Plastic tubes sunk into the lake provide warmth

Sinking collector pipes into lake water?

If close to our place, there is a deep lake that does not freeze over completely in winter, it can provide heat source, which makes really economical the operation of the water to water heat pump system in order to heating or even cooling the buildings.

Heating with heat pump and collector pipes lowered into the lake:

(By taking the advantages of the lake a closed-circuit heat extaction was implemented in this project. There are different kind of fishes were populated in the lake for recreational fishing, therefore it was obviuous the using of closed pipe system. Even more efficient heat source is the open water system, but other special problems may occure with this.)

Among the water-to-water heat pump system solutions the pipe system placed into water can be the cheapest investment, because:

Unnecessary to digging the garden in a large area (1.5 to 2 m depth)
You do not have to drill probes (less than 30 m mining legal permits are needed)
The water temperature can be considered constant
You do not need to deflate the water from the lake and return
Easier reparation
The antifreeze fluid circulating in the closed system does not freeze
There is no risk of corrosion

What you need to pay attention to:

If possible, the collector tubes should be sunk 2 meters deep into the water, in order to avoide the endanger of the small ships or boats movement.
The lake should not freze over in winter, because of the collector pipes, which should always be in a + 5-8 ° C water at least.
The tubes should be placed in a pond, which does not dry out, because without water there is no heat source (Although in this case the solution is to set up an Earth-Collector system by filling up with sand)

The client owns a large-scale fishing lake near the Austrian border, where hundreds of casual angler spend their lake recreation. The owner settled the plastic tubes into the lake by accepting the proposal of his foreig friends, and now he is satisfied with the extremely low heating and cooling costs in reward.

The contractor had no experience in sinking the collector pipes into lake water. He used the technical informations of professional articles and colleagues during the implementation phase. This kind of execution was significanty cheaper and faster that the earth-collector system.
At the beginning they were tricked by the tube floating to the surface, but the result speaks for itself. The pipes are resting at the bottom of the lake 3-years ago, and they provide the heating in winter and the passive cooling in summer for the builing complex (900 m2 area is about), including the the guest house, the restaurant and the private apartment. The heating and the cooling is provided by a Meeting MDS300D water-to-water heat pump, and a solar collector is supporting the preparing of the domestic hot water as well.

Now the anglers are know that with blinker they cannot fishing at the area of the lake where the tubes were hidden.


If the reader has its own experience in heat pump system with collector pipes lowered into the lake water, river, stream, please write us, and we will publish it.


Dear Venture!

I really like the idea. There is a channel with abudant water close to our house, and as far as I know it does no freeze over completely in winter. By reading your article I decided to replace the existing air-to-water heat pump - what I bought from you 1 year ago - with such a kind of water-to-water heat pump system. I understand that you have settled the pipes into lake water. Do you think, that the same solution would work in watercourse? Is it worth to achieve such an implementation for a smaller house. Or should I keep the air-to-water heat pump? I have rejected the idea of using ground collector because of the labor-intensive garden digging. Thank you. István BARNA

Dear István!
We are happy for your questions, and we gladly pass on our experiences.
The watercourse - if the channel really do not freeze in the bottom- even can be a better heat transfer than the still water. In this case the return water is 5-6 C degrees colder and it is taken away by the twisting at the heat winning pipes, so we can obtain energy always from "hotter" water.

The advantages of the water flush collector pipes compated to the ground collector systems:
- In the water, the greater the heat transfer speed
- The water better "encloses" the collector pipes
- There is alwas an optimum temperature flowing around the tubes
- Significantly cheaper than the labour-intensive digging for pipe-laying.

So far as the water surface is sufficient for heating your house, than it is better to use water-to-water heat pump with water flush collector pipes, instead of air-to-water heat pump.