GeoThermal diag questions

[Mosby]

Not completely a garage question, but kind of sort of.

I built a 1400 sq foot apartment into an existing 36x48 pole barn a few years ago. We use it as a weekend property, and it is my work shop.

I told the contractor I wanted to use geo thermal for the hvac system. He got a Geocool system but had his regular HVAC sub install it. He way over estimated the system. It is a 5 ton unit, and the living spaces were spray foamed, then batt insulated with 8 inch walls and with 18 inches of blow in insulation in the ceiling. So it is tight as a drum, and the A/C cycles way too much. It will cool the whole place in no time at all, then it just cycles.

Which makes this one issue really annoying. When the system cycles off there is a huge sucking noise that resonates through out the house. I am thinking it is the water backflowing out the lines?

It is an open loop system with the water returning to the well, it just dumps back into the well it came from.

Can I put a one way check valve on that line to stop this annoying noise? Or is the noise something else?

The other issue is whenever we have been gone for a while I have to manually press and turn the electrical water valve and cycle the breaker on and off because that valve closes and doesn't reopen on its own and the system shuts down for high pressure.

I assume that is just a bad valve. But I am guessing.

Any HVAC guys with Geothermal experience here?

Or can anyone recommend a forum as good as this one that might be able to help me better?

Unfortunately there are no dealers for Geocool within 500 miles of me. Not sure how they got the system to begin with.

 

[theoldwizard1]

Can I put a one way check valve on that line to stop this annoying noise?

Not an expert, but a good quality (brass and stainless steel) should not cause an issue. Beware, there are several different "styles" of check valves and I can not tell you which would be the best (low restriction, longevity, etc) for your application.

 

[Jackfre]

This being an open loop system it is probably best if all the water in the system drains back to the well on shut down. You could be growing bugs in that water if it sits. Should you keep water in the system you should exercise the pump daily to cycle the water through to keep things fresh. Whoever picked a 5 ton unit should be horsewhipped.

 

[Mosby]

Jackfre, is there some other way to stop this noise? It is wake you up in the middle of the night kind of loud. It's not a subtle noise at all. We are not normally there in the summer so I have let it be, and in the winter we mostly heat it with a pellet stove. But now that everything is on lockdown we are spending a lot of time there this summer, and no one can sleep through the night without it waking them up. It is really loud

 

[jkeyser14]

I am not familiar with open loop systems, only closed loop. Is an open loop system supposed to have a roof vent or air admittance valve to prevent suction when discharging back to the well? Or is that forbidden due to possible contamination of the ground water?

 

[gregs]

What type of solenoid valve did they install? I have an open loop system that just dumps to the woods and doesnt return to the well. Originally it had one of the slow closing valves like they use in hydronic heating, but it had constant problems with not opening or staying stuck open. I ended up replacing it with a irrigation style valve. It does make a noise when it turns off because its so quick, but it solved all the other issues I was having. Been working this way for 20 years or so.

 

[Jackfre]

Is there a way to do it? Insulate the pipe. Isolate it from the structure. Perhaps the piping was just thrown together and you have a lot of short radius fittings back to back that create turbulence. I wonder if the problem is to high a flow rate from the well pump? These are the types of things that can drive you crazy...as they are, but you need a good mechanic to come in and evaluate what you have there. Also, you really need to consider the impact of having a system that is double the capacity of your needs. I don't know Geocel systems and it has been some time since I played in the geothermal arena, but I think a chat with the manuf tech service dept would be worthwhile.

 

[gregs]

And mine has a manually operated throttling valve on the output side.

 

[Mosby]

Gregs, I'm not sure what to call the valve. When power is applied it turns, and when it fails to open , which it does when we are away for a while. I have to push and turn a small dial like button on the vale to get it to open. It is kind of slow I guess. Like a few seconds, meaning I can see it turning, when it is activated by the system.

There also is a gate valve just passed it in the water flow. With a float gauge to adjust the flow of water. All of this is on the outlet side of the flow.

Could I replace this valve with a solenoid valve? My valve is 24vac, would a solenoid valve cause a power spike and possibly harm the brains of this system?

I am not familiar with an irrigation valve.

 

[gregs]

Most irrigation systems operate on 24V ac, and if you search for a 24v irrigation valve you shouldn't have a problem finding one. Shouldn't make any difference to the electronics of the unit.

My setup is like this: incoming water pipe>> ball valve to turn water off to be able to make repairs>> irrigation valve>> tee with a petes plug>>>input of unit. Then output of unit>>tee with petes plug>> manual butterfly valve>>outgoing water pipe.

You stick a digital thermometer in the petes plug to get the incoming water temp and outgoing water temp and adjust the butterfly valve as needed. My water temp is constant, so once its adjusted you just leave it alone.

My system is an open loop and just dumps out into the woods. I see yours returns back to your well. I am guessing your well has the capacity to absorb the rejected heat from the unit? If not, wouldn't you have an issue with a increasingly smaller temperature differential the longer it runs? Is this the same well you get your drinking water from?

 

[Mosby]

So the property had an existing well we had planned to use for the geo thermal. We couldn't use it for the house water because it was about 5 feet to close to the septic field. But we thought they would let us use it for the geo thermal. It was completely finished when the inspector failed us for it. We could get an exemption to use it for livestock but not for geo thermal!!

So we reran the lines to the new well we had dug for the household water. That well is 700ft deep. They had to go that deep to get the flow they wanted. But the thought was it might be marginal for the house water and geo thermal if we dumped it into the creek next to the house, which was the original plan. That's why they decided to return the water into the well.

I assume it can absorb the heat, the water level is only about 20 feet down, but we are picking up 700ft down, the return just dumps in about 20 feet down. So the water has almost 700 feet of water column to absorb the heat.

 

[gregs]

OK. That sounds like they have it figured out. I guess with the geo unit being a "closed" loop back to the well there wouldnt be any issues with it affecting the drinking water?

 

[Mosby]

The county passed it like that. So I assume they are ok with it. The water never sees the light of day, and it has a huge column of water to draw from. The unit will freeze you out of the house, after being off for a week, within an hour. And my power bills are very low. So it definitely works. Probably too well. The noise I want to get rid if is just an annoyance.
It is definitely the water rushing back into the well when the system cycles off. Because there is a quarter turn shut off valve on the return line. And this weekend, I stood there and waited for the unit to cycle off, then I manually closed that valve and no whooshing noise.

 

[gregs]

How long does the noise last? When mine turns off it makes a noise that lasts about 2 seconds. The original valve I had was slow closing I assume to eliminate any water hammer. But I had lots of issues with it not closing fully and wasting water. The irrigation valve has been in there a long time with no problems. Maybe post a pic and someone can identify it.

 

[gregs]

I double checked mine last night to see if I was remembering everything correctly and was not. The irrigation valve is on the output side after the tee and before the throttling valve.

Output of unit>>tee with petes plug>>irrigation valve>> manual butterfly valve>>outgoing water pipe.

And its a quick off with almost zero noise.

 

[kevink1955]

I installed a system 40 years ago that had a supply and return well. Used standard lawn sprinkler valves and they closed so fast that I was sure that the piping would explode from the water hammer.

Replaced with honeywell zone valves that had a warning on the box that they were not for potable water. No problem I said as its not handling potable water. Found out 20 years later the warning is because they can not handle water with oxygen content it causes de-zink a f somthing or other, the brass becomes likely to fracture.

1 of the valves broke and the other fell apart while I was replacing the first 1 to break, they were quiet for 20 years though Lol

 

[gregs]

Havent had any issues in the past 15 years. I dont see sprinkler systems exploding when they turn off. I think the zone valves are supposed to be quieter and how heated water affects things in a closed heated loop.

 

[Mosby]

So I installed a 24vdc electric solenoid valve downstream a bit further, closer to where the line goes back underground. Still only about 10 foot of pipe away from the unit.

It has totally stopped the loud whooshing noise as the water got sucked out of the lines and dropped back into the well.

However it does hammer very hard when it shuts off. It is a shock to say the least. Like Kevink1955 sounds like a pipe is going to explode. But in honesty I am not afraid of that. I may try to isolate the piping some to reduce the noise. But I am a bit concerned about the electrical shock of a solenoid slamming closed like that and if that might cause a spike back to the electronics in the unit.

I am a automotive mechanic by trade so I do know a bit about DC electrical systems. And as an example on an older A/C compressor clutch circuit they usually added a diode in the wiring to keep a spike from the compressor clutch field coil from traveling back to the computer when the compressor clutch cycled off and on.

Is that something I should worry about on this AC solenoid?

 

[gregs]

Not a 100% sure, but in a DC system as the field is collapsing from being de-energized (ac clutch coil, or any other field coil, solenoid, motor, etc.) you can have a rush back thru the negative side and damage components. Thats what the diode or "snubber" does to protect it. I dont think you can use the same thing in a ac circuit. I also think its not necessary.

 

[Mosby]

Yes that is what I was referring to. I know it is something in DC systems, but I have little to no knowledge about AC systems.

Thanks for the input

 

[Milton Shaw]

Might try a motorized ball valve instead of solenoid valve. They have much gentlier open/close.

 

[Mosby]

I like that idea, however on a quick google search of them I found something that might be a problem.

The one I found is a normally closed valve, which is what I need. Power opens it, when power is removed it uses a internal capacitor to power the valve closed. Because of this, it states that " The capacitor will require a nominal amount of power to stay charged."

Not sure if this will work for me because of this requirement.