Andy,

This is a really great job you are doing here.

We've had other folks who have posted to EcoRenovator, who were considering the possibility of using water flow from a river or stream, but this is the first I have seen of anyone actually carrying through on this plan.

Your organization of your mechanicals and your brazing all look really great.

So, those three parallel spirals are the actual HX that you will lay in the stream flow, right? And they are made in NZ? Are they being made for the purpose that you are using them for?

One thing that I can think of that could give you a problem is that if you have cold winter water flowing through your HXs, and the evaporator is removing heat, which will further drop the temperature, you might encounter a situation where your water flow will reach the freezing point, which would stop flow, and the non-flowing water in the HX could very quickly freeze solid and expand, thus damaging your HXs. So, you will want to provide a monitoring sub-system to continuously check the temperature of the water at the OUTPUT side of your evaporator HX. You'll want the monitoring circuit to be able to shut down the whole heat pump if the temp gets to, maybe 34F or 34F, as a safeguard. Also with your variable speed controller, if it is under computer control, it could do a soft slow down as freezing conditions were approaching. I think it would be best to have two separate systems working to protect your nicely made equipment.

Really appreciate your photos, too. It makes it so much more likely that other people who can actually see what you have done, will realize that they can do it too.

Great Job!!

-AC

I wish the water tables hadnt dropped here in the area. We used to have (Flowing) artesian wells here. But table dropped the water company drilled there deep well and flows stopped . That would be a great source for a open loop geothermal. No need for a pump

Hi AC , i have attached a few photos showing 2 temperature controllers , the blue is for evaporator temp and set at 1c to prevent ice up , the red one is condenser flow temp for floor .This is how i will control the temp in the house , with a little test and adjustment to get a comfortable inside temp , hoping to not have to go over 35 to get room temp of 20. That will be the big test.
I also plan to add methanol to the cold loop to give me more protection and prevent any growth or abcteria in the warm season.

The stainless steel hx sits in the stream and the company that builds them usually have them inside another stainless pipe that is straight and use them for all sorts of cooling applications. Check out there website vaportec.co.nz
It also shows the evap and condenser i used , coil in shell.

My next hurdle is securely mounting the stream hx to keep it off the bottom (with testing it was covered in weed and sitting on bottom )but also prevent damage or loss in a flood .

Andy


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If it's a closed loop, use a glycol mixture instead of plain water as it is less likely to freeze and will let it be able to run at lower temperatures.

Mike , yes i will be using antifreeze.

Any updates on the system geoheatnz?

Hi there , yes a few things. All numbers Metric .
I have moved the stream heat exchanger to a narrower spot in the stream where it has constantly flow over it , the old place was just the nearest to my shed, this has improved the heat exchange a huge amount.
Instead of a 7K water differential i now only get 2K at the same pump flow which has quite an effect on evaporating temp , so happy as with the stream hx. I also have 120m of pipe in the ground from stream to the house which may contribute a little heat to the system.
Our weather here at moment does not require heating , just a few 10c mornings. I have run it for a couple of hours each morning for a week just to get a feel for running costs , looks to be about 1 NZ$ an hour for a 3.5kw/hr input.
The radiant floor side is running with a 5K water temp so been running the flow temp up to 32c but i really need some cold weather to see how house performs as well.
I am using a R22 drop in replacement , R438a . It has very similar characteristics , with lower discharge temp and 5% lower capacity.

So just waiting on winter really.

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Have things been getting cool enough to start using the heat pump yet?

I think it would be better to put HX perpendicular against stream.?

Hi every one,
well i had a few issues with the stream heat exchanger , performance was excellent but corrision was the problem. i had bolted it to stainless cross braces and where it was touching the tube it rusted out.
I am in the process of building new heatpump with bigger plates and poly pipe in the stream . Ill post some pics soon.
Cheers
Andy