Heat pump from stream

FP Peking Duck

Hi all,
Anyone know anything about using a stream as the heat source?
I have a small stream running close to the house (5 metres away).

I'd be interested in hearing from anyone who has used a stream with a heat pump, or can give advice etc. Does the water have to have a good flow? How much of a flow?...In the hottest weather the stream gets low. I understand that I would have to build a small reservoir so that the collector pipes are always covered. Are there different types of collector (heard of open and closed systems????)...

To me it seems it has to be cheaper to install than vertical / horizontal geothermal? and maintenance has to be easier...all the important bits are accessible...

Thx.

mossy74

Hi, just read your post now, so not sure you're still interested in the thread.

My geothrmal installation uses a small stream outside my house. Before it was installed the supplier reckoned it would provide an increase of approximately 20% efficiency over a standard horizontal array. Although the system has had problems the efficiency of the collector has been fine although I can't say whether there has been any increase over what I would have got from a horizontal collector.

With the horizontal collectors the most efficient environment is where you have some flow of water over the collector pipes, my site was pretty wet and had those rushes growing in it which usually means that the ground water is stagnent i.e. the water doesn't flow so the transfer of "heat" doesn't happen, the same situation occurs in very dry soil. The stream option gets around these issues.

The way that it works in my installation is that the collector pipes (the same number as would have been required in a horizontal collector) are laid in a gravel bed which is surrounded by a plastic membrane and backfilled with soil. Water from the stream is encouraged to use this path by being partially blocked (excess storm water continues to use the stream which has been piped). This may increase the civils cost for your site.

Regarding the flow of water, our stream too becomes quite dry but so far only in the summer when you don't really need it anyway. With the summers this year and last year that's not going to be a problem anyway:)

FP Peking Duck

Hi, Yep still interested. Got advice on using an open loop system..From your description I guess you are using a closed loop? I'd love to visit and have a look...any chance?

The advice I got was to build a container full of sand / stone etc. Let stream water flow over the top...it percolates down and comes out a pipe at the bottom into another similar tank with finer stone etc. Water emerges into a reservoir and a water pump picks it up and pumps it to the heat pump...its returned back to the stream further down. Small stream...always water in it (so far)...on a hill side.

eems to me a closed system would be more maintenance free..with open loop I'd be clearing filters etc every so often.

Anyone out there built a system as described above?

nmacc

A little late catching up on this one - visited a house in France this year and the British owner showed me this odd device he had out in the boiler house; they didn't know what it was, so they hadn't used it.

Of course that was irresistible! Turned out to be a heat pump with an intake pipe & simple strainer at the bottom of their duck pond. They had a stream on the boundary of the property and a portion of this was diverted to ensure some circulation in the pond. The pond was about 1/4 acre in extent.

When I turned on the heat pump I was very impressed with the operation; the temperature of the output piping to the rads rose to 50+ within 10 mins of switch-on. Unfortunately i have no info on the make, model, power consumption, etc. So this post is purely anecdotal alas.