Heat Pumps to heat water

[Arthur]

After a detailed investigation and chatting to many engineers, suppliers, etc I've come to the conclusion that one of the better low-energy technologies for heating water is the Heat Pump. It's widely used in SA by hotels, college residences, mines, hospitals, etc, but hardly known in the domestic sector.

I've found a company in Cape Town that specialises in this - Tekniheat. There are others.

According to them, you can get a domestic heat pump that produces 1400 litres of 60 degree water a day, and which reduces power consumption by 70-80%. Fully installed cost around R18-20K. Apparently you can permanently switch off the heating elements in the geyser(s) - the only power draw is for the compressor/pump, at nominal 1KW. Expected maintenance-free lifespan is 15 years at least, though corrosion can reduce this at the coast.

Anyone here heat their water with a heat pump?

[BattleMoose]

Normal heat pumps have a coefficient of performance of about 3-4 or so, so using a heat pump for heating instead of electrical, you can reduce your energy requirements by about 75% or so. I am assuming heat pumps working up to 60degree C are having a similiar co-efficient of performance. (Hellva an assumption I know)

With that kind of capital outlay, why not just get a solar hot water geyser, it will cost less capital, use less energy, lower operating cost and will meet your hot water requirements. I cannot think of any reason why one would consider a domestic hot water heat pump when a solar hot water geyser is an option. (Unless you have REDICULOUS hot water requirements!)

[Arthur]

...why not just get a solar hot water geyser, it will cost less capital, use less energy, lower operating cost and will meet your hot water requirements. I cannot think of any reason why one would consider a domestic hot water heat pump when a solar hot water geyser is an option. (Unless you have REDICULOUS hot water requirements!)

Hi BM. SWH has been my plan all along. Until yesterday. The main reason I'm reconsidering SWH is days just like we're having right now in Joeys - a week of total cloud cover and rain. People with SWH are either back on the grid or showering at friends, I hear.

If I run the heat pump motor/compressor off solar PV my running costs are effectively zero, other than periodic maintenance. Yes, capital costs are high, but I'm revamping the place anyway and will in any case put in 6000W inverter with PV and battery bank.

[BCO]

The ultimate thing to do is have a "geothermal" heat pump where you put your heat exchanger under the ground where there's a constant warmish temperature. These systems are even more efficient and effective (but more expensive too).

[Peder]

a aircon that makes warm is a heat pump... actually its quite a good idea. and this is the second time this week i've heard someone talk about a heat pump!!

[Arthur]

Yes, first prize is a geothermal heat pump. I've been reading a lot about that config, but they're almost uknown in SA. A good intro is on the US Dept of Energy website here, and also on that wikipedia thingie here. The EPA says "geothermal heat pumps are the most energy-efficient, environmentally clean, and cost-effective systems for temperature control". Haven't been able to find anyone in SA with real practical experience of domestic geothermal systems.

[Paulr]

I remember seeing something like that on Beyond 2000 many years ago. (Giving my age away here)

But, IIRC, those systems are more suitable for "airconditioning" - ie. warming the inside of your house in the winter and cooling it during summer? The energy concentration under the ground won't be sufficient to heat your geyser, but can provide you with 20deg temperatures in your lounge late on a winter night.

[Arthur]

I remember seeing something like that on Beyond 2000 many years ago. (Giving my age away here)

But, IIRC, those systems are more suitable for "airconditioning" - ie. warming the inside of your house in the winter and cooling it during summer? The energy concentration under the ground won't be sufficient to heat your geyser, but can provide you with 20deg temperatures in your lounge late on a winter night.

Not quite the same thing. Perhaps you are thinking of geothermal energy, which uses heat from the earth such as in hot springs, etc? A regular heat pump, whether air or geothermal, will heat 200 litres of cold water to 60 degrees Celsius in under an hour, as long as the temp is above 5 degrees Celsius. It is essentially a mechanism that move ambient air/ground heat (which needn't be high at all, only just above freezing) into the water. Like a fridge in reverse. Today in cold Joeys I saw an atmospheric heat pump do exactly that - extract the heat from the (cold-feeling) air and transfer it into a 150 litre geyser filled with cold water. The water temp reached 40 degrees in 22 minutes. A geothermal heat pump is even more efficient, but it requires a pretty large installation in the ground. It has nothing to do with geothermal energy as such.

[Peder]

I Spoke to my dad about the heat pump thing and he said its very cost effective the only problem is the initial outlay is hectic...

[Arthur]

I Spoke to my dad about the heat pump thing and he said its very cost effective the only problem is the initial outlay is hectic...

About half to two-thirds the price of a modern solar system.

I'm now trying to find someone who can build me a hybrid-combo solar-cum-heatpump system for hot water. There's a company in Germany, but I'd like to get this done locally. It can't be that hard.

[BCO]

Yes, first prize is a geothermal heat pump. I've been reading a lot about that config, but they're almost uknown in SA. A good intro is on the US Dept of Energy website here, and also on that wikipedia thingie here. The EPA says "geothermal heat pumps are the most energy-efficient, environmentally clean, and cost-effective systems for temperature control". Haven't been able to find anyone in SA with real practical experience of domestic geothermal systems.

A couple of months ago I also spent ages looking for Geothermal heat pump installers in SA.

Seems we have none

I was quite impressed by the drilling system that these guys use to avoid having to do excavation on site. I wonder if they're looking for a franchise in SA? With the upcoming massive electricity rate hikes, methinks a system like this will begin making financial sense in South Africa quite soon.

[Paulr]

Not quite the same thing. Perhaps you are thinking of geothermal energy, which uses heat from the earth such as in hot springs, etc? A regular heat pump, whether air or geothermal, will heat 200 litres of cold water to 60 degrees Celsius in under an hour, as long as the temp is above 5 degrees Celsius. It is essentially a mechanism that move ambient air/ground heat (which needn't be high at all, only just above freezing) into the water. Like a fridge in reverse. Today in cold Joeys I saw an atmospheric heat pump do exactly that - extract the heat from the (cold-feeling) air and transfer it into a 150 litre geyser filled with cold water. The water temp reached 40 degrees in 22 minutes. A geothermal heat pump is even more efficient, but it requires a pretty large installation in the ground. It has nothing to do with geothermal energy as such.

Actually, the thing I remembered was more a heat exchanger than a heat pump. 2 totally different things.

The more I read about these heat pumps the more I like them, except for the money part....

[captainwifi]

Fully installed cost around R18-20K.

Anyone here heat their water with a heat pump?

The patent royalties drives up the cost of heat pumps. There are over 20000 patents it seems here is one: http://www.patentstorm.us/patents/5305614.html from Lennox industries.

All these designs can be hacked to build our own solar energy devices

[Arthur]

I've ordered the heat pump. Tecron are building a 4kPa copper geyser for me. The system is so quiet it's being installed above the ceiling. This will bge interesting.

[EchoZA]

I need to heat a 2.5 million litre swimming pool, any idea if the heat pump route will help?