years that empty loop somehow filled up it would drop the water level looking like a leak.

Just a thought I had. I know it can be tough to purge a loop system of all air.

Do you have a picture of the loop pump/s? I’m curious if it’s pressurized or non-pressurized.

 

I'm assuming loop pumps would be in the mech closet with the bosch unit

 

Yes, the two big pipes that come through the foundation will connect to it.

 

The technician told us our loop should be pressurized to 15 psi so I'm assuming there's pumps that I can get a picture of

 

It’s a pressurized system then, non pressurized would have canister that air bubbles could escape from.

 

Before we go full tilt leak outside, how about we isolate the loop field and pressure test. leaks can be anywhere, and the hvac guys tend to always blame the loop. Has a pressure adjustment ever been done on your loop? Some loop fields go for years without adjustment. some need it further down the road, some need it right away. Diagnosis of the leak without prognosis is loop malpractice.
Gather data, verify, and formulate a action plan based on results of data.
Eric

 

Nothing has been done in the 5 years since installation except change filters inside the house. My son worked with the tech when they were out yesterday and he reported she said the loop had no pressure and was dry. They'll be back out next week to try the stop leak stuff.