Discussion in 'Standing Column Well (SCW)' started by geochallenged, Mar 26, 2013.
I speak heat transfer. What do you want to know?
What I want to know is how to determine and then optimize the efficiency of the geothermal units to determine what the best position of the pump should be in the well and the position of the return line and how do I test that?
I like you.
I will try to help. I am not a well guy.
Let us take this one step at a time.
If we assume that the guy that built the system knew what he was doing, dose the two heat pump system make and keep you comfortable? Forget the sand clean out. Does it make/keep you comfortable?
I can think and talk and type for hours, the main point is comfort. You did not have this system built so the first thing to know is if it makes you happy. Once we make the concept true or false then we decide what to do.
Does that ease your pain? I am in this until you are happy and comfortable.
Answering that happiness question is complex. I like the idea of geothermal, but this one is a maintenance nightmare. Fixing the every 3 days filter flush would go a long way towards making me happy .
But, that said, there are other issues with the system. In winter the system freezes up (I was informed of this at the same time I was told about the 3 day rule (AFTER I closed on the house)) and I need to put the system into A/C mode to unfreeze it. I'm not sure if that is water pressure related (as in the filter prob) or related to some back pressure problems associated with the zoning of the 5 ton unit. The 5 ton unit was set up on two zones that have electronic dampers. I have had the dampers disconnected from electrical (they are open when not powered) and that seems to have stopped the freeze up in the heat mode. I am not sure if the zones were creating abnormal backpressure (from lack of return air or being unbalanced) or what was happening there but since I unzoned the system I haven't had a freeze up. Having it unzoned means when either thermostat calls, both zones get heated or cooled. This is an issue because the lower zone is in the basement and it gets colder faster thus keeping the upper zone a bit warm but I have learned to deal with that. I'd like to figure that out too. The 5 ton has one 12x12 and one 6x20 inch return in the lower zone and a exposed circular 12" metal pipe return on the main level that has small holes punched in it in a few places but I can hardly call that a real return - it might equate to one 16x12 in total. I also have one register that is not receiving any airflow (I put a snake down it and it only goes in about 6 feet and then won't move) so I have to cut a hole in the ceiling to see what is happening there and I have a bathroom that doesn't have a supply installed so it is cold in winter and hot in summer.
I think if I can get off the 3 day filter purge I'd be pretty happy and then if I can get some incremental happiness by solving at least some of the other issues I will be even happier and if I can get to the nirvana of running this thing to its peak efficiency, well, then I'd be geo-ecstatic!
Being a Well Guy,
I do not like the idea of sand being sent to the Heat pumps. But in your case and current situation, i think you should filter the inlet domestic water and leave the HP water unfiltered for now to see how things act. Its not ideal but its a start to see the true situation your in. Your well may not be able to handle the house usage, and geo supply at 24 GPM capacity if your geo is running, and your in the shower or doing laundry possibly. But like i said before, this is NOT IDEAL, but its a testing period. Try the spin down with the 60 mesh on domestic water first, before buying the Sandmaster filter, if this works for a while then try the sandmaster and hook it to all water inlet and see how it acts. Its hard for me to help with a sand issue though a forum and also a few states away, but i will do what i can to help too.
I'd be suprised if you couldn't get by on 1.5 gal/ton most of the year.
I am not a huge fan of abrasives through a heat exchanger. I would like to see if dumping for awhile vs recirc couldn't clean the supply up some.
FHP now Bosch can't win by talking to you. If they suggest any course of action and you incur expense and unsuccessful results, they now own the results instead of the original installer.
I have a couple of GE cartridge filters in series (one to capture large particles and one to capture small particles after that) on the domestic supply and they seem to last for about 30/60 days. The finer filter gets clogged before the larger one and it looks red I assume from the clay in the ground here? The spin down filter is only on the line to the geothermal. That said, supposedly before I bought this place a family of 5 was living here comfortably for 6 years, meaning I assume they had plenty of water, but I do worry about the location of the pump in the well. maybe when it was at 300' they never had an issue but now that it is at 160' I worry I might run out. I only have 2 people drawing water right now and I have worried that if I have company there might not be enough water. Thus my questions about where to position the pump in the well.
I also forgot to mention that my desuperheater isn't working and I think it might be clogged. I turn on the button on the front of the unit and it lights up and then shuts off. Another issue related to making these things efficient. I still can't believe it is only a 6 year old system.
Just a couple of other SCW design questions - when you design one of these wells to support Geothermal how do you determine where to put the pump and the return line? What type of measurements do you take on the well? What is the ideal temperature of the well for efficiency? How do I factor in residential usage of the well into the pump location? What effect would no bleed have on the system (e.g. if I remove household usage from the system)? Is there a design reference guide somewhere that you could recommend?
I have done a closed-loop with a heat exchanger. It works great! PM with your email address if interested.
Hi Howard - I'm interested in Open-Loop SCW design which I think is significantly different if I understand it.
I have done an Open loop with a heat exchanger. It keeps your water separate.
sounds like a good idea howard. Didn't occur to me, but you could use a sacrificial heat exchanger (vented) and not filter the water at all.
My concern in all this, is for the well it self. If you continue to cause increased turbidity in the well, trouble is comeing whether that turbidity ever sees any HX. It will build up to a point that the entire well is fouled, not just a filter. If the local well guy does not know how to fix the issue without sleaving the entire well you may be at the point of no return now. My idea about bleed off did not spark any interest???? I thought that was a briliant thought in regard to decreaseing the build up of turbidity by reduceing the amount you are dumping back into the well.
About 1/3 less water using the heat exchanger method. The added benefit of no well water going through your geothermal heat exchanger!!
I missed the bleed off.
In the land of the blind the one eye is king. Great thinking. It will add to Eric's thinking about reducing roiling the well.
I also suggested dumping water even for a short time........In all things well I yield to Eric.
I haven't been able to figure out the proper way to bleed off the system to try it. Do I just run the faucet at the well head?
Warning this is not for the faint of heart or without risk.
You need to determine how long your well can support the domestic usage and the geothermal units in run time with the geo running wide open and letting house service suffer. Once you have that number in minutes you would T into the geo discharge and install a zone valve on a timer switc that would run discharge water from the geo to waste untill you reach the magic number. At the magic number the zone valve would close untill the well recovered. This is typicaly done in a SCW with a temp sensor controlling the zone valve, not a timer. In a perfect world you may be able to reduce the amount of turbid water you are returning to the well, thus redueceing the plugging of the filter frequency. It is a low budget, homeowner modification I would try before moveing onto more expensive filtration, or other HX options.
THIS IS ONLY A TEST, NOT A SOLUTION.
At the current time...... Is the well pump at the bottom of the well with the return line up top?
If so, I would put a standard 3/4" hose valve on the discharge water and let all the geo discharge water go out to waste instead of returning into the well for as long as the well can handle Turn on domestic water too.. Let it pump almost dry if it will. Then turn everything off, and let the well settle for a few hours. This should clear up and turbidity in the well now and let fresh water in. See if this clear the water, and for how long to determine how bad the well really is.
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