Water Source Heat Pump driven by direct run of water pump

[Martin Jenkins]

An architect friend of mine (Sam) explained a renovation project that he is working on, and expressed frustration that he has run up against a brick wall in getting answers to technical questions.

I wonder if this community can help?

His project has an opportunity to install a water source heat pump (all well and good and standard), but the landowner is adamant that it should not use electricity for the pumping of the liquid.

Sam wants to know if there is a simple pump, that can be directly driven by action from the stream.  When I was growing up, we had a ram pump, that lifted water something like 150 feet, from a stream to a farmyard pond, so there are some solutions available - but what about a simple mechanism, that is turned by the flow, perhaps goes via a simple gearbox (presumably manual), that causes the liquid in the heat pump to be moved around?

[rogeriko]

Most old commercial refrigerator compressors are belt driven from a seperate motor. Also truck and bus air condition units are belt driven, this sort of compressor could be directly driven from a water wheel/turbine of some sort.

[Martin Jenkins]

Yes, that is the sort of thing.

Is there likely to be an off-the-shelf component for this, or would something need to be lashed up carefully crafted specifically for the job?

[ringi]

I think a separate water powered generator would be the best option, otherwise everything is becoming too custom.

[rogeriko]

There are several members of this forum that have sucessfully made generators out of waterwheels, I would say the RPM's are similar so just copy them but substitute the electric generator for a compressor. Yes you will have to learn how to weld and many other engineering skills.

[dhaslam]

It might be possible to use compressed air if the purpose is just to keep electricity away from the  water source.

[Martin Jenkins]

I think that Sam would prefer a direct drive mechanism, rather than the perceived inefficiency of "start with kinetic energy; convert that into electricity; convert that electricity back into kinetic energy" - and "just" do "here is a spinning turbine; here is a (devils in the detail) gearbox; here is something that needs to be pumped".

Really good, thank you. I have sent him the link to this forum. Perhaps he can create an account and comment!

[billi]

Sam wants to know if there is a simple pump, that can be directly driven by action from the stream.

??    What size is the stream ? I mean is ther some power to be gained ?

Anyway there are as well direct  driven heatpumps  that have the heatpump fluid in the coil /absorber in the water or ground  and no need of a seperate heatexchanger and a seperate pump

But i heard they are not everywhere legal  the Ochsner Europa mini is one of them ...

http://www.ochsnercz.cz/uploads/produkty/Technick_list_EWP_2.pdf

[ringi]

Don't you want the heat pump inside of the home's insulation, otherwise will you not lose a lot of heat from pipe runs etc.

[titan]

An architect friend of mine (Sam) explained a renovation project that he is working on, and expressed frustration that he has run up against a brick wall in getting answers to technical questions.

I wonder if this community can help?

His project has an opportunity to install a water source heat pump (all well and good and standard), but the landowner is adamant that it should not use electricity for the pumping of the liquid.

Sam wants to know if there is a simple pump, that can be directly driven by action from the stream.  When I was growing up, we had a ram pump, that lifted water something like 150 feet, from a stream to a farmyard pond, so there are some solutions available - but what about a simple mechanism, that is turned by the flow, perhaps goes via a simple gearbox (presumably manual), that causes the liquid in the heat pump to be moved around?

Interesting question but typical from an architect, no relevant details, like the size of the heatpump, massive pumping requirement difference between a 4kW and a 20kW unit. What  size array what  are the required flow rates, distance to pump, what is the potential energy available from the stream, tiny with low flow rates or large with decent depth and flow rates. Why is the owner adamant about no electricity use, the correct flow rate through the array is crucial for the designed heat output.

[Philip R]

If you use a non hermetically sealed compressor. ie like  one with a belt drive pulley on a shaft, then it will be likely to leak refridgerant , unless designed with a sealed magnetic drive arrangement. That is why most smaller refridgeration compresors are inside welded black steel cans!!

Philip R

[pdf27]

Note here that two things seem to be being confused here - circulating the warm water created by the heat pump, and turning the compressor to heat the water in the first place.

Using a completely mechanically-driven heat pump is possible, but very hard to get right. Off the top of my head you're going to need:

• Device to capture energy from the water and turn a shaft - requires either reliable shaft seals or a magnetic coupling: a submerged dynamo is much cheaper.
• Regulating mechanism for the water, with **mechanical** controls to turn it off when the return water temperature gets too high, and govern the turbine speed. Possible but really hard work to do right.
• Magnetic coupling to transfer the shaft power into the compressor (mounting the compressor directly on the turbine is a very bad idea).
• Gearbox inside the refrigerant unit to match magnetic coupling speed to required pump speed (oddly, this might be a very good application for a magnetic gearbox - something I've been trying to think of a good use for for years!).
• Standard heat pump unit - preferably a cheap Chinese jobbie since the better ones won't be able to deal with the poorly controlled mechanical speed.
• Modified circulation pump to run off the shaft power, plus a gearbox and shaft/chain drive to power it.
• Very deep pockets indeed to get someone to pay for all this.

Personally I'd advice them that they have three realistic options:

• Stop being an idiot and go for an electrically driven one like the rest of the world. The control and transmission problems are simplified so much it's crazy. If you've got a stream to generate from then the electricity can then also be used for other things than just a Heath-Robinson heat pump.
• If they're worried about EMC, mount everything remotely and pay someone to do a survey to prove they're safe.
• Get a wood stove for heating. No electrical parts and with the money you save you could buy enough wood to keep you warm for a century.