Open-loop water source heat pump valves keep failing.
We have an open loop water source heat pump. Our water is pumped out of a well, circulates through the system, and is pumped out. The open and close valves that regulate the flow of water into the unit continue to fail. Often they either get stuck in the open position and don’t close or leak and flood the basement. We’ve changed three separate valves with seemingly high quality replacements.
One explanation from our contractor was sand getting in the valves, but we put a sand filter in that’s clearly trapping the sand but the failure continued. The water quality of the water is acidic but the water source heat pump is supposed to be able to tolerate that. Any advice is greatly appreciated.
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I'd try a much better water filter that traps smaller particles. The sediment filter isn't working.
Thanks nynick. I’ll look into it
Would you consider changing the system to a closed loop?
Seems like open loops have fallen out of favor because of similar problems.
What percentage of your electricity is used to operate the pump and compressor. In an open loop the pump must work much harder.
You may get more informed advice on the geo exchange forum because that is all they talk about.
https://forum.old.geoexchange.org/
Walta
Thanks Walta. An open loop system I’m sure is far better but it would be very expensive at this point to retrofit. I appreciate the link to the forum. The valves have been very disappointing. I didn’t know this was an issue with the open loop systems
Walta, I am also not sure what percentage of electricity is used to power the pump and the compressor
Acidic water might be ok for the heat pump itself but not the valves. Fair amount of water volume always with fresh 'acid'
Not sure what the cost to convert to closed loop, but I'm with Walta on that one.
Ok thank you very much gusfhb for the comment
AS a note, I have acidic well water and have lost 3 or 4 brass objects in the plumbing system in the last 15 years, and I have feeling that a heating loop might see more water flow
Gusfhb, the acidic water was doing a lot of damage to our plumbing system as well. For drinking, I put in a calcite filter to raise the ph along with a water softener which really solved the plumbing issue.
My understanding was that it’s ok to treat drinking water from
The acidic well, but bc of the volume of water used by the heat pump, it’s not feasible to filter the water that goes to the heat pump
There are separate pipes in the house for the drinking water and the heat pump
Test the water. Cheap kits online. Try the filter route. Filters or water systems can be pricey too but maybe you can get away with just a filter. At this point it's that or closed loop.
Hi nynick, thanks. My understanding as mentioned above is that due to the sheer volume of water, treating the well water before it goes into the unit is not a feasible approach. I had the water extensively tested and it’s acidic and mildly hard water
The finest commonly available particulate filters are 1 micron filters. Try a 1 micron cartridge and see if that helps. Most common "sand" filters are going to be much coarser, probably 15-25 microns or so. If you have issues with very fine sediment, the 1 micron filters will be better. I use a "dual gradient" filter in my own system, which essentially acts as it's own prefilter and helps the inner 1 micron part of the filter last longer before clogging.
Since you mentioned you're using well water, I suspect you have issues other than just "sand". My guess is you have dissolved minerals (usually that is mostly calcium) accumulating on the valve internals and making things bind. If you have hard water, this is likely at least part of your problem. A water softener will help with this.
I would recommend you switch to a closed system and treat the water in it to solve this problem. Open systems ARE NOT BETTER in this situation, since they are open to all kinds of contamination that can cause problems with operation like you're seeing. With a closed system, YOU control the water chemistry, so you can ensure the longevity of the system components. It is possible to get stainless steel valves if you're stuck though, but they cost a lot more.
Bill
Bill very helpful as usual. I treat the well drinking water but as I said above I was told by multiple contractors you cannot filter the water before it enters the system with respect to ph or hardness. Coarse filters to take out sand or particulates are ok but the whole house system I have for drinking water won’t work for the heating system. Too much water
When you say a "sand filter" are you referring to a mesh or cartridge filter that filters out the sand or a filter that is literally full of sand? All three exist and are commonly used. If you have a filter that is a sand filter (ie: is full of sand) sometimes those filters will lose sand and it will end up downstream of the filters.
Have you tried plastic valves? Plastic is often resistant to acidic water as well as corrosion commonly associated with metal piping and valves. They're often cheaper as well.
Hi krackadile, it’s a centrifugal filter that is clear plastic and you can visualize the particulates that accumulate in it. It traps sand sediment etc via centrifugal force.
Yeah the plastic valve might be a better option. I can look into it